Climate change is just one driver of the Holocene-Anthropocene Mass Extinction. But it will be a powerful one, as global emission reduction commitments – that will be discussed in the following two weeks in the German city of Bonn during the ‘COP23′ UN climate conference – still lead to a three degrees warmer world, or worse, as this updated UNEP graph illustrates:
In Paris the world agreed on the 1.5 degrees climate ambition. But to get there countries need to urgently cut greenhouse gas emissions in the period up to 2030. However if you add up the unconditional 2030 NDCs of all nations, we’re heading for 3.2 degrees warming. And if you look at actual emission reduction policy it’s even worse.
During COP21, the Paris climate conference of 2015, the world agreed on a new climate ambition – to ‘try’ to limit atmospheric warming to no more than 1.5 degrees, an improvement compared to the older UN climate target of 2 degrees.
The above graph shows what trying looks like in reality. Member nations to the UNFCCC have national emission reduction goals called NDCs, Nationally Determined Contributions. Formally the NDCs were known as INDCs: the word Intended has been removed – and since before Paris that is sadly the only progress the world has seen.
The only actual achievement that the graph shows is between business as usual (baseline) emissions and the line that says current policy – a difference between roughly 4.5 and 4 degrees warming. Then there are many gaps in a row, to get to the actual ambition the world agreed on:
First the gap between policy and nations’ unconditional emission targets, that lead to a 3.2 degrees warmer world (based on median climate sensitivity – this could be an underestimation).
Then there is a 2.5 gigatonne CO2eq gap from the unconditional NDCs to the conditional emission targets. If these would represent actual policy (again, they don’t – that line is called ‘current policy’) the world would get on a 3 degrees path, still 11 gigatonnes of greenhouse gas emissions higher than the 2 degrees atmospheric budget allowed, that in turn is 5 gigatonnes above the actual 1.5 degrees budget.
A 3 degrees Celsius warmer world is a world in which three quarters of the Amazon rainforest will dry out and die. It is a world in which the Anthropocene Mass Extinction will be fuelled by a massive biome shift – and the dispersal of millions of species that will be forced to migrate in a direction they don’t know to ecosystems that don’t exist.
That’s what is a stake in the city of Bonn, that’s what should be discussed at COP23.
© Rolf Schuttenhelm | www.bitsofscience.org