Soot, methane and forests: The cheapest ways of addressing climate change?

One of the main points Bjorn Lomborg makes in the current round of Copenhagen Consensus papers, particularly Richard Tol’s report, is that focusing on reducing carbon dioxide emissions (particularly in the developed world) is unnecessarily expensive.

They are far from alone in this argument, and three papers published alongside Tol’s are likely to find a more welcome response. The papers argue that climate change can be more cheaply avoided by pursuing forestry projects, tackling soot or “black carbon”, and reducing methane emissions.  None of these approaches on their own would be enough to avoid dangerous levels of climate change, but all three fare far better on the savings per-dollar-spent approach used in Tol’s paper, than simply reducing carbon dioxide emissions through efficiency and renewable energy.


Planting new forests and conserving and managing existing ones could reduce the cost of meeting a 2 degree celsius climate goal by as much as 50 per cent, a paper by Brent Sohngen of Ohio State University says.

With one caveat: it must be done worldwide.

The benefits, the paper argues, are both near-term and long-term. But such an approach to reducing carbon emissions is not without its challenges:

Measuring monitoring and verification protocols must be established and implemented. People will have to learn how to sell their carbon credits onto a market. There could be some inefficiencies associated with leakage and additionality.

“Leakage” is the big problem: in otherwords, countries simply maintain or increase their own emissions because they are paying for forestry-related emissions reductions overseas. In fact leakage could be as large as 100 per cent, the paper says  – and this could only be reduced by including more countries in the control programme. Sohngen says this is a much bigger problem than additionality, or determining whether projects paid for would have gone ahead (or forests would not have been cut down) regardless of whether it was paid for.


Methane emission abatement is a particularly promising supplement to CO2 mitigation due to large global low-cost abatement potentials. Methane has the largest overall mitigation potentials among all non-CO2 GHG (USEPA 2006). In addition, due to the short atmospheric lifetime of CH4, the beneficial effects of methane mitigation will be more instantaneous than for example in the case of CO2 mitigation.

The opportunities vary from livestock, rice management, coal mining,  natural gas processing and solid waste management. The paper says methane offers a very cost-effective way to reduce greenhouse gas emissions – but that it should only be part of a climate change strategy. About 2 gigatonnes of methane could be removed from the atmosphere by 2020 at a good cost/benefit rate, but beyond that, the report’s authors say, the benefits are more expensive.

Black carbon, or soot

“Black carbon”, or soot (mostly from burning crops and wood fired ovens) is one of the least-considered ways to avert climate change, although it has recently gained more attention. The Copenhagen Consensus paper on this subject, by Robert E Baron, W David Montgomery & Sugandha D Tuladhar of CRA International, shied away from giving an overall cost-benefit analysis for impacts on climate change, but on health (soot is a major cause of respiratory disorders in developing countries) they found it could be as high as $13.60 for every dollar spent. They also published this graph which clearly shows how important black carbon emissions are:

The authors write:

The relatively short atmospheric residence time of black carbon emissions and the availability of existing commercially available reduction technologies create unique opportunities. Reduction in black carbon emissions represents a potential near term opportunity to postpone the effects of rising GHG levels on the global climate. The delay in global warming offered by reducing black carbon emissions creates a window of opportunity for the research and development of new technologies that lower or eliminate GHG emissions at a cost far less than that of current technological options.

Related links:

Climate change report urges cut in costs (FT)
Tackling soot could help reduce Arctic melt (FT Energy Source)

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