A recent post at Climate Science tries to clarify the difference between the terms "global warming" and "climate change" which are often used interchangeably, but are not necessarily equivalent.
Global warming is a increasing trend in earth's average temperature.I suspect that most people are concerned about climate change more than the global warming. They aren't so much concerned about a couple of degrees of warmth versus bad things that might happen to their region's climate. They presume that warming = bad.
Climate change is "Any systematic change in the long-term statistics of climate elements (such as temperature, pressure, or winds) sustained over several decades or longer. Climate change may be due to natural external forcings, such as changes in solar emission or slow changes in the earth’s orbital elements; natural internal processes of the climate system; or anthropogenic forcing.”
But when you look at what human activities affect climate the most, it is not CO2 that causes changes to climates. It is how humans alter their environment.
The most spectacular example is how deforestation in the Amazon rain forest is reducing precipitation and raising temperatures. Another similar example is how crop irrigation in the U.S. plains is increasing rainfall. Meanwhile, deforestation of northern latitude forests increases albedo (reflection) and reduces temperatures in the winter. But expansion of urban areas creates warmer, drier conditions.But won't warmer temperatures turn everything into either a desert or a tropical swamp?
Actually, human manipulation of environment will have more impact on environment than changes in temperatures. Certainly, growing seasons will be extended and animals will have larger habitable ranges, but predicting specific weather patterns and living conditions is a crap shoot given the many variables other than temperature that must be considered.
For more, read here.
ADDENDUM
[thanks to Luboš Motl] CNN showing this.
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