Abrupt climate change
An abrupt climate change occurs when the
Scientists may use different timescales when speaking of abrupt events. For example, the duration of the onset of the Paleocene–Eocene Thermal Maximum may have been anywhere between a few decades and several thousand years. In comparison, climate models predict that under ongoing greenhouse gas emissions, the Earth's near surface temperature could depart from the usual range of variability in the last 150 years as early as 2047.[7]
Definitions
Abrupt climate change can be defined in terms of physics or in terms of impacts: "In terms of physics, it is a transition of the climate system into a different mode on a time scale that is faster than the responsible forcing. In terms of impacts, an abrupt change is one that takes place so rapidly and unexpectedly that human or natural systems have difficulty adapting to it. These definitions are complementary: the former gives some insight into how abrupt climate change comes about; the latter explains why there is so much research devoted to it."[8]
Timescales
Timescales of events described as abrupt may vary dramatically. Changes recorded in the climate of Greenland at the end of the Younger Dryas, as measured by ice-cores, imply a sudden warming of +10 °C (+18 °F) within a timescale of a few years.[9] Other abrupt changes are the +4 °C (+7.2 °F) on Greenland 11,270 years ago[10] or the abrupt +6 °C (11 °F) warming 22,000 years ago on Antarctica.[11]
By contrast, the Paleocene–Eocene Thermal Maximum may have initiated anywhere between a few decades and several thousand years. Finally, Earth System's models project that under ongoing greenhouse gas emissions as early as 2047, the Earth's near surface temperature could depart from the range of variability in the last 150 years.[7]
General
Possible
It has been postulated that teleconnections – oceanic and atmospheric processes on different timescales – connect both hemispheres during abrupt climate change.[13]
A 2013 report from the U.S.
A characteristic of the abrupt climate change impacts is that they occur at a rate that is faster than anticipated. This element makes ecosystems that are immobile and limited in their capacity to respond to abrupt changes, such as forestry ecosystems, particularly vulnerable.[15]
The probability of abrupt change for some climate related feedbacks may be low.[16][17] Factors that may increase the probability of abrupt climate change include higher magnitudes of global warming, warming that occurs more rapidly and warming that is sustained over longer time periods.[17]
Climate models
Climate models are currently[when?] unable to predict abrupt climate change events, or most of the past abrupt climate shifts.[18] A potential abrupt feedback due to thermokarst lake formations in the Arctic, in response to thawing permafrost soils, releasing additional greenhouse gas methane, is currently not accounted for in climate models.[19]
Effects
In the past, abrupt climate change has likely caused wide-ranging and severe effects as follows:
- Loss of biodiversity: without interference from abrupt climate change and other extinction events, the biodiversity of Earth would continue to grow.[22]
- Changes in ocean circulation such as:
- Increasing frequency of
- Potential disruption to the thermohaline circulation, such as that which may have occurred during the Younger Dryas event.[25][26]
- Changes to the North Atlantic oscillation[27]
- Changes in Atlantic Meridional Overturning Circulation (AMOC) which could contribute to more severe weather events.[28]
Tipping points in the climate system
In
Tipping points are often, but not necessarily, abrupt. For example, with average global warming somewhere between 0.8 °C (1.4 °F) and 3 °C (5.4 °F), the
The geological record shows many abrupt changes that suggest tipping points may have been crossed in pre-historic times.[38]Past events
Several periods of abrupt climate change have been identified in the paleoclimatic record. Notable examples include:
- About 25 climate shifts, called
- The Younger Dryas event, notably its sudden end. It is the most recent of the Dansgaard–Oeschger cycles and began 12,900 years ago and moved back into a warm-and-wet climate regime about 11,600 years ago.[citation needed] It has been suggested that "the extreme rapidity of these changes in a variable that directly represents regional climate implies that the events at the end of the last glaciation may have been responses to some kind of threshold or trigger in the North Atlantic climate system."[40] A model for this event based on disruption to the thermohaline circulation has been supported by other studies.[26]
- The Paleocene–Eocene Thermal Maximum, timed at 55 million years ago, which may have been caused by the release of methane clathrates,[41] although potential alternative mechanisms have been identified.[42] This was associated with rapid ocean acidification[43]
- The Permian–Triassic Extinction Event, in which up to 95% of all species became extinct, has been hypothesized to be related to a rapid change in global climate.[44][21] Life on land took 30 million years to recover.[20]
- The Carboniferous Rainforest Collapse occurred 300 million years ago, at which time tropical rainforests were devastated by climate change. The cooler, drier climate had a severe effect on the biodiversity of amphibians, the primary form of vertebrate life on land.[3]
There are also abrupt climate changes associated with the catastrophic draining of glacial lakes. One example of this is the
A 2017 study concluded that similar conditions to today's Antarctic ozone hole (atmospheric circulation and hydroclimate changes), ~17,700 years ago, when stratospheric ozone depletion contributed to abrupt accelerated Southern Hemisphere deglaciation. The event coincidentally happened with an estimated 192-year series of massive volcanic eruptions, attributed to Mount Takahe in West Antarctica.[49]
Possible precursors
Most abrupt climate shifts are likely due to sudden circulation shifts, analogous to a flood cutting a new river channel. The best-known examples are the several dozen shutdowns of the
- The current warming of the Arctic, the duration of the summer season, is considered abrupt and massive.[18]
- Antarctic ozone depletion caused significant atmospheric circulation changes.[18]
- There have also been two occasions when the Atlantic's Meridional Overturning Circulation lost a crucial safety factor. The Greenland Sea flushing at 75 °N shut down in 1978, recovering over the next decade.[51] Then the second-largest flushing site, the Labrador Sea, shut down in 1997[52] for ten years.[53] While shutdowns overlapping in time have not been seen during the 50 years of observation, previous total shutdowns had severe worldwide climate consequences.[50]
Climate feedback effects
One source of abrupt climate change effects is a feedback process, in which a warming event causes a change that adds to further warming.[55] The same can apply to cooling. Examples of such feedback processes are:
- Ice–albedo feedback in which the advance or retreat of ice cover alters the albedo ("whiteness") of the earth and its ability to absorb the sun's energy.[56]
- Soil carbon feedback is the release of carbon from soils in response to global warming.
- The dying and the burning of forests by global warming.[57]
Volcanism
See also
References
- ISBN 9780875904849.
- ISBN 978-0-309-07434-6.
- ^ doi:10.1130/G31182.1.
- S2CID 39544213.
- ISBN 0-309-07434-7.
- S2CID 14173232. Archived from the original(PDF) on 9 March 2013.
- ^ S2CID 4471413.
- ^ "1: What defines "abrupt" climate change?". LAMONT-DOHERTY EARTH OBSERVATORY. Retrieved 8 July 2021.
- .
- .
- .
- ^ PMID 18258748.
- doi:10.1038/ngeo2848.
- ^ Board on Atmospheric Sciences and Climate (2013). "Abrupt Impacts of Climate Change: Anticipating Surprises". Archived from the original on 13 October 2017. Retrieved 12 December 2013.
- S2CID 224860967.
- ^ Clark, P.U.; et al. (December 2008). "Executive Summary". Abrupt Climate Change. A Report by the U.S. Climate Change Science Program and the Subcommittee on Global Change Research. Reston, Virginia: U.S. Geological Survey. pp. 1–7.
- ^ a b IPCC. "Summary for Policymakers". Sec. 2.6. The Potential for Large-Scale and Possibly Irreversible Impacts Poses Risks that have yet to be Reliably Quantified. Archived from the original on 24 September 2015. Retrieved 10 May 2018.
- ^ Bibcode:2016EGUGA..18.2567M.
- ^ "Unexpected Future Boost of Methane Possible from Arctic Permafrost". NASA. 2018.
- ^ PMID 18198148.
- ^ S2CID 44921662.
- PMID 20106856.
- .
- S2CID 4234225.
- PMID 9374450. Archived from the original(PDF) on 22 November 2009.
- ^ S2CID 4302999.
- S2CID 14659582.
- .
Our results at least imply that strong cooling in the North Atlantic from AMOC shutdown does create higher wind speed. * * * The increment in seasonal mean wind speed of the northeasterlies relative to preindustrial conditions is as much as 10–20%. Such a percentage increase of wind speed in a storm translates into an increase of storm power dissipation by a factor ~1.4–2, because wind power dissipation is proportional to the cube of wind speed. However, our simulated changes refer to seasonal mean winds averaged over large grid-boxes, not individual storms.* * * Many of the most memorable and devastating storms in eastern North America and western Europe, popularly known as superstorms, have been winter cyclonic storms, though sometimes occurring in late fall or early spring, that generate near-hurricane-force winds and often large amounts of snowfall. Continued warming of low latitude oceans in coming decades will provide more water vapor to strengthen such storms. If this tropical warming is combined with a cooler North Atlantic Ocean from AMOC slowdown and an increase in midlatitude eddy energy, we can anticipate more severe baroclinic storms.
- ^ "Tipping Elements – big risks in the Earth System". Potsdam Institute for Climate Impact Research. Retrieved 31 January 2024.
- ^ S2CID 252161375.
- PMID 31776487.
- ^ "Climate change driving entire planet to dangerous "global tipping point"". National Geographic. 27 November 2019. Archived from the original on 19 February 2021. Retrieved 17 July 2022.
- ^ S2CID 238651749.
- ^ Armstrong McKay, David (9 September 2022). "Exceeding 1.5°C global warming could trigger multiple climate tipping points – paper explainer". climatetippingpoints.info. Retrieved 2 October 2022.
- ISSN 0006-3568.
- PMID 30082409.
- from the original on 4 June 2021. Retrieved 4 June 2021.
- S2CID 236504982.
- ^ "Heinrich and Dansgaard–Oeschger Events". National Centers for Environmental Information (NCEI) formerly known as National Climatic Data Center (NCDC). NOAA. Archived from the original on 22 December 2016. Retrieved 7 August 2019.
- S2CID 4325976. Archived from the original(PDF) on 17 June 2010.
- .
- S2CID 128375931.
- S2CID 26909706.
- doi:10.1016/S0169-5347(03)00093-4. Archived from the original(PDF) on 18 April 2007.
- .
- S2CID 205238911.
- S2CID 4403135.
- ISBN 0-87590-033-X. Archived from the original(PDF) on 29 October 2008.
- PMID 28874529.
- ^ S2CID 19455675.
- S2CID 21374638.
- .
- hdl:1912/2840.
- ^ "Thermodynamics: Albedo". NSIDC.
- PMID 31776487.
- .
- PMID 19218454.
- .