Before you think we've gone crazy, let's make clear that this is a post about a serious report published in Nature Geoscience. According to this report, lead that was expelled to the atmosphere through exhaust gases stimulated the growth of clouds. Larger clouds imply less solar radiation, which has a definitive cool effect. Investigators from Switzerland, Germany and the U.S. "captured" clouds on some mountains and compared them to artificial ones created in laboratories. Their conclusion: if the air has some lead suspended in it, temperature and humidity didn't pay as significant a role in cloud formation.
What's interesting is that their models show that between 1970 and 1980, before unleaded gasoline became common, most dust on the Earth's suface had lead particles in it. This might have helped more clouds get created, and that reduced the impact of greenhouse gases accumulation in the atmosphere. Now that the lead content in our air is lower, temperatures rise. However, these investigators aren't saying that we should pump lead in our atmosphere - it is toxic, after all - just that when it was there, it helped keep temperatures a bit more stable.
[Source: Nôtre Planete (via Le Blog Auto)]