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113-476: A col in geomorphology is the lowest point on a mountain ridge between two peaks . It may also be called a gap or pass . Particularly rugged and forbidding cols in the terrain are usually referred to as notches . They are generally unsuitable as mountain passes , but are occasionally crossed by mule tracks or climbers' routes. Derived from the French col ("collar, neck") from Latin collum , "neck",

226-532: A {\displaystyle a} = surface albedo, c c {\displaystyle cc} = carbon cycle, p {\displaystyle p} = Planck response, and l r {\displaystyle lr} = lapse rate. All quantities are understood to be global averages, while T is usually translated to temperature at the surface because of its direct relevance to humans and much other life. The negative Planck response, being an especially strong function of temperature,

339-406: A relatively stable equilibrium state , one may consider a perturbation to EEI as indicated by the symbol Δ. Such a perturbation is induced by a radiative forcing ( ΔF ) which can be natural or man-made. Responses within the system to either return towards the stable state, or to move further away from the stable state are called feedbacks λΔT : Collectively the feedbacks are approximated by

452-414: A concept of physiographic regions while a conflicting trend among geographers was to equate physiography with "pure morphology", separated from its geological heritage. In the period following World War II, the emergence of process, climatic, and quantitative studies led to a preference by many earth scientists for the term "geomorphology" in order to suggest an analytical approach to landscapes rather than

565-492: A cooling effect of 0.2 °C (0.36 °F) over a 1000-year average, though the research on these timescales has been limited. An even longer-term effect is the ice-albedo feedback from ice sheets reaching their ultimate state in response to whatever the long-term temperature change would be. Unless the warming is reversed entirely, this feedback would be positive. The total loss of the Greenland Ice Sheet

678-463: A cooling effect. Brighter and more reflective surfaces have a high albedo and darker surfaces have a low albedo, so they heat up more. The most reflective surfaces are ice and snow , so surface albedo changes are overwhelmingly associated with what is known as the ice-albedo feedback. A minority of the effect is also associated with changes in physical oceanography , soil moisture and vegetation cover. The presence of ice cover and sea ice makes

791-491: A decline in the popularity of climatic geomorphology in the late 20th century. Stoddart criticized climatic geomorphology for applying supposedly "trivial" methodologies in establishing landform differences between morphoclimatic zones, being linked to Davisian geomorphology and by allegedly neglecting the fact that physical laws governing processes are the same across the globe. In addition some conceptions of climatic geomorphology, like that which holds that chemical weathering

904-438: A descriptive one. During the age of New Imperialism in the late 19th century European explorers and scientists traveled across the globe bringing descriptions of landscapes and landforms. As geographical knowledge increased over time these observations were systematized in a search for regional patterns. Climate emerged thus as prime factor for explaining landform distribution at a grand scale. The rise of climatic geomorphology

1017-574: A fictional dialogue where the immortal Magu explained that the territory of the East China Sea was once a land filled with mulberry trees . The term geomorphology seems to have been first used by Laumann in an 1858 work written in German. Keith Tinkler has suggested that the word came into general use in English, German and French after John Wesley Powell and W. J. McGee used it during

1130-535: A known positive feedback. I.e. long-term warming changes the balance in the methane-related microbial community within freshwater ecosystems so they produce more methane while proportionately less is oxidised to carbon dioxide. There would also be biogeophysical changes which affect the albedo. For instance, larch in some sub-arctic forests are being replaced by spruce trees. This has a limited contribution to warming, because larch trees shed their needles in winter and so they end up more extensively covered in snow than

1243-803: A large amount of methane is trapped within a crystal structure of water, forming a solid similar to ice . On Earth, they generally lie beneath sediments on the ocean floors, (approximately 1,100 m (3,600 ft) below the sea level). Around 2008, there was a serious concern that a large amount of hydrates from relatively shallow deposits in the Arctic, particularly around the East Siberian Arctic Shelf , could quickly break down and release large amounts of methane, potentially leading to 6 °C (11 °F) within 80 years. Current research shows that hydrates react very slowly to warming, and that it's very difficult for methane to reach

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1356-435: A mountain belt to promote further erosion as mass is removed from the chain and the belt uplifts. Long-term plate tectonic dynamics give rise to orogenic belts , large mountain chains with typical lifetimes of many tens of millions of years, which form focal points for high rates of fluvial and hillslope processes and thus long-term sediment production. Features of deeper mantle dynamics such as plumes and delamination of

1469-525: A short period of time, making them extremely important entities in the high latitudes and meaning that they set the conditions in the headwaters of mountain-born streams; glaciology therefore is important in geomorphology. Climate change feedback Climate change feedbacks are natural processes that impact how much global temperatures will increase for a given amount of greenhouse gas emissions . Positive feedbacks amplify global warming while negative feedbacks diminish it. Feedbacks influence both

1582-430: A target stabilization level of atmospheric greenhouse gas concentrations, or on a target for limiting global warming to a particular magnitude. Both of these targets (concentrations or temperatures) require an understanding of future changes in the carbon cycle. If models incorrectly project future changes in the carbon cycle, then concentration or temperature targets could be missed. For example, if models underestimate

1695-490: A valley causes abrasion and plucking of the underlying rock . Abrasion produces fine sediment, termed glacial flour . The debris transported by the glacier, when the glacier recedes, is termed a moraine . Glacial erosion is responsible for U-shaped valleys, as opposed to the V-shaped valleys of fluvial origin. The way glacial processes interact with other landscape elements, particularly hillslope and fluvial processes,

1808-659: A very brief outline of some of the major figures and events in its development. The study of landforms and the evolution of the Earth's surface can be dated back to scholars of Classical Greece . In the 5th century BC, Greek historian Herodotus argued from observations of soils that the Nile delta was actively growing into the Mediterranean Sea , and estimated its age. In the 4th century BC, Greek philosopher Aristotle speculated that due to sediment transport into

1921-443: Is high confidence that the total land carbon sink will remain positive. Release of gases of biological origin would be affected by global warming, and this includes climate-relevant gases such as methane , nitrous oxide or dimethyl sulfide . Others, such as dimethyl sulfide released from oceans, have indirect effects. Emissions of methane from land (particularly from wetlands ) and of nitrous oxide from land and oceans are

2034-457: Is "the most fundamental feedback in the climate system". As the temperature of a black body increases, the emission of infrared radiation increases with the fourth power of its absolute temperature according to the Stefan–Boltzmann law . This increases the amount of outgoing radiation back into space as the Earth warms. It is a strong stabilizing response and has sometimes been called

2147-450: Is a greenhouse gas , the increase in water vapor content makes the atmosphere warm further, which allows the atmosphere to hold still more water vapor. Thus, a positive feedback loop is formed, which continues until the negative feedbacks bring the system to equilibrium. Increases in atmospheric water vapor have been detected from satellites , and calculations based on these observations place this feedback strength at 1.85 ± 0.32 m /K. This

2260-440: Is absorbed). However, increased droughts in certain regions can still limit plant growth, and the warming beyond optimum conditions has a consistently negative impact. Thus, estimates for the 21st century show that plants would become a lot more abundant at high latitudes near the poles but grow much less near the tropics - there is only medium confidence that tropical ecosystems would gain more carbon relative to now. However, there

2373-603: Is an important aspect of Plio-Pleistocene landscape evolution and its sedimentary record in many high mountain environments. Environments that have been relatively recently glaciated but are no longer may still show elevated landscape change rates compared to those that have never been glaciated. Nonglacial geomorphic processes which nevertheless have been conditioned by past glaciation are termed paraglacial processes. This concept contrasts with periglacial processes, which are directly driven by formation or melting of ice or frost. Soil , regolith , and rock move downslope under

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2486-445: Is called a positive feedback while a feedback that reduces an initial change is called a negative feedback . Climate change feedbacks are in the context of global warming, so positive feedbacks enhance warming and negative feedbacks diminish it. Naming a feedback positive or negative does not imply that the feedback is good or bad. The initial change that triggers a feedback may be externally forced , or may arise through

2599-732: Is drawn out over several centuries. Feedbacks can also result in localized differences, such as polar amplification resulting from feedbacks that include reduced snow and ice cover. While basic relationships are well understood, feedback uncertainty exists in certain areas, particularly regarding cloud feedbacks. Carbon cycle uncertainty is driven by the large rates at which CO 2 is both absorbed into plants and released when biomass burns or decays. For instance, permafrost thaw produces both CO 2 and methane emissions in ways that are difficult to model. Climate change scenarios use models to estimate how Earth will respond to greenhouse gas emissions over time, including how feedbacks will change as

2712-412: Is dynamic. In the future, if the emissions decrease, the fraction they absorb will increase , and they will absorb up to three-quarters of the remaining emissions - yet, the raw amount absorbed will decrease from the present. On the contrary, if the emissions will increase, then the raw amount absorbed will increase from now, yet the fraction could decline to one-third by the end of the 21st century. If

2825-562: Is estimated to add 0.13 °C (0.23 °F) to global warming (with a range of 0.04–0.06 °C), while the loss of the West Antarctic Ice Sheet adds 0.05 °C (0.090 °F) (0.04–0.06 °C), and East Antarctic ice sheet 0.6 °C (1.1 °F) Total loss of the Greenland ice sheet would also increase regional temperatures in the Arctic by between 0.5 °C (0.90 °F) and 3 °C (5.4 °F), while

2938-501: Is expected to alter the distribution of cloud types in a way which collectively reduces their cooling and thus accelerates overall warming. While changes to clouds act as a negative feedback in some latitudes, they represent a clear positive feedback on a global scale. As of 2021, cloud feedback strength is estimated at 0.42 [–0.10 to 0.94] W m /K. This is the largest confidence interval of any climate feedback, and it occurs because some cloud types (most of which are present over

3051-699: Is extremely important in sedimentology . Weathering is the chemical and physical disruption of earth materials in place on exposure to atmospheric or near surface agents, and is typically studied by soil scientists and environmental chemists , but is an essential component of geomorphology because it is what provides the material that can be moved in the first place. Civil and environmental engineers are concerned with erosion and sediment transport, especially related to canals , slope stability (and natural hazards ), water quality , coastal environmental management, transport of contaminants, and stream restoration . Glaciers can cause extensive erosion and deposition in

3164-578: Is found. Consequently, recent Arctic sea ice decline is a key reason behind the Arctic warming nearly four times faster than the global average since 1979 (the start of continuous satellite readings), in a phenomenon known as Arctic amplification . Conversely, the high stability of ice cover in Antarctica , where the East Antarctic ice sheet rises nearly 4 km above the sea level, means that it has experienced very little net warming over

3277-482: Is higher in a warmer atmosphere, and so the absolute amount of water vapor will increase as the atmosphere warms. It is sometimes also called the specific humidity feedback, because relative humidity (RH) stays practically constant over the oceans, but it decreases over land. This occurs because land experiences faster warming than the ocean, and a decline in RH has been observed after the year 2000. Since water vapor

3390-428: Is measured in thousands of years and is believed to occur in two stages. The first stage would be the effect from ice melt on thermohaline circulation . Because meltwater is completely fresh, it makes it harder for the surface layer of water to sink beneath the lower layers, and this disrupts the exchange of oxygen, nutrients and heat between the layers. This would act as a negative feedback - sometimes estimated as

3503-420: Is modified by a combination of surface processes that shape landscapes, and geologic processes that cause tectonic uplift and subsidence , and shape the coastal geography . Surface processes comprise the action of water, wind, ice, wildfire , and life on the surface of the Earth, along with chemical reactions that form soils and alter material properties, the stability and rate of change of topography under

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3616-611: Is more rapid in tropical climates than in cold climates proved to not be straightforwardly true. Geomorphology was started to be put on a solid quantitative footing in the middle of the 20th century. Following the early work of Grove Karl Gilbert around the turn of the 20th century, a group of mainly American natural scientists, geologists and hydraulic engineers including William Walden Rubey , Ralph Alger Bagnold , Hans Albert Einstein , Frank Ahnert , John Hack , Luna Leopold , A. Shields , Thomas Maddock , Arthur Strahler , Stanley Schumm , and Ronald Shreve began to research

3729-448: Is not included in the estimates above, as it is difficult to model, and the estimates of its role is strongly time-dependent as its carbon pools are depleted at different rates under different warming levels. Instead, it is treated as a separate process that will contribute to near-term warming, with the best estimates shown below. Altogether, it is expected that cumulative greenhouse gas emissions from permafrost thaw will be smaller than

3842-444: Is probably of profound importance for the terrestrial geomorphic system as a whole. Biology can influence very many geomorphic processes, ranging from biogeochemical processes controlling chemical weathering , to the influence of mechanical processes like burrowing and tree throw on soil development, to even controlling global erosion rates through modulation of climate through carbon dioxide balance. Terrestrial landscapes in which

3955-415: Is since the 1990s no longer accepted by mainstream scholarship as a basis for geomorphological studies. Albeit having its importance diminished, climatic geomorphology continues to exist as field of study producing relevant research. More recently concerns over global warming have led to a renewed interest in the field. Despite considerable criticism, the cycle of erosion model has remained part of

4068-408: Is sometimes factored out to give an expression in terms of the relative feedback gains g i from other components: For example g w v ≈ 0.5 {\displaystyle g_{wv}\approx 0.5} for the water vapor feedback. Within the context of modern numerical climate modelling and analysis, the linearized formulation has limited use. One such use is to diagnose

4181-461: Is the absorbed solar radiation and OLR is the outgoing longwave radiation at top of atmosphere. When EEI is positive the system is warming, when it is negative they system is cooling, and when it is approximately zero then there is neither warming or cooling. The ASR and OLR terms in this expression encompass many temperature-dependent properties and complex interactions that govern system behavior. In order to diagnose that behavior around

4294-433: Is therefore a quantification of temperature, related to radiation, as a function of altitude, and is not a separate phenomenon in this context. The lapse rate feedback is generally a negative feedback. However, it is in fact a positive feedback in polar regions where it strongly contributed to polar amplified warming, one of the biggest consequences of climate change. This is because in regions with strong inversions , such as

4407-494: Is very similar to model estimates, which are at 1.77 ± 0.20 m /K Either value effectively doubles the warming that would otherwise occur from CO 2 increases alone. Like with the other physical feedbacks, this is already accounted for in the warming projections under climate change scenarios . The lapse rate is the rate at which an atmospheric variable, normally temperature in Earth's atmosphere , falls with altitude . It

4520-597: The Bulletin of the Geological Society of America , and received only few citations prior to 2000 (they are examples of "sleeping beauties" ) when a marked increase in quantitative geomorphology research occurred. Quantitative geomorphology can involve fluid dynamics and solid mechanics , geomorphometry , laboratory studies, field measurements, theoretical work, and full landscape evolution modeling . These approaches are used to understand weathering and

4633-527: The IPCC Fourth Assessment Report (AR4) in 2007. While the scientific understanding of these feedbacks was limited at the time, it had improved since then. These positive feedbacks include an increase in wildfire frequency and severity, substantial losses from tropical rainforests due to fires and drying and tree losses elsewhere. The Amazon rainforest is a well-known example due to its enormous size and importance, and because

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4746-556: The North Pole and the South Pole colder than they would have been without it. During glacial periods , additional ice increases the reflectivity and thus lowers absorption of solar radiation, cooling the planet. But when warming occurs and the ice melts, darker land or open water takes its place and this causes more warming, which in turn causes more melting. In both cases, a self-reinforcing cycle continues until an equilibrium

4859-407: The climate system 's internal variability . External forcing refers to "a forcing agent outside the climate system causing a change in the climate system" that may push the climate system in the direction of warming or cooling. External forcings may be human-caused (for example, greenhouse gas emissions or land use change ) or natural (for example, volcanic eruptions ). Planck response

4972-460: The linearized parameter λ and the perturbed temperature ΔT because all components of λ (assumed to be first-order to act independently and additively) are also functions of temperature, albeit to varying extents, by definition for a thermodynamic system: Some feedback components having significant influence on EEI are: w v {\displaystyle wv} = water vapor, c {\displaystyle c} = clouds,

5085-566: The "no-feedback response" because it is an intensive property of a thermodynamic system when considered to be purely a function of temperature. Although Earth has an effective emissivity less than unity, the ideal black body radiation emerges as a separable quantity when investigating perturbations to the planet's outgoing radiation. The Planck "feedback" or Planck response is the comparable radiative response obtained from analysis of practical observations or global climate models (GCMs). Its expected strength has been most simply estimated from

5198-667: The Earth illustrate this intersection of surface and subsurface action. Mountain belts are uplifted due to geologic processes. Denudation of these high uplifted regions produces sediment that is transported and deposited elsewhere within the landscape or off the coast. On progressively smaller scales, similar ideas apply, where individual landforms evolve in response to the balance of additive processes (uplift and deposition) and subtractive processes ( subsidence and erosion ). Often, these processes directly affect each other: ice sheets, water, and sediment are all loads that change topography through flexural isostasy . Topography can modify

5311-475: The Earth's carbon cycle will shift in response to anthropogenic CO 2 emissions. The primary driver of this is the ocean, which absorbs anthropogenic CO 2 via the so-called solubility pump . At present this accounts for only about one third of the current emissions, but ultimately most (~75%) of the CO 2 emitted by human activities will dissolve in the ocean over a period of centuries: "A better approximation of

5424-655: The Earth, biological processes such as burrowing or tree throw may play important roles in setting the rates of some hillslope processes. Both volcanic (eruptive) and plutonic (intrusive) igneous processes can have important impacts on geomorphology. The action of volcanoes tends to rejuvenize landscapes, covering the old land surface with lava and tephra , releasing pyroclastic material and forcing rivers through new paths. The cones built by eruptions also build substantial new topography, which can be acted upon by other surface processes. Plutonic rocks intruding then solidifying at depth can cause both uplift or subsidence of

5537-530: The International Geological Conference of 1891. John Edward Marr in his The Scientific Study of Scenery considered his book as, 'an Introductory Treatise on Geomorphology, a subject which has sprung from the union of Geology and Geography'. An early popular geomorphic model was the geographical cycle or cycle of erosion model of broad-scale landscape evolution developed by William Morris Davis between 1884 and 1899. It

5650-619: The United States, while under the scenario of high global warming and worst-case permafrost feedback response, they would approach year 2019 emissions of China. The Earth's two remaining ice sheets, the Greenland ice sheet and the Antarctic ice sheet , cover the world's largest island and an entire continent, and both of them are also around 2 km (1 mi) thick on average. Due to this immense size, their response to warming

5763-595: The absence of feedbacks, but that warming will accelerate if emissions continue at current levels. Net feedbacks will stay negative largely because of increased thermal radiation as the planet warms , which is an effect that is several times larger than any other singular feedback. Accordingly, anthropogenic climate change alone cannot cause a runaway greenhouse effect . Feedbacks can be divided into physical feedbacks and partially biological feedbacks. Physical feedbacks include decreased surface reflectivity (from diminished snow and ice cover) and increased water vapor in

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5876-420: The amount of greenhouse gases in the atmosphere and the amount of temperature change that happens in response . While emissions are the forcing that causes climate change, feedbacks combine to control climate sensitivity to that forcing. While the overall sum of feedbacks is negative, it is becoming less negative as greenhouse gas emissions continue. This means that warming is slower than it would be in

5989-441: The anthropogenic greenhouse gas emissions . Ice-albedo feedback strength is not constant and depends on the rate of ice loss - models project that under high warming, its strength peaks around 2100 and declines afterwards, as most easily melted ice would already be lost by then. When CMIP5 models estimate a total loss of Arctic sea ice cover from June to September (a plausible outcome under higher levels of warming), it increases

6102-479: The atmosphere after dissociation on the seafloor. Thus, no "detectable" impact on the global temperatures is expected to occur in this century due to methane hydrates. Some research suggests hydrate dissociation can still cause a warming of 0.4–0.5 °C (0.72–0.90 °F) over several millennia. Earth is a thermodynamic system for which long-term temperature changes follow the global energy imbalance ( EEI stands for Earth's energy imbalance ): where ASR

6215-405: The atmosphere. Water vapor is not only a powerful greenhouse gas, it also influences feedbacks in the distribution of clouds and temperatures in the atmosphere . Biological feedbacks are mostly associated with changes to the rate at which plant matter accumulates CO 2 as part of the carbon cycle . The carbon cycle absorbs more than half of CO 2 emissions every year into plants and into

6328-441: The availability of sediment itself and on the river's discharge . Rivers are also capable of eroding into rock and forming new sediment, both from their own beds and also by coupling to the surrounding hillslopes. In this way, rivers are thought of as setting the base level for large-scale landscape evolution in nonglacial environments. Rivers are key links in the connectivity of different landscape elements. As rivers flow across

6441-539: The centuries. He inferred that the land was reshaped and formed by soil erosion of the mountains and by deposition of silt , after observing strange natural erosions of the Taihang Mountains and the Yandang Mountain near Wenzhou . Furthermore, he promoted the theory of gradual climate change over centuries of time once ancient petrified bamboos were found to be preserved underground in

6554-525: The cumulative anthropogenic emissions, yet still substantial on a global scale, with some experts comparing them to emissions caused by deforestation . The IPCC Sixth Assessment Report estimates that carbon dioxide and methane released from permafrost could amount to the equivalent of 14–175 billion tonnes of carbon dioxide per 1 °C (1.8 °F) of warming. For comparison, by 2019, annual anthropogenic emissions of carbon dioxide alone stood around 40 billion tonnes. A major review published in

6667-457: The cycle over. In the decades following Davis's development of this idea, many of those studying geomorphology sought to fit their findings into this framework, known today as "Davisian". Davis's ideas are of historical importance, but have been largely superseded today, mainly due to their lack of predictive power and qualitative nature. In the 1920s, Walther Penck developed an alternative model to Davis's. Penck thought that landform evolution

6780-426: The damage it experiences from climate change is exacerbated by the ongoing deforestation . The combination of two threats can potentially transform much or all of the rainforest to a savannah -like state, although this would most likely require relatively high warming of 3.5 °C (6.3 °F). Altogether, carbon sinks in the land and ocean absorb around half of the current emissions. Their future absorption

6893-480: The derivative of the Stefan-Boltzmann equation as -4σT = -3.8 W/m /K (watts per square meter per degree of warming). Accounting from GCM applications has sometimes yielded a reduced strength, as caused by extensive properties of the stratosphere and similar residual artifacts subsequently identified as being absent from such models. Most extensive "grey body" properties of Earth that influence

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7006-571: The dry, northern climate zone of Yanzhou , which is now modern day Yan'an , Shaanxi province. Previous Chinese authors also presented ideas about changing landforms. Scholar-official Du Yu (222–285) of the Western Jin dynasty predicted that two monumental stelae recording his achievements, one buried at the foot of a mountain and the other erected at the top, would eventually change their relative positions over time as would hills and valleys. Daoist alchemist Ge Hong (284–364) created

7119-413: The early 1900s, the study of regional-scale geomorphology was termed "physiography". Physiography later was considered to be a contraction of " physi cal" and "ge ography ", and therefore synonymous with physical geography , and the concept became embroiled in controversy surrounding the appropriate concerns of that discipline. Some geomorphologists held to a geological basis for physiography and emphasized

7232-495: The early 19th century, authors – especially in Europe – had tended to attribute the form of landscapes to local climate , and in particular to the specific effects of glaciation and periglacial processes. In contrast, both Davis and Penck were seeking to emphasize the importance of evolution of landscapes through time and the generality of the Earth's surface processes across different landscapes under different conditions. During

7345-418: The emissions remain very high after the 21st century, carbon sinks would eventually be completely overwhelmed, with the ocean sink diminished further and land ecosystems outright becoming a net source. Hypothetically, very strong carbon dioxide removal could also result in land and ocean carbon sinks becoming net sources for several decades. Following Le Chatelier's principle , the chemical equilibrium of

7458-430: The field of geomorphology encompasses a very wide range of different approaches and interests. Modern researchers aim to draw out quantitative "laws" that govern Earth surface processes, but equally, recognize the uniqueness of each landscape and environment in which these processes operate. Particularly important realizations in contemporary geomorphology include: According to Karna Lidmar-Bergström , regional geography

7571-590: The force of gravity via creep , slides , flows, topples, and falls. Such mass wasting occurs on both terrestrial and submarine slopes, and has been observed on Earth , Mars , Venus , Titan and Iapetus . Ongoing hillslope processes can change the topology of the hillslope surface, which in turn can change the rates of those processes. Hillslopes that steepen up to certain critical thresholds are capable of shedding extremely large volumes of material very quickly, making hillslope processes an extremely important element of landscapes in tectonically active areas. On

7684-401: The force of gravity , and other factors, such as (in the very recent past) human alteration of the landscape. Many of these factors are strongly mediated by climate . Geologic processes include the uplift of mountain ranges , the growth of volcanoes , isostatic changes in land surface elevation (sometimes in response to surface processes), and the formation of deep sedimentary basins where

7797-494: The form of landscape elements such as rivers and hillslopes by taking systematic, direct, quantitative measurements of aspects of them and investigating the scaling of these measurements. These methods began to allow prediction of the past and future behavior of landscapes from present observations, and were later to develop into the modern trend of a highly quantitative approach to geomorphic problems. Many groundbreaking and widely cited early geomorphology studies appeared in

7910-670: The formation of soils , sediment transport , landscape change, and the interactions between climate, tectonics, erosion, and deposition. In Sweden Filip Hjulström 's doctoral thesis, "The River Fyris" (1935), contained one of the first quantitative studies of geomorphological processes ever published. His students followed in the same vein, making quantitative studies of mass transport ( Anders Rapp ), fluvial transport ( Åke Sundborg ), delta deposition ( Valter Axelsson ), and coastal processes ( John O. Norrman ). This developed into "the Uppsala School of Physical Geography ". Today,

8023-427: The geologic and atmospheric history of those planets but also extends geomorphological study of the Earth. Planetary geomorphologists often use Earth analogues to aid in their study of surfaces of other planets. Other than some notable exceptions in antiquity, geomorphology is a relatively young science, growing along with interest in other aspects of the earth sciences in the mid-19th century. This section provides

8136-534: The global carbon sink is the state of the Southern Ocean - particularly of the Southern Ocean overturning circulation . Chemical weathering over the geological long term acts to remove CO 2 from the atmosphere. With current global warming , weathering is increasing, demonstrating significant feedbacks between climate and Earth surface. Biosequestration also captures and stores CO 2 by biological processes. The formation of shells by organisms in

8249-451: The global temperatures by 0.19 °C (0.34 °F), with a range of 0.16–0.21 °C, while the regional temperatures would increase by over 1.5 °C (2.7 °F). These calculations include second-order effects such as the impact from ice loss on regional lapse rate, water vapor and cloud feedbacks, and do not cause "additional" warming on top of the existing model projections. Seen from below, clouds emit infrared radiation back to

8362-486: The ground from the lower atmosphere. Thus, the strength of the greenhouse effect depends on the atmosphere's rate of temperature decrease with height. Both theory and climate models indicate that global warming will reduce the rate of temperature decrease with height, producing a negative lapse rate feedback that weakens the greenhouse effect. Albedo is the measure of how strongly the planetary surface can reflect solar radiation, which prevents its absorption and thus has

8475-677: The landscape, they generally increase in size, merging with other rivers. The network of rivers thus formed is a drainage system . These systems take on four general patterns: dendritic, radial, rectangular, and trellis. Dendritic happens to be the most common, occurring when the underlying stratum is stable (without faulting). Drainage systems have four primary components: drainage basin , alluvial valley, delta plain, and receiving basin. Some geomorphic examples of fluvial landforms are alluvial fans , oxbow lakes , and fluvial terraces . Glaciers , while geographically restricted, are effective agents of landscape change. The gradual movement of ice down

8588-474: The landscape. Fluvial geomorphologists focus on rivers , how they transport sediment , migrate across the landscape , cut into bedrock , respond to environmental and tectonic changes, and interact with humans. Soils geomorphologists investigate soil profiles and chemistry to learn about the history of a particular landscape and understand how climate, biota, and rock interact. Other geomorphologists study how hillslopes form and change. Still others investigate

8701-404: The lifetime of fossil fuel CO 2 for public discussion might be 300 years, plus 25% that lasts forever". However, the rate at which the ocean will take it up in the future is less certain, and will be affected by stratification induced by warming and, potentially, changes in the ocean's thermohaline circulation . It is believed that the single largest factor in determining the total strength of

8814-723: The line of the watershed between two mountains , often on a prominent ridge or arête . For example, the highest col in Austria, the Obere Glocknerscharte ("Upper Glockner Col", 3,766  m (AA) ) lies between the Kleinglockner ( 3,783 m above sea level (AA) ) and Grossglockner ( 3,798 m above sea level (AA) ) mountains, giving the Kleinglockner a minimum prominence of 17 metres. Geomorphology Earth 's surface

8927-691: The local climate, for example through orographic precipitation , which in turn modifies the topography by changing the hydrologic regime in which it evolves. Many geomorphologists are particularly interested in the potential for feedbacks between climate and tectonics , mediated by geomorphic processes. In addition to these broad-scale questions, geomorphologists address issues that are more specific or more local. Glacial geomorphologists investigate glacial deposits such as moraines , eskers , and proglacial lakes , as well as glacial erosional features, to build chronologies of both small glaciers and large ice sheets and understand their motions and effects upon

9040-465: The lower lithosphere have also been hypothesised to play important roles in the long term (> million year), large scale (thousands of km) evolution of the Earth's topography (see dynamic topography ). Both can promote surface uplift through isostasy as hotter, less dense, mantle rocks displace cooler, denser, mantle rocks at depth in the Earth. Marine processes are those associated with the action of waves, marine currents and seepage of fluids through

9153-516: The mid-20th century considered both un-innovative and dubious. Early climatic geomorphology developed primarily in continental Europe while in the English-speaking world the tendency was not explicit until L.C. Peltier's 1950 publication on a periglacial cycle of erosion. Climatic geomorphology was criticized in a 1969 review article by process geomorphologist D.R. Stoddart . The criticism by Stoddart proved "devastating" sparking

9266-599: The ocean, over a very long time, removes CO 2 from the oceans. The complete conversion of CO 2 to limestone takes thousands to hundreds of thousands of years. Net primary productivity of plants' and phytoplankton grows as the increased CO 2 fuels their photosynthesis in what is known as the CO2 fertilization effect . Additionally, plants require less water as the atmospheric CO 2 concentrations increase, because they lose less moisture to evapotranspiration through open stomata (the pores in leaves through which CO 2

9379-437: The ocean. Over the long term the percentage will be reduced as carbon sinks become saturated and higher temperatures lead to effects like drought and wildfires . Feedback strengths and relationships are estimated through global climate models , with their estimates calibrated against observational data whenever possible. Some feedbacks rapidly impact climate sensitivity, while the feedback response from ice sheets

9492-544: The oceans) have been very difficult to observe, so climate models don't have as much data to go on with when they attempt to simulate their behaviour. Additionally, clouds have been strongly affected by aerosol particles, mainly from the unfiltered burning of sulfur -rich fossil fuels such as coal and bunker fuel . Any estimate of cloud feedback needs to disentangle the effects of so-called global dimming caused by these particles as well. Thus, estimates of cloud feedback differ sharply between climate models. Models with

9605-505: The outgoing radiation are usually postulated to be encompassed by the other GCM feedback components, and to be distributed in accordance with a particular forcing-feedback formulation of the climate system. Ideally the Planck response strength obtained from GCMs, indirect measurements, and black body estimates will further converge as analysis methods continue to mature. According to Clausius–Clapeyron relation , saturation vapor pressure

9718-417: The past seven decades. As of 2021, the total surface feedback strength is estimated at 0.35 [0.10 to 0.60] W m /K. On its own, Arctic sea ice decline between 1979 and 2011 was responsible for 0.21 (W/m ) of radiative forcing . This is equivalent to a quarter of impact from CO 2 emissions over the same period. The combined change in all sea ice cover between 1992 and 2018 is equivalent to 10% of all

9831-857: The physics of landscapes. Geomorphologists may rely on geochronology , using dating methods to measure the rate of changes to the surface. Terrain measurement techniques are vital to quantitatively describe the form of the Earth's surface, and include differential GPS , remotely sensed digital terrain models and laser scanning , to quantify, study, and to generate illustrations and maps. Practical applications of geomorphology include hazard assessment (such as landslide prediction and mitigation ), river control and stream restoration , and coastal protection. Planetary geomorphology studies landforms on other terrestrial planets such as Mars. Indications of effects of wind , fluvial , glacial , mass wasting , meteor impact , tectonics and volcanic processes are studied. This effort not only helps better understand

9944-483: The planet warms. The Planck response is the additional thermal radiation objects emit as they get warmer. Whether Planck response is a climate change feedback depends on the context. In climate science the Planck response can be treated as an intrinsic part of warming that is separate from radiative feedbacks and carbon cycle feedbacks. However, the Planck response is included when calculating climate sensitivity . A feedback that amplifies an initial change

10057-414: The polar regions, the lapse rate feedback can be positive because the surface warms faster than higher altitudes, resulting in inefficient longwave cooling . The atmosphere's temperature decreases with height in the troposphere . Since emission of infrared radiation varies with temperature, longwave radiation escaping to space from the relatively cold upper atmosphere is less than that emitted toward

10170-602: The regional temperature in Antarctica is likely to go up by 1 °C (1.8 °F) after the loss of the West Antarctic ice sheet and 2 °C (3.6 °F) after the loss of the East Antarctic ice sheet. These estimates assume that global warming stays at an average of 1.5 °C (2.7 °F). Because of the logarithmic growth of the greenhouse effect , the impact from ice loss would be larger at

10283-423: The relationships between ecology and geomorphology. Because geomorphology is defined to comprise everything related to the surface of the Earth and its modification, it is a broad field with many facets. Geomorphologists use a wide range of techniques in their work. These may include fieldwork and field data collection, the interpretation of remotely sensed data, geochemical analyses, and the numerical modelling of

10396-525: The relative strengths of different feedback mechanisms. An estimate of climate sensitivity to a forcing is then obtained for the case where the net feedback remains negative and the system reaches a new equilibrium state ( ΔEEI=0 ) after some time has passed: Uncertainty over climate change feedbacks has implications for climate policy. For instance, uncertainty over carbon cycle feedbacks may affect targets for reducing greenhouse gas emissions ( climate change mitigation ). Emissions targets are often based on

10509-487: The role of biology in mediating surface processes can be definitively excluded are extremely rare, but may hold important information for understanding the geomorphology of other planets, such as Mars . Rivers and streams are not only conduits of water, but also of sediment . The water, as it flows over the channel bed, is able to mobilize sediment and transport it downstream, either as bed load , suspended load or dissolved load . The rate of sediment transport depends on

10622-760: The science of historical geology . While acknowledging its shortcomings, modern geomorphologists Andrew Goudie and Karna Lidmar-Bergström have praised it for its elegance and pedagogical value respectively. Geomorphically relevant processes generally fall into (1) the production of regolith by weathering and erosion , (2) the transport of that material, and (3) its eventual deposition . Primary surface processes responsible for most topographic features include wind , waves , chemical dissolution , mass wasting , groundwater movement, surface water flow, glacial action , tectonism , and volcanism . Other more exotic geomorphic processes might include periglacial (freeze-thaw) processes, salt-mediated action, changes to

10735-409: The science of geomorphology. The model or theory has never been proved wrong, but neither has it been proven. The inherent difficulties of the model have instead made geomorphological research to advance along other lines. In contrast to its disputed status in geomorphology, the cycle of erosion model is a common approach used to establish denudation chronologies , and is thus an important concept in

10848-532: The sea, eventually those seas would fill while the land lowered. He claimed that this would mean that land and water would eventually swap places, whereupon the process would begin again in an endless cycle. The Encyclopedia of the Brethren of Purity published in Arabic at Basra during the 10th century also discussed the cyclical changing positions of land and sea with rocks breaking down and being washed into

10961-525: The sea, their sediment eventually rising to form new continents. The medieval Persian Muslim scholar Abū Rayhān al-Bīrūnī (973–1048), after observing rock formations at the mouths of rivers, hypothesized that the Indian Ocean once covered all of India . In his De Natura Fossilium of 1546, German metallurgist and mineralogist Georgius Agricola (1494–1555) wrote about erosion and natural weathering . Another early theory of geomorphology

11074-704: The seabed caused by marine currents, seepage of fluids through the seafloor or extraterrestrial impact. Aeolian processes pertain to the activity of the winds and more specifically, to the winds' ability to shape the surface of the Earth . Winds may erode, transport, and deposit materials, and are effective agents in regions with sparse vegetation and a large supply of fine, unconsolidated sediments . Although water and mass flow tend to mobilize more material than wind in most environments, aeolian processes are important in arid environments such as deserts . The interaction of living organisms with landforms, or biogeomorphologic processes , can be of many different forms, and

11187-459: The seafloor. Mass wasting and submarine landsliding are also important processes for some aspects of marine geomorphology. Because ocean basins are the ultimate sinks for a large fraction of terrestrial sediments, depositional processes and their related forms (e.g., sediment fans, deltas ) are particularly important as elements of marine geomorphology. There is a considerable overlap between geomorphology and other fields. Deposition of material

11300-486: The slightly lower warming level of 2020s, but it would become lower if the warming proceeds towards higher levels. While Greenland and the West Antarctic ice sheet are likely committed to melting entirely if the long-term warming is around 1.5 °C (2.7 °F), the East Antarctic ice sheet would not be at risk of complete disappearance until the very high global warming of 5–10 °C (9.0–18.0 °F) Methane hydrates or methane clathrates are frozen compounds where

11413-473: The spruce trees which retain their dark needles all year. On the other hand, changes in emissions of compounds such sea salt, dimethyl sulphide, dust, ozone and a range of biogenic volatile organic compounds are expected to be negative overall. As of 2021, all of these non-CO 2 feedbacks are believed to practically cancel each other out, but there is only low confidence, and the combined feedbacks could be up to 0.25 W m /K in either direction. Permafrost

11526-401: The strongest cloud feedback have the highest climate sensitivity , which means that they simulate much stronger warming in response to a doubling of CO 2 (or equivalent greenhouse gas ) concentrations than the rest. Around 2020, a small fraction of models was found to simulate so much warming as the result that they had contradicted paleoclimate evidence from fossils , and their output

11639-407: The surface of the Earth drops and is filled with material eroded from other parts of the landscape. The Earth's surface and its topography therefore are an intersection of climatic , hydrologic , and biologic action with geologic processes, or alternatively stated, the intersection of the Earth's lithosphere with its hydrosphere , atmosphere , and biosphere . The broad-scale topographies of

11752-596: The surface, depending on whether the new material is denser or less dense than the rock it displaces. Tectonic effects on geomorphology can range from scales of millions of years to minutes or less. The effects of tectonics on landscape are heavily dependent on the nature of the underlying bedrock fabric that more or less controls what kind of local morphology tectonics can shape. Earthquakes can, in terms of minutes, submerge large areas of land forming new wetlands. Isostatic rebound can account for significant changes over hundreds to thousands of years, and allows erosion of

11865-415: The surface, which has a warming effect; seen from above, clouds reflect sunlight and emit infrared radiation to space, leading to a cooling effect. Low clouds are bright and very reflective, so they lead to strong cooling, while high clouds are too thin and transparent to effectively reflect sunlight, so they cause overall warming. As a whole, clouds have a substantial cooling effect. However, climate change

11978-434: The term tends to be associated more with mountain than hill ranges. The distinction with other names for breaks in mountain ridges such as saddle , wind gap or notch is not sharply defined and may vary from place to place. Many double summits are separated by prominent cols. The height of a summit above its highest col (called the key col ) is effectively a measure of a mountain's topographic prominence . Cols lie on

12091-469: The year 2022 concluded that if the goal of preventing 2 °C (3.6 °F) of warming was realized, then the average annual permafrost emissions throughout the 21st century would be equivalent to the year 2019 annual emissions of Russia. Under RCP4.5, a scenario considered close to the current trajectory and where the warming stays slightly below 3 °C (5.4 °F), annual permafrost emissions would be comparable to year 2019 emissions of Western Europe or

12204-434: Was German, and during his lifetime his ideas were at times rejected vigorously by the English-speaking geomorphology community. His early death, Davis' dislike for his work, and his at-times-confusing writing style likely all contributed to this rejection. Both Davis and Penck were trying to place the study of the evolution of the Earth's surface on a more generalized, globally relevant footing than it had been previously. In

12317-444: Was an elaboration of the uniformitarianism theory that had first been proposed by James Hutton (1726–1797). With regard to valley forms, for example, uniformitarianism posited a sequence in which a river runs through a flat terrain, gradually carving an increasingly deep valley, until the side valleys eventually erode, flattening the terrain again, though at a lower elevation. It was thought that tectonic uplift could then start

12430-416: Was better described as an alternation between ongoing processes of uplift and denudation, as opposed to Davis's model of a single uplift followed by decay. He also emphasised that in many landscapes slope evolution occurs by backwearing of rocks, not by Davisian-style surface lowering, and his science tended to emphasise surface process over understanding in detail the surface history of a given locality. Penck

12543-507: Was devised by Song dynasty Chinese scientist and statesman Shen Kuo (1031–1095). This was based on his observation of marine fossil shells in a geological stratum of a mountain hundreds of miles from the Pacific Ocean . Noticing bivalve shells running in a horizontal span along the cut section of a cliffside, he theorized that the cliff was once the pre-historic location of a seashore that had shifted hundreds of miles over

12656-661: Was effectively excluded from the climate sensitivity estimate of the IPCC Sixth Assessment Report . There are positive and negative climate feedbacks from Earth's carbon cycle. Negative feedbacks are large, and play a great role in the studies of climate inertia or of dynamic (time-dependent) climate change. Because they are considered relatively insensitive to temperature changes, they are sometimes considered separately or disregarded in studies which aim to quantify climate sensitivity. Global warming projections have included carbon cycle feedbacks since

12769-402: Was foreshadowed by the work of Wladimir Köppen , Vasily Dokuchaev and Andreas Schimper . William Morris Davis , the leading geomorphologist of his time, recognized the role of climate by complementing his "normal" temperate climate cycle of erosion with arid and glacial ones. Nevertheless, interest in climatic geomorphology was also a reaction against Davisian geomorphology that was by

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