Climate change

Climate change is the climate of Earth changing. The Earth's climate has been much hotter and colder than it is today.^[1] Climate change this century and last century is sometimes called global warming, because the average temperature on the surface has risen.^[1] The last decade (2011–2020) was the warmest on record, and each of the last four decades has been warmer than any previous decade since 1850.^[2] The climate is now changing much faster than it has in the recent past. This is because people are putting more greenhouse gases in Earth's atmosphere, and they block some heat from escaping from the Earth into space.

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.^[3]

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.^[4]

At times in the past, the temperature was much cooler, with the last glaciation ending about ten thousand years ago.^[5][3] Ice Ages are times when the Earth got colder, and more ice froze at the North and South Poles.^[6] Sometimes even the whole Earth has been covered in ice, and was much colder than today.^[7][8]

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.^[6] Also how much the Earth is tilted compared to the Sun might make a difference.^[9] Another source of change is the activities of living things (see Great Oxygenation Event and Huronian glaciation).^[10][11]

1. ↑ ^{1.0 1.1} Rosen, Julia; Parshina-Kottas, Yuliya (19 April 2021). "A climate change guide for kids". The New York Times. ISSN 0362-4331. Retrieved 2021-05-29.
2. ↑ Nations, United. "What Is Climate Change?". United Nations. Retrieved 2023-04-30.
3. ↑ ^{3.0 3.1} 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
4. ↑ Lee, Howard (2020-03-19). "Sudden Ancient Global Warming Event Traced to Magma Flood". Quanta Magazine. Retrieved 2022-08-01.
5. ↑ Imbrie J. & Imbrie, K.P. 1979. Ice ages: solving the mystery. Short Hills NJ: Enslow. ISBN 978-0-89490-015-0
6. ↑ ^{6.0 6.1} "Problem Solving Activity: What Causes Ice Ages?" (PDF).
7. ↑ 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.
8. ↑ 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)
9. ↑ "When and how did the ice age end? Could another one start?".
10. ↑ 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.
11. ↑ 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