Saturday, June 04, 2016

Scientists Compare Climate Change Impacts at 1.5C and 2C

Infographic: How do the impacts of 1.5C of warming compare to 2C of warming?  (Credit: Rosamund Pearce for Carbon Brief) Click to Enlarge
Half a degree makes a very big difference when judging how different parts of the world will feel the effects of climate change.

This is the conclusion from the first study to compare and contrast the consequences of 1.5C world compared to a 2C world, published today in Earth System Dynamics.
Acknowledging that capping warming at 1.5C is preferable to 2C is one thing, but it’s important to talk about the realities of getting there.  And the scale of the challenge is immense.

On current emissions, the carbon budget for 1.5C will effectively be blown in about four and a half years, as our graphic above shows (Note: figures are based on 2014 emissions).

The consequence of this is that any realistic possibility of limiting warming to 1.5C in the long term means overshooting the target and somehow coming back down.  Schleussner tells Carbon Brief:
“Scientific findings…show that it is both physically and economically feasible to limit warming to below 1.5°C by 2100, after temporarily exceeding 1.5°C in the 2050s (but still staying well below 2°C)."
But doing so involves relying on being able to “suck” carbon dioxide out of the air, using so-called negative emissions technologies (NETs).  Carbon Brief ran a special series of article last week looking in-depth at possible approaches and how feasible experts think they are.

Even if overshooting and coming back down to 1.5C were technically possible, there’s no guarantee the consequences for ecosystems would be the same as if we hadn’t cross the 1.5C boundary at all.  Whether or not climate change impacts are “reversible” is a very important research topic right now, says Schleussner.

[This] study is an important first step to understanding the real-world consequences of what countries agreed to do, in principle, in Paris.

While it lays out the scientific reasoning behind a 1.5C target, the question of if and how we get there is part of a far bigger conversation, one that’s particularly pertinent as nations gather in New York this week to reaffirm their collective commitment.

Read more at Scientists Compare Climate Change Impacts at 1.5C and 2C

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