Lindley Hanson's List: Climate Change

It’s a Global Issue

The increase in the greenhouse effect is global, affecting climate and communities worldwide.

Some countries emit more CO2 into the atmosphere than others, and each country will be affected differently by the changing climate. The international pattern of CO2 emissions and greenhouse warming impacts will change through time. The challenge for policy makers is to pursue globally equitable solutions that address these changing international differences.

In the following sections, explore the possible responses to global warming both at a personal and national level.

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Join the Exploratorium for another season of Ice Stories:Dispatches from Polar Scientists. We will kick off this Antarctic season with a series of nearly 20 Webcasts, every Tuesday, Thursday, Friday, and Sunday, starting December 7th through January 4th, 2009, at 1pm. Watch here for highlights from our last Antarctic season. For more information, please visit: http://icestories.exploratorium.edu/dispatches/

The last glacial period from 70 000 to 10 000 years ago was punctuated by abrupt climate changes, switching within a few decades between warm and cold stages that lasted for a few thousand years. These abrupt changes are intensively studied in order to improve our knowledge about the climate system behavior and especially to provide insights into how system responses and interactions can be expected to occur in the future. In a new study, which appeared in the journal Nature Geoscience, scientists from the Netherlands and Germany suggest that the rapid glacial cooling events in the North Atlantic region are an expression of dramatic winter conditions rather than a reflection of summer cooling.

Abrupt glacial climate changes have first been documented in great detail in Greenland ice cores and demonstrate how large and rapid these changes were: the annual average air temperature warmed by up to 16º C within two to three decades. These abrupt changes are related to changes in the Atlantic meridional overturning circulation. During periods of increased meltwater influx from the continental ice sheets, deepwater formation in the North Atlantic ceased with the consequence that the northward heat transfer to the high northern latitudes was dramatically reduced. In consequence, these areas cooled. Based on the recognition of these cooling events a scenario evolved in which a reduction of the overturning circulation in response to global warming and sea surface salinity reduction may have eventually lead to severe cooling in NW-Europe in the future.

The study of lake sediments as recorders of past climate change has been a major focus of the Geologic Division's Global Change and Climate History Program. In particular, lakes of the Upper Mississippi Basin (UMB) provide some of the most detailed records of climate and environmental change during the Holocene (last 10,000 years). The UMB is particularly sensitive to climate change because the three airmasses that control the climate of North America (fig. 1) intersect here.

In climate studies, obviously one of the most important aspects is the ability to constrain a time period. For example, many climatologists study deep lakes that show pairs of layered sediments indicative of seasonal deposition throughout the year. There sediment couplets, known as varves, show light colored sediments that are often washed into a lake during the spring melt, topped by a darker material that contains organics from a summer algal bloom. Varved sediments therefore lend themselves well to biological, chemical, and mineralogical testing that can indicate very specific yearly data about climate and environmental change.