Title : Mass Extinctions And Climate Change: Why The Speed Of Rising Greenhouse Gases Matters
link : Mass Extinctions And Climate Change: Why The Speed Of Rising Greenhouse Gases Matters
Mass Extinctions And Climate Change: Why The Speed Of Rising Greenhouse Gases Matters
Matters id = " now know that greenhouse gases are increasing faster than at any time since the demise of the dinosaurs, and possibly even earlier. According to a study published in the journal Nature Geoscience this week, carbon dioxide (CO₂) is added to the atmosphere, at least ten times faster than during a major warming event about 50 million years ago.
have issued almost 600 million tons of carbon since the beginning of the industrial revolution , and atmospheric CO₂ concentrations are increasing at a rate of 3 parts per million (ppm) per year. With increased CO₂ levels, temperatures and ocean acidification will also increase, and it is an open question how ecosystems will cope under such rapid change. Coral reefs , our canary in the coal mine, suggest that the current rate of climate change is too fast for many species to adapt :. next event of widespread extinction may have already begun In the past, rapid increases in greenhouse gases have been associated with mass extinctions. It is therefore important to understand how unusual the current rate of increase in atmospheric CO₂ is regarding climate variability of the past. In the ice ages There is no doubt that atmospheric CO₂ concentrations and global temperatures have changed in the past. leaves ice, for example, are reliable bookkeepers old climate and we can give an idea of the weather conditions long before the thermometer was invented. By drilling holes in the ice sheets that can recover ice cores and analyze the accumulation of old snow, layer upon layer. These ice cores not only recorded atmospheric temperatures over time, but also contain frozen that give us small samples of ancient air bubbles. Our longest ice core extending over 800,000 years in the past . During this time, the Earth was between ice ages cold and warm "interglacial". To move from an ice age to an interglacial , it is necessary to increase by about 100 ppm CO₂. This increase was repeatedly melted layers of ice one kilometer thick covering the locations of modern cities such as Toronto, Boston, Chicago or Montreal. With increasing levels of CO₂ at the end of the last ice age, temperatures rose as well. Some ecosystems could not keep up with the exchange rate, resulting in several extinctions of megafauna, although human impacts were almost certainly part of the story . However, the rate of change of CO₂ over the past million years was tame compared with today. The highest rate of change before the industrial revolution is less than 0.15 ppm per year, only one-twentieth of what we are experiencing today. 
temperature has fluctuated with greenhouse gases. Kaitlin Alexander, data :. Luthi et al, 2006: http://www.nature.com/nature/journal/v453/n7193/full/nature06949.html Loulergue et al, 2008 :. http://www.nature.com/nature/journal/v453/n7193/full/nature06950.html Etheridge et al, 1996 :. http: // onlinelibr Looking further back To find an analogue for current climate change, therefore we to look back at a time when the ice sheets were small or nonexistent at all. Several abrupt warming events occurred between 56 million and makes 52 million years . These events are characterized by a rapid rise in temperature and ocean acidification. The most prominent of these events was the Paleocene Eocene Thermal Maximum (PETM). This event led to one of the largest known extinctions of life forms in the ocean depths. Atmospheric temperatures increased by C5-8 within a few thousand years. Reconstructions of the amount of carbon added to the atmosphere during this event range from 2000-10,000 million tons of carbon. The new research, led by Professor Richard Zeebe of the University of Hawaii, ocean sediments analyzed to quantify the gap between warming and changes in the carbon cycle during the PETM. Although climate records become less true the more we look back, the authors found that carbon release must have been below 1.1 billion tons of carbon per year. That's about one-tenth of the speed of today's carbon emissions from human activities such as burning fossil fuels. What happens when the brakes are out? Although the MTPE led to one of the largest deepwater known extinctions, it is a small event compared to the five major extinctions in the past. The Permian-Triassic extinction, nicknamed "The Great Dying", ended with 90% of marine species and 250 million years ago, 70% of families of terrestrial vertebrates. Like his four brothers, this extinction event occurred long ago. climate archives that go as far back they lack the resolution necessary to reconstruct reliably exchange rates. There is, however, evidence of extensive volcanic activity during the Great Dying, which would have resulted in a release of CO₂ as well as the possible release of methane along the continental margins. Ocean acidification caused by high atmospheric CO₂ concentrationsand acid rain have been proposed as potential mechanisms killer. Other hypotheses include oxygen depletion of the ocean due to global warming or escape of hydrogen sulfide, which would have caused both direct poisoning and damage to the ozone layer. The latter warming events occurred without human influence. They point to the existence of positive feedback in the climate system that have the power to intensify the warming dramatically. The thresholds to trigger these assessments are difficult to predict and their impacts are difficult to quantify. Examples of assessments include the melting of permafrost, releasing methane hydrates from ocean sediments, changes in ocean carbon cycle and changes in peatlands and wetlands. All these processes have the potential to quickly add more greenhouse gases into the atmosphere. Because these assessments were enough in the past to end a considerable proportion of life forms in the solid Earth, there is no reason to believe that they will not be strong enough in the near future, it was caused by the heat fast enough. rate of change of atmospheric CO₂ today is unprecedented in weather files. carbon release is exceeded during abrupt events extreme heating in the last 66 million years at least an order of magnitude. We therefore can not rely on past records to predict whether and how our ecosystems are able to adapt. We know, however, that mass extinctions have occurred in the past and that these extinctions, at least in the case of PETM have been caused by much smaller exchange rates. Katrin and Kaitlin will be on hand for an author Q & A 14: 00-15: 00 AEDT on Thursday 24 March submit questions in the comments section. Katrin Meissner, Associate Professor, Center for Climate Change Research, UNSW Australiaand Kaitlin Alexander, PhD, Climate Change Research Centre, UNSW; ARC Centre of Excellence for Climate System Science, UNSW Australia This article was originally published in the conversation. Read the original article. (source)
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