In one of his first public policy statements as the US President-elect Barack Obama focused on climate change, and clearly stated both his priorities and the facts on which these priorities rest. Unfortunately, both are weak, or even wrong.

Obama's policy outline was presented via video to California Governor Arnold Schwarzenegger's Governors' Global Warming Summit, and has again been shown in Poznan, Poland, to leaders assembled to flesh out a global warming roadmap. According to Obama, "few challenges facing America and the world are more urgent than combating climate change".

Such a statement is now commonplace for most political leaders around the world, even though it neglects to address the question of how much we can do to help the United States and the world through climate policies versus other policies.

Consider, for example, hurricanes in the US. Clearly, a policy of reducing CO2 emissions would have had zero consequence on Katrina's devastating impact on New Orleans, where such a disaster was long expected. Over the next half-century, even large reductions in CO2 emissions would have only a negligible impact.

Instead, direct policies to address New Orleans' vulnerabilities could have avoided the huge and unnecessary cost in human misery and economic loss. These should have included stricter building codes, smarter evacuation policies, and better preservation of wetlands (which could have reduced the ferociousness of the hurricane). Most importantly, a greater focus on upkeep and restoration of the levees could have spared the city entirely. Perhaps these types of preventive actions should be Obama's priority.

Likewise, consider world hunger. Pleas for action on climate change reflect fears that global warming might undermine agricultural production, especially in the developing world. But global agricultural/economic models indicate that even under the most pessimistic assumptions, global warming would reduce agricultural production by just 1.4 percent by the end of the century. Because agricultural output will more than double over this period, climate change would at worst cause global food production to double not in 2080 but in 2081.

Moreover, by implementing the Kyoto Protocol at a cost of US$180 billion annually would keep 2 million people from going hungry only by the end of the century. Yet by spending just US$10 billion annually, the United Nations estimates that we could help 229 million hungry people today. Every time spending on climate policies saves one person from hunger in a hundred years, the same amount could have saved 5,000 people now. Arguably, this should be among Obama's top priorities.

Obama went on to say why he wants to prioritize global warming policies: "The science is beyond dispute and the facts are clear. Sea levels are rising. Coastlines are shrinking. We've seen record drought, spreading famine, and storms that are growing stronger with each passing hurricane season."

Yes, global warming is happening, and mankind is partly responsible, but these statements are - however eloquent - seriously wrong or misleading.

Sea levels are rising, but they have been rising at least since the early 1800s. In the era of satellite measurements, the rise has not accelerated (actually we've seen a sea-level fall over the past two years). The UN expects about a 30-cm sea-level rise over this century - about what we saw over the past 150 years.

In that period, many coastlines increased, most obviously in the Netherlands, because rich countries can easily protect and even expand their territory. But even for oft-cited Bangladesh, scientists just this year showed that the country grows by 20 sq km each year, because river sedimentation win out over rising sea levels.

Obama's claim about record droughts similarly fails even on a cursory level - the US has in all academic estimates been getting wetter over the century (with the 1930s "dust bowl" setting the drought high point). This is even true globally over the past half-century, as one of the most recent scientific studies of actual soil moisture shows: "there is an overall small wetting trend in global soil moisture."

Furthermore, famine has rapidly declined over the past half century. The main deviation has been the past two years of record-high food prices, caused not by climate change but by the policies designed to combat it: the dash for ethanol, which put food into cars and thus upward pressure on food prices. The World Bank estimates that this policy has driven at least 30 million more people into hunger. To cite policy-driven famine as an argument for more of the same policy seems unreasonable, to say the least.

Finally, it is simply wrong to say that storms are growing stronger every hurricane season. Even for the Atlantic hurricane basin, which we tend to hear about the most, the total hurricane energy (ACE) as measured by the US National Oceanic and Atmospheric Administration has declined by two-thirds since the record was set in 2005.

For the world, this trend has been more decisive: maximum ACE was reached in 1994, and has plummeted for the past three years, while hurricanes around the world have for the past year been about as inactive as at any time since records began being kept.

Global warming should be tackled, but smartly through research and development of low-carbon alternatives. If we are to get our policies right, it is crucial that we get our facts right.

(China Daily December 24, 2008)