This week sees the start of an environment season on Channel 4, which is welcome news, since we should all take our world more seriously. The summer heat wave of 2003 killed 27,000 people in Europe. During the last 15 years, a quarter of a million people have died in floods, which have become increasingly common as human beings change the climate.

Are we really changing the climate? Yes, the scientific evidence is now overwhelming. For me the simplest statistic is the amount of carbon dioxide in the atmosphere. When I was at school it was 30 parts per million; now it’s 37. That is a 20 per cent increase, and almost certainly due directly to our consumption of coal, oil, and gas.

The Americans use more fossil fuels than anyone else on Earth, but President Bush has declared that carbon dioxide is not a problem. This is truly amazing; does he really believe that by saying it isn’t a problem it will go away? It’s almost like King Knut, whose courtiers were so sycophantic they said he could command the tide not to come in, but when they put him in his throne on the beach he got wet feet.

No one knows for sure what will happen if we go on producing carbon dioxide at an ever-increasing rate, but we are already seeing a variety of  extreme weather events – floods, severe storms, hurricanes - and a strong possibility is that the gulf stream will be switched off. If that happened we should lose its warming effect, and Britain would quickly become as cold as Finland.

Then there is the problem of water. Already there is not enough water for the 6 billion people on the planet, the population is growing, and people are generally using more water from year to year. Water tables are falling around the world, and this is having dire and consequences that in some cases were hard to foresee – harvests have fallen sharply in China, and hundreds of people have been poisoned in eastern India and Bangladesh, when the falling level of water somehow allowed arsenic into the system.

What can we do to reverse some of these trends? First we should put pressure on governments to take action, for there has to be political will,  and meanwhile we should use less water – even by flushing the loo less often - and save fossil fuels by getting out of our SUVs and on to our bicycles.