For years my father has been arguing that:
. . . attempts to “control” the climate system, and to prevent a “dangerous intervention” into the climate system by humans that focuses just on CO2 and a few other greenhouse gases will necessarily be significantly incomplete, unless all of the other first order climate forcings are considered.His views are now being robustly vindicated as a quiet revolution is occurring in climate science. Here is how PhysOrg reports on a study out today in Science by NASA's Drew Shindell and others:
Of note, Shindell et al. cautiously suggest that the entire framework of international climate policy may be based on an overly-simplistic view of the human effect on climate, by focusing on carbon dioxide equivalencies in radiative forcing (i.e.,g "global warming potential" or GWP), from their Science paper out today (emphasis added):
According to Shindell, the new findings underscore the importance of devising multi-pronged strategies to address climate change rather than focusing exclusively on carbon dioxide. “Our calculations suggest that all the non-carbon dioxide greenhouse gases together have a net impact that rivals the warming caused by carbon dioxide."
In particular, the study reinforces the idea that proposals to reduce methane may be an easier place for policy makers to start climate change agreements. “Since we already know how to capture methane from animals, landfills, and sewage treatment plants at fairly low cost, targeting methane makes sense,” said Michael MacCracken, chief scientist for the Climate Institute in Washington, D.C.
This research also provides regulators insight into how certain pollution mitigation strategies might simultaneously affect climate and air quality. Reductions of carbon monoxide, for example, would have positive effects for both climate and the public’s health, while reducing nitrogen oxide could have a positive impact on health but a negative impact on the climate.
“The bottom line is that the chemistry of the atmosphere can get hideously complicated,” said Schmidt. “Sorting out what affects climate and what affects air quality isn’t simple, but we’re making progress.”
There are many limitations to the GWP concept (25). It includes only physical properties, and its definition is equivalent to an unrealistic economic scenario of no discounting through the selected time horizon followed by discounting to zero value thereafter. The 100-year time horizon conventionally chosen strongly reduces the influence of species that are short-lived relative to CO2. Additionally, GWPs assume that integrated global mean RF is a useful indicator of climate change. Although this is generally reasonable at the global scale, GWP does not take into account the rate of change, and it neglects that the surface temperature response to regionally distributed forcings depends on the location of the RF (26) and that precipitation and circulation responses may be even more sensitive to RF location (27). Along with their dependence on emission timing and location, this makes GWPs particularly ill-suited to very short-lived species such as NOx, SO2, or ammonia, although they are more reasonable for longer-lived CO. Inclusion of short-lived species in agreements alongside long-lived greenhouse gases is thus problematic (28, 29).The Shindell et al. paper comes fast on the heels of a paper published a few weeks ago in PNAS by Molina et al. which argued similarly that a broader perspective is needed on the human role in altering climate. They write (emphasis added):
Efforts to limit CO2 emissions alone may not be sufficient to avoid or reduce the risk of DAI on a decadal time scale, including the risk of abrupt climate change from committed warming (8, 9). . . there is growing demand among governments and commentators for fast-action mitigation to complement cuts in CO2 emissions, including cuts in non-CO2 climate forcing agents, which together are estimated to be as much as 40–50% of positive anthropogenic radiative forcing (17, 18). . .This recent research suggests that we must now be open to the possibility that there will not and cannot be a single policy approach to addressing the full spectrum of human influences on the climate system. The recognition of complexity may present an opportunity to move climate policy forward, by providing a justification for reconsidering the flawed (and some would say doomed) approach. My father has argued that (PDF),
The 2008 Major Economies Forum Declaration calls for ‘‘urgent action’’ to strengthen the Montreal Protocol for climate protection (22). The 2009 G8 Leaders Declaration calls for ‘‘rapid action’’ on BC [black carbon] and pledges to ensure HFC reductions (23). The 2009 North American Leaders Declaration commits to phasing down HFCs under the Montreal Protocol (24). The 2009 Arctic Council Tromsø Declaration urges ‘‘early actions’’ on short-lived climate forcers (25) including tropospheric ozone. A Nature editorial in July 2009, Time for early action, calls for ‘‘early action’’ on BC and methane, and on HFCs under the Montreal Protocol (26), and another in April 2009, Time to act, notes ‘‘short-term opportunities’’ to cut BC and methane (27). Wallack and Ramanathan call for action on BC and tropospheric ozone in their 2009 policy paper in Foreign Affairs to produce ‘‘rapid results’’ (28).
. . . humans have an even greater effect on climate that is suggested by the IPCC. The human influence on climate is significant and multi-faceted.As the community begins to realize these significant, multi-faceted and hideous complexities, it would not be a surprise to learn that a policy framework design 20 years ago is now somewhat out of step with current scientific understandings. The upshot is that as presently designed, international climate policy is both too complex and too simplistic. It is too simplistic because it is built upon a set of scientific perspectives on climate change that are increasingly seen as outdated and appropriate only for dealing with a narrow set of very important human influences -- long-lived greenhouse gases. It is too complex because in trying to deal with added complexity it has become unwieldy and clearly impractical from the standpoint of not just implementation but the politics of even reaching an agreement about implementation.
Climate policy can be improved by reconstructing climate policy from the bottom up. This process should begin by recognizing that no single policy instrument will ever deal with "climate change" (human caused or otherwise). An approach to climate policy that is decentralized and more focused in its elements will be better able to adjust as science evolves (and it will continue to evolve, to be sure) and allows for progress to be made incrementally along a set of parallel paths. The all-or-nothing approach to climate policy that dominates the present agenda is incapable of keeping pace with evolving scientific understandings as they relate to policy implementation, and from a pragmatic perspective, pretty much guarantees the "nothing" outcome.
As Molina et al. accurately point out in PNAS, there are already a large number of policies in place that might be considered as part of a multi-pronged approach to minimizing the human influence on climate. And it is certain that new policy vehicles will need to be developed. The most important short-term step that can be taken is, as my colleague Steve Rayner has persuasively argued to me, to reconceptualize the Framework Convention on Climate Change as a Framework Convention on Long-Lived Greenhouse Gases, which would signify a more focused approach. Dealing with long-lived greenhouse gases presents a daunting enough challenge by itself, and is impossible if burdened with other aspects of climate change. Once reconceptualized, climate policy can proceed upon multiple, parallel tracks, and thus have a greater chance to keep in step with evolving science and actually have a chance to make progress with respect to policy goals.