State of the Planet

News from the Columbia Climate School


Complex Models, Simple Solutions

This is the twenty-ninth of a continuing series of essays and interviews from Earth Institute scientists on the prospects for a global climate-change treaty. Check with us daily for news and perspectives, and to make comments, as events unfold throughout the Copenhagen meetings.

complex_wordsEveryone knows that climate change is complex. The multitude of potential impacts, the uncertainties in projections, the intersection of historical responsibilities and current political realities all make negotiations fiendishly difficult. But can the very complexity of the subject be helpful in finding solutions? The answer might be yes.

The first ground for optimism is that the activities creating the bulk of CO2 emissions are associated with other problems: air pollution, water pollution and stress on ecosystems. Secondly, there are climatic impacts associated with other emissions: for instance, the warming effects of ozone precursors and soot, and the cooling effects of sulfur dioxide. These observations certainly complicate climate calculations; but they also provide potential opportunities for benefits that would come along with actions to reduce pollutants that affect climate. First, though, we need to address how to quantify these impacts.

Over the last five years, there has been a revolution in the models used to simulate the climate system. The models have become far more comprehensive. In addition to the more traditional function of examining the impacts of increasing CO2, they now include many previously neglected earth processes, such as the workings of atmospheric chemistry; the creation, transport and deposition of different particles that float around in the air; representations of how carbon move in and out of oceans and land surfaces; and other manmade changes to the earth, from deforestation to stratospheric ozone depletion. This means it is now possible to calculate the net impact on climate and air pollution of particular industrial, residential and agricultural sectors, including many indirect effects that we never really looked at before.

Our own research the Goddard Institute for Space Studies has identified two sectors in particular where there are significant co-benefits to reducing what we introduce to the atmosphere. The first is emissions associated with surface transportation–a sector that produces a lot of CO2, but also nitrous oxides (which are ozone precursors) and black carbon from diesel engines. Thus, reducing emissions from this sector-accomplished by increased use of public transport, switching to electric vehicles, or improved urban design–will lead not only to reductions in three kinds of drivers of a warming climate, but reductions in local air pollution, with accompanying improvements in public health. These reductions will occur even if the energy for transportation is produced with the same mix of sources that produces electricity today. Increases in renewable sources would make it an even better proposition.

Second, there is tremendous opportunity to reduce emissions from residential burning of coal or biomass for cooking and heating. This type of energy generation has largely disappeared in the more developed economies, but is still common in India and China, where there is a great deal of low-temperature combustion. Inefficient coal burning produces carbon monoxide (another ozone precursor), copious quantities of soot, and also sulfur dioxide, depending on the source of the coal. The use of biomass instead (wood or dung for instance) also produces air pollution, often leads to very serious interior air quality problems, and drives deforestation. Electrification of rural areas where these practices are prevalent would make sound sense not only for climate, but economic development.

By looking at a complete analysis of the different sectors and sources of emissions, we can get a better quantification of the true impact of any particular activity. In the cases on India and China, the co-benefits of better air quality, reduced deforestation and better public health may be enough to encourage the exploration of international collaborations to reduce CO2 emissions. Developed countries would see many of the same benefits by moving ahead with new technologies.

Climate and climate models may be complex, but some of the answers to our problems might be simpler than we think.

Gavin Schmidt is a climate modeler at NASA Goddard Institute for Space Studies, and cofounder of the blog

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Cida Medeiros
Cida Medeiros
14 years ago

It is all about the way we are still acquiring stuff. The consumption way and awareness must change. This is the focal point of the problem. Rich and poor countries must find a middle way to build together.

14 years ago

i think that wall street should engage in this insurance of global warming like it did according to the nytimes this past week that wall street goldman sachs and others insured an fire that they knew could not be put out, and then went beyond hedging against or ebtting against the fire from beign put out and went beyond that to make more monies and when the fire couldnt be put out finally recession happened but then jeffrey sachs the director and founder of cu earth insitue coulnt say this nore e lee bollginer nor many academcis at princeton unvierstiy nor many on wall street or even the nobel peace prize cmte or the obama whitehosue adn htat relfects why there was only 2.5 pgs of resutls in un global warming conference in copenhagen this yr less results then last yr thanks!!

Recipe Club
Recipe Club
13 years ago

We definitely need to move ahead with new technologies. To me it’s fairly simple. We know what we are doing wrong, we know how to help the problem (reducing emissions from coal and fuel), now we just need to implement it. Nice post.