Climate change

Climate change refers to long-term changes in temperature, precipitation, and other atmospheric conditions on Earth. It primarily involves the warming of the planet due to increased concentrations of greenhouse gases, like carbon dioxide and methane, from human activities such as burning fossil fuels, deforestation, and industrial processes. These changes can lead to a variety of impacts, including more extreme weather events, rising sea levels, and disruptions to ecosystems and agriculture.

When people talk about climate change they are usually talking about the problem of human-caused global warming, which is happening now (see global warming for more details). But the climate of the Earth has changed over not just thousands of years, but tens or hundreds of millions of years.^[1]

Sometimes, before there were people, the Earth's climate was much hotter than it is today. For example about 60 million years ago there were a lot of volcanoes, which burnt a lot of underground organic matter (squashed and fossilized dead plants and animals became coal, gas and oil). A lot of carbon dioxide and methane went up in the air.^[2]

At times in the past, the temperature was much cooler, with the last glaciation ending about ten thousand years ago.^[3][1] Ice Ages are times when the Earth got colder, and more ice froze at the North and South Poles.^[4] Sometimes even the whole Earth has been covered in ice, and was much colder than today.^[5][6]

There is no one reason why there are Ice Ages. Changes in the Earth's orbit around the Sun, and the Sun getting brighter or dimmer are events which do happen.^[4] Also how much the Earth is tilted compared to the Sun might make a difference.^[7] Another source of change is the activities of living things (see Great Oxygenation Event and Huronian glaciation).^[8][9]

1. ↑ ^{1.0 1.1} Alley R.B. 2000. The two-mile time machine: ice cores, abrupt climate change, and our future. Princeton University Press. ISBN 0-691-10296-1
2. ↑ Lee, Howard (2020-03-19). "Sudden Ancient Global Warming Event Traced to Magma Flood". Quanta Magazine. Retrieved 2022-08-01.
3. ↑ Imbrie J. & Imbrie, K.P. 1979. Ice ages: solving the mystery. Short Hills NJ: Enslow. ISBN 978-0-89490-015-0
4. ↑ ^{4.0 4.1} "Problem Solving Activity: What Causes Ice Ages?" (PDF).
5. ↑ Williams G.E. & Schmidt P.W. (1997). "Paleomagnetism of the Paleoproterozoic Gowganda and Lorrain formations, Ontario: low palaeolatitude for Huronian glaciation" (PDF). EPSL. 153 (3): 157–169. Bibcode:1997E&PSL.153..157W. doi:10.1016/S0012-821X(97)00181-7. ISSN 0012-821X.
6. ↑ Evans D.A; Beukes N.J. & Kirschvink J.L. (1997). "Low-latitude glaciation in the Palaeoproterozoic era". Nature. 386 (6622): 262–6. Bibcode:1997Natur.386..262E. doi:10.1038/386262a0. S2CID 4364730.{{cite journal}}: CS1 maint: multiple names: authors list (link)
7. ↑ "When and how did the ice age end? Could another one start?".
8. ↑ Robert E. Kopp; et al. (2005). "The Paleoproterozoic snowball Earth: a climate disaster triggered by the evolution of oxygenic photosynthesis". Proc. Natl. Acad. Sci. U.S.A. 102 (32): 11131–6. Bibcode:2005PNAS..10211131K. doi:10.1073/pnas.0504878102. PMC 1183582. PMID 16061801.
9. ↑ Lane, Nick (2010). "First breath: Earth's billion-year struggle for oxygen". New Scientist (2746). A snowball period, c2.4–c2.0 billion years ago, was triggered by the Great Oxygenation Event [1] Archived 2011-01-06 at the Wayback Machine