The draft of the latest National Climate Assessment was released on January 12th, and it is chock full of key facts about an already changed climate and projections that vary, depending on the amount of heat trapping gas that is pumped around the world into the atmosphere in the years ahead.
http://ncadac.globalchange.gov/download/NCAJan11-2013-publicreviewdraft-fulldraft.pdf. It is well worth reviewing.
The draft National Climate Assessment states that temperatures in the USA are already up 1.5 degrees from the average temperature during 1900 to 1960. Sea levels are already up 8 inches since that time too. The length of the frost free season has grown by up to 21 days, a remarkable change that those who tend crops and gardens know very well. Those are just some of the striking facts about an already changed climate.
The projections of what lies ahead depend on how much heat trapping gas is pumped into the global atmosphere in the coming decades. If current trends of increasing amounts of heat trapping gas going into the atmosphere continue, the National Climate Assessment projects a horror show. More on this in subsequent posts.