The heat and droughts of 2001 and 2002, and the unending winter of 2002-2003 in the Northeast have people wondering what on Earth is happening to the weather. Is there anything natural about such variability?
To answer that question, researchers at the Harvard-Smithsonian Center for Astrophysics (CfA) - right in the heart of New England's bad weather - took a look at how things have changed in the past 1,000 years. They looked at studies of changes in glaciers, corals, stalagmites, and fossils. They checked investigations of cores drilled out of ice caps and sediments lying on the bottom of lakes, rivers, and seas. They examined research on pollen, tree rings, tree lines, and junk left over from old cultures and colonies. Their conclusion: We are not living either in the warmest years of the past millennium nor in a time with the most extreme weather.
This review of changes in nature and culture during the past 1,000 years was published in the April 11 issue of the Journal of Energy and Environment. It puts subjective observations of climate change on a much firmer objective foundation. For example, tree-ring data show that temperatures were warmer than now in many far northern regions from 950 to 1100 A.D.
From 800 to 1300 A.D., the Medieval Warm Period, many parts of the world were warmer than they have been in recent decades. But temperatures now (including last winter) are generally much milder than they were from 1300 to 1900, the Little Ice Age.
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