\"Getting warm is easy, getting cold takes effort\" referring to the graph of Ea
ID: 160617 • Letter: #
Question
"Getting warm is easy, getting cold takes effort" referring to the graph of Earth's temperature for the past several 100,000 years. What does that mean and what implications does it have for current anthropogenic climate change?
It was eventually realized that the 18O/16O of marine calcite was the result of TWO processes – temperature-dependent fractionation and changes in the isotopic composition of sea-water itself.
Once this correction was applied, 18O/16O could be used for determining BOTH ocean temperatures and ice volumes.
Explanation / Answer
ANSWER:
Global warming is understood to result from an overall, long-term increase in the retention of the sun’s heat around Earth due to blanketing by “greenhouse gases,” especially CO2 and methane. Emissions of CO2 have been rising at a speed unprecedented in human history, due to accelerating fossil fuel burning that began in the Industrial Revolution. The effects of the resulting “climate change” are uneven and can even produce localized cooling (if warm currents change direction). The climate change may also initiate positive feedback in which the initial impact is further enhanced by its own effects, for example if melting ice reduces the reflective properties of white surfaces or if melting tundra releases frozen methane, leading to further warming. Global warming involves an unprecedented speeding up of the rate of change in natural processes, which now converges with the (previously much faster) rate of change in human societies, leading to a crisis of adaptation. It was natural scientists who first discovered and raised global warming as a political problem. This makes many of the global warming concerns unique. “Science becomes the author of issues that dominate the political agenda and become the sources of political conflict”.
To date, no Earth system model has been able to adequately account for the growth and maintenance of large ice sheets which occupied most of Canada and Scandinavia during peak glacial time. The paleoclimatic record challenges us by demonstrating that much more must be learned about the Earth’s climate system before we can have any confidence in model based predictions of the changes which will result from the buildup of CO2 and other greenhouse gases in our atmosphere. Just before the end of the twentieth century, American researchers released ice-thickness data, gathered by nuclear submarines. The data showed that over the previous forty years the ice depth in all regions of the Arctic Ocean had declined by approximately 40 percent. Five yearly aerial photographs show the ice cover on the Arctic Ocean at a record low, with a loss of 50 cubic kilometers annually and glacier retreat doubling to 12 kilometers a year. Although rising temperatures; melting tundra, ice and glaciers; droughts; extreme storms; stressed coral reefs; changing geographical range of plants, animals, and diseases; and sinking atolls may conceivably all be results of many temporary climate variations, their cumulative impact is hard to refute.
Measurements from satellites and balloons in the lower troposphere have until recently indicated cooling, which contradicted measurements from the surface and the upper troposphere. Another anomaly was that observed temperature rises were in fact less than the modeling of CO2 impacts predicted. The record of temperature shown in the ice core is not a global record. It is a record of local Antarctic temperature change. The rest of the globe does indeed parallel the polar changes closely, but the global mean temperature changes are smaller. While we don’t know precisely why the CO2 changes occur on long timescales, , we do know that explaining the magnitude of global temperature change requires including CO2. But CO2 does not explain all of the change, and the relationship between temperature and CO2 is therefore by no means linear. That is, a given amount of CO2 increase as measured in the ice cores need not necessarily correspond with a certain amount of temperature increase. A rise of over 2 degrees is considered inevitable if CO2 concentrations pass 400 ppm. At current growing emission rates, the concentration would reach 700 ppm by the end of the twenty-first century.
It will be essential for social and natural scientists to learn to cooperate in understanding and preempting the potentially catastrophic collision of nature and society. In order to accomplish this, market mechanisms; technological innovation; international, national, and local regulations; and cultural change will all be needed. Agents of change include governments, nongovernmental organizations, and public opinion, but the most likely front-runner might be sectors of capital seeking profit by retooling the energy and transport systems, while able to mobilize political enforcement.
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