There is no question that global warming will have a significant impact on already existing problems such as malaria, malnutrition, and water shortages. But this doesn't mean the best way to solve them is to cut carbon emissions.
Think on a 50-year scale, which is a much more natural time-scale for global warming. The US is right now spending about 200 million dollars annually on research into renewable energy.
In the rich world, the environmental situation has improved dramatically. In the United States, the most important environmental indicator, particulate air pollution, has been cut by more than half since 1955, rivers and coastal waters have dramatically improved, and forests are increasing.
The obvious issue is providing clean drinking water and sanitation to every single human being on earth at the cost of little more than one year of the Kyoto treaty.
Listen, global warming is a real problem, but it' s not the end of the world. A 30-centimetre sea level rise is just not going to bring the world to a standstill, just like it didn't over the last 150 years.
To some, a cap-and-trade system might sound like a neat approach where the market sorts everything out. But in fact, in some ways it is worse than a tax. With a tax, the costs are obvious. With a cap-and-trade system, the costs are hidden and shifted around. For that reason, many politicians tend to like it. But that is dangerous.