So what does that mean in real, ecological terms? Well the 3 to 5oC rise in average temperatures over the U.S. and Canada are located squarely on top of our agricultural belt. If you look at precipitation data for, say, North Dakota, which is sitting on the 3oC edge of the warm mass, you also find that average precipitation is up over the last 180 days. Taking that into account, and looking at the annual average change in both temperature and precipitation, what you see is that our agricultural belt is heating up, and while it is wet right now, if annual and inter annual temperatures continue to rise, they will soon pass a point where existing agriculture can be sustained, since temperatures will become too hot for both the plants themselves, and for existing precipitation to keep the plants properly watered.
In other words, If this keeps up, we may well start seeing persistent drought in the upper mid-west and Canada, which would result in significant crop losses, or significant diversions of water for irrigation – unless we as a nation have the intestinal fortitude to move our agricultural apparatus to some other part of the country.
These, dear readers, are the kind of decisions we need to make NOW, not in 10 or 20 or 50 years when we have “better” data. Otherwise, our national economy may be imperiled, as well as our national food supply.
Think I’m blowing smoke? Consider this – “the global ocean surface temperature was 1.03°F (0.57°C) above the 20th century average of 60.9°F (16.0°C) and the warmest on record for April. The warmth was most pronounced in the equatorial portions of the major oceans, especially the Atlantic.” That means that we’re half way to the temperature increase needed to cause coral reefs to bleach (1-2O). And coral bleaching has nasty consequences. Not only do corals die, but the reef structure destabilizes, and becomes more susceptible to storm damage. This in turn leads to looses of local reef fish community productivity, and reefs, particularly in tropical areas serve as the fundamental nursery grounds for commercially important fish species. They also form the protein basis for some of the world’s poorest coastal economies. If a single degree or two rise in ocean temperature can lead to that sort of cascade – and evidence is now pointing that way – then a rate of global average temperature increase like we’re seeing here in the U.S. can just as easily threaten our purported “bread basket.”