In most of the discussions about anthropogenic (i.e., human-influenced) climate change, the concept of greenhouse gas (GHG) emissions is usually short-handed to carbon dioxide (CO2) emissions. In fact, humans are responsible for emissions of many other pollutants that contribute to climate change, and while these emissions are sometimes converted into “CO2-equivalents” to make discussions simpler, it’s pretty clear that — when it comes to climate change — some emissions are much more important than others.
While CO2 represents the bulk of GHG emissions (in terms of quantities), methane (CH4) is about 20-25 times as potent on a per-unit basis. And, when it falls to the ground, soot (technically referred to as “black carbon”) increases the rate of snow/ice melt, and is possibly at the root of accelerating melt in the polar ecosystems.
Accordingly, in a recent issue of the journal Science, a new study by a long list of collaborators posits that the fastest way to a significantly better (i.e., less dramatically increasing) trajectory in future average planetary temperatures is for society to focus on reducing methane and soot emissions, rather than CO2 emissions. Based on the study’s projections, it appears that concerted efforts to reduce methane and soot emissions will achieve a large share of the reduced rate of temperature increase that an all-out effort to curb CO2 emissions would achieve.
Since methane and soot have short residence times in the atmosphere (unlike CO2), an immediate reduction on these emissions will translate to immediate improvements in GHG levels. Also, reducing methane and soot emissions will have significant benefits in alleviating local air quality issues and thereby improving human health, by mitigating ground-level ozone formation and reducing airborne particulates.
Of course, the big kahuna in anthropogenic climate change remains CO2, which is emitted into the atmosphere when anything is burned — and much of what gets burned is fossil fuels. Alas, fossil fuels represent a very lucrative enterprise for many of the world’s largest corporations in the energy business, and a critical enabler of the commercial output and social lifestyles that define 21st Century human existence. Consequently, there’s immense political and public resistance to imposing any limitations on fossil fuel consumption in order to reduce CO2 emissions.
So, perhaps a shifting of focus by the cleantech world away from CO2 reductions toward methane/soot reductions would be much more politically acceptable for the foreseeable future and thus would actually gain some real traction.
It would certainly be more helpful to the planet than another series of endless climate negotiations in far-flung exotic cities that themselves produce a lot of emissions (figuratively and literally) and little substantive progress.
Some of the most strident opponents of cap-and-trade on CO2 emissions will have a hard time objecting to measures that reduce methane and soot emissions. Indeed, the more that methane can be captured rather than released to the air, the more it can be used to supply our energy needs. Thus, cleantech innovators and investors should put soot and methane emissions higher on the list of areas to tackle with their incremental efforts — as they are more likely to be rewarded than a continued frontal-assault on CO2 emissions.