And that understanding has just ended the Age of Coal. Thank you coal – it’s been great fun. We’ll have to leave the rest of you where you’ve been for the previous millions of years.

In our quest to uncover the ‘Real’ Global Temperature Trend we are closing in on a value for the ‘Real’ Global Temperature (RGT) – that is the observed temperature minus all masking factors, including thermal inertia. Today we take a look at values the latest IPCC report (2014) uses – to establish a sense of ‘how long we still have’ before we breach the newly agreed 1.5 degrees climate target.

As a regular to Bits of Science we are sure you recognise the above molecular structure. It is long, variable, complex – and for a hydrocarbon contains few spaces for those innocent hydrogen atoms (that turn to H2O when you burn them) and contain a lot of ‘aromatic structures’ where carbon just binds with other carbon atoms, in hexagons and pentagons. This is where climate policy draws from very basic chemistry: if you use coal (compared to for instance gas – 4 hydrogen atoms for 1 carbon atom) you produce a lot of CO2 for a given amount of thermal energy. (And also a lot of additional pollutants that are also caught in this molecular structure, heavy metals like mercury and arsenic.) In all political scenarios (this also goes for the 2 degrees target!) one thing is evidently clear: there is no more room for coal in the global energy mix. Now who is listening, on national political levels – who is listening, on energy company investors’ level? They all better hurry up.

Image: Understanding the Chemical Properties of Macerals and Minerals in Coal and its Potential Application for Occupational Lung Disease Prevention, Journal of Toxicology and Environmental Health, Part B: Critical Reviews (2008).

(We could have changed the title of this piece to something like ‘IPCC’s climate senstivity places current global temperature around +1.4 degrees’, or ‘World has 8 years current emissions before breaching 1.5 degrees climate target, according to IPCC’. The reason we don’t is these are conservative estimates, and a likely underestimation of actual scientific urgency. We will show you what we think is the ‘real’ current global temperature very soon. The ‘real’ emissions budget is probaly negative already.)

One thing everyone agrees on: there is simply no more room for coal – anywhere

Are you personally involved in a campaign to stop coal? Then feel assured that not only the scientific but also the global political community agrees with what you do.

In Paris, during UNFCCC’s COP21 climate conference in December 2015, the world agreed we should limit/’try to limit’ [politics] global average warming to 1.5 degrees Celsius, compared to pre-industrial temperature.

Using conservative estimates of the IPCC, which serves as the foundation for the UN climate process, this means we have (most likely value) just 8 years left under current global emissions, before we’ve used the entire international CO2 emissions budget for the rest of the 21^st century.

As coal is the most carbon-intensive fossil fuel (see image at top) we are left with the following ‘choice’:

We either stop coal immediately and internationally (in campaigner terms, that’s on all fronts – from coal plants to coal mines to coal transports to coal politics to coal investors – ‘no more’) and phase out all other remaining fossil fuels as quickly as we can – or we stick to business as usual and blow the entire 1.5 degrees emission budget in the next 8 years – and continue on the track towards 3.5 degrees that the world is currently still on.

There is one additional complicating factor to this story: It is based on the warming projection of the IPCC…

What’s ‘wrong’ with the above (otherwise really beautiful) infographic? Two things:

1. It’s 2016 now; the image is 2 years old – so turn that clock accordingly: where you read 6 years for 66% chance to stay below 1.5 degrees, that has now become 4 years (as global CO2 emissions have remained equally high) and for the 50% chance (the one we use in this article) we’re now down to 8 years of remaining atmospheric CO2 emissions budget. (Translating this to ‘unburnable carbon’, using 2011 data of Carbon Tracker Initiative, even this 50% chance to stay below 1.5 degrees required (in 2014!) required 93 percent of all the world’s fossil fuels reserves to ‘remain in the ground’ – easy to comprehend that means 100 percent of global coal reserves.)

2. It’s based on IPCC’s warming scenarios for rising CO2. And that’s good, in the sense that also global politics uses these IPCC values. It leads to further underestimation of the urgency though, possibly for more than one reason: firstly the IPCC’s range of Equilibrium Climate Sensitivity (ECS) is (90% interval) 1.5-4.5 degrees Celsius. New established climate research agrees climate sensitivity is not in the lower half of that range (1.5-3) – and, according to individual studies, could even surpass the upper limit (>4.5). Also the ECS value only looks at direct warming of CO2 + direct atmospheric feedbacks (water vapour, clouds) but ignores important (slower) terrestrial positive climate feedbacks, like decreasing sea ice albedo and positive biosphere carbon feedbacks – which are likely to lead to some further amplification of 21st century warming. It means where you now read we still have 8 years to go – reality is probably somewhat darker: we have already surpassed 1.5 degrees’ emission budget (but no one knows exactly how far).

(We think it may be time for an update dear CarbonBrief.org!)

© Rolf Schuttenhelm | www.bitsofscience.org