Policy & Societal Relevance
Exploring past climate change is a scientific pursuit worthwhile in and of itself. But paleoclimate studies have a wide range of implications for the larger climate science community and, more broadly, society. Paleoclimate records are critical to our understanding of anthropogenic warming in a number of ways, as they provide: (1) contextual understanding of natural climate variability to which modern warming can be compared; (2) opportunities to validate climate models against the paleo-record; (3) improved understanding of the functioning of certain parts of the climate system and estimates of climate sensitivity; and (4) insights into ecosystem responses to climate perturbations. The following are ways in which the general public and policymakers benefit from an understanding of paleoclimate.
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Reconstructions of past warm times (e.g., the Paleocene-Eocene Thermal Maximum and Early Eocene Climatic Optimum) help humans to imagine a potential future state of the planet if GHG emissions are not mitigated. Drastic changes in vegetation cover or ice sheet extent, for example, are a more intuitive way of visualizing change than changes in mean temperature or precipitation amount.
An Inuk man holds up a picture of what his home on Baffin Island, Arctic Canada, may have looked like during the PETM, when ocean temperatures at the North Pole hit 74ºF. Photo by Ira Block, National Geographic.
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Paleoclimate studies on the rate of past climate change also highlight that the natural systems on the planet, like flora and fauna that are adapted to a pre-industrial climate, are unlikely to be able to fully adjust to the rapid changes of the modern. Studies of the Paleocene-Eocene Thermal Maximum, a very warm period that was likely caused by a rapid, massive release of carbon naturally (e.g., DeConto et al., 2012), have shown that despite the extreme climate of this period, modern rates of warming and carbon release are even greater.
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The ability of climate models to correctly reproduce paleoclimate events gives credibility to the models and reinforces that policymakers should take future projections seriously. Conversely, when models fail to reproduce paleoclimate conditions--like the magnitude of polar amplification--it is an indication that future projections may even be underestimating future warming in some areas.
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Understanding the unprecedented nature of anthropogenic climate change (i.e., knowledge that anthropogenic climate change is larger in some measureable way than in the past X number of years) puts our impact into perspective. For example, a recent paper by Miller et al. (2013) states that summertime warming in the Arctic is unprecedented in the past 44,000 years at least; this study received significant media coverage as its conclusions challenged current thought that the early Holocene was warmer than present.
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An understanding of past climate events allows for better constraining the functioning of the climate system, including the all-important value of climate sensitivity—how much the Earth will warm with a doubling of atmospheric CO2. If the public develops a better intuition for concepts like this, they will have a greater appreciation for where the Earth is heading.
A plot of temperature versus duration of climate event, showing that the rate of current warming (and carbon emissions) is significantly greater than that of the Paleocene-Eocene Thermal Maximum (PETM). From www.wunderground.com/climate.