To prepare adequately for the challenge of global warming, we must acknowledge both the good and the bad that it will bring. If our starting point is to prove that Armageddon is on its way, we will not consider all of the evidence, and will not identify the smartest policy choices.
Just because there is a problem doesn't mean that we have to solve it, if the cure is going to be more expensive than the original ailment.
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.
I think Al Gore has done a great service in making global warming cool. He's basically taken it from a nerdy, almost ignored issue to making it what it is - namely, a problem.
There is no doubt that we should take solar radiation into account. We have seen ground temperatures rising since 1975, and it is important to know to what extent that has been caused by the sun or by carbon dioxide.
Money spent on carbon cuts is money we can't use for effective investments in food aid, micronutrients, HIV/AIDS prevention, health and education infrastructure, and clean water and sanitation.
I tentatively believe in a god. I was brought up in a fairly religious home. I think the world is compatible with reincarnation, karma, all that stuff.
For the longest time in Denmark I didn't want to say what I was politically. I thought it was irrelevant.
When thinking about the future, it is fashionable to be pessimistic. Yet the evidence unequivocally belies such pessimism. Over the past centuries, humanity's lot has improved dramatically - in the developed world, where it is rather obvious, but also in the developing world, where life expectancy has more than doubled in the past 100 years.
On average, global warming is not going to harm the developing world.
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.
My suggestion is that we should first work to ensure the Third World has clean drinking water and sanitation.
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.
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.
Global warming is real - it is man-made and it is an important problem. But it is not the end of the world.
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.
'The Skeptical Environmentalist' was much more the idea of the scientific argument of realizing that we need to be skeptical about a lot of these stories that we hear and to put them in context.
The Kyoto treaty has an estimated cost of between US$150 and $350 billion a year, starting in 2010.
I think it's great that we have organisations like Greenpeace. In a pluralistic society, we want to have people who point out all the problems that the Earth could encounter. But we need to understand that they are not presenting a full and rounded view.
I'm an old member of Greenpeace. I worried intensely, as I think most of my friends did, that the world was coming apart.
