Bjorn Lomborg

Even if every major government were to slap huge taxes on carbon fuels - which is not going to happen - it wouldn't do much to halt climate change any time soon. What it would do is cost us hundreds of billions - if not trillions - of dollars, because alternative energy technologies are not yet ready to take up the slack.

The saddest fact of climate change - and the chief reason we should be concerned about finding a proper response - is that the countries it will hit hardest are already among the poorest and most long-suffering.

If we invest in researching and developing energy technology, we'll do some real good in the long run, rather than just making ourselves feel good today. But climate change is not the only challenge of the 21st century, and for many other global problems we have low-cost, durable solutions.

The only thing that will really change global warming in the long run is if we radically increase the speed with which we get alternative technologies to deal with climate change.

For the longest time in Denmark I didn't want to say what I was politically. I thought it was irrelevant.

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.

If every country committed to spending 0.05 per cent of GDP on researching non-carbon-emitting energy technologies, that would cost $25 billion a year, and it would do a lot more than massive carbon cuts to fight warming and save lives.

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.

My suggestion is that we should first work to ensure the Third World has clean drinking water and sanitation.

The main environmental challenge of the 21st century is poverty. When you don't know where your next meal is coming from, it's hard to consider the environment 100 years down the line.

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.