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159-547: EJN trains journalists to cover a wide variety of issues, including climate change , biodiversity, the ocean, and One Health. EJN also works to establish networks of environmental journalists in countries where they don't exist and build their capacity where they do. This work is done through workshops and the development of training materials and by offering Fellowship programs, grants to media organizations, story stipends, and support for story production and distribution. Both independently and in partnership with other organizations,

318-562: A broader sense also includes previous long-term changes to Earth's climate. The current rise in global temperatures 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

477-590: 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

636-480: A factor of two when comparing the periods from 1950 to 1995 (0.7 m (2.3 ft) per year) and 1995 to 2001 (1.8 m (5.9 ft) per year). This is a systemic trend with loss in mass equating to loss in thickness, which leads to increasing retreat—the glaciers are not only retreating, but they are also becoming much thinner. In Denali National Park , all glaciers monitored are retreating, with an average retreat of 20 m (66 ft) per year. The terminus of

795-624: A faster rate than a few decades ago. In a paper published in 2009 by the University of Zurich, the Swiss glacier survey of 89 glaciers found 76 retreating, 5 stationary and 8 advancing from where they had been in 1973. The Trift Glacier had the greatest recorded retreat, losing 350 m (1,150 ft) of its length between the years 2003 and 2005. The Grosser Aletsch Glacier is the largest glacier in Switzerland and has been studied since

954-770: A few decades. However, the Grinnell Glacier in Montana, U.S. will shrink at an increasing rate until it disappears. The difference is that the upper section of Easton Glacier remains healthy and snow-covered, while even the upper section of the Grinnell Glacier is bare, is melting and has thinned. Small glaciers with minimal altitude range are most likely to fall into disequilibrium with the climate. Methods for measuring retreat include staking terminus location , global positioning mapping, aerial mapping and laser altimetry . The key symptom of disequilibrium

1113-609: A frontal retreat of more than 100 m (330 ft). Overall, from 1999 to 2005, Briksdalsbreen retreated 336 metres (1,102 ft). Gråfjellsbrea, an outlet glacier of the Folgefonna ice cap , had a retreat of almost 100 m (330 ft). In the Spanish Pyrenees , recent studies have shown important losses in extent and volume of the glaciers of the Maladeta massif during the period 1981–2005. These include

1272-695: A general retreat of all glaciers in the Altai Mountains with the exception of volcanic glaciers in Kamchatka. Sakha's glaciers, totaling seventy square kilometers, have shrunk by around 28 percent since 1945 reaching several percent annually in some places, whilst in the Altai and Chukotkan mountains and non-volcanic areas of Kamchatka, the shrinkage is considerably larger. The Himalayas and other mountain chains of central Asia support large glaciated regions. An estimated 15,000 glaciers can be found in

1431-475: A general state of retreat. During the 20th century, the glaciers of Tajikistan lost 20 km (4.8 cu mi) of ice. The 70 km (43 mi) long Fedchenko Glacier , which is the largest in Tajikistan and the largest non-polar glacier on Earth, retreated 1 km (0.62 mi) between the years 1933 and 2006, and lost 44 km (17 sq mi) of its surface area due to shrinkage between

1590-411: A large iceberg calving front. By 1948 the adjacent fjord had filled in, and the glacier no longer calved and was able to continue its advance. By 2005 the glacier was only 1.5 km (0.93 mi) from reaching Taku Point and blocking Taku Inlet . The advance of Taku Glacier averaged 17 m (56 ft) per year between 1988 and 2005. The mass balance was very positive for the 1946–88 period fueling

1749-482: A large reduction in the number of monitoring stations. Another factor is that in the Verkhoyansk and Cherskiy Ranges it was thought glaciers were absent before they were discovered during the 1940s, whilst in ultra-remote Kamchatka and Chukotka, although the existence of glaciers was known earlier, monitoring of their size dates back no earlier than the end of World War II. Nonetheless, available records do indicate

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1908-541: A little over 2 feet (65 centimeters) and backstops neighboring glaciers that would raise sea levels an additional 8 feet (2.4 meters) if all the ice were lost." The fact that the IPCC estimates did not include rapid ice sheet decay into their sea level predictions makes it difficult to ascertain a plausible estimate for sea level rise but a 2008 study found that the minimum sea level rise will be around 0.8 metres (2.6 ft) by 2100. The continued retreat of glaciers will have

2067-542: 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

2226-412: 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

2385-692: A mean annual retreat rate of approximately 17 m (56 ft) per year. This long-term average was markedly surpassed in recent years with the glacier receding 30 m (98 ft) per year during the period between 1999 and 2005. Similarly, of the glaciers in the Italian Alps, only about a third were in retreat in 1980, while by 1999, 89% of these glaciers were retreating. In 2005, the Italian Glacier Commission found that 123 glaciers in Lombardy were retreating. A random study of

2544-444: A number of different quantitative effects. In areas that are heavily dependent on water runoff from glaciers that melt during the warmer summer months, a continuation of the current retreat will eventually deplete the glacial ice and substantially reduce or eliminate runoff. A reduction in runoff will affect the ability to irrigate crops and will reduce summer stream flows necessary to keep dams and reservoirs replenished. This situation

2703-528: A part. The glacier mass balance is the key determinant of the health of a glacier. If the amount of frozen precipitation in the accumulation zone exceeds the quantity of glacial ice the ablation zone lost due to melting, a glacier will advance. If the accumulation is less than the ablation, the glacier will retreat. Glaciers in retreat will have negative mass balances. They will eventually disappear if they do not reach an equilibrium between accumulation and ablation. Mid-latitude mountain ranges show some of

2862-408: 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

3021-538: A polar region, owing to the dryness of the winter climate and has glaciers only in the high Altai Mountains , Verkhoyansk Range , Cherskiy Range and Suntar-Khayata Range , plus possibly a few very small glaciers in the ranges near Lake Baikal , which have never been monitored and may have completely disappeared since 1989. Between the years 1952 and 2006, the glaciers found in the Aktru Basin region shrank by 7.2 percent. This shrinkage has been primarily in

3180-581: A reduction in area of 35.7%, from 2.41 km (600 acres) to 1.55 km (380 acres), a loss in total ice volume of 0.0137 km (0.0033 cu mi) and an increase in the mean altitude of the glacial termini of 43.5 m (143 ft). For the Pyrenees as a whole 50–60% of the glaciated area has been lost since 1991. The Balaitus, Perdigurero and La Munia glaciers have disappeared in this period. Monte Perdido Glacier has shrunk from 90 hectares to 40 hectares. As initial cause for glacier retreat in

3339-410: 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

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3498-474: 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

3657-417: 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

3816-546: A state of retreat. This rate has increased rapidly since around 1980, and overall each decade since has seen greater rates of retreat than the preceding one. There are also small remnant glaciers scattered throughout the Sierra Nevada mountains of California and Nevada . The Cascade Range of western North America extends from southern British Columbia in Canada to northern California. Excepting Alaska, about half of

3975-476: A study of 16 glaciers between 1990 and 2001 found that 14 glaciers were retreating, one was advancing and one was stable. In Norway, glacier studies have been performed since the early 19th century, with systematic surveys undertaken regularly since the 1990s. Inland glaciers have had a generally negative mass balance, whereas during the 1990s, maritime glaciers showed a positive mass balance and advanced. The maritime advances have been attributed to heavy snowfall in

4134-511: A third of their former size when first studied in 1850, and numerous smaller glaciers have disappeared completely. Only 27% of the 99 km (38 sq mi) area of Glacier National Park covered by glaciers in 1850 remained covered by 1993. Researchers believe that between the year 2030 and 2080, that some glacial ice in Glacier National Park will be gone unless current climate patterns reverse their course. Grinnell Glacier

4293-548: 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

4452-519: 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,

4611-558: Is a particularly dramatic example. The glacier area shrank from 3.1 km (1.2 sq mi) in 1958 to 0.9 km (0.35 sq mi) by 2002. Between 1850 and 1950, the Boulder Glacier on the southeast flank of Mount Baker retreated 8,700 feet (2,700 m). William Long of the United States Forest Service observed the glacier beginning to advance due to cooler/wetter weather in 1953. This

4770-540: Is a well-documented effect of climate change . The retreat of mountain glaciers provide evidence for the rise in global temperatures since the late 19th century. Examples include mountain glaciers in western North America, Asia, the Alps in central Europe, and tropical and subtropical regions of South America and Africa. Since glacial mass is affected by long-term climatic changes, e.g. precipitation , mean temperature , and cloud cover , glacial mass changes are one of

4929-417: Is also out of equilibrium and will advance to reestablish equilibrium. Currently, nearly all glaciers have a negative mass balance and are retreating. Glacier retreat results in the loss of the low-elevation region of the glacier. Since higher elevations are cooler, the disappearance of the lowest portion decreases overall ablation, thereby increasing mass balance and potentially reestablishing equilibrium. If

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5088-564: 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

5247-711: 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

5406-427: Is fed by three large glaciers— Guyot , Yahtse , and Tyndall Glaciers —all of which have experienced a loss in length and thickness and, consequently, a loss in area. Tyndall Glacier became separated from the retreating Guyot Glacier in the 1960s and has retreated 24 km (15 mi) since, averaging more than 500 m (1,600 ft) per year. The Juneau Icefield Research Program has monitored outlet glaciers of

5565-399: 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

5724-482: Is just one of many glaciers in Glacier National Park that have been well documented by photographs for many decades. The photographs below clearly demonstrate the retreat of this glacier since 1938. The semiarid climate of Wyoming still manages to support about a dozen small glaciers within Grand Teton National Park , which all show evidence of retreat over the past 50 years. Schoolroom Glacier

5883-562: Is located slightly southwest of Grand Teton is one of the more easily reached glaciers in the park and it is expected to disappear by 2025. Research between 1950 and 1999 demonstrated that the glaciers in Bridger-Teton National Forest and Shoshone National Forest in the Wind River Range shrank by over a third of their size during that period. Photographs indicate that the glaciers today are only half

6042-668: Is particularly acute for irrigation in South America, where numerous artificial lakes are filled almost exclusively by glacial melt. Central Asian countries have also been historically dependent on the seasonal glacier melt water for irrigation and drinking supplies. In Norway, the Alps, and the Pacific Northwest of North America, glacier runoff is important for hydropower . In the Himalayas , retreating glaciers could reduce summer water flows by up to two thirds. In

6201-450: 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

6360-444: 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

6519-516: 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

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6678-407: 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

6837-403: Is thinning along the entire length of the glacier. This indicates a diminishment of the accumulation zone. The result is marginal recession of the accumulation zone margin, not just of the terminus. In effect, the glacier no longer has a consistent accumulation zone and without an accumulation zone cannot survive. Water runoff from melting glaciers causes global sea level to rise , a phenomenon

6996-417: 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

7155-564: The Aconcagua River Basin, glacier retreat has resulted in a 20% loss in glacier area, declining from 151 km (58 sq mi) to 121 km (47 sq mi). The Marinelli Glacier in Tierra del Fuego has been in retreat since at least 1960 through 2008. In New Zealand, mountain glaciers have been in general retreat since 1890, with an acceleration since 1920. Most have measurably thinned and reduced in size, and

7314-595: The Aleutian Low , has much more extensive glaciation totaling around 906 km (350 sq mi) with 448 known glaciers as of 2010. Despite generally heavy winter snowfall and cool summer temperatures, the high summer rainfall of the more southerly Kuril Islands and Sakhalin in historic times melt rates have been too high for a positive mass balance even on the highest peaks. In the Chukotskiy Peninsula small alpine glaciers are numerous, but

7473-710: The Alps ; the Pyrenees ; Rocky Mountains ; the Caucasus and Pacific Coast Ranges of North America; the Patagonian Andes in South America; and mountain ranges in New Zealand. Glaciers in these latitudes are more widespread and tend to be greater in mass the closer they are to the polar regions. They are the most widely studied over the past 150 years. As with examples located in the tropical zone, virtually all

7632-511: 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

7791-661: 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

7950-599: The Exxon Valdez oil spill, when the tanker changed course to avoid the ice tips. The Valdez Glacier is in the same area, and though it does not calve, has also retreated significantly. "A 2005 aerial survey of Alaskan coastal glaciers identified more than a dozen glaciers, many former tidewater and calving glaciers, including Grand Plateau, Alsek , Bear, and Excelsior Glaciers that are rapidly retreating. Of 2,000 glaciers observed, 99% are retreating." Icy Bay in Alaska

8109-690: The Ganges area, this would cause a water shortage for 500 million people. In the Hindu Kush Himalaya area, around 1.4 billion people are dependent on the five main rivers of the Himalaya mountains. Although the impact will vary from place to place, the amount of meltwater is likely to increase at first as glaciers retreat. Then it will gradually decrease because of the fall in glacier mass. Many species of freshwater and saltwater plants and animals are dependent on glacier-fed waters to ensure

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8268-573: 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

8427-840: 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

8586-455: The IPCC terms a "slow onset" event. The potential for major sea level rise depends mostly on a significant melting of the polar ice caps of Greenland and Antarctica, as this is where the vast majority of glacial ice is located. If all the ice on the polar ice caps were to melt away, the oceans of the world would rise an estimated 70 m (230 ft). Although previously it was thought that

8745-635: 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

8904-933: The Juneau Icefield since 1946. On the west side of the ice field, the terminus of the Mendenhall Glacier , which flows into suburban Juneau, Alaska , has retreated 580 m (1,900 ft). Of the nineteen glaciers of the Juneau Icefield, eighteen are retreating, and one, the Taku Glacier, is advancing. Eleven of the glaciers have retreated more than 1 km (0.62 mi) since 1948 – Antler Glacier, 5.4 km (3.4 mi); Gilkey Glacier, 3.5 km (2.2 mi); Norris Glacier, 1.1 km (0.68 mi) and Lemon Creek Glacier, 1.5 km (0.93 mi). Taku Glacier has been advancing since at least 1890, when naturalist John Muir observed

9063-646: The Selkirk Mountains (west of the Rockies) has retreated 2 km (1.2 mi) since first photographed in 1887. In Garibaldi Provincial Park in Southwestern British Columbia over 505 km (195 sq mi), or 26%, of the park, was covered by glacier ice at the beginning of the 18th century. Ice cover decreased to 297 km (115 sq mi) by 1987–1988 and to 245 km (95 sq mi) by 2005, 50% of

9222-548: The Sforzellina Glacier in the Italian Alps indicated that the rate of retreat from 2002 to 2006 was much higher than in the preceding 35 years. To study glaciers located in the alpine regions of Lombardy, researchers compared a series of aerial and ground images taken from the 1950s through the early 21st century and deduced that between the years 1954–2003 the mostly smaller glaciers found there lost more than half of their area. Repeat photography of glaciers in

9381-710: The Svartisen ice cap , had several advances in the 20th century, though it retreated 200 m (660 ft) between 1999 and 2014. Brenndalsbreen glacier retreated 56 m (184 ft) between the years 2000 and 2014, while the Rembesdalsskåka glacier, which has retreated 2 km (1.2 mi) since the end of the Little Ice Age, retreated 200 m (660 ft) between 1997 and 2007. The Briksdalsbreen glacier retreated 230 m (750 ft) between 1996 and 2004 with 130 m (430 ft) of that in

9540-679: The Tien Shan mountains, which Kyrgyzstan shares with China and Kazakhstan , studies in the northern areas of that mountain range show that the glaciers that help supply water to this arid region, lost nearly 2 km (0.48 cu mi) of ice per year between 1955 and 2000. The University of Oxford study also reported that an average of 1.28% of the volume of these glaciers had been lost per year between 1974 and 1990. The Pamirs mountain range located primarily in Tajikistan , has approximately eight thousand glaciers, many of which are in

9699-518: 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

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9858-414: 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

10017-402: 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

10176-971: 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

10335-441: The oceans , may affect existing fisheries upon which humans depend as well. One major concern is the increased risk of Glacial Lake Outburst Floods (GLOF), which have in the past had great effect on lives and property. Glacier meltwater left behind by the retreating glacier is often held back by moraines that can be unstable and have been known to collapse if breached or displaced by earthquakes, landslides or avalanches. If

10494-463: The polar regions . Glaciers also exist in mountain ranges on every continent other than the Australian mainland, including Oceania's high-latitude oceanic island countries such as New Zealand . Glacial bodies larger than 50,000 km (19,000 sq mi) are called ice sheets . They are several kilometers deep and obscure the underlying topography. Deglaciation occurs naturally at

10653-432: 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

10812-521: The 1850 area. The 50 km (19 sq mi) loss in the last 20 years coincides with negative mass balance in the region. During this period all nine glaciers examined have retreated significantly. There are thousands of glaciers in Alaska but only few have been named. The Columbia Glacier near Valdez in Prince William Sound retreated 15 km (9.3 mi) in the 25 years from 1980 to 2005. Its calved icebergs partially caused

10971-405: 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

11130-612: 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

11289-500: 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

11448-401: The 21st century if current climate trends persist. The Bossons Glacier once extended from the summit of Mont Blanc at 4,807 m (15,771 ft) to an elevation of 1,050 m (3,440 ft) in 1900. By 2008 Bossons Glacier had retreated to a point that was 1,400 m (4,600 ft) above sea level. Other researchers have found that glaciers across the Alps appear to be retreating at

11607-651: The 26 years from 1993 to 2018 were likely 5500 gigatons, or 210 gigatons per yr. The Little Ice Age was a period from about 1550 to 1850 when certain regions experienced relatively cooler temperatures compared to the time before and after. Subsequently, until about 1940, glaciers around the world retreated as the climate warmed substantially. Glacial retreat slowed and even reversed temporarily, in many cases, between 1950 and 1980 as global temperatures cooled slightly . Since 1980, climate change has led to glacier retreat becoming increasingly rapid and ubiquitous, so much so that some glaciers have disappeared altogether, and

11766-415: The Alps indicates that there has been significant retreat since studies commenced. Research, published in 2019 by ETH Zurich, says that two-thirds of the ice in the glaciers of the Alps is doomed to melt by the end of the century due to climate change. In the most pessimistic scenario, the Alps will be almost completely ice-free by 2100, with only isolated ice patches remaining at high elevation. Though

11925-440: 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

12084-435: 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,

12243-545: 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

12402-1077: The Earth Journalism Network awards fellowships to journalists which allow them to attend conferences within the field of environmentalism. In particular, EJN’s Climate Change Media Partnership, currently run together with the Stanley Center for Peace and Security based in Muscatine, Iowa, has brought more than 500 journalists to the UNFCCC Conferences of the Parties (COPs) since 2007. CCMP is EJN’s most popular program, drawing more than 500 applications each year for only 20 spots. Applications typically open in May or June of each year, with final results announced in September. EJN has also offered fellowships to other COPs, including

12561-621: The Earth Journalism Network established a partnership with the graduate School of Communication of the University of California in Berkeley. In September 2012, the Earth Journalism Network and the Society of Environmental Journalists circulated a joint petition calling on the Cambodian government to launch a full investigation into the murder of environmental journalist Hang Serei Oudom . Oudom had been covering illegal logging activities for

12720-604: 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,

12879-648: The Greater Himalaya that has seen glacial advances is in the Karakoram Range and only in the highest elevation glaciers, but this has been attributed possibly increased precipitation as well as to the correlating glacial surges, where the glacier tongue advances due to pressure build up from snow and ice accumulation further up the glacier. Between the years 1997 and 2001, 68 km (42 mi) long Biafo Glacier thickened 10 to 25 m (33 to 82 ft) mid-glacier, however it did not advance. With

13038-656: The North Cascade glaciers were retreating and the pace had increased each decade since the mid-1970s. Between 1984 and 2005 the North Cascade glaciers lost an average of more than 12.5 metres (41 ft) in thickness and 20–40 percent of their volume. Glaciologists researching the North Cascades found that all 47 monitored glaciers are receding while four glaciers— Spider Glacier , Lewis Glacier , Milk Lake Glacier and Mt. David Glacier—are almost completely gone. The White Chuck Glacier (near Glacier Peak )

13197-547: The Toklat Glacier has been retreating 26 m (85 ft) per year and the Muldrow Glacier has thinned 20 m (66 ft) since 1979. Well documented in Alaska are surging glaciers that have been known to rapidly advance, even as much as 100 m (330 ft) per day. Variegated , Black Rapids, Muldrow , Susitna and Yanert are examples of surging glaciers in Alaska that have made rapid advances in

13356-539: The UN Convention on Biological Diversity and the UN Convention to Combat Desertification; other fellowships have included visits to the UN Ocean Conference, World Conservation Congress, World Water Forum, Global Environment Facility Assembly, among others. Prior to and throughout these events, EJN holds workshops to train reporters on environmental journalism best practices. At the start of 2013,

13515-445: The ablation zone of the glaciers, with recession of several hundred meters being observed for some glaciers. The Altai region has also experienced an overall temperature increase of 1.2 degrees Celsius in the last 120 years according to a report from 2006, with most of that increase occurring since the late 20th century. In the more maritime and generally wetter Russian Far East , Kamchatka , exposed during winter to moisture from

13674-441: 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

13833-624: The advance; however, since 1988 the mass balance has been slightly negative, which should in the future slow the advance of this mighty glacier. Long-term mass balance records from Lemon Creek Glacier in Alaska show slightly declining mass balance with time. The mean annual balance for this glacier was −0.23 m (0.75 ft) each year during the period of 1957 to 1976. Mean annual balance has been increasingly negatively averaging −1.04 m (3.4 ft) per year from 1990 to 2005. Repeat glacier altimetry, or altitude measuring, for 67 Alaska glaciers find rates of thinning have increased by more than

13992-508: The alps since 1850, a decrease of the glaciers' albedo , caused by industrial black carbon can be identified. According to a report, this may have accelerated the retreat of glaciers in Europe which otherwise might have continued to expand until approximately the year 1910. All the glaciers in Turkey are in retreat and glaciers have been developing proglacial lakes at their terminal ends as

14151-411: 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

14310-452: 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

14469-454: 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

14628-540: 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

14787-728: The climate continues to warm, but will be much reduced in size. On the sheltered slopes of the highest peaks of Glacier National Park in Montana , the eponymous glaciers are diminishing rapidly. The area of each glacier has been mapped for decades by the National Park Service and the U.S. Geological Survey. Comparing photographs from the mid-19th century with contemporary images provides ample evidence that they have retreated notably since 1850. Repeat photography since clearly show that glaciers such as Grinnell Glacier are all retreating. The larger glaciers are now approximately

14946-551: 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

15105-441: The cold water habitat to which they have adapted. Some species of freshwater fish need cold water to survive and to reproduce, and this is especially true with salmon and cutthroat trout . Reduced glacial runoff can lead to insufficient stream flow to allow these species to thrive. Alterations to the ocean currents , due to increased freshwater inputs from glacier melt, and the potential alterations to thermohaline circulation of

15264-684: 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

15423-593: The danger of future GLOFs. Middle latitude glaciers are located either between the Tropic of Cancer and the Arctic Circle , or between the Tropic of Capricorn and the Antarctic Circle . Both areas support glacier ice from mountain glaciers, valley glaciers and even smaller icecaps, which are usually located in higher mountainous regions. All are located in mountain ranges, notably the Himalayas ;

15582-403: 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

15741-427: 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

15900-401: 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

16059-444: 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

16218-414: The early 1970s and early 2000s, there had been a 9 percent reduction in ice mass, while there has been a significant increase in mass loss since the Little Ice Age with a 10-fold increase when compared to rates seen currently. Change in temperature has led to melting and the formation and expansion of glacial lakes which could cause an increase in the number of glacial lake outburst floods (GLOFs). If

16377-610: 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

16536-853: 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. Retreat of glaciers since 1850 The retreat of glaciers since 1850

16695-431: The end of ice ages . But the current glacier retreat is accelerated by global warming due to human-caused greenhouse gas emissions . Human activities since the start of the industrial era have increased the concentration of carbon dioxide and other heat-trapping greenhouse gases in the air, causing current global warming. Human influence is the principal driver of changes to the cryosphere , of which glaciers are

16854-430: 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

17013-421: The existence of many of the remaining glaciers is threatened. The mass balance, or difference between accumulation and ablation (melting and sublimation ), of a glacier is crucial to its survival. Climate change may cause variations in both temperature and snowfall, resulting in changes in mass balance. A glacier with a sustained negative balance loses equilibrium and retreats. A sustained positive balance

17172-409: The extent of glaciation, though larger than further west, is much smaller than in Kamchatka, totaling around 300 square kilometres (120 sq mi). Details on the retreat of Siberian and Russian Far East glaciers have been less adequate than in most other glaciated areas of the world. There are several reasons for this, the principal one being that since the collapse of Communism there has been

17331-578: The front of the main Himalaya of 15 glaciers examined from 1976 to 2007 all retreated significantly and the average retreat was 28 m (92 ft) per year. The most famous of these, the Khumbu Glacier, retreated at a rate of 18 m (59 ft) per year from 1976 to 2007. In India, the Gangotri Glacier retreated 1,147 m (3,763 ft) between the years 1936 and 1996 with 850 m (2,790 ft) of that retreat occurring in

17490-693: The glacial area in the U.S. is contained within the over 700 glaciers of the North Cascades , a portion of those located between the Canada–US border and I-90 in central Washington . These contain as much water as is found in all the lakes and reservoirs in the rest of the state, and provide much of the stream and river flow in the dry summer months, approximating some 870,000 m (1,140,000 cu yd). As recently as 1975 many North Cascade glaciers were advancing due to cooler weather and increased precipitation that occurred from 1944 to 1976. By 1987

17649-631: The glacial retreat over the past 20 years. Satellite imagery indicates that these lakes are continuing to expand. There has been significant and ongoing ice volume losses on the largest New Zealand glaciers, including the Tasman , Ivory, Classen, Mueller , Maud, Hooker , Grey, Godley, Ramsay, Murchison , Therma, Volta and Douglas Glaciers. The retreat of these glaciers has been marked by expanding proglacial lakes and terminus region thinning. The loss in Southern Alps total ice volume from 1976 to 2014

17808-809: The glaciers in the mid-latitudes are in a state of negative mass balance and are retreating. All the glaciers in the French alps are retreating. On Mont Blanc , the highest peak in the Alps, the Argentière Glacier has receded 1,150 m (3,770 ft) since 1870. Other Mont Blanc glaciers have also been in retreat, including the Mer de Glace , which is the largest glacier in France at 12 km (7.5 mi) in length but retreated 500 m (1,600 ft) between 1994 and 2008. The Argentière and Mer de Glace glaciers are expected to disappear completely by end of

17967-579: The glaciers of the Alps have received more attention from glaciologists than in other areas of Europe, research indicates that glaciers in northern Europe are also retreating. Since the end of World War II, Storglaciären in Sweden has undergone the longest continuous mass balance study in the world conducted from the Tarfala research station . In the Kebnekaise Mountains of northern Sweden ,

18126-603: The glaciers studied were retreating. After 1990, 95% of these glaciers were measured to be retreating, indicating that retreat of these glaciers was becoming more widespread. Glaciers in the Mount Everest region of the Himalayas are all in a state of retreat. The Rongbuk Glacier , draining the north side of Mount Everest into Tibet , has been retreating 20 m (66 ft) per year. In the Khumbu region of Nepal along

18285-417: The glaciers thin and retreat. Between the 1970s and 2013, the glaciers in Turkey lost half their area, going from 25 km (9.7 sq mi) in the 1970s to 10.85 km (4.19 sq mi) in 2013. Of the 14 glaciers studied, five had disappeared altogether. Mount Ararat has the largest glacier in Turkey, and that is forecast to be completely gone by 2065. Siberia is typically classified as

18444-604: 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

18603-497: The greater Himalayas, with double that number in the Hindu Kush and Karakoram and Tien Shan ranges, and comprise the largest glaciated region outside the poles. These glaciers provide critical water supplies to arid countries such as Mongolia , western China, Pakistan , Afghanistan and India . As with glaciers worldwide, those of the greater Himalayan region are experiencing a decline in mass, and researchers claim that between

18762-473: The greatest risk. In 1892 a GLOF released some 200,000 m (260,000 cu yd) of water from the lake of the Tête Rousse Glacier , resulting in the deaths of 200 people in the French town of Saint-Gervais-les-Bains . GLOFs have been known to occur in every region of the world where glaciers are located. Continued glacier retreat is expected to create and expand glacial lakes, increasing

18921-555: The lake had swollen to a length of 1.94 km (1.21 mi), 1.13 km (0.70 mi) in width and a depth of 107 m (351 ft). In 1994 a GLOF from Luggye Tsho, a glacial lake adjacent to Raphstreng Tsho, killed 23 people downstream. Glaciers in the Ak-shirak Range in Kyrgyzstan experienced a slight loss between 1943 and 1977 and an accelerated loss of 20% of their remaining mass between 1977 and 2001. In

19080-491: The large ice caps on the highest Andes will be gone if current climate trends continue. In Patagonia on the southern tip of the continent, the large ice caps have retreated a 1 km (0.62 mi) since the early 1990s and 10 km (6.2 mi) since the late 19th century. It has also been observed that Patagonian glaciers are receding at a faster rate than in any other world region. The Northern Patagonian Ice Field lost 93 km (36 sq mi) of glacier area during

19239-807: The largest proportionate glacial losses. Examples of such mountain ranges are the Himalayas in Asia, the Rocky Mountains and the Cascade Range in North America, the Alps in Europe, the Southern Alps in New Zealand, the southern Andes in South America, as well as isolated tropical summits such as Mount Kilimanjaro in Africa. Glacial ice is the largest reservoir of fresh water on Earth, holding with ice sheets about 69 percent of

19398-572: 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

19557-499: The last 25 years of the 20th century. However, the glacier is still over 30 km (19 mi) long. In Sikkim , 26 glaciers examined between the years 1976 and 2005 were retreating at an average rate of 13.02 m (42.7 ft) per year. Overall, glaciers in the Greater Himalayan region that have been studied are retreating an average of between 18 and 20 m (59 and 66 ft) annually. The only region in

19716-436: 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

19875-483: The last year of that study; the greatest annual retreat recorded on that glacier since studies began there in 1900. This figure was exceeded in 2006 with five glaciers retreating over 100 m (330 ft) from the fall of 2005 to the fall of 2006. Four outlets from the Jostedalsbreen ice cap, the largest body of ice in continental Europe, Kjenndalsbreen , Brenndalsbreen, Briksdalsbreen and Bergsetbreen had

20034-441: 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

20193-498: The late 19th century. Aletsch Glacier retreated 2.8 km (1.7 mi) from 1880 to 2009. This rate of retreat has also increased since 1980, with 30%, or 800 m (2,600 ft), of the total retreat occurring in the last 20% of the time period. The Morteratsch Glacier in Switzerland has had one of the longest periods of scientific study with yearly measurements of the glacier's length commencing in 1878. The overall retreat from 1878 to 1998 has been 2 km (1.2 mi) with

20352-544: The late 19th century. Its rate of retreat has increased since 1980, following a period of slow retreat from 1950 to 1980. The Peyto Glacier in Alberta covers an area of about 12 km (4.6 sq mi), and retreated rapidly during the first half of the 20th century, stabilized by 1966, and resumed shrinking in 1976. The Illecillewaet Glacier in British Columbia's Glacier National Park (Canada) , part of

20511-760: The local newspaper Vorakchun Khmer Daily when his body was discovered with several axe blows to the head. The New York Times ' Andrew Revkin called attention to this petition on his blog Dot Earth . James Fahn is the executive director of Earth Journalism Network. Fahn was originally based in Thailand for nine years where he was a reporter and editor for The Nation , an English-language daily newspaper based in Bangkok. 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

20670-608: The lower atmosphere. Carbon dioxide , the primary greenhouse gas driving global warming, has grown by about 50% and 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

20829-476: The mass balance of a significant portion of the accumulation zone of the glacier is negative, it is in disequilibrium with the climate and will melt away without a colder climate and/or an increase in frozen precipitation. For example, Easton Glacier in Washington state, U.S. will likely shrink to half its size but at a slowing rate of reduction and stabilize at that size despite the warmer temperature over

20988-413: 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

21147-411: The most sensitive indicators of climate change . The retreat of glaciers is also a major reason for sea level rise . Excluding peripheral glaciers of ice sheets , the total cumulated global glacial losses over the 26 years from 1993 to 2018 were likely 5500 gigatons, or 210 gigatons per year. On Earth, 99% of glacial ice is contained within vast ice sheets (also known as "continental glaciers") in

21306-433: The past. These glaciers are all retreating overall, punctuated by short periods of advance. A large region of population surrounding the central and southern Andes of Argentina and Chile reside in arid areas that are dependent on water supplies from melting glaciers. The water from the glaciers also supplies rivers that have in some cases been dammed for hydroelectric power. Some researchers believe that by 2030, many of

21465-639: The period 1947–96, with a net gain of 4.1 km (2.5 mi). This glacier has advanced since 1947, and has been essentially stable since 1992. Perito Moreno Glacier is one of three glaciers in Patagonia known to have advanced, compared to several hundred others in retreat. The two major glaciers of the Southern Patagonia Icefield to the north of Moreno, Upsala and Viedma Glacier have retreated 4.6 km (2.9 mi) in 21 years and 1 km (0.62 mi) in 13 years respectively. In

21624-455: The period 1989–1995. However, reduced snowfall since has caused most Norwegian glaciers to retreat significantly. A survey of 31 Norwegian glaciers in 2010 indicated that 27 were in retreat, one had no change and three advanced. Similarly, in 2013, of 33 Norwegian glaciers surveyed, 26 were retreating, four showed no change and three advanced. Engabreen Glacier in Norway, an outlet glacier of

21783-481: The polar ice caps were not contributing heavily to sea level rise (IPCC 2007), recent studies have confirmed that both Antarctica and Greenland are contributing 0.5 millimetres (0.020 in) a year each to global sea level rise. The Thwaites Glacier alone, in Western Antarctica is "currently responsible for approximately 4 percent of global sea level rise. It holds enough ice to raise the world ocean

21942-775: The present trends persist the ice mass will gradually be reduced, and will affect the availability of water resources, though water loss is not expected to cause problems for many decades. In the Wakhan Corridor of Afghanistan 28 of 30 glaciers examined retreated significantly between 1976 and 2003, with an average retreat of 11 m (36 ft) per year. One of these glaciers, the Zemestan Glacier , retreated 460 m (1,510 ft) during this period, not quite 10% of its 5.2 km (3.2 mi) length. In examining 612 glaciers in China between 1950 and 1970, 53% of

22101-619: 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

22260-522: 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

22419-622: 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

22578-405: 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

22737-411: 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

22896-476: 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

23055-807: The remaining glaciers in Wyoming will disappear by the middle of the 21st century if the current climate patterns continue. In the Canadian Rockies , glaciers are generally larger and more widespread than to the south in the Rocky Mountains. One of the more accessible in the Canadian Rockies is the Athabasca Glacier , which is an outlet glacier of the 325 km (125 sq mi) Columbia Icefield . The Athabasca Glacier has retreated 1,500 m (4,900 ft) since

23214-591: The retreat of glaciers in the Himalayas, a number of glacial lakes have been created. A growing concern is the potential for GLOFs researchers estimate 21 glacial lakes in Nepal and 24 in Bhutan pose hazards to human populations should their terminal moraines fail. One glacial lake identified as potentially hazardous is Bhutan's Raphstreng Tsho , which measured 1.6 km (0.99 mi) long, 0.96 km (0.60 mi) wide and 80 m (260 ft) deep in 1986. By 1995

23373-510: The same period. The reduced snowpack has occurred despite a small increase in winter precipitation—thus, it reflects warmer winter temperatures leading to rainfall and melting on glaciers even during the winter. As of 2005, 67% of the North Cascade glaciers observed are in disequilibrium and will not survive the continuation of the present climate. These glaciers will eventually disappear unless temperatures fall and frozen precipitation increases. The remaining glaciers are expected to stabilize, unless

23532-583: 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

23691-458: The size as when first photographed in the late 1890s. Research also indicates that the glacial retreat was proportionately greater in the 1990s than in any other decade over the last 100 years. Gannett Glacier on the northeast slope of Gannett Peak is the largest single glacier in the Rocky Mountains south of Canada. It has reportedly lost over 50% of its volume since 1920, with almost half of that loss occurring since 1980. Glaciologists believe

23850-445: The snow accumulation zones have risen in elevation as the 20th century progressed. Between 1971 and 1975 Ivory Glacier receded 30 m (98 ft) from the glacial terminus, and about 26% of its surface area was lost. Since 1980 numerous small glacial lakes formed behind the new terminal moraines of several of these glaciers. Glaciers such as Classen, Godley and Douglas now all have new glacial lakes below their terminal locations due to

24009-586: The spine of the Rocky Mountains in the United States and Canada, and the Pacific Coast Ranges extending from northern California to Alaska . While Greenland is geologically associated with North America, it is also a part of the Arctic region. Apart from the few tidewater glaciers such as Taku Glacier , in the advance stage of their tidewater glacier cycle prevalent along the coast of Alaska, virtually all of those in North America are in

24168-419: The terminal moraine is not strong enough to hold the rising water behind it, it can burst, leading to a massive localized flood. The likelihood of such events is rising due to the creation and expansion of glacial lakes resulting from glacier retreat. Past floods have been deadly and have resulted in enormous property damage. Towns and villages in steep, narrow valleys that are downstream from glacial lakes are at

24327-463: The world's freshwater. The retreat of glaciers has near term impacts on the availability of fresh water for drinking water and irrigation . For example, in the Andes and Himalayas the demise of glaciers will affect water supplies for people in that region. Melting glaciers also lead the sea level rise. Excluding peripheral glaciers of ice sheets , the total cumulated global glacial losses over

24486-438: 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

24645-480: The years 1966 and 2000. Tajikistan and neighboring countries of the Pamir Range are highly dependent upon glacial runoff to ensure river flow during droughts and the dry seasons experienced every year. The continued demise of glacier ice will result in a short-term increase, followed by a long-term decrease in glacial melt water flowing into rivers and streams. North American glaciers are primarily located along

24804-466: The years between 1944 and 1986. The largest retreat was on O'Higgins Glacier , which during the period 1896–1995 retreated 14.6 km (9.1 mi). The Perito Moreno Glacier is 30 km (19 mi) long and is a major outflow glacier of the Patagonian ice sheet, as well as the most visited glacier in Patagonia. Perito Moreno Glacier is in equilibrium, but has undergone frequent oscillations in

24963-401: The years between 1945 and 1975, and 174 km (67 sq mi) from 1975 to 1996, which indicates that the rate of retreat is increasing. This represents a loss of 8% of the ice field, with all glaciers experiencing significant retreat. The Southern Patagonian Ice Field has exhibited a general trend of retreat on 42 glaciers, while four glaciers were in equilibrium and two advanced during

25122-475: Was followed by a 743 metres (2,438 ft) advance by 1979. The glacier again retreated 450 m (1,480 ft) from 1987 to 2005, leaving barren terrain behind. This retreat has occurred during a period of reduced winter snowfall and higher summer temperatures. In this region of the Cascades, winter snowpack has declined 25% since 1946, and summer temperatures have risen 0.7  °C (1.2  °F ) during

25281-524: 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

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