This month, as national delegations meet in Lima, Peru for the UNFCCC's COP20, there will be much discussion of emissions reductions targets, base-year emissions, voluntary contributions, legally binding agreements, and so on. What is to be made of all these goals? What do they all mean? And does any of it matter?
The short answer is no, none of it matters, at least not directly. What does matter? Two things: the carbon budget and the emissions gap.
What is the carbon budget? Fiona Harvey at the Guardian explains:
The IPCC said that in order to stay within the 2C threshold, the total carbon emitted could not exceed 1,000 gigatons of carbon. Of that, more than half – 531 gigatons – had already been emitted by 2011. But it also noted that if other greenhouse gases were also taken into account, the budget would be reduced to 820-880 gigatons. This implies that two thirds of the emissions available have already been used up.
Roughly speaking, the carbon budget is being depleted at an alarming rate, and that rate is only accelerating as more of the world's economies develop. Unless serious changes are made, a "business as usual" emissions would mean exhausting the budget by 2035.
The emissions gap, for its part, is just the difference between the current emissions trajectory and a trajectory that would lead to staying within the budget. Essentially: how far off is the emissions trajectory now, and how far off is it expected to be in the future? A useful way to think about future greenhouse gas (GHG) emissions is to compare a few different scenarios:
- The first is the business-as-usual (BAU) case, which projects future emissions levels absent any international agreements or serious coordinated efforts to reduce GHG emissions. Basically, if countries and companies do what they want, as they have been doing up until now, one would expect the BAU-level emissions projections to bear out.
- The second might be called the "pledges" case. Under the current international negotiation efforts, national delegations are making voluntary pledges to reduce future emissions, typically expressed as a percent reduction in GHG emissions compared to emissions in a stated base year (e.g., US President Barack Obama recently announced a target to reduce US GHG emissions by 26-28% by 2030 compared to 2005 levels). What these reductions pledges actually amount to is hard to tell, since each country is free to set its own base year. This makes comparisons between countries difficult as countries are free to choose any previous year that makes their emissions reductions appear the most significant. Moreover, there currently is no penalty in place if a country fails to meet its voluntary pledge. Even under the legally binding Kyoto Protocol, there was nothing to keep countries from withdrawing from or "unsigning" the treaty (e.g., see the US and Canada), effectively exonerating themselves from any sense of wrongdoing.
- The third could be deemed the "scientific" case. The IPCC has established bounds around emissions scenarios that are likely to limit global warming to 2ºC by the end of the twenty-first century. This third case is simply where emissions levels would need to be in order not to exceed the 2ºC warming limit.
Given these three cases, there are at least two relevant comparisons to be made:
- What is the gap between current and projected emissions on the one hand (the "where emissions are today / where they are expected to be tomorrow") and the scientific consensus of emissions levels that will limit warming to 2ºC (the "where emissions need to be today and tomorrow")?
- What is the gap between current pledges and the BAU scenario? Essentially, how good of a job are nations doing at sticking to their pledges? Are nations doing better than, as well as, or worse than pledged?
The first comparison shows how far nations have to go; the second gives at least an initial indication of how good they are at sticking to what they say they're going to do. These are perhaps the two most important questions to ask in establishing a climate action report card.
The United Nations Environment Program (UNEP)'s recently released 2014 Emissions Gap Report addresses both these questions, and the results are not good. Not only is there a sizable gap between what nations have pledged to do and what the science says will be necessary, but there is also a gap between what nations have pledged to do and what they have done. In other words, not only are nations' pledges not ambitious enough to tackle climate change even if they were to achieve their pledged reductions, but nations have been providing reason to believe they will not even meet their pledges.
The chart below comes from the executive summary of the 2014 Emissions Gap Report, page xx, and shows the three different scenarios discussed in the bullet points above:
The Emissions Gap
In light of the discussion above, barring significant coordinated action by governments around the world, a "likely" emissions path might fall somewhere between the gray "pledges" and blue "BAU" paths, significantly off course from the tan "scientific" path. However, even if new, more significant pledges are made that are in line with the "scientific" path, skepticism might still be warranted if nations fail to provide concrete, achievable plans for meeting their pledges that leave room for unforeseen challenges.
Thus, to the extent targets and voluntary emissions reductions pledges contribute to staying within the carbon budget, they are useful. But if setting relative emissions reductions or carbon intensity goals distracts from the overall carbon budget and the emissions gap, then these goals are counterproductive. If, as a global society, nations are serious about limiting global warming to no more than 2ºC (the globally agreed goal at COP15 in Copenhagen in 2009), they need to keep their eye on the prize. And that prize is staying within the carbon budget. The carbon budget is the only relevant starting point for policy discussions and decisions.
Working backward from the budget, a few things become apparent. First, barring a major technological breakthrough in scaling carbon capture and storage (CCS), it won't be possible to burn even half the fossil fuels we already know exist (i.e., fossil fuel companies' proven reserves, which are already factored into their market valuations) and remain within the 2ºC limit. This has serious financial implications for fossil fuel companies, which means staunch opposition from them is to be expected. But it also means significant investment in clean energy technology will be required to meet global energy demand, which continues to grow.
And so whenever nations and negotiators talk about an X% reduction over year Y emissions levels by year Z, it is important not forget what matters: is such a goal in line with the types of reductions that are necessary to meet the 2ºC limit? Whenever goals fall short, leaders of nations, as well as businesses, should be held to account. This might mean a serious conversation about whether current lifestyles and economic styles are compatible with meeting the 2ºC limit.
And if global society decides it can't or doesn't want to adjust its lifestyles and economic structures to meet that limit, it must be honest with the current and future generations that it was a decision taken knowingly. The science explains what will happen if the BAU path is pursued, or even if a half-witted effort at reducing emissions is made. Political destabilizations, mass migrations, disastrous storms, droughts, conflicts are all expected. There's even the potential for out-of-control temperature increases, which would occur tipping points in climate stability are passed, creating feedback loops that result in more and more warming (e.g., the melting of the West Antarctic Ice Sheet, the thawing of permafrost in the arctic, albedo effects from settling black carbon in the arctic associated with burning coal, etc.). And so even if the decision is taken to "do nothing" for now, society at a minimum needs to prepare to cope with the ramifications of its inaction.
The knowledge to mitigate climate change is available, but whether global society will decide to act on that knowledge remains to be seen.