Jefferson on Climate Change

Reading Mickey Glantz’s Climate Affairs, I ran across this odd reference to what appears on first blush to be Thomas Jefferson’s great insight into the effects of humans on climate. It quotes an 1824 letter in which Jefferson writes that climate surveys “should be repeated oce or twice in a century to show the effect of clearing (of land) and culture (settlements) towards changes of climate.” Insightful man, that Jefferson, eh?


  1. There was a widely believed notion in the 19th century that can be summarized as “rain follows the plow”. Settlers who worried about how dry the Great Plains were were given this “reassurance”, that the climate would somehow become wetter as more crops were planted. Perhaps Jefferson wanted to test this “theory”.

  2. The reason for the formation of the BOR was to redistribute water in the west to grow trees, so that they could pull up moisture from the south.

    China’s deforestation in the south and central portion of the country has led to widespread droughts in the northern half of the country, leading to a large afforestation campaign, like South Korea did after they found the same thing.

    Anyway, I wonder what the climate naysayers back then said when Jefferson published his views?


  3. What is the exact citation? It should be pretty easy to find in context. Jefferson wrote most of his letters using a polygraph, so we have copies. The text is on the web transcribed to HTML at the Univ of Virginia[1] and scanned images in his (legible) handwriting at the Library of Congress[2].


    (I searched both of those sites and Google, but couldn’t find the quotation.)

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