text: Should you respond that any journey begins with a tiny step, consider the following. The Obama climate policy calls for a 17 percent reduction below 2005 levels in U.S. GHG emissions by 2020. If we apply the EPA's own climate model, that would reduce temperatures by the year 2100 by fifteen one-thousandths of a degree. In addition, the U.S.-China Joint Announcement on Climate Change calls for an additional 10 percent reduction by the U.S. by 2025. (The Chinese commitment it's unenforceable is for a "peak" in their emissions by 2030. Total emissions at that peak and the emissions path after the peak are not addressed.) The additional 10 percent U.S. reduction yields another one one-hundredth of a degree. The standard deviation of the temperature record is about 0.1 degrees, so that these effects would be too small even to be measured, let alone to affect sea levels and cyclones and all the rest.