The IPCC just released its third assessment report on mitigating climate change.  I’ve spent the morning reading the full summary, and to help you save a little time I’ve whittled it down to a six word summary.
Fossils fuels are for making stuff
When you strip away all the technical language about ‘stock and flows of greenhouse gases’, ‘mitigation pathways’ and ‘mitigation costs’ climate mitigation is pretty simple.  To limit warming to 2°C  above the pre-industrial level we need to start limiting our use of fossil fuels to only processes that we can’t effectively substitute with a form of low carbon energy.
Of course, we’ll continue to use fossils fuels for making stuff where absolutely necessary (steel, plastic, fertilizer . . )  but we need to stop using them as our go to energy source for doing things (power, transport, heating and cooling).  This of course is a simplification, with obvious exceptions like heavy transport, but it’s a pretty solid way to think about the challenge.
If that sounds radical that is simply because it is.  According to the IPCC, limiting warming to 2°C means increasing the world’s low carbon energy share from 15% in 2010, to 60% by 2050 and to 90% by 2100.  And just to be very clear here when the IPCC says ‘energy’ they don’t mean electricity. They are talking about all the energy we use in industry, transport, buildings and agriculture.
The next few graphs explain a little about how the IPCC sees climate mitigation. Â If they are a little hard to read click on them and they should expand.
The Need to Slash Emissions
The graph above shows greenhouse gas emissions pathways between 2000 and 2100.  The four black lines are the IPCC’s five representative concentration pathways (RCPs) which come from the science working group. Colored in light blue you can see the low pathway for 430-480ppm CO2eq.  This is the 450ppm scenario which is likely to keep warming below 2°C in 2100.  It involves reducing total greenhouse gas emissions from around 49 Gt CO2eq/yr in 2010 down to about 20 Gt in 2050, and to slightly negative net emissions in 2100.
Upscaling Low Carbon Energy
This graph shows just how rapid the coming deployment of low carbon energy will need to be in order to mitigate the worst of climate change.  If we look at the blue section to the right we can see that low carbon energy needs to soar from about 15% of total primary energy in 2010 to 60% of the total by 2050 in the 450 ppm scenario.  By 2100 this figure would need to reach 90%.
Reducing Energy Demand
On top of a revolutionary increase in the use of low carbon energy, a 450ppm scenario would require significant reductions in energy demand through efficiency, planning and behaviour. Â In each of the blue columns above you can see how final energy demand is reduced through 2030 and 2050 in the transport, buildings and industry. Â These reductions are over and above the normal efficiency gains built into the baseline.
Trying to Capture Carbon
This last graph shows which sectors need to provide the heavy lifting and highlights how important carbon capture and storage (CCS) is for reaching 450 ppm by the end of the century.  Without any viable CCS 450ppm looks even more unlikely and is dependent on huge emissions reductions in  Agriculture, Forestry and Other Land Use (AFOLU).  If you want some context for just how colossal the challenge is compare the yellow electricity emissions for 2100 in the baseline and to the 450 ppm with CSS scenario.  In the former electricity emissions are +30 Gt each year while in the latter they are -12 Gt/yr.
Mitigating Climate Change
So there you have it.  I hope that was a vaguely intelligible summary of the IPCC new report.  If you are really interested I highly suggest having a go atreading the summary yourself.  It’s not an easy read due to the need for constant qualification and referencing, but hey, it’s pretty damn important stuff.  If you are looking to do some mitigation a bit closer to home then check out our free eBook with 13 tips for cutting your own carbon emissions.
Source: Shrink That Footprint. Reproduced with permission.
