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climate change
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{{About||current warming of the Earth's climate system due to human activities|Global warming|the study of past climate change|Paleoclimatology||||}}{{pp-semi-indef}}{{Merge to |Climate system#Changes in the climate system |discuss=Talk:Climate_change#Alternative_-_Merge_this_content_to_Climate_system |date=October 2019}}{{short description|Change in the statistical distribution of weather patterns for an extended period}}{{Use dmy dates|date=November 2013}}{{atmospheric sciences}}Climate change occurs when changes in Earth's climate system result in new weather patterns that remain in place for an extended period of time. This length of time can be as short as a few decades to as long as millions of years. The climate system receives nearly all of its energy from the sun, with a relatively tiny amount from earth's interior. The climate system also gives off energy to outer space. The balance of incoming and outgoing energy, and the passage of the energy through the climate system, determines Earth's energy budget. When the incoming energy is greater than the outgoing energy, earth's energy budget is positive and the climate system is warming. If more energy goes out, the energy budget is negative and earth experiences cooling.The energy moving through Earth's climate system finds expression in weather, varying on geographic scales and time. Long-term averages of weather in a region constitute the region's climate. Climate change is a long-term, sustained trend of change in climate. Such changes can be the result of "internal variability", when natural processes inherent to the various parts of the climate system alter the distribution of energy. Examples include variability in ocean basins such as the Pacific decadal oscillation and Atlantic multidecadal oscillation. Climate change can also result from external forcing, when events outside of the climate system's components nonetheless produce changes within the system. Examples include changes in solar output and volcanism. Human activities can also change climate, and are presently driving climate change through global warming.BOOK, The National Academies Press, 978-0-309-14588-6, America's Climate Choices: Panel on Advancing the Science of Climate Change; National Research Council, Advancing the Science of Climate Change, Washington, D.C., 2010,weblink (p1) ... there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities. While much remains to be learned, the core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanations. (pp. 21–22) Some scientific conclusions or theories have been so thoroughly examined and tested, and supported by so many independent observations and results, that their likelihood of subsequently being found to be wrong is vanishingly small. Such conclusions and theories are then regarded as settled facts. This is the case for the conclusions that the Earth system is warming and that much of this warming is very likely due to human activities., dead,weblink" title="web.archive.org/web/20140529161102weblink">weblink 29 May 2014, The field of climatology incorporates many fields of research. For ancient periods of climate change, researchers rely on evidence preserved in climate proxies, such as ice cores, ancient tree rings, geologic records of changes in sea level, and glacial geology. Physical evidence of current climate change covers many independent lines of evidence, a few of which are temperature records, the disappearance of ice, and extreme weather events.

Terminology

The most general definition of climate change is a change in the statistical properties (principally its mean and spread)WEB
, Understanding and Attributing Climate Change
, Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
, Intergovernmental Panel on Climate Change (IPCC), 2007
, Solomon, S.
, D., Qin
, M., Manning
, Z., Chen
, M., Marquis
, K.B., Averyt
, M., Tignor
, H.L., Miller
,weblink
, of the climate system when considered over long periods of time, regardless of cause.WEB, Glossary â€“ Climate Change, Education Center â€“ Arctic Climatology and Meteorology, NSIDC National Snow and Ice Data Center,weblink ; Glossary, in {{Harvnb|IPCC TAR WG1|2001}}. Accordingly, fluctuations over periods shorter than a few decades, such as El Niño, do not represent climate change.The term "climate change" is often used to refer specifically to anthropogenic climate change (also known as global warming). Anthropogenic climate change is caused by human activity, as opposed to changes in climate that may have resulted as part of Earth's natural processes.WEB, 21 March 1994, The United Nations Framework Convention on Climate Change,weblink Climate change means a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods., In this sense, especially in the context of environmental policy, the term climate change has become synonymous with anthropogenic global warming. Within scientific journals, global warming refers to surface temperature increases while climate change includes global warming and everything else that increasing greenhouse gas levels affect.WEB, What's in a Name? Global Warming vs. Climate Change, NASA,weblink 23 July 2011, A related term, "climatic change", was proposed by the World Meteorological Organization (WMO) in 1966 to encompass all forms of climatic variability on time-scales longer than 10 years, but regardless of cause. During the 1970s, the term climate change replaced climatic change to focus on anthropogenic causes, as it became clear that human activities had a potential to drastically alter the climate. Climate change was incorporated in the title of the Intergovernmental Panel on Climate Change (IPCC) and the UN Framework Convention on Climate Change (UNFCCC). Climate change is now used as both a technical description of the process, as well as a noun used to describe the problem.JOURNAL, Hulme, Mike, 2016, Concept of Climate Change, in: The International Encyclopedia of Geography, The International Encyclopedia of Geography, Wiley-Blackwell/Association of American Geographers (AAG),weblink 16 May 2016,

Causes

{{See also|Attribution of recent climate change}}On the broadest scale, the rate at which energy is received from the Sun and the rate at which it is lost to space determine the equilibrium temperature and climate of Earth. This energy is distributed around the globe by winds, ocean currents,JOURNAL, Estimates of Global Oceanic Meridional Heat Transport, Jane, Hsiung, Journal of Physical Oceanography, 15, 11, 1405–1413, November 1985, 10.1175/1520-0485(1985)0152.0.CO;2, JOURNAL, Meridional energy transport in the coupled atmosphere–ocean system: scaling and numerical experiments, Geoffrey K., Vallis, Riccardo, Farneti, 135, 644, October 2009, 1643–1660, Quarterly Journal of the Royal Meteorological Society, 10.1002/qj.498, and other mechanisms to affect the climates of different regions.JOURNAL, Earth's Global Energy Budget, Trenberth, Kevin E., Fasullo, John T., Kiehl, Jeffrey, 1, Bulletin of the American Meteorological Society, 90, 3, 311–323, 2009, 10.1175/2008BAMS2634.1, 2009BAMS...90..311T, Factors that can shape climate are called climate forcings or "forcing mechanisms".BOOK, Smith, Ralph C., 2013, Uncertainty Quantification: Theory, Implementation, and Applications, Computational Science and Engineering, SIAM, 978-1611973228, 12, 23,weblink These include processes such as variations in solar radiation, variations in the Earth's orbit, variations in the albedo or reflectivity of the continents, atmosphere, and oceans, mountain-building and continental drift and changes in greenhouse gas concentrations. There are a variety of climate change feedbacks that can either amplify or diminish the initial forcing. Some parts of the climate system, such as the oceans and ice caps, respond more slowly in reaction to climate forcings, while others respond more quickly. There are also key threshold factors which when exceeded can produce rapid change.Climate change can either occur due to external forcing or due to internal processes. Internal unforced processes often involve changes in the distribution of energy in the ocean and atmosphere, for instance changes in the thermohaline circulation. External forcing mechanisms can be either anthropogenic (e.g. increased emissions of greenhouse gases and dust) or natural (e.g., changes in solar output, the earth's orbit, volcano eruptions).{{harvnb|Cronin|2010|pp=17–18}}Whether the initial forcing mechanism is internal or external, the response of the climate system might be fast (e.g., a sudden cooling due to airborne volcanic ash reflecting sunlight), slow (e.g. thermal expansion of warming ocean water), or a combination (e.g., sudden loss of albedo in the Arctic Ocean as sea ice melts, followed by more gradual thermal expansion of the water). Therefore, the climate system can respond abruptly, but the full response to forcing mechanisms might not be fully developed for centuries or even longer.

Internal variability

File:Ecinfigtwo.jpg|thumb|right|Pacific decadal oscillationPacific decadal oscillationScientists generally define the five components of earth's climate system to include atmosphere, hydrosphere, cryosphere, lithosphere (restricted to the surface soils, rocks, and sediments), and biosphere.WEB, 2011, Glossary, NASA Earth Observatory,weblink 8 July 2011, Climate System: The five physical components (atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere) that are responsible for the climate and its variations., Natural changes in the climate system result in internal "climate variability".WEB, IPCC, Intergovernmental Panel on Climate Change, 2007, What are Climate Change and Climate Variability?, Intergovernmental Panel on Climate Change, IPCC,weblink Examples include the type and distribution of species, and changes in ocean-atmosphere circulations.

Ocean-atmosphere variability

File:Ocean circulation conveyor belt.jpg|thumb|right|A schematic of modern thermohaline circulation. Tens of millions of years ago, continental-plate movement formed a land-free gap around Antarctica, allowing the formation of the ACC, which keeps warm waters away from Antarctica.]]{{See also|Thermohaline circulation}}The ocean and atmosphere can work together to spontaneously generate internal climate variability that can persist for years to decades at a time.JOURNAL, Brown, Patrick T., Li, Wenhong, Cordero, Eugene C., Mauget, Steven A., 2015-04-21, Comparing the model-simulated global warming signal to observations using empirical estimates of unforced noise, Scientific Reports, 2045-2322, 10.1038/srep09957, 4404682, 25898351, 5, 9957, 2015NatSR...5E9957B, JOURNAL, Hasselmann, K., 1976-12-01, Stochastic climate models Part I. Theory, Tellus, 2153-3490, 10.1111/j.2153-3490.1976.tb00696.x, 28, 6, 473–85, 1976TellA..28..473H, Examples of this type of variability include the El Niño–Southern Oscillation, the Pacific decadal oscillation, and the Atlantic Multidecadal Oscillation. These variations can affect global average surface temperature by redistributing heat between the deep ocean and the atmosphereJOURNAL, Meehl, Gerald A., Hu, Aixue, Arblaster, Julie M., Fasullo, John, Trenberth, Kevin E., 2013-04-08, Externally Forced and Internally Generated Decadal Climate Variability Associated with the Interdecadal Pacific Oscillation, Journal of Climate, 0894-8755, 10.1175/JCLI-D-12-00548.1, 26, 18, 7298–310, 2013JCli...26.7298M, JOURNAL, England, Matthew H., McGregor, Shayne, Spence, Paul, Meehl, Gerald A., Timmermann, Axel, Axel Timmermann, Cai, Wenju, Gupta, Alex Sen, McPhaden, Michael J., Purich, Ariaan, 2014-03-01, Recent intensification of wind-driven circulation in the Pacific and the ongoing warming hiatus, Nature Climate Change, 1758-678X, 10.1038/nclimate2106, 4, 3, 222–27, 2014NatCC...4..222E, and/or by altering the cloud/water vapor/sea ice distribution which can affect the total energy budget of the earth.JOURNAL, Brown, Patrick T., Li, Wenhong, Li, Laifang, Ming, Yi, 2014-07-28, Top-of-atmosphere radiative contribution to unforced decadal global temperature variability in climate models, Geophysical Research Letters, 1944-8007, 10.1002/2014GL060625, 41, 14, 2014GL060625, 2014GeoRL..41.5175B, 10161/9167, JOURNAL, Palmer, M. D., McNeall, D. J., 2014-01-01, Internal variability of Earth's energy budget simulated by CMIP5 climate models, Environmental Research Letters, 1748-9326, 10.1088/1748-9326/9/3/034016, 9, 3, 034016,weblink 2014ERL.....9c4016P, The oceanic aspects of these circulations can generate variability on centennial timescales due to the ocean having hundreds of times more mass than in the atmosphere, and thus very high thermal inertia. For example, alterations to ocean processes such as thermohaline circulation play a key role in redistributing heat in the world's oceans. Due to the long timescales of this circulation, ocean temperature at depth is still adjusting to effects of the Little Ice AgeKirk Bryan, Geophysical Fluid Dynamics Laboratory. Man's Great Geophysical Experiment. U.S. National Oceanic and Atmospheric Administration. which occurred between the 1600 and 1800s.

Random forcing

From a climate perspective, the weather can be considered as being random.JOURNAL, Hasselmann, K., 1976, Stochastic climate models Part I. Theory,weblink Tellus, 28, 6, 473–485, 10.1111/j.2153-3490.1976.tb00696.x, 2153-3490, If there are little clouds in a particular year, there is an energy imbalance and extra heat can be absorbed by the oceans. Due to climate inertia, this signal can be 'stored' in the ocean and be expressed as variability on longer time scales than the original weather disturbances.JOURNAL, Liu, Zhengyu, 2011-10-14, Dynamics of Interdecadal Climate Variability: A Historical Perspective,weblink Journal of Climate, 25, 6, 1963–1995, 10.1175/2011JCLI3980.1, 0894-8755,

Life

Life affects climate through its role in the carbon and water cycles and through such mechanisms as albedo, evapotranspiration, cloud formation, and weathering.JOURNAL, Spracklen, D. V., Bonn, B., Carslaw, K. S., 2008, Boreal forests, aerosols and the impacts on clouds and climate, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 10.1098/rsta.2008.0201, 18826917, 2008RSPTA.366.4613S, 366, 1885, 4613–26, harv, JOURNAL, Christner, B. C., Morris, C. E., Foreman, C. M., Cai, R., Sands, D. C., 2008, Ubiquity of Biological Ice Nucleators in Snowfall, Science, 10.1126/science.1149757, 18309078, 2008Sci...319.1214C, 319, 5867, 1214, harv,weblink JOURNAL, Schwartzman, David W., Volk, Tyler, 1989, Biotic enhancement of weathering and the habitability of Earth, Nature, 1989Natur.340..457S, 10.1038/340457a0, 340, 6233, 457–60, harv, Examples of how life may have affected past climate include:
  • glaciation 2.3 billion years ago triggered by the evolution of oxygenic photosynthesis, which depleted the atmosphere of the greenhouse gas carbon dioxide and introduced free oxygenJOURNAL, harv, 10.1073/pnas.0504878102, The Paleoproterozoic snowball Earth: A climate disaster triggered by the evolution of oxygenic photosynthesis, 2005, Kopp, R.E., Kirschvink, J.L., Hilburn, I.A., Nash, C.Z., Proceedings of the National Academy of Sciences, 102, 32, 11131–36, 16061801, 1183582, 2005PNAS..10211131K, JOURNAL, harv, 10.1126/science.1071184, Life and the Evolution of Earth's Atmosphere, 2002, Kasting, J.F., Science, 296, 5570, 1066–68, 12004117, Siefert, JL, 2002Sci...296.1066K,
  • another glaciation 300 million years ago ushered in by long-term burial of decomposition-resistant detritus of vascular land-plants (creating a carbon sink and forming coal)JOURNAL, harv, 10.1126/science.271.5252.1105, Middle to Late Paleozoic Atmospheric CO2 Levels from Soil Carbonate and Organic Matter, 1996, Mora, C.I., Driese, S.G., Colarusso, L. A., Science, 271, 5252, 1105–07, 1996Sci...271.1105M, JOURNAL, harv, 10.1073/pnas.96.20.10955, Atmospheric oxygen over Phanerozoic time, 1999, Berner, R.A., Proceedings of the National Academy of Sciences, 96, 20, 10955–57, 10500106, 34224, 1999PNAS...9610955B,
  • termination of the Paleocene–Eocene Thermal Maximum 55 million years ago by flourishing marine phytoplanktonJOURNAL, harv, 10.1038/35025035, 2000, Bains, Santo, Norris, Richard D., Corfield, Richard M., Faul, Kristina L., Nature, 407, 6801, 171–74, 11001051, Termination of global warmth at the Palaeocene/Eocene boundary through productivity feedback, 2000Natur.407..171B, JOURNAL, harv, 10.1080/11035890001221188, An assessment of the biogeochemical feedback response to the climatic and chemical perturbations of the LPTM, 2000, Zachos, J.C., Dickens, G.R., GFF, 122, 188–89,
  • reversal of global warming 49 million years ago by 800,000 years of arctic azolla bloomsJOURNAL, 10.1111/j.1472-4669.2009.00195.x, The Eocene Arctic Azolla bloom: Environmental conditions, productivity and carbon drawdown, 2009, Speelman, E.N., Van Kempen, M.M.L., Barke, J., Brinkhuis, H., Reichart, G.J., Smolders, A.J.P., Roelofs, J.G.M., Sangiorgi, F., De Leeuw, J.W., Lotter, A.F., Sinninghe Damsté, J.S., Geobiology, 7, 2, 155–70, 19323694, JOURNAL, harv, 10.1038/nature04692, Episodic fresh surface waters in the Eocene Arctic Ocean, 2006, Brinkhuis, Henk, Schouten, Stefan, Collinson, Margaret E., Sluijs, Appy, Sinninghe Damsté, Jaap S. Sinninghe, Dickens, Gerald R., Huber, Matthew, Cronin, Thomas M., Onodera, Jonaotaro, Takahashi, Kozo, Bujak, Jonathan P., Stein, Ruediger, Van Der Burgh, Johan, Eldrett, James S., Harding, Ian C., Lotter, André F., Sangiorgi, Francesca, Van Konijnenburg-Van Cittert, Han van Konijnenburg-van, De Leeuw, Jan W., Matthiessen, Jens, Backman, Jan, Moran, Kathryn, Expedition 302, Nature, 441, 7093, 606–09, 16752440, Scientists, 2006Natur.441..606B, 11250/174278,
  • global cooling over the past 40 million years driven by the expansion of grass-grazer ecosystemsJOURNAL, harv, 10.1086/320791, Cenozoic Expansion of Grasslands and Climatic Cooling, 2001, Retallack, Gregory J., The Journal of Geology, 109, 4, 407–26, 2001JG....109..407R, JOURNAL, 10.1130/0091-7613(1997)0252.3.CO;2, Miocene to present vegetation changes: A possible piece of the Cenozoic cooling puzzle, 1997, Dutton, Jan F., Barron, Eric J., Geology, 25, 1, 39, 1997Geo....25...39D,

External climate forcing

Greenhouse gases

(File:Mauna Loa CO2 monthly mean concentration.svg|thumb|right|Increase in atmospheric {{CO2}} levels)Whereas greenhouse gases released by the biosphere is often seen as a feedback or internal climate process, greenhouse gases emitted from volcanoes are typically classified as external by climatologists.{{harvnb|Cronin|2010|p=17}} Greenhouse gases, such as {{CO2}}, methane and nitrous oxide, heat the climate system by trapping infrared light.The scientific consensus on climate change is "that climate is changing and that these changes are in large part caused by human activities",BOOK
, The National Academies Press
, 978-0-309-14588-6
, America's Climate Choices: Panel on Advancing the Science of Climate Change; National Research Council
, Advancing the Science of Climate Change
, Washington, D.C.
, 2010
,weblink
, dead
,weblink" title="web.archive.org/web/20140529161102weblink">weblink
, 29 May 2014
,
, and it "is largely irreversible".JOURNAL, Irreversible climate change due to carbon dioxide emissions, Susan Solomon, Gian-Kasper Plattner, Reto Knutti, Reto Knutti, Pierre Friedlingstein, 2009, 19179281, 10.1073/pnas.0812721106, 106, 6, 1704–09, 2632717, Proceedings of the National Academy of Sciences of the United States of America, 2009PNAS..106.1704S, harv, There has been multiple indications of how human activities affect global warming and continue to do so.JOURNAL, Nickerson, Raymond S., October 2014, Is Global Warming a Challenge to Human Factors/Ergonomics?,weblink Ergonomics in Design: The Quarterly of Human Factors Applications, 22, 4, 4–7, 10.1177/1064804614547127, 1064-8046, {{quotation|"... there is a strong, credible body of evidence, based on multiple lines of research, documenting that climate is changing and that these changes are in large part caused by human activities. While much remains to be learned, the core phenomenon, scientific questions, and hypotheses have been examined thoroughly and have stood firm in the face of serious scientific debate and careful evaluation of alternative explanations."|United States National Research Council, Advancing the Science of Climate Change}}Human's main impact is by emitting CO2 from fossil fuel combustion, followed by aerosols (particulate matter in the atmosphere), and the CO2 released by cement manufacture.WEB,weblink 3. Are human activities causing climate change? {{!, Australian Academy of Science|website=www.science.org.au|access-date=2017-08-12}} Other factors, including land use, ozone depletion, animal husbandry (ruminant animals such as cattle produce methaneBOOK, Steinfeld, H., P. Gerber, T. Wassenaar, V. Castel, M. Rosales, C. de Haan, Livestock's long shadow, 2006,weblink ), and deforestation, are also play a role.NEWS, The Editorial Board, What the Paris Climate Meeting Must Do,weblink 28 November 2015, The New York Times, 28 November 2015, Volcanoes are also part of the extended carbon cycle. Over very long (geological) time periods, they release carbon dioxide from the Earth's crust and mantle, counteracting the uptake by sedimentary rocks and other geological carbon dioxide sinks. The US Geological Survey estimates are that volcanic emissions are at a much lower level than the effects of current human activities, which generate 100–300 times the amount of carbon dioxide emitted by volcanoes.WEB,weblink Volcanic Gases and Their Effects, 2006-01-10, U.S. Department of the Interior, 21 January 2008, The annual amount put out by human activities may be greater than the amount released by supererruptions, the most recent of which was the Toba eruption in Indonesia 74,000 years ago.WEB,weblink Human Activities Emit Way More Carbon Dioxide Than Do Volcanoes, 14 June 2011, American Geophysical Union, 20 June 2011,

Orbital variations

{{multiple image| direction = vertical| width = 220| footer = | image1 = MilankovitchCyclesOrbitandCores.png| caption1 = Milankovitch cycles from 800,000 years ago in the past to 800,000 years in the future.
CO2>CO2, temperature and dust from the Vostok ice core over the last 450,000 years}}Slight variations in Earth's motion lead to changes in the seasonal distribution of sunlight reaching the Earth's surface and how it is distributed across the globe. There is very little change to the area-averaged annually averaged sunshine; but there can be strong changes in the geographical and seasonal distribution. The three types of kinematic change are variations in Earth's eccentricity, changes in the tilt angle of Earth's axis of rotation, and precession of Earth's axis. Combined together, these produce Milankovitch cycles which affect climate and are notable for their correlation to glacial and interglacial periods,WEB,weblinkweblink" title="web.archive.org/web/20110716144130weblink">weblink 2011-07-16, Milankovitch Cycles and Glaciation, 2 April 2009, University of Montana, their correlation with the advance and retreat of the Sahara, and for their appearance in the stratigraphic record.JOURNAL, 10.1111/j.1365-3121.1989.tb00403.x, A Milankovitch scale for Cenomanian time, 1989, Gale, Andrew S., Terra Nova, 1, 420–25, 5, harv, 1989TeNov...1..420G, WEB, Same forces as today caused climate changes 1.4 billion years ago,weblink sdu.dk, University of Denmark., dead,weblink" title="web.archive.org/web/20150312163250weblink">weblink 12 March 2015, dmy-all, The IPCC notes that Milankovitch cycles drove the ice age cycles, CO2 followed temperature change "with a lag of some hundreds of years", and that as a feedback amplified temperature change.FAQ 6.1: What Caused the Ice Ages and Other Important Climate Changes Before the Industrial Era? in {{Harvnb|IPCC AR4 WG1|2007}}. The depths of the ocean have a lag time in changing temperature (thermal inertia on such scale). Upon seawater temperature change, the solubility of CO2 in the oceans changed, as well as other factors affecting air-sea CO2 exchange.Box 6.2: What Caused the Low Atmospheric Carbon Dioxide Concentrations During Glacial Times? in {{Harvnb|IPCC AR4 WG1|2007}} .

Solar output

File:Solar Activity Proxies.png|thumb|Variations in solar activity during the last several centuries based on observations of sunspots and beryllium isotopes. The period of extraordinarily few sunspots in the late 17th century was the alt=|leftThe Sun is the predominant source of energy input to the Earth's climate system. Other sources include geothermal energy from the Earth's core, tidal energy from the Moon and heat from the decay of radioactive compounds. Both long- and short-term variations in solar intensity are known to affect global climate.Three to four billion years ago, the Sun emitted only 75% as much power as it does today.CONFERENCE, Ribas, Ignasi, Proceedings of the IAU Symposium 264 'Solar and Stellar Variability – Impact on Earth and Planets', The Sun and stars as the primary energy input in planetary atmospheres, 264, 3–18, February 2010, 10.1017/S1743921309992298, 2010IAUS..264....3R, 0911.4872, If the atmospheric composition had been the same as today, liquid water should not have existed on the Earth's surface. However, there is evidence for the presence of water on the early Earth, in the HadeanJOURNAL, 10.2138/rmg.2006.62.18, Water in the Early Earth, 2006, Marty, B., Reviews in Mineralogy and Geochemistry, 62, 1, 421–50, harv, 2006RvMG...62..421M, JOURNAL, harv, 10.1126/science.1110873, Zircon Thermometer Reveals Minimum Melting Conditions on Earliest Earth, 2005, Watson, E.B., Science, 308, 5723, 841–44, 15879213, Harrison, TM, 2005Sci...308..841W, and ArcheanJOURNAL, harv, 10.1130/0091-7613(1994)0222.3.CO;2, Surface-water influx in shallow-level Archean lode-gold deposits in Western, Australia, 1994, Hagemann, Steffen G., Gebre-Mariam, Musie, Groves, David I., Geology, 22, 12, 1067, 1994Geo....22.1067H, eons, leading to what is known as the faint young Sun paradox.BOOK, Sagan, C., G. Mullen, Earth and Mars: Evolution of Atmospheres and Surface Temperatures, 1972,weblink Hypothesized solutions to this paradox include a vastly different atmosphere, with much higher concentrations of greenhouse gases than currently exist.JOURNAL, harv, 10.1126/science.276.5316.1217, The Early Faint Sun Paradox: Organic Shielding of Ultraviolet-Labile Greenhouse Gases, 1997, Sagan, C., Science, 276, 5316, 1217–21, 11536805, Chyba, C, 1997Sci...276.1217S, Over the following approximately 4 billion years, the energy output of the Sun increased and atmospheric composition changed. The Great Oxygenation Event—oxygenation of the atmosphere around 2.4 billion years ago—was the most notable alteration. Over the next five billion years from the present, the Sun's ultimate death as it becomes a red giant and then a white dwarf will have large effects on climate, with the red giant phase possibly ending any life on Earth that survives until that time.{{citation | last1=Schröder | first1=K.-P. | last2=Connon Smith | first2=Robert | title=Distant future of the Sun and Earth revisited | journal=Monthly Notices of the Royal Astronomical Society | volume=386 | issue=1 | pages=155–63 | doi=10.1111/j.1365-2966.2008.13022.x | date=2008 | bibcode=2008MNRAS.386..155S | arxiv=0801.4031 }}Solar output varies on shorter time scales, including the 11-year solar cycleJOURNAL, harv, 10.1038/351042a0, The Sun's luminosity over a complete solar cycle, 1991, Willson, Richard C., Hudson, Hugh S., Nature, 351, 6321, 42–44, 1991Natur.351...42W, and longer-term modulations.JOURNAL, harv, 10.1029/2002GL016038, Secular total solar irradiance trend during solar cycles 21–23, 2003, Willson, Richard C., Geophysical Research Letters, 30, 5, n/a, 2003GeoRL..30.1199W, Solar intensity variations, possibly as a result of the Wolf, Spörer, and the Maunder Minima, are considered to have been influential in triggering the Little Ice Age.BOOK, Solar Irradiance Changes and the Relatively Recent Climate,weblink Solar influences on global change, National Academy Press, Washington, D.C, 1994, 36, 0-309-05148-7,weblink This event extended from 1550 to 1850 AD and was marked by relative cooling and greater glacier extent than the centuries before and afterward.WEB, NASA Earth Observatory, Glossary I-M,weblink 28 February 2011, JOURNAL, harv, 10.1034/j.1600-0889.2000.d01-7.x, Solar irradiance during the last 1200 years based on cosmogenic nuclides, 2000, Bard, Edouard, Raisbeck, Grant, Yiou, Françoise, Jouzel, Jean, Tellus B, 52, 3, 985–92, 2000TellB..52..985B, Solar variation may also have affected some of the warming observed from 1900 to 1950.{{citation needed|date=September 2019}}

Volcanism

File:Msu 1978-2010.jpg|thumb|right|In atmospheric temperature from 1979 to 2010, determined by MSU NASA satellites, effects appear from aerosols released by major volcanic eruptions (El Chichón and Pinatubo). El Niño is a separate event, from ocean variability.]]The eruptions considered to be large enough to affect the Earth's climate on a scale of more than 1 year are the ones that inject over 100,000 tons of SO2 into the stratosphere.MILES > FIRST1 = M.G.
FIRST2 = R.G. FIRST3 = E.J., The significance of volcanic eruption strength and frequency for climate, Quarterly Journal of the Royal Meteorological Society, 2004 pages = 2361–76, 602, 10.1256/qj.30.60, 2019-08-20, This is due to the optical properties of SO2 and sulfate aerosols, which strongly absorb or scatter solar radiation, creating a global layer of sulfuric acid haze.WEB, Volcanic Gases and Climate Change Overview,weblink usgs.gov, USGS, 31 July 2014, On average, such eruptions occur several times per century, and cause cooling (by partially blocking the transmission of solar radiation to the Earth's surface) for a period of several years. Although volcanoes are technically part of the lithosphere, which itself is part of the climate system, the IPCC explicitly defines volcanism as an external forcing agent.Annexes, in {{Harvnb|IPCC AR4 SYR|2008|p=58}}.Notable eruptions in the historical records are the eruption of Mount Pinatubo in 1991 which lowered global temperatures by about 0.5 Â°C (0.9 Â°F) for up to three years,WEB,weblink The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines, Diggles, Michael, 28 February 2005, U.S. Geological Survey Fact Sheet 113-97, United States Geological Survey, 8 October 2009, DIGGLES > FIRST1 = MICHAEL, The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines,weblink usgs.gov, 31 July 2014, and the Mount Tambora eruption in 1815 causing the Year Without a Summer.JOURNAL, 10.1191/0309133303pp379ra, Climatic, environmental and human consequences of the largest known historic eruption: Tambora volcano (Indonesia) 1815, 2003first1=Clive, Progress in Physical Geography, 27, 230–59, 2, harv, Much larger eruptions, known as large igneous provinces, occur only a few times every 50,000,000–100,000,000 years through flood basalts; in Earth's past, they have caused global warming and mass extinctions.JOURNAL, 10.1016/S0012-8252(00)00037-4, Large igneous provinces and mass extinctions, 2001first1=P, Earth-Science Reviews, 53, 1, 1–33, 2001ESRv...53....1W, harv, Small eruptions, with injections of less than 0.1 Mt of sulfur dioxide into the stratosphere, affect the atmosphere only subtly, as temperature changes are comparable with natural variability. However, because smaller eruptions occur at a much higher frequency, they too significantly affect Earth's atmosphere.GRAF > FIRST1 = H.-F. FIRST2 = J. FIRST3 = B., Volcanic sulphur emissions: Estimates of source strength and its contribution to the global sulphate distribution, Journal of Geophysical Research: Atmospheres, 1997 issue = D9, 10727–38, 10.1029/96JD03265, 1997JGR...10210727G, 21.11116/0000-0003-2CBB-A, Seismic monitoring maps current and future trends in volcanic activities, and tries to develop early warning systems. In climate modelling the aim is to study the physical mechanisms and feedbacks of volcanic forcing.WEB, IPCC Fourth Assessment Report: Climate Change 2007,weblink archive.ipcc.ch, 31 July 2014,

Plate tectonics

Over the course of millions of years, the motion of tectonic plates reconfigures global land and ocean areas and generates topography. This can affect both global and local patterns of climate and atmosphere-ocean circulation.JOURNAL, 1999, Paleoaltimetry incorporating atmospheric physics and botanical estimates of paleoclimate, Geological Society of America Bulletin, 111, 497–511, 4, 10.1130/0016-7606(1999)1112.3.CO;2, K.A., Wolfe, C.E., Molnar, J.A., P., Emanuel, Forest, 1999GSAB..111..497F, The position of the continents determines the geometry of the oceans and therefore influences patterns of ocean circulation. The locations of the seas are important in controlling the transfer of heat and moisture across the globe, and therefore, in determining global climate. A recent example of tectonic control on ocean circulation is the formation of the Isthmus of Panama about 5 million years ago, which shut off direct mixing between the Atlantic and Pacific Oceans. This strongly affected the ocean dynamics of what is now the Gulf Stream and may have led to Northern Hemisphere ice cover.WEB,weblink Panama: Isthmus that Changed the World, 1 July 2008, NASA Earth Observatory, dead,weblink" title="web.archive.org/web/20070802015424weblink">weblink 2 August 2007, dmy, JOURNAL,weblink How the Isthmus of Panama Put Ice in the Arctic, Gerald H., Haug, Lloyd D., Keigwin, 22 March 2004, Oceanus, 42, 2, Woods Hole Oceanographic Institution, 1 October 2013, During the Carboniferous period, about 300 to 360 million years ago, plate tectonics may have triggered large-scale storage of carbon and increased (wikt:glaciation|glaciation).JOURNAL, Isotope stratigraphy of the European Carboniferous: proxy signals for ocean chemistry, climate and tectonics, 1999-09-30, 161, 1–3, 10.1016/S0009-2541(99)00084-4, 127–63, Peter, Bruckschen, Susanne, Oesmanna, Ján, Veizer, harv, Chemical Geology, 1999ChGeo.161..127B, Geologic evidence points to a "megamonsoonal" circulation pattern during the time of the supercontinent Pangaea, and climate modeling suggests that the existence of the supercontinent was conducive to the establishment of monsoons.JOURNAL, Judith T., Parrish, Climate of the Supercontinent Pangea, Chemical Geology, 1993, 101, 215–33, 10.1086/648217, 2, The University of Chicago Press, 30081148, harv, 1993JG....101..215P, The size of continents is also important. Because of the stabilizing effect of the oceans on temperature, yearly temperature variations are generally lower in coastal areas than they are inland. A larger supercontinent will therefore have more area in which climate is strongly seasonal than will several smaller continents or islands.

Other mechanisms

In 1997, it was postulated that ionized particles known as cosmic rays could impact cloud cover and thereby the climate. As the sun shields the earth from these particles, changes in solar activity were hypothesized to influence climate indirectly as well. To test the hypothesis, CERN designed the CLOUD experiment, which showed the effect of cosmic rays is too weak to influence climate noticeably.WEB,weblink Explainer: Why the sun is not responsible for recent climate change, Hausfather, Zeke, 2017-08-18, Carbon Brief, live, 2019-09-05, JOURNAL, Pierce, J. R., 2017, Cosmic rays, aerosols, clouds, and climate: Recent findings from the CLOUD experiment,weblink Journal of Geophysical Research: Atmospheres, 122, 15, 8051–8055, 10.1002/2017JD027475, 2169-8996, Evidence exists that the Chicxulub asteroid impact some 66 million years ago had severely affected the Earth's climate. Large quantities of sulfate aerosols were kicked up into the atmosphere, decreasing global temperatures by up to 26 Â°C and producing sub-freezing temperatures for a period of 3–16 years. The recovery time for this event took more than 30 years.{{citation
| contribution=Severe environmental effects of Chicxulub impact imply key role in end-Cretaceous mass extinction
| last1=Brugger | first1=Julia
| last2=Feulner | first2=Georg | last3=Petri | first3=Stefan
| title=19th EGU General Assembly, EGU2017, proceedings from the conference held 23–28 April, 2017 in Vienna, Austria., p.17167
| volume=19 | pages=17167 | date=April 2017 | bibcode=2017EGUGA..1917167B | postscript=. }}

Study of past climates

A number of disciplines throw light on past climates. Paleoclimatology is the study of changes in climate taken on the scale of the entire history of Earth. It uses a variety of proxy methods from the Earth and life sciences to obtain data previously preserved within things such as rocks, sediments, ice sheets, tree rings, corals, shells, and microfossils. It then uses the records to determine the past states of the Earth's various climate regions and its atmospheric system. Notable climate events known to paleoclimatology are provided in this list of periods and events in climate history.Historical climatology is the study of historical changes in climate and their effect on human history and development. The primary sources include written records such as sagas, chronicles, maps and local history literature as well as pictorial representations such as paintings, drawings and even rock art.Climate change in the recent past may be detected by corresponding changes in settlement and agricultural patterns.JOURNAL, P.B., Cultural Responses to Climate Change During the Late Holocene,weblink Demenocal, Science (journal), Science, 292, 667–73, 2001, 10.1126/science.1059827, 11303088, 5517, 2001Sci...292..667D, Archaeological evidence, oral history and historical documents can offer insights into past changes in the climate. Climate change effects have been linked to the riseJOURNAL, S.M., Networks and nodal points: the emergence of towns in early Viking Age Scandinavia, Sindbaek, Antiquity (journal), Antiquity, 81, 119–32, 2007, 311, 10.1017/s0003598x00094886, and also the collapse of various civilizations.

Change in different elements climate system

All elements of the climate systems portray changes as a consequence of climate change. Evidence for climatic change is taken from a variety of sources that can be used to reconstruct past climates. Reasonably complete global records of surface temperature are available beginning from the mid-late 19th century. For earlier periods, most of the evidence is indirect—climatic changes are inferred from changes in proxies, indicators that reflect climate, such as vegetation, ice cores,JOURNAL, Petit, J.R., Climate and atmospheric history of the past 420,000 years from the Vostok ice core, Antarctica, Nature (journal), Nature, 399, 429–46, 1999-06-03, 10.1038/20859, 1, J., Jouzel, D., Raynaud, N.I., Barkov, J.-M., Barnola, I., Basile, M., Bender, J., Chappellaz, M., Davis, G., Delaygue, M., Delmotte, V.M., Kotlyakov, M., Legrand, V.Y., Lipenkov, C., Lorius, C., Ritz, E., Saltzman, 3, harv, 1999Natur.399..429P,weblink dendrochronology, sea level change, and glacial geology.

Atmosphere

Surface temperature

File:Five Myr Climate Change.svg|thumb|The Antarctic temperature changes during the last several glacial and interglacial cycles of the present ice age, according to δ18Oδ18OThe instrumental temperature record from surface stations was supplemented by radiosonde balloons, extensive atmospheric monitoring by the mid-20th century, and, from the 1970s on, with global satellite data as well. Taking the record as a whole, most of the 20th century had been unprecedentedly warm, while the 19th and 17th centuries were quite cool.WEB,weblink CLIMATE WARMEST SINCE MIDDLE AGES, Von Radowitz, John, April 23, 1998, Century Newspapers LTD, Analysis of ice in a core drilled from an ice sheet such as the Antarctic ice sheet, can be used to show a link between temperature and global sea level variations. The air trapped in bubbles in the ice can also reveal the CO2 variations of the atmosphere from the distant past, well before modern environmental influences. The study of these ice cores has been a significant indicator of the changes in CO2 over many millennia, and continues to provide valuable information about the differences between ancient and modern atmospheric conditions.

Cloud cover and precipitation

{{see also|Cloud|Precipitation}}Climatological temperatures substantially affect cloud cover and precipitation. At lower temperatures, air can hold less water vapour, which can lead to decreased precipitation.JOURNAL, Haerter, Jan O., Moseley, Christopher, Berg, Peter, 2013, Strong increase in convective precipitation in response to higher temperatures,weblink Nature Geoscience, 6, 3, 181–185, 10.1038/ngeo1731, 1752-0908, For instance, during the Last Glacial Maximum of 18,000 years ago, thermal-driven evaporation from the oceans onto continental landmasses was low, causing large areas of extreme desert, including polar deserts (cold but with low rates of cloud cover and precipitation). In contrast, the world's climate was cloudier and wetter than today near the start of the warm Atlantic Period of 8000 years ago.Cloud formation is not only influenced by how much water is in the air and the temperature, but also by the amount of aerosols in the air such as dust.WEB,weblink Mineral dust plays key role in cloud formation and chemistry, Hadlington, May 2013, Simon 9, Chemistry World, 2019-09-05, Globally, more dust is available if there are many regions with dry soils, little vegetation and strong winds.JOURNAL, Mahowald, Natalie, Albani, Samuel, Kok, Jasper F., Engelstaeder, Sebastian, Scanza, Rachel, Ward, Daniel S., Flanner, Mark G., 2014-12-01, The size distribution of desert dust aerosols and its impact on the Earth system,weblink Aeolian Research, 15, 53–71, 10.1016/j.aeolia.2013.09.002, 1875-9637, Satellite cloud and precipitation data has been available since the 1970s.JOURNAL, New, M., Todd, M., Hulme, M. and Jones, P., Review: Precipitation measurements and trends in the twentieth century, International Journal of Climatology, 21, 15, 1889–922, 10.1002/joc.680, December 2001, 2001IJCli..21.1889N, harv, Quantification of climatological variation of precipitation in prior centuries and epochs is less complete but approximated using proxies such as marine sediments, ice cores, cave stalagmites, and tree rings.JOURNAL, Dominic, F., Burns, S.J., Neff, U., Mudulsee, M., Mangina, A. and Matter, A., Palaeoclimatic interpretation of high-resolution oxygen isotope profiles derived from annually laminated speleothems from Southern Oman, Quaternary Science Reviews, 23, 7–8, 935–45, 10.1016/j.quascirev.2003.06.019, April 2004, 2004QSRv...23..935F, harv,

Oceans and other water bodies

The 18O/16O ratio in calcite and ice core samples used to deduce ocean temperature in the distant past is an example of a temperature proxy method, as are other climate metrics noted in subsequent categories.

Sea level change

{{see also|Sea level rise}}Global sea level change for much of the last century has generally been estimated using tide gauge measurements collated over long periods of time to give a long-term average. More recently, altimeter measurements—in combination with accurately determined satellite orbits—have provided an improved measurement of global sea level change.WEB,weblink Sea Level Change, University of Colorado at Boulder,weblink" title="web.archive.org/web/20090219163602weblink">weblink 19 February 2009, 21 July 2009, dead, To measure sea levels prior to instrumental measurements, scientists have dated coral reefs that grow near the surface of the ocean, coastal sediments, marine terraces, ooids in limestones, and nearshore archaeological remains. The predominant dating methods used are uranium series and radiocarbon, with cosmogenic radionuclides being sometimes used to date terraces that have experienced relative sea level fall. In the early Pliocene, global temperatures were 1–2ËšC warmer than the present temperature, yet sea level was 15–25 meters higher than today.WEB,weblink Science Briefs: Earth's Climate History, Hansen, James, NASA GISS, 25 April 2013, NEWS,weblink Singapore underwater, The Straits Times, 2017-05-31, NEWS,weblink How Singapore is responding to the threat of rising sea levels, The Straits Times, 2017-05-31, According to recent studies, global-mean sea level rose by 195 mm during the period from 1870 to 2004.JOURNAL, Church, John A., White, Neil J., 2006-01-16, A 20th century acceleration in global sea-level rise, Geophysical Research Letters, 33, 1, n/a, 2006GeoRL..33.1602C, 10.1029/2005gl024826, 1944-8007, Since 2004, satellite-based records indicate that there has been a further 43 mm of global-mean sea levels rise, {{as of|2017|July|lc=y}}.WEB,weblink NASA Global Climate Change, Vital Signs, 2 April 2018,

Cryosphere

Glaciers and ice sheets

Glaciers are considered among the most sensitive indicators of climate change.REPORT, Seiz, G., N. Foppa, The activities of the World Glacier Monitoring Service (WGMS), 2007,weblink 21 June 2009, dead,weblink" title="web.archive.org/web/20090325100331weblink">weblink 25 March 2009, Their size is determined by a mass balance between snow input and melt output. As temperatures warm, glaciers retreat unless snow precipitation increases to make up for the additional melt; the converse is also true.Glaciers grow and shrink due both to natural variability and external forcings. Variability in temperature, precipitation, and englacial and subglacial hydrology can strongly determine the evolution of a glacier in a particular season. Therefore, one must average over a decadal or longer time-scale and/or over many individual glaciers to smooth out the local short-term variability and obtain a glacier history that is related to climate.The most significant climate processes since the middle to late Pliocene (approximately 3 million years ago) are the glacial and interglacial cycles. The present interglacial period (the Holocene) has lasted about 11,700 years.WEB,weblink International Stratigraphic Chart, 2008, International Commission on Stratigraphy, 3 October 2011, dead,weblink" title="web.archive.org/web/20111015042711weblink">weblink 15 October 2011, dmy-all, Shaped by orbital variations, responses such as the rise and fall of continental ice sheets and significant sea-level changes helped create the climate. Other changes, including Heinrich events, Dansgaard–Oeschger events and the Younger Dryas, however, illustrate how glacial variations may also influence climate without the orbital forcing.Glaciers leave behind moraines that contain a wealth of material—including organic matter, quartz, and potassium that may be dated—recording the periods in which a glacier advanced and retreated. Similarly, by tephrochronological techniques, the lack of glacier cover can be identified by the presence of soil or volcanic tephra horizons whose date of deposit may also be ascertained.From satellite data and aerial photographs, glaciers worldwide have been found to be shrinking significantlyREPORT, Zemp, M., I.Roer, A.Kääb, M.Hoelzle, F.Paul, W. Haeberli, United Nations Environment Programme â€“ Global Glacier Changes: facts and figures, PDF, 2008,weblink 21 June 2009,weblink" title="web.archive.org/web/20090325100332weblink">weblink 25 March 2009, dead, WEB,weblink Climate Change Indicators: Glaciers, US, EPA, OA, US EPA, Data from NASA's Grace satellites show that the land ice sheets in both Antarctica (upper chart) and Greenland (lower) have been losing mass since 2002. Both ice sheets have seen an acceleration of ice mass loss since 2009.WEB,weblink Land ice – NASA Global Climate Change,

Sea ice

{{see also|Arctic sea ice decline|Climate change in the Arctic}}Sea ice plays an important role in Earth's climate as it affects the total amount of sunlight that is reflected away from the Earth.JOURNAL, Belt, Simon T., Cabedo-Sanz, Patricia, Smik, Lukas, Navarro-Rodriguez, Alba, Berben, Sarah M. P., Knies, Jochen, Husum, Katrine, 3, 2015, Identification of paleo Arctic winter sea ice limits and the marginal ice zone: Optimised biomarker-based reconstructions of late Quaternary Arctic sea ice,weblink Earth and Planetary Science Letters, 431, 127–139, 10.1016/j.epsl.2015.09.020, 0012-821X, In the past, the Earth's oceans have been almost entirely covered by sea ice on a number of occasions, when the Earth was in a so-called Snowball Earth state,JOURNAL, Warren, Stephen G., Voigt, Aiko, Tziperman, Eli, Sadler, Peter M., Rose, Catherine V., Rose, Brian E. J., Ramstein, Gilles, Partin, Camille A., Maloof, Adam C., 3, 2017-11-01, Snowball Earth climate dynamics and Cryogenian geology-geobiology,weblink Science Advances, 3, 11, e1600983, 10.1126/sciadv.1600983, 2375-2548, and completely ice-free in periods of warm climate.JOURNAL, Caballero, R., Huber, M., 2013, State-dependent climate sensitivity in past warm climates and its implications for future climate projections,weblink Proceedings of the National Academy of Sciences, 110, 35, 14162–14167, 10.1073/pnas.1303365110, 0027-8424, When there is a lot of sea ice present globally, especially in the tropics and subtropics, the climate is more sensitive to forcings as the ice–albedo feedback is very strong.JOURNAL, Hansen James, Sato Makiko, Russell Gary, Kharecha Pushker, 2013, Climate sensitivity, sea level and atmospheric carbon dioxide,weblink Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 371, 2001, 20120294, 10.1098/rsta.2012.0294, 3785813, 24043864, The decline in Arctic sea ice, both in extent and thickness, over the last several decades is further evidence for rapid climate change.WEB,weblink 2017-12-16, Earth Science Communications Team at NASA's Jet Propulsion Laboratory, NASA Global Climate Change, Climate Change: How do we know?, Holly, Shaftel, Sea ice is frozen seawater that floats on the ocean surface. It covers millions of square kilometers in the polar regions, varying with the seasons. In the Arctic, some sea ice remains year after year, whereas almost all Southern Ocean or Antarctic sea ice melts away and reforms annually. Satellite observations show that Arctic sea ice is now declining at a rate of 13.2 percent per decade, relative to the 1981 to 2010 average.WEB, Holly, Shaftel, Arctic Sea Ice Minimum,weblink NASA Global Climate Change, Earth Science Communications Team at NASA's Jet Propulsion Laboratory, 21 June 2015,

Biosphere

File:Aridity ice age vs early holocene vs modern.jpg|thumb|right|Top: Arid ice age climate{{Clear}}Middle: (Atlantic period|Atlantic Period]], warm and wet{{Clear}}Bottom: Potential vegetation in climate now if not for human effects like agriculture.JOURNAL, Adams, J.M., Faure, H., 1997,weblink Review and Atlas of Palaeovegetation: Preliminary land ecosystem maps of the world since the Last Glacial Maximum, Oak Ridge National Laboratory, Tennessee, dead,weblink" title="web.archive.org/web/20080116122058weblink">weblink 16 January 2008, dmy-all, QEN members.)

Vegetation

A change in the type, distribution and coverage of vegetation may occur given a change in the climate. Some changes in climate may result in increased precipitation and warmth, resulting in improved plant growth and the subsequent sequestration of airborne CO2. The effects are expected to affect the rate of many natural cycles like plant litter decomposition rates.JOURNAL, Ochoa-Hueso, R, Delgado-Baquerizo, N, King, PTA, Benham, M, Arca, V, Power, SA, Ecosystem type and resource quality are more important than global change drivers in regulating early stages of litter decomposition, Soil Biology and Biochemistry, 2019, 129, 144–152, 10.1016/j.soilbio.2018.11.009, A gradual increase in warmth in a region will lead to earlier flowering and fruiting times, driving a change in the timing of life cycles of dependent organisms. Conversely, cold will cause plant bio-cycles to lag.WEB, Kinver, Mark, 2011-11-15, UK trees' fruit ripening '18 days earlier', Bbc.co.uk,weblink 1 November 2012, Larger, faster or more radical changes, however, may result in vegetation stress, rapid plant loss and desertification in certain circumstances.JOURNAL, Sahney, S., Benton, M.J., Falcon-Lang, H.J., 2010, Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica, Geology, 10.1130/G31182.1, 2010Geo....38.1079S, 38, 12, 1079–82, harv,weblink PDF, 27 November 2013, JOURNAL, Bachelet, D., Dominique Bachelet, Neilson, R., Lenihan, J. M., Drapek, R.J., 2001, Climate Change Effects on Vegetation Distribution and Carbon Budget in the United States, Ecosystems, 10.1007/s10021-001-0002-7, 4, 3, 164–85, harv, An example of this occurred during the Carboniferous Rainforest Collapse (CRC), an extinction event 300 million years ago. At this time vast rainforests covered the equatorial region of Europe and America. Climate change devastated these tropical rainforests, abruptly fragmenting the habitat into isolated 'islands' and causing the extinction of many plant and animal species. Such stress can alter the growth rate of trees, which allows scientists to infer climate trends by analyzing the growth rate of tree rings. This branch of climate science is called dendroclimatology, and is one of the many ways they research climate trends prior to written records.BOOK,weblink Dendroclimatology: progress and prospect, Springer Science & Business Media, 2010, 978-1-4020-4010-8, Hughes, Malcolm K., Developments in Paleoenvironmental Research, 11, New York, Swetnam, Thomas W., Diaz, Henry F.,

Pollen analysis

Palynology is the study of contemporary and fossil palynomorphs, including pollen. Palynology is used to infer the geographical distribution of plant species, which vary under different climate conditions. Different groups of plants have pollen with distinctive shapes and surface textures, and since the outer surface of pollen is composed of a very resilient material, they resist decay. Changes in the type of pollen found in different layers of sediment in lakes, bogs, or river deltas indicate changes in plant communities. These changes are often a sign of a changing climate.JOURNAL, Langdon, P.G., Barber, K.E., Lomas-Clarke, S.H., Lomas-Clarke, S.H., August 2004, Reconstructing climate and environmental change in northern England through chironomid and pollen analyses: evidence from Talkin Tarn, Cumbria, Journal of Paleolimnology, 10.1023/B:JOPL.0000029433.85764.a5, 32, 2, 197–213, harv, 2004JPall..32..197L, JOURNAL, Birks, H.H., The importance of plant macrofossils in the reconstruction of Lateglacial vegetation and climate: examples from Scotland, western Norway, and Minnesota, US, Quaternary Science Reviews, 22, 5–7, 453–73, March 2003, 10.1016/S0277-3791(02)00248-2, 2003QSRv...22..453B, harv,weblink 1956/387, As an example, palynological studies have been used to track changing vegetation patterns throughout the Quaternary glaciationsJOURNAL, Miyoshi, N, Palynology of a 250-m core from Lake Biwa: a 430,000-year record of glacial–interglacial vegetation change in Japan, Review of Palaeobotany and Palynology, 104, 267–83, 1999, 10.1016/S0034-6667(98)00058-X, 3–4, Fujiki, Toshiyuki, Morita, Yoshimune, harv, and especially since the last glacial maximum.JOURNAL, I. Colin, Prentice, Bartlein, Patrick J, Webb, Thompson, Vegetation and Climate Change in Eastern North America Since the Last Glacial Maximum, Ecology, 72, 6, 2038–56, 1991, 10.2307/1941558, 1941558, harv,

Animals

Remains of beetles are common in freshwater and land sediments. Different species of beetles tend to be found under different climatic conditions. Given the extensive lineage of beetles whose genetic makeup has not altered significantly over the millennia, knowledge of the present climatic range of the different species, and the age of the sediments in which remains are found, past climatic conditions may be inferred.JOURNAL, Coope, G.R., Temperature gradients in northern Europe during the last glacial – Holocene transition (14–9 14 C kyr BP) interpreted from coleopteran assemblages, Journal of Quaternary Science, 13, 5, 419–33, 1999-05-04, 10.1002/(SICI)1099-1417(1998090)13:53.0.CO;2-D, Lemdahl, G.; Lowe, J.J.; Walkling, A., 1998JQS....13..419C, harv,

Notes

{{Reflist}}

References

  • BOOK, harv, Cronin, Thomas N., Paleoclimates: understanding climate change past and present, New York, Columbia University Press, 2010, 978-0-231-14494-0,
  • BOOK, {{harvid, IPCC AR4 WG1, 2007, |title = Climate Change 2007: The Physical Science Basis |series = Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change |author = IPCC |author-link = IPCC |year = 2007 |display-editors= 4 |editor-first1= S. |editor-last1= Solomon |editor-first2= D. |editor-last2= Qin |editor-first3= M. |editor-last3= Manning |editor-first4= Z. |editor-last4= Chen |editor-first5= M. |editor-last5= Marquis |editor-first6= K.B. |editor-last6= Averyt |editor-first7= M. |editor-last7= Tignor |editor-first8= H.L. |editor-last8= Miller |publisher = Cambridge University Press |url =weblink |isbn = 978-0-521-88009-1}} (pb: {{ISBNT|978-0-521-70596-7}}).
  • BOOK, {{harvid, IPCC AR4 SYR, 2008, |author= IPCC |author-link= IPCC |year= 2008 |title= Climate Change 2008: Synthesis Report |series= Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change |editor1 = The Core Writing Team |editor-first2= R. K. |editor-last2= Pachauri |editor-first3= A. R |editor-last3= Reisinger |publisher= IPCC |place= Geneva, Switzerland |isbn= 92-9169-122-4 |url=weblink}}.
  • BOOK, 2001, IPCC TAR WG1, IPCC, Climate Change 2001: The Scientific Basis, Contribution of Working Group I to the IPCC Third Assessment Report, Third Assessment Report of the Intergovernmental Panel on Climate Change, Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Dai, X., Maskell, K., Johnson, C.A., Cambridge University Press,weblink 0-521-80767-0, harv, dead,weblink" title="web.archive.org/web/20160330214626weblink">weblink


, 30 March 2016, 5 July 2019, (pb: {{ISBNT|0-521-01495-6}}).

Further reading

  • BOOK, Ipcc ar4 wg1, IPCC, 2007, Summary for Policymakers,weblink
series = Contribution of Working Group I to the IPCC Fourth Assessment Report of the Intergovernmental Panel on Climate Change> editor1-last = Solomon editor2-last=Qin editor3-last=Manning editor4-last=Chen editor5-last=Marquis editor6-last=Averyt editor7-last=Tignor editor8-last=Miller publisher = Cambridge University Press url =weblink (pb: {{ISBNT|978-0-521-70596-7}}).
  • BOOK, Ipcc ar4 syr, IPCC, 2007, Summary for Policymakers,weblink
series = Contribution of Working Groups I, II and III to the IPCC Fourth Assessment Report of the Intergovernmental Panel on Climate Change> editor1 = Core Writing Team editor2-first=R.K editor3-first=A. isbn = 978-92-9169-122-7,weblink
  • BOOK, Edwards, Paul Geoffrey, Miller, Clark A., 2001, Changing the atmosphere: expert knowledge and environmental governance, MIT Press, Cambridge, Massachusetts, 0-262-63219-5,
  • Francis, Jennifer, "Rough Weather Ahead: Recent disasters show how climate change is making winter storms, flooding rains and summer heat waves more extreme", Scientific American, vol. 320, no. 6 (June 2019), pp. 46–53.
  • BOOK, McKibben, Bill, 2011, The Global Warming Reader, OR Books, New York, N.Y., 978-1-935928-36-2,
  • BOOK, Ruddiman, William F., 2005, Plows, plagues, and petroleum: how humans took control of climate, Princeton University Press, Princeton, N.J, 0-691-13398-0,
  • BOOK, Wagner, Frederic H., 2009, Climate Change in Western North America: Evidence and Environmental Effects, 978-0-87480-906-0,

External links

{{Wikinews category|Climate change}}{{Commons category|Climate change}}{{sister project|project=wikisource
(:s:en:Portal:Climate change>Climate change)}} {{global warming|gstate=expanded}}{{Doomsday}}{{Use dmy dates|date=July 2011}}{{authority control}}


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