And now it has to go sharply down. To summarise the entire IPCC WG3 report on climate mitigation:

All greenhouse gases combined in 1970 mankind emitted 27 gigatonnes worth of CO2 equivalents. Forty years later this had risen to 49 gigatonnes. The net share of methane, nitrous oxide and CO2 from land use changes (like deforestation) have all slightly decreased, whereas the share of CO2 from fossil fuels combustion has risen.

Fossil fuel CO2 emissions have more than doubled over the 4 decades, from some 15 gigatonnes in 1970 to around 32 gigatonnes in 2010. This rise has sped up over the last decade. [Also after 2010, and despite the recession, fossil CO2 emissions have continued to rise.]

This graph illustrates the deep urgency of the climate crisis. The CO2 ocean-atmosphere thermic climate inertia is also around 40 years. This implies we are currently only feeling delayed effects of (cumulative) CO2 emissions up to around 1970.

This means the entire emissions rise you see in the graph is the inevitable part of climate change. Therefore the carbon budget for the official 2 degrees climate target [as we have already had +0.8C] is VERY limited, also under the (rather risky – around a 50% chance, see WG1) 450 Scenario.

The message is simple: Fossil fuels use has to sharply decrease over decades to come. It now delivers 80 percent of global energy demand – and under assumed rising consumption scenario this has to decrease to below a third before the second half of this century, the WG3 summary (PDF) states.

So what about investing in long-lasting fossil fuels infrastructure, pipelines, coal plants, combustion engines. Indeed. That does not fit. And neither does that half a billion dollars of annual fossil fuels subsidies.

© Rolf Schuttenhelm | www.bitsofscience.org