The most important findings to emerge from the 4th Assessment Report published on 4 May are found in the Working Group III report entitled 'Mitigation of Climate Change'.
A number of climate-change response options are presented in the report, along with an assessment of the economic and social impact of mitigation efforts. The reports of the other two Working Groups deal with the scientific basis used to assess climate change, and with the likely impact of climate change on human populations and ecosystems.
- Technologies
The role of technologies in mitigating climate change is mentioned several times in connection with various sectors, including buildings, waste and agriculture. "Deployment of a portfolio of technologies that are currently available and those that are expected to be commercialised in coming decades," so the report, would lead to the most favourable results. Initial investments in technologies may produce significant costs, but these decrease over time through efficiency gains.
- Economic potential and costs
There is "substantial economic potential" that can result from GHG mitigation efforts. Costs resulting from mitigation can be offset if, for example, "revenues from carbon taxes or auctioned permits under an emission trading system are used to promote low-carbon technologies or reform of existing taxes". The report states that mitigation will have a negative effect on countries' GDP if it is not accompanied by appropriate investments in infrastructure and technologies, in addition to reforms in tax and market structures.
If done correctly, the report claims that keeping the rise in global temperatures to beneath 2 degree centigrade would cost a mere 0.12% of global annual GDP.
- Transport
On a somewhat less encouraging note, the report states that despite a number of options for reducing emissions in the transport sector, "their effect may be counteracted by growth in the sector". Growth in the air transport and vehicle sectors, in other words, may outpace advances in vehicle and airplane fuel efficiency, and the potential of biofuels is still largely dependant production methods. The report goes on to say that mitigation in the transport sector must be linked with other measures since a reduction of vehicle emissions "is often a co-benefit of addressing traffic congestion, air quality and energy security".
- Investments in energy infrastructure
Upgrades in energy and other infrastructure are generally seen as a significant GHG mitigating factor, yet the effects of certain upgrades may require decades to take effect. In this light, the report notes that it "is often more cost-effective to invest in end-use energy efficiency improvement than in increasing energy supply to satisfy demand for energy services".
The use of renewable energies is of course encouraged in the report, but alongside other energy sources including nuclear power.
- Policy instruments
The report presents a mixed picture on the benefits of policy instruments, stating that there are advantages and disadvantages to all systems. Standards and regulations, for example, may provide certainty on allowed emissions levels, but they "may not induce innovations and more advanced technologies".
- Lifestyle changes
Adjustments in individual lifestyles is also mentioned in the report as a significant GHG mitigating factor.
