Following on from yesterday’s post, The Institute of Physics has a paper summarising the results of various CO2 reduction schemes based on running the scenarios through all of the best climate models around. The results are pretty interesting:
Using a scheme to emulate the range of state-of-the-art model results for climate feedback strength, including the modelled range of climate sensitivity and other key uncertainties, we analyse recent global targets. The G8 target of a 50% cut in emissions by 2050 leaves CO2 concentrations rising rapidly, approaching 1000 ppm by 2300. The Stern Review’s proposed 25% cut in emissions by 2050, continuing to an 80% cut, does in fact approach stabilization of CO2 concentration on a policy-relevant (century) timescale, with most models projecting concentrations between 500 and 600 ppm by 2100. However concentrations continue to rise gradually. Long-term stabilization at 550 ppm CO2 requires cuts in emissions of 81 to 90% by 2300, and more beyond as a portion of the CO2 emitted persists for centuries to millennia. Reductions of other greenhouse gases cannot compensate for the long-term effects of emitting CO2.
So if we want to avoid trashing the place, we need to reduce to less than 10% of today’s emissions! That’s more than most people realise. Thankfully we’ve got more than two hundred years to get there, which should be doable.