The Guardian provides a helpful guide to what all these global warming trends could mean for different parts of the planet by century's end. Please note: the relatively "small" increase of 2C in global temps that's considered "acceptable" by most governments and scientists is still really really bad:

2C -- The temperature limit the scientists want

The heatwaves seen in Europe during 2003, which killed tens of thousands of people, will come back every year with a 2C global average temperature rise. Southern England will regularly see temperatures around 40C in summer. The Amazon turns into desert and grasslands, while increasing CO2 levels in the atmosphere make the world's oceans too acidic for remaining coral reefs and thousands of other marine lifeforms. More than 60 million people, mainly in Africa, would be exposed to higher rates of malaria. Agricultural yields around the world will drop and half a billion people will be at greater risk of starvation. The West Antarctic ice sheet collapses, the Greenland ice sheet melts and the world's sea level begins to rise by seven metres over the next few hundred years. Glaciers all over the world will recede, reducing the fresh water supply for major cities including Los Angeles. Coastal flooding affects more than 10 million extra people. A third of the world's species will become extinct as the 2C rise changes their habitats too quickly for them to adapt.

But don't fool yourself into thinking that any of the cuts the US (or anyone else) is talking about at the moment would limit warming to 2C. The best we can probably hope for with current emissions targets (the ones the House passed and the Senate is considering, for example) would be this:

3C -- Looking increasingly likely

After a 3C global temperature rise, global warming may run out of control and efforts to mitigate it may be in vain. Millions of square kilometres of Amazon rainforest could burn down, releasing carbon from the wood, leaves and soil and thus making the warming even worse, perhaps by another 1.5C. In southern Africa, Australia and the western US, deserts take over. Billions of people are forced to move from their traditional agricultural lands, in search of scarcer food and water. Around 30-50% less water is available in Africa and around the Mediterranean. In the UK, summers of droughts are followed by winter floods. Sea levels rise to engulf small islands and low-lying areas such as Florida, New York and London. The Gulf Stream, which warms the UK all year round, will decline and changes in weather patterns will lead to higher sea levels at the Atlantic coasts.

Note also the bit about the possibility for runaway warming if we reach a 3C increase -- somewhat concerning since we're heading for that neighborhood. Gee, kinda makes all this concern trolling about the near-term effect on the economy of cap-and-trade sorta, um, stupid. Good thing our fearless leaders have everything under control!

h/t Brad Plumer

Photo by flydime used under a CC license

Labels: climate, politics