The state-of-the-art British-sponsored fasttrack assessment of the global impacts of climate change, a major input to the much-heralded Stern Review on the Economics of Climate Change, indicates that through the year 2100, the contribution of climate change to human health and environmental threats will generally be overshadowed by factors not related to climate change. Hence, climate change is unlikely to be the world's most important environmental problem of the 21st century.
Analysis using both the Stern Review and the fast-track assessment reveals that notwithstanding climate change, for the foreseeable future, human and environmental well-being will be highest under the "richest-but-warmest" scenario and lower for the poorer (lower-carbon) scenarios. The developing world's future wellbeing should exceed present levels by several-fold under each scenario, even exceeding present wellbeing in today's developed world under all but the poorest scenario. Accordingly, equity-based arguments, which hold that present generations should divert scarce resources from today's urgent problems to solve potential problems of tomorrow's wealthier generations, are unpersuasive.
Halting climate change would reduce cumulative mortality from various climate-sensitive threats, namely, hunger, malaria, and coastal flooding, by 4-10 percent in 2085, while increasing populations at risk from water stress and possibly worsening matters for biodiversity. But according to cost information from the UN Millennium Program and the IPCC, measures focused specifically on reducing vulnerability to these threats would reduce cumulative mortality from these risks by 50-75 percent at a fraction of the cost of reducing greenhouse gases (GHGs). Simultaneously, such measures would reduce major hurdles to the developing world's sustainable economic development, the lack of which is why it is most vulnerable to climate change.
The world can best combat climate change and advance well-being, particularly of the world's most vulnerable populations, by reducing present-day vulnerabilities to climate-sensitive problems that could be exacerbated by climate change rather than through overly aggressive GHG reductions.