And if you buy into human-caused global warming in its entirety, there’s also Bjorn Lomborg’s view of it: guardian.co.uk

“Yet the really inconvenient truth, demonstrated by a group of economists who gathered in Denmark in 2004, is that combating climate change through the Kyoto Protocol has a social value of less than a dollar for each dollar spent. These economists, who included four Nobel laureates, took part in a project called the Copenhagen Consensus which compared the social value of solutions to different challenges facing humankind. The question that they strove to answer was: ‘How could you spend $50bn to achieve the most good possible?’

The costs and benefits of different ways of combating HIV/Aids, starvation, global conflict, climate change, corruption and other challenges were studied in detail. With access to specially commissioned research, the team came up with a concrete, prioritised ‘to do’ list that outlined how policy-makers could achieve the most good possible.

The economists found that spending $27bn on an HIV/Aids prevention programme would be the best possible investment for humanity. It would save more than 28 million lives within six years and have massive flow-on effects, including increased productivity.

Providing micronutrient-rich dietary supplements to the malnourished was their second-highest priority. More than half the world suffers from deficiencies of iron, iodine, zinc or vitamin A, so cheap solutions such as nutrient fortification have an exceptionally high ratio of benefits to costs.

Third on the list was trade liberalisation. Although this would require politically difficult decisions, it would be remarkably cheap and would benefit the entire world, not least the developing world. A staggering GDP increase of $2,400bn annually would accrue equally to developed and developing countries with free trade.

The economists would then focus on the huge benefits possible from controlling malaria with chemically treated mosquito nets. Next on their list would be agricultural research and improving sanitation and water quality for a billion of the world’s poorest people. The benefits of these ventures far outweigh the costs.”