DeSmogBlog reports that a majority of world leaders want to scrap the 2C warming target limit.
The idea has been that, if we can just keep global warming at 2C or less, civilization might avoid triggering runaway global warming from the Earth's own natural feedback loops. A lot of the research coming in lately has shown that the 2C target, itself a "political number," is unduly and dangerously optimistic. That's why we have the drive now to reset the target to just 1.5 degrees Celsius above pre-industrial levels.
There's a problem with these numbers. 2015 has seen man-made global warming reach the 1 degree Celsius mark, hotter than the Earth has experienced in around 800,000 years. Unfortunately, the atmospheric greenhouse gas loading that brought us to 1C is persistent and will keep warming the atmosphere for a century or more. 1C is where we are today, not where we're going to be even if we were to somehow decarbonize our global civilization tomorrow.
Those who have run the numbers conclude that the existing atmospheric GHG loading has already "locked in" 1.5C of warming over the course of this century. In other words that horse has already left the barn.
Every gigatonne of greenhouse gas we emit from here on in simply goes on top of that 1.5C. In preparation for the Paris climate summit, COP 21, every country submitted a GHG reduction pledge to the UN. Those numbers show that if every nation actually met its pledge (a big "if"), we're still looking at something upwards of 3.5C of man-made warming.
Another problem is the major emitters. They're kind of stuck on the 2C number. It's the little countries, the poorest and most vulnerable states, that are pushing for 1.5C and they don't have a lot of clout, at least not yet. Still it's a concerted effort to move in the right direction, better than nothing.