The state-of-the-art British-sponsored fasttrackassessment of the global impacts of climatechange, a major input to the much-heralded SternReview on the Economics of Climate Change, indicatesthat through the year 2100, the contribution ofclimate change to human health and environmentalthreats will generally be overshadowed byfactors not related to climate change. Hence, climatechange is unlikely to be the world's mostimportant environmental problem of the 21stcentury.
Analysis using both the Stern Review and thefast-track assessment reveals that notwithstandingclimate change, for the foreseeable future,human and environmental well-being will behighest under the "richest-but-warmest" scenarioand lower for the poorer (lower-carbon)scenarios. The developing world's future wellbeingshould exceed present levels by several-foldunder each scenario, even exceeding present wellbeingin today's developed world under all but thepoorest scenario. Accordingly, equity-based arguments,which hold that present generationsshould divert scarce resources from today'surgent problems to solve potential problems oftomorrow's wealthier generations, are unpersuasive.
Halting climate change would reduce cumulativemortality from various climate-sensitivethreats, namely, hunger, malaria, and coastalflooding, by 4–10 percent in 2085, while increasingpopulations at risk from water stress andpossibly worsening matters for biodiversity. Butaccording to cost information from the UNMillennium Program and the IPCC, measuresfocused specifically on reducing vulnerability tothese threats would reduce cumulative mortalityfrom these risks by 50–75 percent at a fraction ofthe cost of reducing greenhouse gases (GHGs).Simultaneously, such measures would reducemajor hurdles to the developing world's sustainableeconomic development, the lack of which iswhy it is most vulnerable to climate change.
The world can best combat climate changeand advance well-being, particularly of theworld's most vulnerable populations, by reducingpresent-day vulnerabilities to climate-sensitiveproblems that could be exacerbated by climatechange rather than through overly aggressiveGHG reductions.