President Barack Obama is spending this Earth Day visiting the Florida Everglades and talking about his efforts to combat climate change and environmental degradation. His proposed policies face a hard slog. According to this map by ThinkProgress, 56 percent of Congressional Republicans "deny or question the science" behind human-caused global warming. But once upon a time, American politicians were eager to prove that North America, at least, was warming.
Around the same time that Britons began colonizing New England, some European philosophers and naturalists started to speculate that the New England climate—harsher in the winter and hotter in the summer than regular old England—was unhealthy for people and animals. Because the New World climate was less comfortable than the Old World climate, the argument went, people and animals who live in the New World were smaller and stupider than their Old World counterparts. That's what led Thomas Jefferson to publish his famed list of the weights of American versus European land mammals in 1785. Jefferson was trying to defend his nation's honor, by proving that the average American bear is 256.3 pounds heavier than the average European one.
(The Unhealthy Effects of Exotic Climates idea would persist throughout Great Britain's colonial history. You can see it in the beloved children's book, The Secret Garden, published in 1911. The novel's protagonist, Mary Lennox, was born in India and is sickly, bratty, and "yellow" in complexion until she's sent to live in England.)
Thomas Jefferson and some other American thinkers pushed the idea that their activity was altering their home climate for the better.
While Jefferson wanted to show that the American climate is perfectly fine for people and animals, he and some other American thinkers also pushed the idea that all their activity—namely, land development—was altering their home climate for the better, as the Public Domain Review reports. At the time, Harvard University professor Samuel Williams pioneered the idea that the clearing of America's forests was making their winters milder. At least once, Jefferson also talked about the effect of "culture toward changes of climate," although it's unclear by what mechanism he imagined the presence of European philosophy and afternoon tea could alter continental temperatures.
Were those early American climate change proponents so different from America's climate deniers today? Perhaps not. Both forwarded political agendas with scientific-seeming arguments. Both faced scientifically based challenges too. There's plenty published today, of course, about the science supporting human-driven climate change. In colonial times, Williams and Jefferson's climate change campaign ended after journalist Noah Webster used measurements from thermometers—then a relatively new invention—to refute Williams' claim that New England's winters had warmed by 10 degrees or more.