I think there is no point in further debunking the myth that unrestricted greenhouse gas emissions leads to tolerable impacts (or even a more optimal world). Even the incredibly centrist Brookings Institution now recognizes that:
The Earth is on a trajectory to warm more than 4.5 degrees Fahrenheit by around mid-century. Exceeding that threshold could trigger a series of phenomena: Arable land will turn into desert, higher sea levels will flood coastal areas….
Those who have any doubts about what we risk on our current emissions path should read my full discussion, “Is 450 ppm politically possible? Part 0: The alternative is humanity’s self-destruction.”
I think the more important question to address at the end of our discussion is the myth that action is costly. The IPCC’s Fourth Assessment Report, Working Group III, Summary for Policymakers concludes that stabilizing at 445-535 parts per million atmospheric concentration of CO2-equivalent would reduce average annual GDP growth rates by less than 0.12% per year. And that conclusion was signed off on by every member government, including China, Saudi Arabia, and the Bush administration. Note that this is CO2-equivalent.
That means stabilizing at 350-440 ppm of CO2 would reduce annual GDP less than 0.12% per year. Moreover, the report finds:
… in all analyzed world regions near-term health co-benefits from reduced air pollution as a result of actions to reduce GHG emissions can be substantial and may offset a substantial fraction of mitigation costs (high agreement, much evidence).
Including co-benefits other than health, such as increased energy security, and increased agricultural production and reduced pressure on natural ecosystems, due to decreased tropospheric ozone concentrations, would further enhance cost savings.
Integrating air pollution abatement and climate change mitigation policies offers potentially large cost reductions compared to treating those policies in isolation.
And let’s not even count the enormous benefits of avoiding widespread desertification and catastrophic sea level rise.
Two other major recent studies have found an even lower cost of action. First, the McKinsey Global Institute, for instance, did a comprehensive cost curve for global greenhouse gas reduction measures (reprinted below), which came to the stunning conclusion that the measures needed to stabilize emissions at 450 ppm CO2 have a net cost near zero. A new analysis, “The carbon productivity challenge: curbing climate change and sustaining economic growth,” has its own stunning conclusion:
In fact, depending on how new low-carbon infrastructure is financed, the transition to a low-carbon economy may increase annual GDP growth in many countries.
The new analysis explains that “at a global, macroeconomic level, the costs of transitioning to a low-carbon economy are not, in an economic ‘welfare’ sense, all that daunting — even with currently known technologies.” Indeed, 70% of the total 2030 emissions reduction potential (below $60 a ton of CO2 equivalent) is “not dependent on new technology.”
The final reality is perhaps the most important:
The macroeconomic costs of this carbon revolution are likely to be manageable, being in the order of 0.6–1.4 percent of global GDP by 2030. To put this figure in perspective, if one were to view this spending as a form of insurance against potential damage due to climate change, it might be relevant to compare it to global spending on insurance, which was 3.3 percent of GDP in 2005. Borrowing could potentially finance many of the costs, thereby effectively limiting the impact on near-term GDP growth. In fact, depending on how new low-carbon infrastructure is financed, the transition to a low-carbon economy may increase annual GDP growth in many countries.
I am reprinting the cost curve here, because MGI have provided a much bigger version of it (click to enlarge):
The report notes that “we have been fairly conservative in our assumptions about technological progress in these projections.” For instance, the analysis appears to ignore the enormous potential of concentrated solar thermal electricity entirely (see “Concentrated solar thermal power — a core climate solution”).
Finally, the normally conservative International Energy Agency (IEA) also makes clear the cost of action is low in its recent report, “Energy Technology Perspectives, 2008″ (Exec. Sum. here). In all the scenarios the IEA considers,
… the estimated total undiscounted fuel cost savings for coal, oil and gas over the period to 2050 are greater than the additional investment required (valuing these fuels at Baseline prices). If we discount at 3%, fuel savings exceed additional investment needs in the ACT Map scenario [in which CO2 emissions in 2050 only return to 2005 levels].
In the BLUE Map (i.e. 450 ppm) scenario, where CO2 emissions in 2050 go to half of 2005 levels, we get “oil demand actually 27% less than today in 2050.”
The report warns of the high cost of inaction:
Unsustainable pressure on natural resources and on the environment is inevitable if energy demand is not de-coupled from economic growth and fossil fuel demand reduced.
The situation is getting worse… . [T]oday’s best estimates under our “business as usual” baseline scenario foreshadow a 70% increase in oil demand by 2050 and a 130% rise in CO2 emissions…. a rise in CO2 emissions of such magnitude could raise global average temperatures by 6°C (eventual stabilisation level), perhaps more. The consequences would be significant change in all aspects of life and irreversible change in the natural environment.
Those who not aggressively pushing for sharply and rapidly reversing our emissions trend with a goal of stabilizing at 450 ppm CO2 or less are simply inviting the self-destruction of modern civilization.