Several recent reports have pointed out that without significant, immediate action to lower global warming emissions, we are getting dangerously close to blowing past emissions levels that would lead to a 2°C or more increase in global temperatures. That may lead some to think that the 2°C benchmark is becoming increasingly irrelevant, but nothing could be further from the truth.
The growing risk that we may reach 2°C is an ever more urgent reminder that we must make swift, deep emissions reductions and invest in building resilience to the worsening climate impacts that we are locking in.
This is a moment for sober stock-taking (i.e. not the usual passing-the-buck, gratuitous finger-pointing, or creative emissions accounting — all of which are currently much in evidence at the UNFCCC negotiations underway in Doha) of why we’ve failed to act despite the very real risks of climate change that are even now starting to affect millions of people. And it provides a renewed sense of urgency that we must take all prudent steps to keep future temperature increases as low as possible. To do otherwise would be risking the health and well-being of people and our planet now and in the future.
Why the 2°C goal matters
The 2°C goal for climate action has been broadly endorsed by the world’s leaders, first at the G8 summit in Aquila in July 2009 and then later by a much larger group of countries at the Copenhagen climate talks in December 2009. (Several countries have endorsed an even lower target of 1.5°C, including the small island states, and most African countries and other least developed countries, which are and will be most seriously affected by climate change.)
In some sense, from a scientific point of view, the exact numeric target has always been an arbitrary choice. The relationship between atmospheric greenhouse gas concentrations and temperature increases is a probabilistic one. Global temperature increases occur on a continuum over time and their impacts often play out over even longer time scales. There’s no magic “stop button” at 2°C. But scientists have warned about the growing dangers as we get close to 2°C and go beyond it. One of the most riveting portrayals of this is the familiar “burning embers” graphic.
The risks of harmful effects from global warming rise with its magnitude. This figure shows that even a 2°C rise in global temperature poses significant risks. The left-hand panel is based on the 2001 Third Assessment Report of the IPCC (TAR). The right-hand panel is an updated version from 2009 based on Smith et. al. Source: Adapted from Smith et al 2009; Schneider 2009.
So what 2°C represents is a policy consensus informed by climate science. Accepting that goal was supposed to motivate programs of deep emissions reductions around the world that would help fulfill it and thereby help lessen some of the worst consequences of climate change.
Why the prospects of staying below 2°C look so grim
In a nutshell, the reason we are failing so far to meet our global goal is a complete and utter lack of political will and sense of urgency in major emitting countries. It seems fruitless to point fingers at individual major emitting countries when the fact is that none are doing what they need to do. The stalemate at Doha only further highlights this (although I still hold out hope for a breakthrough in the final hours of the negotiations).
We have the technologies and know the policies that are needed to deliver deep emissions reductions. That is definitely NOT what’s held us back. We know that because we’ve seen several of them adopted around the world, just not at the scale and speed at which we need them to come online.
Why it is all the more urgent that we take all prudent steps to limit further temperature increases
Of course, it is of foremost importance that we put pressure on our political leaders to live up to their promise to limit global temperature increases to no more than 2°C. But if they fail to deliver, let’s remember that climate impacts and risks only increase (in non-linear and sometimes irreversible ways) with temperature increases so it is still important to limit those increases as much as possible. We have to double down, not give up!
Here in the U.S. the political prospects for comprehensive climate and energy legislation seem dim, but nevertheless this call to action from scientists and economists to U.S. policymakers is as relevant today as the day it was first released.
The risks of a ‘Beyond 2°C’ world
As the recent World Bank report on the risks of a 4°C world points out, the burden of climate risks will fall disproportionately on poorer countries. Countries like Bangladesh, India, Mexico, and Indonesia have large populations that will face increasing risks from rising sea levels, and parts of sub-Saharan Africa will be increasingly vulnerable to widespread droughts and food crises.
Rising temperatures will likely also lead to increases in tropical cyclone intensity, which are likely to be felt disproportionately in low-latitude regions (Typhoon Bopha, which has had a catastrophic impact on the Philippines, formed at an unusually low latitude and may be an example of this phenomenon); extreme heat waves, which are likely to affect many parts of the world; and loss of vital ecosystems like coral reefs, which are at risk from ocean acidification.
Even here in the U.S., we have recently experienced a spate of devastating extreme weather events — such as the Drought of 2012 and Hurricane Sandy — that have likely links to climate change. It’s past time that we had in place a serious national plan to lower emissions and build resilience in the face of climate change that is already unfolding. Our obligations to the international community, especially to those countries that are least responsible for generating emissions and yet are facing the most severe consequences of climate change, should also be clear.
World Bank President Dr. Jim Yong Kim’s foreword to the recent report opens with the sentence “It is my hope that this report shocks us into action….” As we teeter on the brink of a ‘beyond 2°C’ world, I hope indeed that the world’s leaders will be galvanized into action.