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158-661: The basin usually has two rainy seasons, a shorter one around March ( Belg ), and a longer one between June and September ( Kiremt ), which partly fall into one longer rainy season. Climate change is predicted to increase the water deficiency in all seasons and for parts of the basin, due to a projected increase in temperature and decrease in precipitation. The Awash River basin is the most developed, utilized, abused, impacted, and most populous (over 15% or nearly 18.6 million out of 120 million) basin in Ethiopia (as of 2021). Rapid growth of agriculture, industries and urbanization within

316-469: A rise in sea levels due to the expansion of water as it warms and the melting ice sheets on land. Other effects on oceans include sea ice decline , reducing pH values and oxygen levels , as well as increased ocean stratification . All this can lead to changes of ocean currents , for example a weakening of the Atlantic meridional overturning circulation (AMOC). The main cause of these changes are

474-482: A bigger impact. The impacts of climate change on nature are likely to become bigger in the next few decades. The stresses caused by climate change, combine with other stresses on ecological systems such as land conversion, land degradation , harvesting, and pollution. They threaten substantial damage to unique ecosystems. They can even result in their complete loss and the extinction of species. This can disrupt key interactions between species within ecosystems. This

632-517: A cascade of effects. This remains a possibility even well below 2 °C (3.6 °F) of warming. A 2018 study states that 45% of environmental problems, including those caused by climate change, are interconnected. This increases the risk of a domino effect . Further impacts may be irreversible, at least over the timescale of many human generations. This includes warming of the deep ocean and acidification. These are set to continue even when global temperatures stop rising. In biological systems,

790-502: A cause of heavy metal pollution (As, Cd, Cu, Pb, U, and Zn) in aquatic bodies, and industrial disposal could also lead to high heavy metals concentrations such as As, Cd, Cr, Hg, Ni, Zn, and Pb concentrations. A study of river water quality in 2023 showed that high levels of heavy metals, such as Al, Mn, Mo, As, V, Fe, and Ba were exhibited with values of 1257 μg/L, 626.8 μg/L, 116.7 μg/L, 61.2 μg/L, 100.5 μg/L, 1082.7 μg/L, and 211.7 μg/L, respectively. Among 20 heavy metals analyzed, 20% of

948-642: A decadal timescale. Other changes are caused by an imbalance of energy from external forcings . Examples of these include changes in the concentrations of greenhouse gases , solar luminosity , volcanic eruptions, and variations in the Earth's orbit around the Sun. To determine the human contribution to climate change, unique "fingerprints" for all potential causes are developed and compared with both observed patterns and known internal climate variability . For example, solar forcing—whose fingerprint involves warming

1106-428: A few exceptions of small eucalyptus plantations. Outside of Awash National Park the open and woody savannas have been almost completely cultivated with crops. This especially accounts for all escarpment terraces. Thereby the scattered tree cover remained similar to the primary state of the savannas, while the grass layer has been replaced by crops. Only highest altitudes still show connected woodlands. Partly reforestation

1264-480: A fire starts in an area with very dry vegetation, it can spread rapidly. Higher temperatures can also lengthen the fire season. This is the time of year in which severe wildfires are most likely, particularly in regions where snow is disappearing. Weather conditions are raising the risks of wildfires. But the total area burnt by wildfires has decreased. This is mostly because savanna has been converted to cropland , so there are fewer trees to burn. Prescribed burning

1422-897: A high risk at 2.5 °C (4.5 °F). It is possible that some tipping points are close or have already been crossed. Examples are the West Antarctic and Greenland ice sheets, the Amazon rainforest, and warm-water coral reefs. Tipping points are perhaps the most dangerous aspect of future climate change, potentially leading to irreversible impacts on society. A collapse of the Atlantic meridional overturning circulation would likely halve rainfall in India and lead to severe drops in temperature in Northern Europe. Many tipping points are interlinked such that triggering one may lead to

1580-487: A lot of light to being dark after the ice has melted, they start absorbing more heat . Local black carbon deposits on snow and ice also contribute to Arctic warming. Arctic surface temperatures are increasing between three and four times faster than in the rest of the world. Melting of ice sheets near the poles weakens both the Atlantic and the Antarctic limb of thermohaline circulation , which further changes

1738-525: A lot year by year. This makes it difficult to determine a trend, and record highs and record lows have been observed between 2013 and 2023. The general trend since 1979, the start of the satellite measurements , has been roughly flat. Between 2015 and 2023, there has been a decline in sea ice, but due to the high variability, this does not correspond to a significant trend. Globally, permafrost warmed by about 0.3 °C between 2007 and 2016. The extent of permafrost has been falling for decades. More decline

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1896-412: A marked increase in temperature. Ongoing changes in climate have had no precedent for several thousand years. Multiple independent datasets all show worldwide increases in surface temperature, at a rate of around 0.2 °C per decade. The 2014–2023 decade warmed to an average 1.19 °C [1.06–1.30 °C] compared to the pre-industrial baseline (1850–1900). Not every single year was warmer than

2054-408: A physical climate model. These models simulate how population, economic growth , and energy use affect—and interact with—the physical climate. With this information, these models can produce scenarios of future greenhouse gas emissions. This is then used as input for physical climate models and carbon cycle models to predict how atmospheric concentrations of greenhouse gases might change. Depending on

2212-585: A range of activities around the world that seek to ameliorate these issues or prevent them from happening. The effects of climate change vary in timing and location. Up until now the Arctic has warmed faster than most other regions due to climate change feedbacks . Surface air temperatures over land have also increased at about twice the rate they do over the ocean, causing intense heat waves . These temperatures would stabilize if greenhouse gas emissions were brought under control . Ice sheets and oceans absorb

2370-469: A rate of decline of 4.7% per decade. It has declined over 50% since the first satellite records. Ice-free summers are expected to be rare at 1.5 °C (2.7 °F) degrees of warming. They are set to occur at least once every decade with a warming level of 2 °C (3.6 °F). The Arctic will likely become ice-free at the end of some summers before 2050. Sea ice extent in Antarctica varies

2528-461: A result of climate change. Global sea level is rising as a consequence of thermal expansion and the melting of glaciers and ice sheets . Sea level rise has increased over time, reaching 4.8 cm per decade between 2014 and 2023. Over the 21st century, the IPCC projects 32–62 cm of sea level rise under a low emission scenario, 44–76 cm under an intermediate one and 65–101 cm under

2686-474: A result. The World Health Organization calls climate change one of the biggest threats to global health in the 21st century. Societies and ecosystems will experience more severe risks without action to limit warming . Adapting to climate change through efforts like flood control measures or drought-resistant crops partially reduces climate change risks, although some limits to adaptation have already been reached. Poorer communities are responsible for

2844-532: A severe drought and a humanitarian response targeting over 10 million people nationally, with many priority districts located in the Awash basin. Municipal and industrial wastewater treatment plants are scant and inefficient in the Awash River basin. Where they exist, their effluents (often poorly treated) are channeled into nearby streams, thus polluting them. Growing industrialization and urbanization in

3002-417: A small share of global emissions , yet have the least ability to adapt and are most vulnerable to climate change . Many climate change impacts have been observed in the first decades of the 21st century, with 2023 the warmest on record at +1.48 °C (2.66 °F) since regular tracking began in 1850. Additional warming will increase these impacts and can trigger tipping points , such as melting all of

3160-406: A study in 2023 in the river and shallow groundwater systems: "Pesticides, veterinary drugs , artificial sweeteners , and personal care products were detected in samples from all sources (surface, ground, and tap water). Endocrine disruptors and equine drugs were found in both surface and groundwater sources." The river water and shallow groundwater are intrinsically connected. Contaminants in

3318-469: A thousand years, 20% to 30% of human-emitted CO 2 would remain in the atmosphere. The ocean and land would not have taken them. This would commit the climate to a warmer state long after emissions have stopped. With current mitigation policies the temperature will be about 2.7 °C (2.0–3.6 °C) above pre-industrial levels by 2100. It would rise by 2.4 °C (4.3 °F) if governments achieved all their unconditional pledges and targets. If all

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3476-489: A very high emission scenario. Marine ice sheet instability processes in Antarctica may add substantially to these values, including the possibility of a 2-meter sea level rise by 2100 under high emissions. Climate change has led to decades of shrinking and thinning of the Arctic sea ice . While ice-free summers are expected to be rare at 1.5 °C degrees of warming, they are set to occur once every three to ten years at

3634-519: A warming level of 2 °C. Higher atmospheric CO 2 concentrations cause more CO 2 to dissolve in the oceans, which is making them more acidic . Because oxygen is less soluble in warmer water, its concentrations in the ocean are decreasing , and dead zones are expanding. Greater degrees of global warming increase the risk of passing through ' tipping points '—thresholds beyond which certain major impacts can no longer be avoided even if temperatures return to their previous state. For instance,

3792-512: Is driven by human activities , especially fossil fuel burning since the Industrial Revolution . Fossil fuel use, deforestation , and some agricultural and industrial practices release greenhouse gases . These gases absorb some of the heat that the Earth radiates after it warms from sunlight , warming the lower atmosphere. Carbon dioxide , the primary greenhouse gas driving global warming, has grown by about 50% and

3950-428: Is 'flood-centric' in its thinking and approach [...]. This means identifying (and protecting) flood zones near build-up areas and identifying zones that can be allowed to flood to absorb the impact of extreme events." Groundwater recharge varies between values exceeding 350 millimetres (14 in) per year in the upper highlands and no recharge at the bottom of the rift valley. Groundwater is predominantly recharged at

4108-687: Is a dry season, called Bega . Semi-arid to arid conditions prevail in the Rift Valley. In contrast, the highlands partly receive more than 1,600 millimetres (63 in) of rainfall in ca. six months per year. A study in 2018 investigated the effects of climate change on water resources in the Awash basin. They used three climate models from Coupled Models Intercomparison Project phase 5 (CMIP5) and for three future periods (2006–2030, 2031–2055, and 2056–2080). The models were selected based on their performance in capturing historical precipitation characteristics. The baseline period used for comparison

4266-452: Is a greenhouse gas, so this process is a self-reinforcing feedback . The excess water vapour also gets caught up in storms. This makes them more intense, larger, and potentially longer-lasting. This in turn causes rain and snow events to become stronger and leads to increased risk of flooding. Extra drying worsens natural dry spells and droughts. This increases risk of heat waves and wildfires. Scientists have identified human activities as

4424-409: Is a self-reinforcing feedback of climate change. Large-scale measurements of sea ice have only been possible since satellites came into use. Sea ice in the Arctic has declined in recent decades in area and volume due to climate change. It has been melting more in summer than it refreezes in winter. The decline of sea ice in the Arctic has been accelerating during the early twenty-first century. It has

4582-564: Is an estimated total sea level rise of 2.3 metres per degree Celsius (4.2 ft/°F) after 2000 years. Oceanic CO 2 uptake is slow enough that ocean acidification will also continue for hundreds to thousands of years. Deep oceans (below 2,000 metres (6,600 ft)) are also already committed to losing over 10% of their dissolved oxygen by the warming which occurred to date. Further, the West Antarctic ice sheet appears committed to practically irreversible melting, which would increase

4740-557: Is an indigenous practice in the US and Australia. It can reduce wildfire burning. The carbon released from wildfires adds to carbon dioxide in Earth's atmosphere and therefore contributes to the greenhouse effect . Climate models do not yet fully reflect this climate change feedback . There are many effects of climate change on oceans . One of the most important is an increase in ocean temperatures . More frequent marine heatwaves are linked to this. The rising temperature contributes to

4898-483: Is approximately 1600 gigatons. This is twice the atmospheric pool. Recent warming has had a big effect on natural biological systems. Species worldwide are moving poleward to colder areas. On land, species may move to higher elevations. Marine species find colder water at greater depths. Climate change had the third biggest impact on nature out of various factors in the five decades up to 2020. Only change in land use and sea use and direct exploitation of organisms had

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5056-488: Is at levels not seen for millions of years. Climate change has an increasingly large impact on the environment . Deserts are expanding , while heat waves and wildfires are becoming more common. Amplified warming in the Arctic has contributed to thawing permafrost , retreat of glaciers and sea ice decline . Higher temperatures are also causing more intense storms , droughts, and other weather extremes . Rapid environmental change in mountains , coral reefs , and

5214-776: Is because species from one location do not leave the warming habitat at the same rate. The result is rapid changes in the way the ecosystem functions. Impacts include changes in regional rainfall patterns. Another is earlier leafing of trees and plants over many regions. Movements of species to higher latitudes and altitudes, changes in bird migrations, and shifting of the oceans' plankton and fish from cold- to warm-adapted communities are other impacts. These changes of land and ocean ecosystems have direct effects on human well-being. For instance, ocean ecosystems help with coastal protection and provide food. Freshwater and land ecosystems can provide water for human consumption. Furthermore, these ecosystems can store carbon. This helps to stabilize

5372-711: Is determined by modelling the carbon cycle and climate sensitivity to greenhouse gases. According to UNEP , global warming can be kept below 1.5 °C with a 50% chance if emissions after 2023 do not exceed 200 gigatonnes of CO 2 . This corresponds to around 4 years of current emissions. To stay under 2.0 °C, the carbon budget is 900 gigatonnes of CO 2 , or 16 years of current emissions. The climate system experiences various cycles on its own which can last for years, decades or even centuries. For example, El Niño events cause short-term spikes in surface temperature while La Niña events cause short term cooling. Their relative frequency can affect global temperature trends on

5530-480: Is different for the upper, middle and lower Awash basin. Research has found that "the type and range of flooding in the Awash Basin varies widely reflecting the basin’s complex geography". For example, in urban areas, flash floods and river overflows are known to occur. Rapid growth of agriculture, industries and urbanization within the Awash basin, as well as population growth is placing increasing demands on

5688-413: Is expected in the future. Permafrost thaw makes the ground weaker and unstable. The thaw can seriously damage human infrastructure in permafrost areas such as railways, settlements and pipelines. Thawing soil can also release methane and CO 2 from decomposing microbes. This can generate a strong feedback loop to global warming . Some scientists believe that carbon storage in permafrost globally

5846-497: Is expected to become rarer. This depends on several factors. These include changes in rain and snowmelt, but also soil moisture . Climate change leaves soils drier in some areas, so they may absorb rainfall more quickly. This leads to less flooding. Dry soils can also become harder. In this case heavy rainfall runs off into rivers and lakes. This increases risks of flooding. Climate change affects many factors associated with droughts . These include how much rain falls and how fast

6004-399: Is independent of where greenhouse gases are emitted, because the gases persist long enough to diffuse across the planet. Since the pre-industrial period, the average surface temperature over land regions has increased almost twice as fast as the global average surface temperature. This is because oceans lose more heat by evaporation and oceans can store a lot of heat . The thermal energy in

6162-465: Is limited evidence for its importance. A partial collapse of the ice sheet would lead to rapid sea level rise and a local decrease in ocean salinity. It would be irreversible for decades and possibly even millennia. The complete loss of the West Antarctic ice sheet would cause over 5 metres (16 ft) of sea level rise. In contrast to the West Antarctic ice sheet, melt of the Greenland ice sheet

6320-552: Is partly located in the Main Ethiopian Rift . The Awash River is 1,200 kilometers long. It starts in Ethiopia’s central highlands at an elevation of 3000 m and passes through a number of locations before joining Lake Abbe at a height of 250 m. The Awash River basin is divided into three sections: upper, middle, and lower. The Awash rises south of Mount Warqe , west of Addis Ababa in the woreda of Dandi , close to

6478-450: Is primarily attributed to sulfate aerosols produced by the combustion of fossil fuels with heavy sulfur concentrations like coal and bunker fuel . Smaller contributions come from black carbon (from combustion of fossil fuels and biomass), and from dust. Globally, aerosols have been declining since 1990 due to pollution controls, meaning that they no longer mask greenhouse gas warming as much. Aerosols also have indirect effects on

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6636-458: Is projected to take place more gradually over millennia. Sustained warming between 1 °C (1.8 °F) (low confidence) and 4 °C (7.2 °F) (medium confidence) would lead to a complete loss of the ice sheet. This would contribute 7 m (23 ft) to sea levels globally. The ice loss could become irreversible due to a further self-enhancing feedback. This is called the elevation-surface mass balance feedback. When ice melts on top of

6794-444: Is radiating into space. Warming reduces average snow cover and forces the retreat of glaciers . At the same time, warming also causes greater evaporation from the oceans , leading to more atmospheric humidity , more and heavier precipitation . Plants are flowering earlier in spring, and thousands of animal species have been permanently moving to cooler areas. Different regions of the world warm at different rates . The pattern

6952-467: Is related to temperature. It also increases if humidity is higher. The wet-bulb temperature measures both temperature and humidity. Humans cannot adapt to a wet-bulb temperature above 35 °C (95 °F). This heat stress can kill people. If global warming is kept below 1.5 or 2 °C (2.7 or 3.6 °F), it will probably be possible to avoid this deadly heat and humidity in most of the tropics. But there may still be negative health impacts. There

7110-516: Is shaped by feedbacks, which either amplify or dampen the change. Self-reinforcing or positive feedbacks increase the response, while balancing or negative feedbacks reduce it. The main reinforcing feedbacks are the water-vapour feedback , the ice–albedo feedback , and the net effect of clouds. The primary balancing mechanism is radiative cooling , as Earth's surface gives off more heat to space in response to rising temperature. In addition to temperature feedbacks, there are feedbacks in

7268-478: Is some evidence climate change is leading to a weakening of the polar vortex . This would make the jet stream more wavy. This would lead to outbursts of very cold winter weather across parts of Eurasia and North America and incursions of very warm air into the Arctic. Warming increases global average precipitation . Precipitation is when water vapour condenses out of clouds, such as rain and snow. Higher temperatures increase evaporation and surface drying. As

7426-407: Is the major reason why different climate models project different magnitudes of warming for a given amount of emissions. A climate model is a representation of the physical, chemical and biological processes that affect the climate system. Models include natural processes like changes in the Earth's orbit, historical changes in the Sun's activity, and volcanic forcing. Models are used to estimate

7584-563: Is to investigate past natural changes in climate. To assess changes in Earth's past climate scientists have studied tree rings , ice cores , corals , and ocean and lake sediments . These show that recent temperatures have surpassed anything in the last 2,000 years. By the end of the 21st century, temperatures may increase to a level last seen in the mid-Pliocene . This was around 3 million years ago. At that time, mean global temperatures were about 2–4 °C (3.6–7.2 °F) warmer than pre-industrial temperatures. The global mean sea level

7742-417: Is unclear. A related phenomenon driven by climate change is woody plant encroachment , affecting up to 500 million hectares globally. Climate change has contributed to the expansion of drier climate zones, such as the expansion of deserts in the subtropics . The size and speed of global warming is making abrupt changes in ecosystems more likely. Overall, it is expected that climate change will result in

7900-794: The Amazon Rainforest . At 2 °C (3.6 °F) of warming, around 10% of species on land would become critically endangered. Humans are vulnerable to climate change in many ways. Sources of food and fresh water can be threatened by environmental changes. Human health can be impacted by weather extremes or by ripple effects like the spread of infectious diseases . Economic impacts include changes to agriculture , fisheries , and forestry . Higher temperatures will increasingly prevent outdoor labor in tropical latitudes due to heat stress . Island nations and coastal cities may be inundated by rising sea levels. Some groups of people may be particularly at risk from climate change, such as

8058-455: The Amazon rainforest is recycled when it evaporates back into the atmosphere instead of running off away from the rainforest. This water is essential for sustaining the rainforest. Due to deforestation the rainforest is losing this ability. This effect is even worse because climate change brings more frequent droughts to the area. The higher frequency of droughts in the first two decades of

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8216-459: The Atlantic meridional overturning circulation (AMOC), and irreversible damage to key ecosystems like the Amazon rainforest and coral reefs can unfold in a matter of decades. The long-term effects of climate change on oceans include further ice melt, ocean warming , sea level rise, ocean acidification and ocean deoxygenation. The timescale of long-term impacts are centuries to millennia due to CO 2 's long atmospheric lifetime. The result

8374-661: The Earth's energy budget . Sulfate aerosols act as cloud condensation nuclei and lead to clouds that have more and smaller cloud droplets. These clouds reflect solar radiation more efficiently than clouds with fewer and larger droplets. They also reduce the growth of raindrops , which makes clouds more reflective to incoming sunlight. Indirect effects of aerosols are the largest uncertainty in radiative forcing . While aerosols typically limit global warming by reflecting sunlight, black carbon in soot that falls on snow or ice can contribute to global warming. Not only does this increase

8532-572: The Germama (or Kasam) River, before turning northeast at approximately 11° N 40° 30' E as far north as 12° before turning completely east to reach lake Gargori. Other tributaries of the Awash include (in order upstream): the Logiya , Mille , Borkana , Ataye , Hawadi , Kabenna and Durkham Rivers . Towns and cities along its course include Metehara , Awash , Gewane and Asaita . There are tributary rivers, lakes, hot springs , and swamps in

8690-573: The Greenland ice sheet is already melting, but if global warming reaches levels between 1.7 °C and 2.3 °C, its melting will continue until it fully disappears. If the warming is later reduced to 1.5 °C or less, it will still lose a lot more ice than if the warming was never allowed to reach the threshold in the first place. While the ice sheets would melt over millennia, other tipping points would occur faster and give societies less time to respond. The collapse of major ocean currents like

8848-840: The Greenland ice sheet . Under the 2015 Paris Agreement , nations collectively agreed to keep warming "well under 2 °C". However, with pledges made under the Agreement, global warming would still reach about 2.8 °C (5.0 °F) by the end of the century. Limiting warming to 1.5 °C would require halving emissions by 2030 and achieving net-zero emissions by 2050. Fossil fuel use can be phased out by conserving energy and switching to energy sources that do not produce significant carbon pollution. These energy sources include wind , solar , hydro , and nuclear power . Cleanly generated electricity can replace fossil fuels for powering transportation , heating buildings , and running industrial processes. Carbon can also be removed from

9006-635: The Industrial Revolution , naturally-occurring amounts of greenhouse gases caused the air near the surface to be about 33 °C warmer than it would have been in their absence. Human activity since the Industrial Revolution, mainly extracting and burning fossil fuels ( coal , oil , and natural gas ), has increased the amount of greenhouse gases in the atmosphere. In 2022, the concentrations of CO 2 and methane had increased by about 50% and 164%, respectively, since 1750. These CO 2 levels are higher than they have been at any time during

9164-573: The Koka Reservoir ), has an area of about 180 square kilometres (69 sq mi). Both lake and dam are threatened by increasing sedimentation . The valley of the Awash from about 9° N downstream is the traditional home of the Afar people and Issa people . The valley of the Awash have been included as part of the Fatagar , Ifat , and Shewa . The Awash International Bank is named after

9322-671: The Middle Awash ) is internationally famous for its high density of hominin fossils, offering unparalleled insight into the early evolution of humans . " Lucy ", one of the most famous early hominin fossils, was discovered in the lower Awash Valley. For its paleontological and anthropological importance, the lower valley of the Awash was inscribed on the UNESCO World Heritage List in 1980. The Awash River basin, spanning 23 administrative zones, covers 10% of Ethiopia's area and hosts about 17% of its population. It

9480-518: The World Economic Forum , 14.5 million more deaths are expected due to climate change by 2050. 30% of the global population currently live in areas where extreme heat and humidity are already associated with excess deaths. By 2100, 50% to 75% of the global population would live in such areas. While total crop yields have been increasing in the past 50 years due to agricultural improvements, climate change has already decreased

9638-414: The carbon cycle . While plants on land and in the ocean absorb most excess emissions of CO 2 every year, that CO 2 is returned to the atmosphere when biological matter is digested, burns, or decays. Land-surface carbon sink processes, such as carbon fixation in the soil and photosynthesis, remove about 29% of annual global CO 2 emissions. The ocean has absorbed 20 to 30% of emitted CO 2 over

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9796-418: The climate system include an overall warming trend , changes to precipitation patterns , and more extreme weather . As the climate changes it impacts the natural environment with effects such as more intense forest fires , thawing permafrost , and desertification . These changes impact ecosystems and societies, and can become irreversible once tipping points are crossed. Climate activists are engaged in

9954-402: The climate system . Solar irradiance has been measured directly by satellites , and indirect measurements are available from the early 1600s onwards. Since 1880, there has been no upward trend in the amount of the Sun's energy reaching the Earth, in contrast to the warming of the lower atmosphere (the troposphere ). The upper atmosphere (the stratosphere ) would also be warming if the Sun

10112-415: The emissions of greenhouse gases from human activities, mainly burning of fossil fuels and deforestation . Carbon dioxide and methane are examples of greenhouse gases. The additional greenhouse effect leads to ocean warming because the ocean takes up most of the additional heat in the climate system . The ocean also absorbs some of the extra carbon dioxide that is in the atmosphere . This causes

10270-971: The extinction of many species. The oceans have heated more slowly than the land, but plants and animals in the ocean have migrated towards the colder poles faster than species on land. Just as on land, heat waves in the ocean occur more frequently due to climate change, harming a wide range of organisms such as corals, kelp , and seabirds . Ocean acidification makes it harder for marine calcifying organisms such as mussels , barnacles and corals to produce shells and skeletons ; and heatwaves have bleached coral reefs . Harmful algal blooms enhanced by climate change and eutrophication lower oxygen levels, disrupt food webs and cause great loss of marine life. Coastal ecosystems are under particular stress. Almost half of global wetlands have disappeared due to climate change and other human impacts. Plants have come under increased stress from damage by insects. The effects of climate change are impacting humans everywhere in

10428-415: The outlet glaciers . Future melt of the West Antarctic ice sheet is potentially abrupt under a high emission scenario, as a consequence of a partial collapse. Part of the ice sheet is grounded on bedrock below sea level. This makes it possibly vulnerable to the self-enhancing process of marine ice sheet instability . Marine ice cliff instability could also contribute to a partial collapse. But there

10586-415: The pH value of the seawater to drop . Scientists estimate that the ocean absorbs about 25% of all human-caused CO 2 emissions. The various layers of the oceans have different temperatures. For example, the water is colder towards the bottom of the ocean. This temperature stratification will increase as the ocean surface warms due to rising air temperatures. Connected to this is a decline in mixing of

10744-468: The poor , children , and indigenous peoples . Industrialised countries , which have emitted the vast majority of CO 2 , have more resources to adapt to global warming than developing nations do. Cumulative effects and extreme weather events can lead to displacement and migration . Global warming affects all parts of Earth's climate system . Global surface temperatures have risen by 1.1 °C (2.0 °F). Scientists say they will rise further in

10902-432: The socioeconomic scenario and the mitigation scenario, models produce atmospheric CO 2 concentrations that range widely between 380 and 1400 ppm. The environmental effects of climate change are broad and far-reaching, affecting oceans , ice, and weather. Changes may occur gradually or rapidly. Evidence for these effects comes from studying climate change in the past, from modelling, and from modern observations. Since

11060-405: The 18th century and 1970 there was little net warming, as the warming impact of greenhouse gas emissions was offset by cooling from sulfur dioxide emissions. Sulfur dioxide causes acid rain , but it also produces sulfate aerosols in the atmosphere, which reflect sunlight and cause global dimming . After 1970, the increasing accumulation of greenhouse gases and controls on sulfur pollution led to

11218-560: The 1950s, droughts and heat waves have appeared simultaneously with increasing frequency. Extremely wet or dry events within the monsoon period have increased in India and East Asia. Monsoonal precipitation over the Northern Hemisphere has increased since 1980. The rainfall rate and intensity of hurricanes and typhoons is likely increasing , and the geographic range likely expanding poleward in response to climate warming. Frequency of tropical cyclones has not increased as

11376-500: The 1980s, the terms global warming and climate change became more common, often being used interchangeably. Scientifically, global warming refers only to increased surface warming, while climate change describes both global warming and its effects on Earth's climate system , such as precipitation changes. Climate change can also be used more broadly to include changes to the climate that have happened throughout Earth's history. Global warming —used as early as 1975 —became

11534-410: The 21st century and other data signal that a tipping point from rainforest to savanna might be close. A 2019 study concluded that this ecosystem could begin a 50-year-long collapse to a savanna around 2021. After that it would become increasingly and disproportionally more difficult to prevent or reverse this shift. Marine heatwaves are happening more often. They have widespread impacts on life in

11692-443: The 21st century the hotter the world will be by 2100. For a doubling of greenhouse gas concentrations, the global mean temperature would rise by about 2.5–4 °C (4.5–7.2 °F). If emissions of CO 2 stopped abruptly and there was no use of negative emission technologies , the Earth's climate would not start moving back to its pre-industrial state. Temperatures would stay at the same high level for several centuries. After about

11850-440: The Arctic is forcing many species to relocate or become extinct . Even if efforts to minimize future warming are successful, some effects will continue for centuries. These include ocean heating , ocean acidification and sea level rise . Climate change threatens people with increased flooding , extreme heat, increased food and water scarcity, more disease, and economic loss . Human migration and conflict can also be

12008-435: The Arctic is another major feedback, this reduces the reflectivity of the Earth's surface in the region and accelerates Arctic warming . This additional warming also contributes to permafrost thawing, which releases methane and CO 2 into the atmosphere. Around half of human-caused CO 2 emissions have been absorbed by land plants and by the oceans. This fraction is not static and if future CO 2 emissions decrease,

12166-550: The Awash River basin has severely damaged the ecosystem due to the toxins discharged into water bodies. The main sources of water pollution in the upper Awash River basin come from industrial and urban wastes, agricultural runoff ( pesticides , fertilizers ), and sewage discharge. Both anthropogenic and geogenic activities contribute to the observed water quality degradation. The term geogenic refers to naturally occurring contamination through tectonic, clay, volcanic ash, and sand weathering phenomena. Heavy metal pollution in

12324-457: The Awash River. 11°06′00″N 40°34′46″E  /  11.10000°N 40.57944°E  / 11.10000; 40.57944 Climate change Present-day climate change includes both global warming —the ongoing increase in global average temperature —and its wider effects on Earth's climate . Climate change in a broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures

12482-591: The Awash basin is part of the Ethiopian montane forests ecoregion. At high altitudes the Ethiopian montane grasslands and woodlands and Ethiopian montane moorlands predominate. The Somali Acacia–Commiphora bushlands and thickets ecoregion occupies low elevations in the Rift. The basin's vegetation has a strong anthropogenic impact. All over the upper and central Awash basin, remains of different savanna types are still clearly visible. They range from thorn savannas in

12640-532: The Awash basin, as well as population growth is placing increasing demands on the basin’s water resources . The main sources of water pollution in the upper Awash River basin come from industrial and urban wastes, agricultural runoff ( pesticides , fertilizers ), and sewage discharge. Polluting industries in the Awash River basin include tanneries , paint factories, slaughterhouses , textiles , breweries , soft drink factories, sugar factories, hospitals, and pharmaceuticals. The Awash Valley (and especially

12798-430: The Awash basin. Recurrent extreme wet and dry weather events challenge economic activities in the basin. The large portion of rural poor engaged in rainfed agriculture in the drought-prone marginal lands located in the middle and lower reaches of the basin suffer greatly from recurring drought. Climate variability already has a severe impact on populations and economic productivity in the Awash basin. Severe droughts in

12956-545: The CO 2 released by the chemical reactions for making cement , steel , aluminum , and fertilizer . Methane emissions come from livestock , manure, rice cultivation , landfills, wastewater, and coal mining , as well as oil and gas extraction . Nitrous oxide emissions largely come from the microbial decomposition of fertilizer . While methane only lasts in the atmosphere for an average of 12 years, CO 2 lasts much longer. The Earth's surface absorbs CO 2 as part of

13114-604: The Earth will be able to absorb up to around 70%. If they increase substantially, it'll still absorb more carbon than now, but the overall fraction will decrease to below 40%. This is because climate change increases droughts and heat waves that eventually inhibit plant growth on land, and soils will release more carbon from dead plants when they are warmer . The rate at which oceans absorb atmospheric carbon will be lowered as they become more acidic and experience changes in thermohaline circulation and phytoplankton distribution. Uncertainty over feedbacks, particularly cloud cover,

13272-537: The Himalayas in Asia, the retreat of glaciers could impact water supply. The melting of those glaciers could also cause landslides or glacial lake outburst floods . The melting of the Greenland and West Antarctic ice sheets will continue to contribute to sea level rise over long time-scales. The Greenland ice sheet loss is mainly driven by melt from the top. Antarctic ice loss is driven by warm ocean water melting

13430-581: The Main Ethiopian Rift and in southern Afar. The Awash Basin is a densely populated and industrialized area where numerous enterprises rely on groundwater for their operation. Therefore, the majority of human development initiatives in the basin will continue to depend heavily on the quantity and quality of groundwater. Groundwater management requires proactive measures due to the global challenges posed by rapid population growth, urbanization, climate change, and various human activities. Most of

13588-666: The Middle Awash Basin. The climate of the Awash River basin is mostly influenced by the movement of the intertropical convergence zone (ITCZ). During its movement northwards in March/April and its retreat southwards, ITCZ creates two rainy seasons, a shorter one around March ( Belg ), and a longer one between June and September ( Kiremt ), which partly fall into one longer rainy season. The rainy season tends to be bimodal towards eastern Ethiopia and almost unimodal towards western Ethiopia. The time between October and March

13746-441: The absorption of sunlight, it also increases melting and sea-level rise. Limiting new black carbon deposits in the Arctic could reduce global warming by 0.2 °C by 2050. The effect of decreasing sulfur content of fuel oil for ships since 2020 is estimated to cause an additional 0.05 °C increase in global mean temperature by 2050. As the Sun is the Earth's primary energy source, changes in incoming sunlight directly affect

13904-451: The air warms it can hold more water. For every degree Celsius it can hold 7% more water vapour . Scientists have observed changes in the amount, intensity, frequency, and type of precipitation. Overall, climate change is causing longer hot dry spells, broken by more intense rainfall. Climate change has increased contrasts in rainfall amounts between wet and dry seasons. Wet seasons are getting wetter and dry seasons are getting drier. In

14062-411: The atmosphere , for instance by increasing forest cover and farming with methods that capture carbon in soil . Before the 1980s it was unclear whether the warming effect of increased greenhouse gases was stronger than the cooling effect of airborne particulates in air pollution . Scientists used the term inadvertent climate modification to refer to human impacts on the climate at this time. In

14220-508: The atmosphere. The ecosystems most immediately threatened by climate change are in the mountains , coral reefs , and the Arctic . Excess heat is causing environmental changes in those locations that exceed the ability of animals to adapt. Species are escaping heat by migrating towards the poles and to higher ground when they can. Sea level rise threatens coastal wetlands with flooding . Decreases in soil moisture in certain locations can cause desertification and damage ecosystems like

14378-452: The atmosphere. volcanic CO 2 emissions are more persistent, but they are equivalent to less than 1% of current human-caused CO 2 emissions. Volcanic activity still represents the single largest natural impact (forcing) on temperature in the industrial era. Yet, like the other natural forcings, it has had negligible impacts on global temperature trends since the Industrial Revolution. The climate system's response to an initial forcing

14536-425: The basin have led to a significant depression of crop yields and death of livestock, resulting in increases in food insecurity . A modest (5%) decrease in rainfall was estimated to reduce the basin’s gross domestic product (GDP) 5%, with a 10% decrease in agricultural productivity. Humanitarian assistance requests are relatively common due to climate shocks , such as the 2015/2016 El Niño events which resulted in

14694-575: The basin, further threatening water security for different sectors. Rainfall varies a lot in the basin from one year to the next (this is called high intra-annual variability ). Dry season water shortage is recognized as a challenge for various activities such as irrigation and domestic water supply by the Awash Basin Authority. However, flooding also occurs frequently during the main rainy season in July and August. The type of flooding

14852-406: The basin’s water resources. The basin is known for high climate variability involving droughts and floods, and climate change will likely intensify the existing challenges. Future water management strategies needs to be inclusive of all sectors and consider the equity for different users. Flood adaption measures have been investigated and one of the recommendations is to use " land-use planning that

15010-421: The basis for economic growth in the coming years. Crop production in particular is a major component of the basin's economy and has seen rapid growth in recent years, with the value of output expanding by 7.9% per year in real terms between 2004 and 2014. As of 2012, the total irrigated area of the basin is less than 2% of the total area under cultivation. Forestry hardly exists inside the Awash River basin, with

15168-454: The biggest threats to global health in the 21st century. Scientists have warned about the irreversible harms it poses. Extreme weather events affect public health, and food and water security . Temperature extremes lead to increased illness and death. Climate change increases the intensity and frequency of extreme weather events. It can affect transmission of infectious diseases , such as dengue fever and malaria . According to

15326-540: The carbon cycle, such as the fertilizing effect of CO 2 on plant growth. Feedbacks are expected to trend in a positive direction as greenhouse gas emissions continue, raising climate sensitivity. These feedback processes alter the pace of global warming. For instance, warmer air can hold more moisture in the form of water vapour , which is itself a potent greenhouse gas. Warmer air can also make clouds higher and thinner, and therefore more insulating, increasing climate warming. The reduction of snow cover and sea ice in

15484-456: The cause of recent climate trends. They are now able to estimate the impact of climate change on extreme weather events using a process called extreme event attribution . For instance such research can look at historical data for a region and conclude that a specific heat wave was more intense due to climate change. In addition , the time shifts of the season onsets, changes in the length of the season durations have been reported in many regions of

15642-551: The climate cycled through ice ages . One of the hotter periods was the Last Interglacial , around 125,000 years ago, where temperatures were between 0.5 °C and 1.5 °C warmer than before the start of global warming. This period saw sea levels 5 to 10 metres higher than today. The most recent glacial maximum 20,000 years ago was some 5–7 °C colder. This period has sea levels that were over 125 metres (410 ft) lower than today. Temperatures stabilized in

15800-601: The climate system. Climate change is a major driver of biodiversity loss in different land types. These include cool conifer forests, savannas , mediterranean-climate systems, tropical forests , and the Arctic tundra . In other ecosystems, land-use change may be a stronger driver of biodiversity loss, at least in the near term. Beyond 2050, climate change may be the major cause of biodiversity loss globally. Climate change interacts with other pressures. These include habitat modification, pollution and invasive species . Through this interaction, climate change increases

15958-465: The countries that have set or are considering net-zero targets achieve them, the temperature will rise by around 1.8 °C (3.2 °F). There is a big gap between national plans and commitments and the actions that governments have taken around the world. The lower and middle atmosphere, where nearly all weather occurs, are heating due to the greenhouse effect . Evaporation and atmospheric moisture content increase as temperatures rise. Water vapour

16116-684: The current interglacial period beginning 11,700 years ago . This period also saw the start of agriculture. Historical patterns of warming and cooling, like the Medieval Warm Period and the Little Ice Age , did not occur at the same time across different regions. Temperatures may have reached as high as those of the late 20th century in a limited set of regions. Climate information for that period comes from climate proxies , such as trees and ice cores . Around 1850 thermometer records began to provide global coverage. Between

16274-403: The degree of warming future emissions will cause when accounting for the strength of climate feedbacks . Models also predict the circulation of the oceans, the annual cycle of the seasons, and the flows of carbon between the land surface and the atmosphere. The physical realism of models is tested by examining their ability to simulate current or past climates. Past models have underestimated

16432-427: The destroyed trees release CO 2 , and are not replaced by new trees, removing that carbon sink . Between 2001 and 2018, 27% of deforestation was from permanent clearing to enable agricultural expansion for crops and livestock. Another 24% has been lost to temporary clearing under the shifting cultivation agricultural systems. 26% was due to logging for wood and derived products, and wildfires have accounted for

16590-401: The distribution of heat and precipitation around the globe. The World Meteorological Organization estimates there is an 80% chance that global temperatures will exceed 1.5 °C warming for at least one year between 2024 and 2028. The chance of the 5-year average being above 1.5 °C is almost half. The IPCC expects the 20-year average global temperature to exceed +1.5 °C in

16748-444: The dominant direct influence on temperature from land use change. Thus, land use change to date is estimated to have a slight cooling effect. Air pollution, in the form of aerosols, affects the climate on a large scale. Aerosols scatter and absorb solar radiation. From 1961 to 1990, a gradual reduction in the amount of sunlight reaching the Earth's surface was observed. This phenomenon is popularly known as global dimming , and

16906-610: The early 2030s. The IPCC Sixth Assessment Report (2021) included projections that by 2100 global warming is very likely to reach 1.0–1.8 °C under a scenario with very low emissions of greenhouse gases , 2.1–3.5 °C under an intermediate emissions scenario , or 3.3–5.7 °C under a very high emissions scenario . The warming will continue past 2100 in the intermediate and high emission scenarios, with future projections of global surface temperatures by year 2300 being similar to millions of years ago. The remaining carbon budget for staying beneath certain temperature increases

17064-946: The emissions continue to increase for the rest of century, then over 9 million climate-related deaths would occur annually by 2100. Economic damages due to climate change may be severe and there is a chance of disastrous consequences. Severe impacts are expected in South-East Asia and sub-Saharan Africa , where most of the local inhabitants are dependent upon natural and agricultural resources. Heat stress can prevent outdoor labourers from working. If warming reaches 4 °C then labour capacity in those regions could be reduced by 30 to 50%. The World Bank estimates that between 2016 and 2030, climate change could drive over 120 million people into extreme poverty without adaptation. Effects of climate change Effects of climate change are well documented and growing for Earth's natural environment and human societies. Changes to

17222-430: The entire atmosphere—is ruled out because only the lower atmosphere has warmed. Atmospheric aerosols produce a smaller, cooling effect. Other drivers, such as changes in albedo , are less impactful. Greenhouse gases are transparent to sunlight , and thus allow it to pass through the atmosphere to heat the Earth's surface. The Earth radiates it as heat , and greenhouse gases absorb a portion of it. This absorption slows

17380-401: The escarpments and highlands above 1,900 m a.s.l., where annual rainfall is higher than 1,000 millimetres (39 in). Localized small-scale recharge is also supposed to occur at the flanks of the rift valley volcanoes. Artificial groundwater recharge takes further place at irrigated plantations at the rift valley. Recharge from river channel losses and via infiltration from lakes plays a role in

17538-628: The explorer L. M. Nesbitt had followed parts of the course of the Awash in 1928, he turned away from the river at Asaita and proceeded north through the Afar Depression to the Red Sea.) In 1960, the Koka Dam was completed across the Awash River at a point around 75 kilometres (47 mi) from Addis Ababa. With its opening, it became a major source of hydroelectric power in the area. The resulting freshwater lake, Lake Gelila (also known as

17696-415: The extinction of species would be an irreversible impact. In social systems, unique cultures may be lost. Climate change could make it more likely that endangered languages disappear. Humans have a climate niche. This is a certain range of temperatures in which they flourish. Outside that niche, conditions are less favourable. This leads to negative effects on health, food security and more. This niche

17854-555: The far western Sahel. Storms become wetter under climate change. These include tropical cyclones and extratropical cyclones . Both the maximum and mean rainfall rates increase. This more extreme rainfall is also true for thunderstorms in some regions. Furthermore, tropical cyclones and storm tracks are moving towards the poles. This means some regions will see large changes in maximum wind speeds. Scientists expect there will be fewer tropical cyclones. But they expect their strength to increase. There has probably been an increase in

18012-442: The future. The changes in climate are not uniform across the Earth. In particular, most land areas have warmed faster than most ocean areas. The Arctic is warming faster than most other regions. Night-time temperatures have increased faster than daytime temperatures. The impact on nature and people depends on how much more the Earth warms. Scientists use several methods to predict the effects of human-caused climate change. One

18170-604: The global climate system has grown with only brief pauses since at least 1970, and over 90% of this extra energy has been stored in the ocean . The rest has heated the atmosphere , melted ice, and warmed the continents. The Northern Hemisphere and the North Pole have warmed much faster than the South Pole and Southern Hemisphere . The Northern Hemisphere not only has much more land, but also more seasonal snow cover and sea ice . As these surfaces flip from reflecting

18328-560: The groundwater sources were unsuitable for drinking, posing significant health risks to local communities that rely heavily on these sources due to limited access to clean surface water. In the Middle Awash Basin and the country at large, the water quality of most groundwater sources is inadequately monitored and insufficiently regulated. Consequently, areas within the upstream Awash Basin, particularly around Modjo, Bishoftu, Gelan, and Addis Ababa, are highly susceptible to unregulated abstraction and pollution of groundwater. Humans have lived in

18486-429: The ice sheet, the elevation drops. Air temperature is higher at lower altitudes, so this promotes further melting. Sea ice reflects 50% to 70% of the incoming solar radiation back into space. Only 6% of incoming solar energy is reflected by the ocean. As the climate warms, the area covered by snow or sea ice decreases. After sea ice melts, more energy is absorbed by the ocean, so it warms up. This ice-albedo feedback

18644-731: The impact of acidification. Warm-water coral reefs are very sensitive to global warming and ocean acidification. Coral reefs provide a habitat for thousands of species. They provide ecosystem services such as coastal protection and food. But 70–90% of today's warm-water coral reefs will disappear even if warming is kept to 1.5 °C (2.7 °F). Coral reefs are framework organisms. They build physical structures that form habitats for other sea creatures. Other framework organisms are also at risk from climate change. Mangroves and seagrass are considered to be at moderate risk from lower levels of global warming. The climate system exhibits "threshold behavior" or tipping points when parts of

18802-472: The intensity of individual heat waves to global warming. Some extreme events would have been nearly impossible without human influence on the climate system. A heatwave that would occur once every ten years before global warming started now occurs 2.8 times as often. Under further warming, heatwaves are set to become more frequent. An event that would occur every ten years would occur every other year if global warming reaches 2 °C (3.6 °F). Heat stress

18960-406: The irrigation waters for local and commercial agricultural lands (such as sugarcane plantation) depend on the Awash River and its tributaries. The Awash basin's economy is dominated by the agricultural and service sectors, with the latter prevailing in the large urban center of Addis Ababa . Agriculture dominates water use (about 89% of total water use in the basin) and is expected to continue to be

19118-530: The largest declines have been observed in the spring. During the 21st century, snow cover is projected to continue its retreat in almost all regions. Since the beginning of the twentieth century, there has been a widespread retreat of glaciers . Those glaciers that are not associated with the polar ice sheets lost around 8% of their mass between 1971 and 2019. In the Andes in South America and in

19276-572: The last 14 million years. Concentrations of methane are far higher than they were over the last 800,000 years. Global human-caused greenhouse gas emissions in 2019 were equivalent to 59 billion tonnes of CO 2 . Of these emissions, 75% was CO 2 , 18% was methane , 4% was nitrous oxide, and 2% was fluorinated gases . CO 2 emissions primarily come from burning fossil fuels to provide energy for transport , manufacturing, heating , and electricity. Additional CO 2 emissions come from deforestation and industrial processes , which include

19434-436: The last two decades. CO 2 is only removed from the atmosphere for the long term when it is stored in the Earth's crust, which is a process that can take millions of years to complete. Around 30% of Earth's land area is largely unusable for humans ( glaciers , deserts , etc.), 26% is forests , 10% is shrubland and 34% is agricultural land . Deforestation is the main land use change contributor to global warming, as

19592-441: The last: internal climate variability processes can make any year 0.2 °C warmer or colder than the average. From 1998 to 2013, negative phases of two such processes, Pacific Decadal Oscillation (PDO) and Atlantic Multidecadal Oscillation (AMO) caused a short slower period of warming called the " global warming hiatus ". After the "hiatus", the opposite occurred, with years like 2023 exhibiting temperatures well above even

19750-629: The lower rift, bush, grass and open savannas above 800 m and woody savannas on the escarpments and the highlands. The lower Awash Valley is one of the last wildlife preserves for the African wild ass . The mammal is now extinct in Yangudi Rassa National Park , but still found in the adjacent Mille-Serdo Wildlife Reserve . Other large animals native to the area include Beisa Oryx , Soemmering's gazelle , Dorcas gazelle , gerenuk and Grevy's zebra . Crocodiles also flourish within

19908-413: The more popular term after NASA climate scientist James Hansen used it in his 1988 testimony in the U.S. Senate . Since the 2000s, climate change has increased usage. Various scientists, politicians and media may use the terms climate crisis or climate emergency to talk about climate change, and may use the term global heating instead of global warming . Over the last few million years

20066-494: The natural environment enter into a new state. Examples are the runaway loss of ice sheets or the dieback of forests. Tipping behavior is found in all parts of the climate system. These include ecosystems, ice sheets, and the circulation of the ocean and atmosphere. Tipping points are studied using data from Earth's distant past and by physical modeling. There is already moderate risk of global tipping points at 1 °C (1.8 °F) above pre-industrial temperatures. That becomes

20224-477: The northern high latitudes , warming has also caused an increase in the amount of snow and rain. In the Southern Hemisphere, the rain associated with the storm tracks has shifted south. Changes in monsoons vary a lot. More monsoon systems are becoming wetter than drier. In Asia summer monsoons are getting wetter. The West African monsoon is getting wetter over the central Sahel , and drier in

20382-649: The number of tropical cyclones that intensify rapidly. Meteorological and seismological data indicate a widespread increase in wind-driven global ocean wave energy in recent decades that has been attributed to an increase in storm intensity over the oceans due to climate change. Atmospheric turbulence dangerous for aviation (hard to predict or that cannot be avoided by flying higher) probably increases due to climate change. Due to an increase in heavy rainfall events, floods are likely to become more severe when they do occur. The interactions between rainfall and flooding are complex. There are some regions in which flooding

20540-423: The ocean layers, so that warm water stabilises near the surface. A reduction of cold, deep water circulation follows. The reduced vertical mixing makes it harder for the ocean to absorb heat. So a larger share of future warming goes into the atmosphere and land. One result is an increase in the amount of energy available for tropical cyclones and other storms. Another result is a decrease in nutrients for fish in

20698-615: The oceans. These include mass dying events and coral bleaching . Harmful algae blooms have increased. This is in response to warming waters, loss of oxygen and eutrophication . Melting sea ice destroys habitat, including for algae that grows on its underside. Ocean acidification can harm marine organisms in various ways. Shell-forming organisms like oysters are particularly vulnerable. Some phytoplankton and seagrass species may benefit. However, some of these are toxic to fish phytoplankton species. Their spread poses risks to fisheries and aquaculture . Fighting pollution can reduce

20856-635: The parameters within the study area were above the WHO limit for drinking water ; Al (157 μg/L), V (100.5 μg/L), Fe (1082.7 μg/L), Mn (626.8 μg/L), and Mo (103.8 μg/L) were exhibited at sites along the river system. This is a problem as water from the river is used as a source of drinking water and irrigation . The presence of emerging organic contaminants in the river water is another concern. These substances include pharmaceuticals, personal care products , industrial byproducts, and agricultural chemicals. High levels of emerging organic contaminants were detected in

21014-521: The past 3,000 years. The rate accelerated to 4.62 mm (0.182 in)/yr for the decade 2013–2022. Climate change due to human activities is the main cause. Between 1993 and 2018, melting ice sheets and glaciers accounted for 44% of sea level rise , with another 42% resulting from thermal expansion of water . The cryosphere , the area of the Earth covered by snow or ice, is extremely sensitive to changes in global climate. There has been an extensive loss of snow on land since 1981. Some of

21172-580: The past. Several impacts make their impacts worse. These are increased water demand, population growth and urban expansion in many areas. Land restoration can help reduce the impact of droughts. One example of this is agroforestry . Climate change promotes the type of weather that makes wildfires more likely. In some areas, an increase of wildfires has been attributed directly to climate change. Evidence from Earth's past also shows more fire in warmer periods. Climate change increases evapotranspiration . This can cause vegetation and soils to dry out. When

21330-589: The rain evaporates again. Warming over land increases the severity and frequency of droughts around much of the world. In some tropical and subtropical regions of the world, there will probably be less rain due to global warming. This will make them more prone to drought. Droughts are set to worsen in many regions of the world. These include Central America, the Amazon and south-western South America. They also include West and Southern Africa. The Mediterranean and south-western Australia are also some of these regions. Higher temperatures increase evaporation. This dries

21488-619: The rate at which heat escapes into space, trapping heat near the Earth's surface and warming it over time. While water vapour (≈50%) and clouds (≈25%) are the biggest contributors to the greenhouse effect, they primarily change as a function of temperature and are therefore mostly considered to be feedbacks that change climate sensitivity . On the other hand, concentrations of gases such as CO 2 (≈20%), tropospheric ozone , CFCs and nitrous oxide are added or removed independently from temperature, and are therefore considered to be external forcings that change global temperatures. Before

21646-522: The rate of Arctic shrinkage and underestimated the rate of precipitation increase. Sea level rise since 1990 was underestimated in older models, but more recent models agree well with observations. The 2017 United States-published National Climate Assessment notes that "climate models may still be underestimating or missing relevant feedback processes". Additionally, climate models may be unable to adequately predict short-term regional climatic shifts. A subset of climate models add societal factors to

21804-622: The rate of yield growth . Fisheries have been negatively affected in multiple regions. While agricultural productivity has been positively affected in some high latitude areas, mid- and low-latitude areas have been negatively affected. According to the World Economic Forum, an increase in drought in certain regions could cause 3.2 million deaths from malnutrition by 2050 and stunting in children. With 2 °C warming, global livestock headcounts could decline by 7–10% by 2050, as less animal feed will be available. If

21962-405: The recent average. This is why the temperature change is defined in terms of a 20-year average, which reduces the noise of hot and cold years and decadal climate patterns, and detects the long-term signal. A wide range of other observations reinforce the evidence of warming. The upper atmosphere is cooling, because greenhouse gases are trapping heat near the Earth's surface, and so less heat

22120-411: The release of chemical compounds that influence clouds, and by changing wind patterns. In tropic and temperate areas the net effect is to produce significant warming, and forest restoration can make local temperatures cooler. At latitudes closer to the poles, there is a cooling effect as forest is replaced by snow-covered (and more reflective) plains. Globally, these increases in surface albedo have been

22278-476: The remaining 23%. Some forests have not been fully cleared, but were already degraded by these impacts. Restoring these forests also recovers their potential as a carbon sink. Local vegetation cover impacts how much of the sunlight gets reflected back into space ( albedo ), and how much heat is lost by evaporation . For instance, the change from a dark forest to grassland makes the surface lighter, causing it to reflect more sunlight. Deforestation can also modify

22436-406: The risk of extinction for many terrestrial and freshwater species. At 1.2 °C (2.2 °F) of warming (around 2023 ) some ecosystems are threatened by mass die-offs of trees and from heatwaves. At 2 °C (3.6 °F) of warming, around 10% of species on land would become critically endangered. This differs by group. For instance insects and salamanders are more vulnerable. Rainfall on

22594-441: The river water can pollute the groundwater and vice versa. A study in 2024 investigated the characteristics of groundwater in a region of Middle Awash for multipurpose use. It found that contaminants such as arsenic, vanadium, gallium, lithium, rubidium, chromium, manganese, copper, and zinc were found enriched in groundwater near Lake Beseka, majorly influenced by geogenic activities, volcanic ash, and weathering of rocks. Over half of

22752-427: The river. The Awash basin is the most developed, utilized, abused, impacted, and most populous (over 15% or nearly 18.6 million out of 120 million) basin in Ethiopia. Middle Awash is known for having both large- and small-scale irrigation, as well as agroindustry and sugar factories (Wenji, Methara, and Kesem Sugar factories). The water supplies of the major urban centers like Addis Ababa, Mojo and Adama, and also,

22910-583: The sea levels by at least 3.3 m (10 ft 10 in) over approximately 2000 years. Recent warming has driven many terrestrial and freshwater species poleward and towards higher altitudes . For instance, the range of hundreds of North American birds has shifted northward at an average rate of 1.5 km/year over the past 55 years. Higher atmospheric CO 2 levels and an extended growing season have resulted in global greening. However, heatwaves and drought have reduced ecosystem productivity in some regions. The future balance of these opposing effects

23068-610: The site include Homo erectus and Ardipithecus . In the 16th century the Awash River was called the great Dir river and lay in the country of the Muslims. The first European to trace the course of the Awash to its end in the Aussa oasis was Wilfred Thesiger in 1933/1934, who started at the city of Awash, followed the river's course to its final end in Lake Abhebad, and continued his expedition east to Tadjoura . (Although

23226-445: The soil and increases plant stress . Agriculture suffers as a result. This means even regions where overall rainfall is expected to remain relatively stable will experience these impacts. These regions include central and northern Europe. Without climate change mitigation, around one third of land areas are likely to experience moderate or more severe drought by 2100. Due to global warming droughts are more frequent and intense than in

23384-445: The surface water has become a growing concern for the environment and people’s health. Polluting industries in the Awash River basin include tanneries , paint factories, slaughterhouses , textiles , breweries , soft drink factories, sugar factories, hospitals, and pharmaceuticals. Wastewater enters the river from cities such as Addis Abeba , Awash 7 Kilo, Ambo, Sebeta , Bishoftu , Gelan, Adama , Modjo. Agricultural runoff may be

23542-579: The town of Ginchi , West Shewa Zone , Oromia . After entering the bottom of the Great Rift Valley , the Awash flows south to loop around Mount Zuqualla in an easterly then northeasterly direction, before entering Koka Reservoir . There, water is used for the irrigation of sugar cane plantations. Downstream, the Awash passes the city of Adama and the Awash National Park . It is then joined on its left bank by its chief affluent,

23700-440: The upper ocean layers. These changes also reduce the ocean's capacity to store carbon . At the same time, contrasts in salinity are increasing. Salty areas are becoming saltier and fresher areas less salty. Between 1901 and 2018, the average sea level rose by 15–25 cm (6–10 in), with an increase of 2.3 mm (0.091 in) per year since the 1970s. This was faster than the sea level had ever risen over at least

23858-496: The valley of the Awash almost since the beginning of the species. Numerous pre-human hominid remains have been found in the Middle Awash . The remains found in the Awash Valley date from the late Miocene , Pliocene , and early Pleistocene (roughly 5.6–2.5 million years ago), and include fossils of many Australopithecines , including "Lucy", the most famous individual Australopithecus . Other extinct hominids discovered at

24016-430: The vast majority of excess heat in the atmosphere, delaying effects there but causing them to accelerate and then continue after surface temperatures stabilize. Sea level rise is a particular long term concern as a result. The effects of ocean warming also include marine heatwaves , ocean stratification , deoxygenation , and changes to ocean currents .  The ocean is also acidifying as it absorbs carbon dioxide from

24174-584: The world. As a result, the timing of extreme weather events, such as heavy precipitation and heat waves, is changing to coincide more closely with changes in seasonal patterns. Heatwaves over land have become more frequent and more intense in almost all world regions since the 1950s, due to climate change . Heat waves are more likely to occur simultaneously with droughts. Marine heatwaves are twice as likely as they were in 1980. Climate change will lead to more very hot days and fewer very cold days. There are fewer cold waves . Experts can often attribute

24332-438: The world. Impacts can be observed on all continents and ocean regions, with low-latitude, less developed areas facing the greatest risk. Continued warming has potentially "severe, pervasive and irreversible impacts" for people and ecosystems. The risks are unevenly distributed, but are generally greater for disadvantaged people in developing and developed countries. The World Health Organization calls climate change one of

24490-582: Was 1981–2005. The future water availability was estimated as the difference between precipitation and potential evapotranspiration projections using the Representative Concentration Pathway (RCP8.5) emission scenarios. The projections for the future three periods show an increase in water deficiency in all seasons and for parts of the basin, due to a projected increase in temperature and decrease in precipitation. This decrease in water availability will increase water stress in

24648-415: Was carried out on not cultivable altitudes with secondary coniferous forests. The cultivated crops are (endemic) teff , maize, sorghum , beans and vegetables. Pastures hardly exist where agriculture is possible. The cattle graze on field edges and waysides and on steep escarpments. This is one major reason for erosion , because vegetation cover is partly destroyed. Stubble-grazing is a common practice in

24806-524: Was sending more energy to Earth, but instead, it has been cooling. This is consistent with greenhouse gases preventing heat from leaving the Earth's atmosphere. Explosive volcanic eruptions can release gases, dust and ash that partially block sunlight and reduce temperatures, or they can send water vapour into the atmosphere, which adds to greenhouse gases and increases temperatures. These impacts on temperature only last for several years, because both water vapour and volcanic material have low persistence in

24964-404: Was up to 25 metres (82 ft) higher than it is today. The modern observed rise in temperature and CO 2 concentrations has been rapid. Even abrupt geophysical events in Earth's history do not approach current rates. How much the world warms depends on human greenhouse gas emissions and on how sensitive the climate is to greenhouse gases . The more carbon dioxide (CO 2 ) is emitted in

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