A major cause of climate change is the increase in concentration of heat-trapping gases in the Earth's atmosphere. Of these gases, the most abundant is carbon dioxide, but methane, nitrous oxide, and certain hydrocarbons and fluorinated gases also play significant roles. Mitigation refers to interventions that aim to reduce the emission of carbon dioxide and other such gases into the atmosphere. Following the Kyoto Protocol and other international conventions, many schemes aimed at encouraging such mitigation interventions already exist around the world. The most prominent of these are various emissions trading schemes (cap-and-trade schemes), market-based approaches used to control pollution by providing economic incentives for achieving reductions in the emissions of pollutants.
Other mitigation strategies are linked with these markets through emission reductions certifications, which allow the 'sale' of abated tonnes of carbon dioxide or equivalent global warming potential. Major strategies in this category include the development of renewable energy production or more energy-efficient technologies, the collection and destruction of methane or industrial pollutants, and encouraging land use change. Some additional mitigation strategies can be harder to analyse, and as a result are often not linked with trading schemes, including research into new, non-fossil fuel-based methods of energy production, and campaigns to induce behavioural change towards less environmentally-damaging living practices.
Carbon retirement refers to the purchase of the right to emit carbon under an emissions trading scheme with the intent not to exercise this right. This reduces the total carbon emissions of the parties subject to the trading scheme. While prices fluctuate, at present the price of carbon on some of these markets is about $2 per tonne of carbon dioxide (or equivalent global warming potential) emitted. This puts the cost of averting a DALY through carbon retirement at $10,000 per DALY: less cost-effective than our recommended interventions when accounting for an uncertainty multiple of 10 or even up to 100. It should also be noted that individuals are in general not able to purchase carbon rights on these markets, and costs of abating carbon on an individual level may be increased via action through a third party. (Also, retiring a tonne of carbon from the market does not necessarily mean that one tonne of CO2 will not be emitted as a result. The market could contain 'hot air', meaning that it could contain surplus emissions credits such that the emissions reduction target would be met even if all market players made no effort to reduce their own emissions .)
There are a couple of areas that we have identified within climate change mitigation that may be more cost-effective than most other climate change mitigation interventions. These are abatement of the potent greenhouse gas HFC-23, and improving the efficiency of aluminium production. At present we do not know of any organisations that focus purely on these types of mitigation, and as such we have been unable to identify any opportunities for donors in this area. We will investigate these mitigation opportunities further to see whether they present cost-effective opportunities.
Beyond cap-and-trade, mitigation may take place through programmes like clean energy research or campaigning. These tend not to be linked to emissions trading schemes, as their effects are hard to quantify. Here philanthropy may be effective, as there is no incentive provided through trading schemes to undertake these inventions. Our on-going research, however, has so far been unable to analyse their impact in a reliable way. We thus leave open the possibility that such interventions may be competitively cost-effective, but make no recommendation.
See our analysis of other climate change interventions.