Last week, the leaders of the two biggest emitters of greenhouse gases, China and the US, signed a historic pact to curb those emissions post-2020.
The deal is hoped to ease the international deadlock on climate negotiations and remove any remaining excuses other countries have for not following with similar targets. All eyes will now be aimed at the Paris summit next year for what could be our last chance to get meaningful top-down action on climate.
Timing is everything, and this is no exception, coming barely days after the Intergovernmental Panel on Climate Change issued its starkest warning yet.
Launching the fifth synthesis report, the United Nation’s Secretary-General Ban Ki-moon spoke about the need to act “quickly and decisively” to avoid increasingly destructive climate change. Widely reported was the key message to phase out fossil fuels by the end of the century.
But even if other nations follow the US/China lead and deepen their targets, will it be enough?
The IPCC’s fifth report broke new ground by including the concept of a carbon “budget”, which tells us that humanity needs to keep our entire future carbon dioxide emissions below 1000 billion tonnes (about 30 years worth of emissions at current levels) to have a reasonable chance at staying under the 2°C temperature rise threshold.
Because carbon dioxide is such a long-lived greenhouse gas in our atmosphere, the budget approach is superior as it embodies the fact that it’s our cumulative emissions that count, not any particular year’s worth.
The pathway to meet that budget is also important as it provides a framework for setting international and domestic targets. The IPCC’s 2°C pathway (RCP2.6) assumes “negative emissions” in the latter half of this century, meaning we’ll have to start pulling out carbon dioxide from the atmosphere in large amounts and store it somewhere where it won’t leak.
However, it’s becoming increasingly obvious that carbon capture and storage (CCS) as a means of lowering emissions from fossil power stations just hasn’t – and probably won’t – deliver the promise of clean energy compared to other cheaper, less risky, not to mention cleaner alternatives. In many countries it would now be possible to shift to an almost entirely clean grid using a smart combination of renewables with a modest amount of storage.
But here’s the catch: achieving negative emissions when the carbon dioxide is already diffused throughout the atmosphere is far harder than capturing the emissions from the output of a fossil power plant. Richard Branson’s $25m Earth Challenge was launched in 2007 as an attempt to discover such a technology, yet despite the announcement of a number of finalists a few years ago, a workable solution remains elusive.
If negative emissions turn out not to be possible on a large scale, we’d have to phase out fossil fuel electricity production towards the middle of the century, not the end, causing a considerable knock-on effect to targets. Yet surely the precautionary principle dictates that we shouldn’t put all our eggs in a basket of wishful thinking, regardless of our belief in humanity’s ability to innovate?
But there’s another aspect of the report that I find even more troubling.
The IPCC’s headline scenario gives humanity a “likely” (defined as 66%) chance of staying within the 2°C limit. This translates to about the same odds as playing Russian Roulette with not one, but two bullets in a six-barrel chamber; perhaps a reasonable risk if you have a death wish, but surely not appropriate when seeking to avoid a serious and potentially catastrophic outcome for the inhabitants of our planet.
To get better odds, we’d have to recalibrate our carbon budget.
Continuing the analogy, if we choose to gamble with a single bullet in the barrel, our 1000 billion tonne budget (two bullet scenario) shrinks to under 300 billion tonnes, giving us less than a mere decade at current levels of emissions. An entirely different prospect.
Keeping to this budget would require the Herculean task of reducing global emissions by an average of just over 6% per year, starting immediately and not stopping until all our emissions were eliminated. Do-able? I’m not sure, but certainly unprecedented, probably requiring an equally unprecedented level of international co-operation.
The surprise deal between China and the US has certainly shifted the political terrain somewhat, injecting fresh hope for climate negotiations. By itself it’s clearly not enough to give us a great chance of keeping below 2°C but it’s certainly given us a better chance.
Steve O’Connor is a Climate Reality Leader based in Australia, currently working for SolarShare Canberra. These are his personal views. He tweets at @stevepoconnor