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An ecological or environmental crisis occurs when changes to the environment of a species or population destabilizes its continued survival. Some of the important causes include:

Degradation of an abiotic ecological factor (for example, increase of temperature, less significant rainfalls)
Increased pressures from predation
Rise in the number of individuals (i.e. overpopulation)

The evolutionary theory of punctuated equilibrium sees infrequent ecological crises as a potential driver of rapid evolution.

Because of the impact of humans on the natural environment in the recent geological period, the term ecological crisis is often applied to environmental issues caused by human civilizations such as: the climate crisis, biodiversity loss and plastic pollution which have emerged as major global challenges during the first few decades of the 21st century.

Examples

Crises caused by abiotic factors

Climate change is starting to have major impacts on ecosystems. With global temperature rising, there is a decrease in snow-fall, and sea levels are rising. Ecosystems will change or evolve to cope with the increase in temperature. Consequently, many species are being driven out of their habitats.

Polar bears are being threatened. They need ice for hunting seals, their primary prey. However, the ice caps are melting, making their hunting periods shorter each year. As a result, the polar bears are not developing enough fat for the winter; therefore, they are not able to reproduce at a healthy rate.

Fresh water and wetland ecosystems are dealing with extreme effects of the increase of temperature. The climate change could be devastating to salmon and trout and to other aquatic life. The increase in temperature will disrupt the current life patterns of the salmon and trout. The cold-water fish will eventually leave their natural geographical range to live in cooler waters by migrating to higher elevations.

While many species have been able to adapt to the new conditions by moving their range further towards the poles, other species are not as fortunate. The option to move is not available for polar bears and for some aquatic life.

Climate change

Climate change is already now altering biomes, adversely affecting terrestrial and marine ecosystems.^[2]^[3] Climate change represents long-term changes in temperature and average weather patterns.^[4]^[5] This leads to a substantial increase in both the frequency and the intensity of extreme weather events.^[6] As a region's climate changes, a change in its flora and fauna follows.^[7] For instance, out of 4000 species analyzed by the IPCC Sixth Assessment Report, half were found to have shifted their distribution to higher latitudes or elevations in response to climate change.^[8]

Furthermore, climate change may cause ecological disruption among interacting species, via changes in behaviour and phenology, or via climate niche mismatch.^[9] For example, climate change can cause species to move in different directions, potentially disrupting their interactions with each other.^[10]^[11]

Examples of effects on some biome types are provided in the following.^{[clarification needed]}^[where?] Research into desertification is complex, and there is no single metric which can define all aspects. However, more intense climate change is still expected to increase the current extent of drylands on the Earth's continents. Most of the expansion will be seen over regions such as "southwest North America, the northern fringe of Africa, southern Africa, and Australia".^[12]

Mountains cover approximately 25 percent of the Earth's surface and provide a home to more than one-tenth of the global human population. Changes in global climate pose a number of potential risks to mountain habitats.^[13]

Boreal forests, also known as taiga, are warming at a faster rate than the global average,^[14] leading to drier conditions in the Taiga, which leads to a whole host of subsequent impacts.^[15] Climate change has a direct impact on the productivity of the boreal forest, as well as its health and regeneration.^[15]

Almost no other ecosystem is as vulnerable to climate change as coral reefs. Updated 2022 estimates show that even at a global average increase of 1.5 °C (2.7 °F) over pre-industrial temperatures, only 0.2% of the world's coral reefs would still be able to withstand marine heatwaves, as opposed to 84% being able to do so now, with the figure dropping to 0% at 2 °C (3.6 °F) warming and beyond.^[16]^[17]

Biodiversity extinction

Biodiversity loss happens when plant or animal species disappear completely from Earth (extinction) or when there is a decrease or disappearance of species in a specific area. Biodiversity loss means that there is a reduction in biological diversity in a given area. The decrease can be temporary or permanent. It is temporary if the damage that led to the loss is reversible in time, for example through ecological restoration. If this is not possible, then the decrease is permanent. The cause of most of the biodiversity loss is, generally speaking, human activities that push the planetary boundaries too far.^[18]^[19]^[20] These activities include habitat destruction^[21] (for example deforestation) and land use intensification (for example monoculture farming).^[22]^[23] Further problem areas are air and water pollution (including nutrient pollution), over-exploitation, invasive species^[24] and climate change.^[21]

Many scientists, along with the Global Assessment Report on Biodiversity and Ecosystem Services, say that the main reason for biodiversity loss is a growing human population because this leads to human overpopulation and excessive consumption.^[25]^[26]^[27]^[28]^[29] Others disagree, saying that loss of habitat is caused mainly by "the growth of commodities for export" and that population has very little to do with overall consumption. More important are wealth disparities between and within countries.^[30]

Climate change is another threat to global biodiversity.^[31]^[32] For example, coral reefs—which are biodiversity hotspots—will be lost by the year 2100 if global warming continues at the current rate.^[33]^[34] Still, it is the general habitat destruction (often for expansion of agriculture), not climate change, that is currently the bigger driver of biodiversity loss.^[35]^[36] Invasive species and other disturbances have become more common in forests in the last several decades. These tend to be directly or indirectly connected to climate change and can cause a deterioration of forest ecosystems.^[37]^[38]

Groups that care about the environment have been working for many years to stop the decrease in biodiversity. Nowadays, many global policies include activities to stop biodiversity loss. For example, the UN Convention on Biological Diversity aims to prevent biodiversity loss and to conserve wilderness areas. However, a 2020 United Nations Environment Programme report found that most of these efforts had failed to meet their goals.^[39] For example, of the 20 biodiversity goals laid out by the Aichi Biodiversity Targets in 2010, only six were "partially achieved" by 2020.^[40]^[41]

This ongoing global extinction is also called the holocene extinction or sixth mass extinction.

Animal overpopulation

In the wilderness, the problem of animal overpopulation is solved by predators. Predators tend to look for signs of weakness in their prey, and therefore usually first eat the old or sick animals. This has the side effects of ensuring a strong stock among the survivors and controlling the population.

In the absence of predators, animal species are bound by the resources they can find in their environment, but this does not necessarily control overpopulation. In fact, an abundant supply of resources can produce a population boom that ends up with more individuals than the environment can support. In this case, starvation, thirst, and sometimes violent competition for scarce resources may effect a sharp reduction in population, and in a very short lapse, a population crash. Lemmings, as well as other less popular species of rodents, are known to have such cycles of rapid population growth and subsequent decrease.

In an ideal setting, when animal populations grow, so do the number of predators that feed on that particular animal. Animals that have birth defects or weak genes (such as the runt of the litter) also die off, unable to compete over food with stronger, healthier animals.

In reality, an animal that is not native to an environment may have advantages over the native ones, such being unsuitable for the local predators. If left uncontrolled, such an animal can quickly overpopulate and ultimately destroy its environment.

Examples of animal overpopulation caused by introduction of a foreign species abound.

In the Argentine Patagonia, for example, European species such as the trout and the deer were introduced into the local streams and forests, respectively, and quickly became a plague, competing with and sometimes driving away the local species of fish and ruminants.
In Australia, when rabbits were introduced (unwillingly) by European immigrants, they bred out of control and ate the plants that other native animals needed to survive. Farmers hunted the rabbits to reduce their population and prevent the damage the rabbits did to the crops. They also brought cats to guard against rabbits and rats. These cats created another problem, since they became predators of local species.

More examples

Some common examples of ecological crises are:

Deforestation and desertification, with disappearance of many species.
Extinction events
- Permian-Triassic extinction event 250 million years ago^[42]
- Cretaceous–Paleogene extinction event 66 million years ago
The Exxon Valdez oil spill off the coast of Alaska in 1989
Global warming related to the Greenhouse effect. Warming could involve flooding of the Asian deltas (see also eco refugees), multiplication of extreme weather phenomena and changes in the nature and quantity of the food resources (see Global warming and agriculture). See also international Kyoto Protocol.
The nuclear meltdown at Chernobyl in 1986 caused the death of many people and animals from cancer, and caused mutations in a large number of animals and people. The area around the plant is now abandoned by humans because of the large amount of radiation generated by the meltdown. Twenty years after the accident, the animals have returned.^[43]
Ozone layer depletion.
Volcanic eruptions such as Mount St. Helens and the Tunguska and other impact events
Coral bleaching
Acid rain
Groundwater depletion
North Atlantic garbage patch

References

^ Kummu, Matti; Heino, Matias; Taka, Maija; Varis, Olli; Viviroli, Daniel (21 May 2021). "Climate change risks pushing one-third of global food production outside the safe climatic space". One Earth. 4 (5): 720–729. Bibcode:2021OEart...4..720K. doi:10.1016/j.oneear.2021.04.017. PMC 8158176. PMID 34056573.
^ "IPCC Special Report on Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse gas fluxes in Terrestrial Ecosystems:Summary for Policymakers" (PDF).
^ "Summary for Policymakers — Special Report on the Ocean and Cryosphere in a Changing Climate". Retrieved 2019-12-23.
^ "Climate Change". National Geographic. 28 March 2019. Retrieved 1 November 2021.
^ Witze, Alexandra. "Why extreme rains are gaining strength as the climate warms". Nature. Retrieved 30 July 2021.
^ "Summary for Policymakers". Climate Change 2021: The Physical Science Basis. Working Group I contribution to the WGI Sixth Assessment Report of the Intergovernmental Panel on Climate Change (PDF). Intergovernmental Panel on Climate Change. 9 August 2021. p. SPM-23; Fig. SPM.6. Archived (PDF) from the original on 4 November 2021.
^ Van der Putten, Wim H.; Macel, Mirka; Visser, Marcel E. (2010-07-12). "Predicting species distribution and abundance responses to climate change: why it is essential to include biotic interactions across trophic levels". Philosophical Transactions of the Royal Society B: Biological Sciences. 365 (1549): 2025–2034. doi:10.1098/rstb.2010.0037. PMC 2880132. PMID 20513711.
^ Parmesan, C., M.D. Morecroft, Y. Trisurat, R. Adrian, G.Z. Anshari, A. Arneth, Q. Gao, P. Gonzalez, R. Harris, J. Price, N. Stevens, and G.H. Talukdarr, 2022: Chapter 2: Terrestrial and Freshwater Ecosystems and Their Services. In Climate Change 2022: Impacts, Adaptation and Vulnerability [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke,V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 257-260 |doi=10.1017/9781009325844.004
^ Sales, L. P.; Culot, L.; Pires, M. (July 2020). "Climate niche mismatch and the collapse of primate seed dispersal services in the Amazon". Biological Conservation. 247 (9): 108628. Bibcode:2020BCons.24708628S. doi:10.1016/j.biocon.2020.108628. S2CID 219764670.
^ Malhi, Yadvinder; Franklin, Janet; Seddon, Nathalie; Solan, Martin; Turner, Monica G.; Field, Christopher B.; Knowlton, Nancy (2020-01-27). "Climate change and ecosystems: threats, opportunities and solutions". Philosophical Transactions of the Royal Society B: Biological Sciences. 375 (1794): 20190104. doi:10.1098/rstb.2019.0104. ISSN 0962-8436. PMC 7017779. PMID 31983329.
^ Sales, L. P.; Rodrigues, L.; Masiero, R. (November 2020). "Climate change drives spatial mismatch and threatens the biotic interactions of the Brazil nut". Global Ecology and Biogeography. 30 (1): 117–127. doi:10.1111/geb.13200. S2CID 228875365.
^ "Explainer: Desertification and the role of climate change". Carbon Brief. 2019-08-06. Archived from the original on 2022-02-10. Retrieved 2019-10-22.
^ Nogués-Bravoa D.; Araújoc M.B.; Erread M.P.; Martínez-Ricad J.P. (August–October 2007). "Exposure of global mountain systems to climate warming during the 21st Century". Global Environmental Change. 17 (3–4): 420–8. Bibcode:2007GEC....17..420N. doi:10.1016/j.gloenvcha.2006.11.007.
^ "SPECIAL REPORT: GLOBAL WARMING OF 1.5 °C; Chapter 3: Impacts of 1.5°C global warming on natural and human systems". ilcc.ch. Intergovernmental Panel on Climate Change. 2018. Archived from the original on 2019-03-05.
^ ^a ^b Hogg, E.H.; P.Y. Bernier (2005). "Climate change impacts on drought-prone forests in western Canada". Forestry Chronicle. 81 (5): 675–682. doi:10.5558/tfc81675-5.
^ Dixon, Adele M.; Forster, Piers M.; Heron, Scott F.; Stoner, Anne M. K.; Beger, Maria (1 February 2022). "Future loss of local-scale thermal refugia in coral reef ecosystems". PLOS Climate. 1 (2): e0000004. doi:10.1371/journal.pclm.0000004. S2CID 246512448.
^ Dunne, Daisy (1 February 2022). "Last refuges for coral reefs to disappear above 1.5C of global warming, study finds". Carbon Brief.
^ ^a ^b Bradshaw, Corey J. A.; Ehrlich, Paul R.; Beattie, Andrew; Ceballos, Gerardo; Crist, Eileen; Diamond, Joan; Dirzo, Rodolfo; Ehrlich, Anne H.; Harte, John; Harte, Mary Ellen; Pyke, Graham; Raven, Peter H.; Ripple, William J.; Saltré, Frédérik; Turnbull, Christine; Wackernagel, Mathis; Blumstein, Daniel T. (2021). "Underestimating the Challenges of Avoiding a Ghastly Future". Frontiers in Conservation Science. 1. doi:10.3389/fcosc.2020.615419.
^ Ripple WJ, Wolf C, Newsome TM, Galetti M, Alamgir M, Crist E, Mahmoud MI, Laurance WF (13 November 2017). "World Scientists' Warning to Humanity: A Second Notice". BioScience. 67 (12): 1026–1028. doi:10.1093/biosci/bix125. hdl:11336/71342. Moreover, we have unleashed a mass extinction event, the sixth in roughly 540 million years, wherein many current life forms could be annihilated or at least committed to extinction by the end of this century.
^ Cowie RH, Bouchet P, Fontaine B (April 2022). "The Sixth Mass Extinction: fact, fiction or speculation?". Biological Reviews of the Cambridge Philosophical Society. 97 (2): 640–663. doi:10.1111/brv.12816. PMC 9786292. PMID 35014169. S2CID 245889833.
^ ^a ^b "Global Biodiversity Outlook 3". Convention on Biological Diversity. 2010. Archived from the original on May 19, 2022. Retrieved January 24, 2017.
^ Kehoe L, Romero-Muñoz A, Polaina E, Estes L, Kreft H, Kuemmerle T (August 2017). "Biodiversity at risk under future cropland expansion and intensification". Nature Ecology & Evolution. 1 (8): 1129–1135. Bibcode:2017NatEE...1.1129K. doi:10.1038/s41559-017-0234-3. ISSN 2397-334X. PMID 29046577. S2CID 3642597. Archived from the original on April 23, 2022. Retrieved March 28, 2022.
^ Allan E, Manning P, Alt F, Binkenstein J, Blaser S, Blüthgen N, Böhm S, Grassein F, Hölzel N, Klaus VH, Kleinebecker T, Morris EK, Oelmann Y, Prati D, Renner SC, Rillig MC, Schaefer M, Schloter M, Schmitt B, Schöning I, Schrumpf M, Solly E, Sorkau E, Steckel J, Steffen-Dewenter I, Stempfhuber B, Tschapka M, Weiner CN, Weisser WW, Werner M, Westphal C, Wilcke W, Fischer M (August 2015). "Land use intensification alters ecosystem multifunctionality via loss of biodiversity and changes to functional composition". Ecology Letters. 18 (8): 834–843. Bibcode:2015EcolL..18..834A. doi:10.1111/ele.12469. PMC 4744976. PMID 26096863.
^ Walsh JR, Carpenter SR, Vander Zanden MJ (April 2016). "Invasive species triggers a massive loss of ecosystem services through a trophic cascade". Proceedings of the National Academy of Sciences of the United States of America. 113 (15): 4081–5. Bibcode:2016PNAS..113.4081W. doi:10.1073/pnas.1600366113. PMC 4839401. PMID 27001838.
^ Stokstad, Erik (6 May 2019). "Landmark analysis documents the alarming global decline of nature". Science. doi:10.1126/science.aax9287. For the first time at a global scale, the report has ranked the causes of damage. Topping the list, changes in land use—principally agriculture—that have destroyed habitat. Second, hunting and other kinds of exploitation. These are followed by climate change, pollution, and invasive species, which are being spread by trade and other activities. Climate change will likely overtake the other threats in the next decades, the authors note. Driving these threats are the growing human population, which has doubled since 1970 to 7.6 billion, and consumption. (Per capita of use of materials is up 15% over the past 5 decades.)
^ Pimm SL, Jenkins CN, Abell R, Brooks TM, Gittleman JL, Joppa LN, Raven PH, Roberts CM, Sexton JO (May 2014). "The biodiversity of species and their rates of extinction, distribution, and protection". Science. 344 (6187): 1246752. doi:10.1126/science.1246752. PMID 24876501. S2CID 206552746. The overarching driver of species extinction is human population growth and increasing per capita consumption.
^ Cafaro, Philip; Hansson, Pernilla; Götmark, Frank (August 2022). "Overpopulation is a major cause of biodiversity loss and smaller human populations are necessary to preserve what is left" (PDF). Biological Conservation. 272. 109646. Bibcode:2022BCons.27209646C. doi:10.1016/j.biocon.2022.109646. ISSN 0006-3207. S2CID 250185617. Archived (PDF) from the original on December 8, 2023. Retrieved December 25, 2022. Conservation biologists standardly list five main direct drivers of biodiversity loss: habitat loss, overexploitation of species, pollution, invasive species, and climate change. The Global Assessment Report on Biodiversity and Ecosystem Services found that in recent decades habitat loss was the leading cause of terrestrial biodiversity loss, while overexploitation (overfishing) was the most important cause of marine losses (IPBES, 2019). All five direct drivers are important, on land and at sea, and all are made worse by larger and denser human populations.
^ Crist, Eileen; Mora, Camilo; Engelman, Robert (21 April 2017). "The interaction of human population, food production, and biodiversity protection". Science. 356 (6335): 260–264. Bibcode:2017Sci...356..260C. doi:10.1126/science.aal2011. PMID 28428391. S2CID 12770178. Retrieved 2 January 2023. Research suggests that the scale of human population and the current pace of its growth contribute substantially to the loss of biological diversity. Although technological change and unequal consumption inextricably mingle with demographic impacts on the environment, the needs of all human beings—especially for food—imply that projected population growth will undermine protection of the natural world.
^ Ceballos, Gerardo; Ehrlich, Paul R. (2023). "Mutilation of the tree of life via mass extinction of animal genera". Proceedings of the National Academy of Sciences of the United States of America. 120 (39): e2306987120. Bibcode:2023PNAS..12006987C. doi:10.1073/pnas.2306987120. PMC 10523489. PMID 37722053. Current generic extinction rates will likely greatly accelerate in the next few decades due to drivers accompanying the growth and consumption of the human enterprise such as habitat destruction, illegal trade, and climate disruption.
^ Hughes, Alice C.; Tougeron, Kévin; Martin, Dominic A.; Menga, Filippo; Rosado, Bruno H. P.; Villasante, Sebastian; Madgulkar, Shweta; Gonçalves, Fernando; Geneletti, Davide; Diele-Viegas, Luisa Maria; Berger, Sebastian; Colla, Sheila R.; de Andrade Kamimura, Vitor; Caggiano, Holly; Melo, Felipe (2023-01-01). "Smaller human populations are neither a necessary nor sufficient condition for biodiversity conservation". Biological Conservation. 277: 109841. Bibcode:2023BCons.27709841H. doi:10.1016/j.biocon.2022.109841. ISSN 0006-3207. Through examining the drivers of biodiversity loss in highly biodiverse countries, we show that it is not population driving the loss of habitats, but rather the growth of commodities for export, particularly soybean and oil-palm, primarily for livestock feed or biofuel consumption in higher income economies.
^ "Climate change and biodiversity" (PDF). Intergovernmental Panel on Climate Change. 2005. Archived from the original (PDF) on 5 February 2018. Retrieved 12 June 2012.
^ Kannan, R.; James, D. A. (2009). "Effects of climate change on global biodiversity: a review of key literature" (PDF). Tropical Ecology. 50 (1): 31–39. Archived from the original (PDF) on 15 April 2021. Retrieved 21 May 2014.
^ "Climate change, reefs and the Coral Triangle". wwf.panda.org. Archived from the original on May 2, 2018. Retrieved 9 November 2015.
^ Aldred, Jessica (2 July 2014). "Caribbean coral reefs 'will be lost within 20 years' without protection". The Guardian. Archived from the original on October 20, 2022. Retrieved 9 November 2015.
^ Ketcham, Christopher (December 3, 2022). "Addressing Climate Change Will Not "Save the Planet"". The Intercept. Archived from the original on February 18, 2024. Retrieved December 8, 2022.
^ Caro, Tim; Rowe, Zeke (2022). "An inconvenient misconception: Climate change is not the principal driver of biodiversity loss". Conservation Letters. 15 (3): e12868. Bibcode:2022ConL...15E2868C. doi:10.1111/conl.12868. S2CID 246172852.
^ Bank, European Investment (2022-12-08). Forests at the heart of sustainable development: Investing in forests to meet biodiversity and climate goals. European Investment Bank. ISBN 978-92-861-5403-4. Archived from the original on March 21, 2023. Retrieved March 9, 2023.
^ Finch, Deborah M.; Butler, Jack L.; Runyon, Justin B.; Fettig, Christopher J.; Kilkenny, Francis F.; Jose, Shibu; Frankel, Susan J.; Cushman, Samuel A.; Cobb, Richard C. (2021). "Effects of Climate Change on Invasive Species". In Poland, Therese M.; Patel-Weynand, Toral; Finch, Deborah M.; Miniat, Chelcy Ford (eds.). Invasive Species in Forests and Rangelands of the United States: A Comprehensive Science Synthesis for the United States Forest Sector. Cham: Springer International Publishing. pp. 57–83. doi:10.1007/978-3-030-45367-1_4. ISBN 978-3-030-45367-1. S2CID 234260720.
^ United Nations Environment Programme (2021). Making Peace with Nature: A scientific blueprint to tackle the climate, biodiversity and pollution emergencies. Nairobi: United Nations. Archived from the original on March 23, 2021. Retrieved March 9, 2021.
^ Cohen L (September 15, 2020). "More than 150 countries made a plan to preserve biodiversity a decade ago. A new report says they mostly failed". CBS News. Archived from the original on May 15, 2022. Retrieved September 16, 2020.
^ "Global Biodiversity Outlook 5". Convention on Biological Diversity. Archived from the original on October 6, 2021. Retrieved 2023-03-23.
^ A. G. Sennikov, V. K. Golubev (2006). "Vyazniki biotic assemblage of the terminal Permian". Paleontological Journal. 40 (4): S475-S481. doi:10.1134/S0031030106100078.
^ "Wildlife defies Chernobyl radiation". 20 April 2006.