“The average temperature of the planet for the next several thousand years will be determined this century—by those of us living today.”

That’s the dire pronouncement of my former Sci Am colleague David Biello in his writeup of a National Research Council report issued last week, which I’ll use as an excuse to take stock of where we stand on climate change. The NRC put a different twist on climate projections by estimating not how much warming we’re in for, but what impacts a given amount of warming will have on the environment.

According to the report, for every degree Celsius of warming, impacts include:

* A 5 to 15 percent lower yield for some crops, including corn in Africa and the U.S., and wheat in India
* A 3 to 10 percent increase in heavy rainfall globally
* A 5 to 10 percent drop in rainfall in southwestern North America, southern Africa and the Mediterranean, among other precipitation changes
* A 5 to 10 percent change (increases in some regions, decreases in others) in stream flow in many river basins globally
* A 15 to 25 percent decrease in the extent of Arctic Ocean sea ice

Here’s what the IPCC projected in 2007:

The average surface temperature of the Earth is likely to increase by 2 to 11.5°F (1.1-6.4°C) by the end of the 21st century, relative to 1980-1990, with a best estimate of 3.2 to 7.2°F (1.8-4.0°C) (see Figure 1). The average rate of warming over each inhabited continent is very likely to be at least twice as large as that experienced during the 20th century.

So, to take heavy rainfall as an example, that’s a best estimate of a 10 to 72 percent increase globally. In case you’ve forgotten, Tennessee experienced a 1,000-year flood in early May (see the red streak below), killing 21 and causing an estimated $1.5 billion-plus in damages.

Climate change was surely a major contributor to the flooding, according to Kevin Trenberth, head of the Climate Analysis Section at the National Center for Atmospheric Research, who was quoted back in June on Climate Progress (emphasis CP’s):

I find it systematically tends to get underplayed and it often gets underplayed by my fellow scientists. Because one of the opening statements, which I’m sure you’ve probably heard is “Well you can’t attribute a single event to climate change.” But there is a systematic influence on all of these weather events now-a-days because of the fact that there is this extra water vapor lurking around in the atmosphere than there used to be say 30 years ago. It’s about a 4% extra amount, it invigorates the storms, it provides plenty of moisture for these storms and it’s unfortunate that the public is not associating these with the fact that this is one manifestation of climate change. And the prospects are that these kinds of things will only get bigger and worse in the future.

For good measure, please keep in mind too that 2010 is on pace to be the warmest year since record keeping began in 1880.

Surely the wise leaders of business and industry who foresaw the implosion of the housing bubble will save us from choking on our own emissions, right? Oh, wait. No. This week Senate Majority Leader Harry Reid (D-Nev.) officially ruled out the possibility of a carbon cap, saying, “we know we don’t have the votes.”

Scroll down this page for a little video on how Obama and his team squandered the opportunity for serious action on climate change.

More in my next post.