So now we have the World Bank, in a report prepared by the Potsdam Institute for Climate Impact Research and Climate Analytics, saying, basically, we sure better cap it at 4 degrees, otherwise there will be hell to pay. (Bear in mind, we've already seen a 0.8-degree Celsius increase from preindustrial levels.)
That's not to say a 4-degree increase will itself be a stable or moderate plateau. Dramatic effects will be felt. "It is also useful to recall that a global mean temperature increase of 4Â°C approaches the difference between temperatures today and those of the last ice age, when much of central Europe and the northern United States were covered with kilometers of ice and global mean temperatures were about 4.5Â°C to 7Â°C lower," the report said. "And this magnitude of climate change--human induced--is occurring over a century, not millennia."
The executive summary is magazine-article length and worth your perusal.
The larger point though is that current political and economic trends don't suggest any kind of substantial reordering of the carbon-based economy is going to happen now or in the near future. In the intermediate term, the prospects of reducing carbon emissions don't seem any better. The World Bank report is another warning sign that the road ahead is very dangerous. But we're pushing harder on the accelerator.
Late Update: The original version of this post wasn't as clear as it could have been that the World Bank report is still officially committed to limiting the increase to 2 degrees.
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