NASA - Just 5 Questions: Weather vs. Climate

Dr. Eric Fetzer is a scientist at NASA's Jet Propulsion Laboratory. He works on NASA's AIRS mission, recently named the "best new tool for climate science."
...
The important thing to remember is that global warming is a fairly small effect on top of large temperature variability across the world. Let's say we expect a 1°F (0.6°C) warming. The temperature on the East Coast of the United States varies by up to 20°F (11°C) over a year. So typical weather events can easily overwhelm the slow, small signature of global warming.

Also, global warming is expected to cause more extreme weather events, and that includes cold ones. A simple example is in South Florida. The mangrove line there has retreated southward by about 100 miles (160 kilometers) since the mid-1970s. Mangrove trees don't tolerate frost, and the number of very cold events in Florida has been increasing. Last winter Florida experienced one of the worst cold snaps on record. Yet we know, from the data, that the Earth has warmed on average since the mid-1970s.
...
If you want to invest in global warming, buy wheat futures in southern Canada or southern Russia. That's where it will become warmer and wetter. It will be better wheat country than it is today.