I took Carbon Brief’s “Six years worth of current emissions would blow the carbon budget for 1.5 degrees” seriously and used it in “Is Green Growth a Fantasy”. This estimates the rate of decarbonisation of world GDP necessary to keep within 2 degrees.

The argument relies on reducing and restricting carbon emissions until the time when the world can balances carbon emissions with carbon sequestration.

According to quite straightforward (but rather optimistic) calculations, the world can reach 2050, without exceeding the 2°C limit by cutting the carbon intensity of production by 3.7% a year. This is assuming the average world citizen’s consumption remains the same. See “Optimism and pessimism on climate”.

However, the 3.7% decarbonisation in 2015 seems a fluke maximum (as Carbon Brief reported in “Decrease in China’s coal use sees global emissions fall in 2015”). The average decarbonisation for the past 25 years has been 1.3%.

Worryingly, Carbon Brief’s has a video of Michael Jacobs. He says 2080 is the date for BECCS to work. That’s long after the 2050 date I had assumed. That would mean global GWP per person must fall – even if it were possible to keep up the improbable rate of decarbonisation of 3.7% . Will this be politically possible?

Is it really possible to keep temperature to below 2°C without falling consumption?

And the COP21 aim of 1.5°C. Is that just fantasy,  just like “Green Growth”?