San Antonio Express: A new report from the Intergovernmental Panel on Climate Change confirms what we already know. First, the climate system is definitely warming. Second, humans are now a dominant driver of the climate and are very likely to be responsible for most of the recent warming we have experienced. And future warming over the 21st century will likely be several degrees. While a few degrees may not sound like a lot of warming, changes in the global average temperature this large have, in the past, been...