The debate about the existence of human-caused climate change seems finally at an end. If you are in some doubt, have a look at the reports of the Intergovernmental Panel on Climate Change [http://www.ipcc.ch/]. I’m happy to discuss scepticism in the comments, but for now consider just the changes apparently already underway and the prospects for us on our warming world. Brace yourself for a few numbers.

The average surface temperature of our planet has increased by about 0.7º C over the twentieth century. That might not seem like much to you, but those who know how to read the bubbles in ice cores tell us that the speed of the change is without precedent over at least the past 10,000 years. As the world heats up, a number of changes have already been set in motion. The average sea level has risen by an annual rate of 2mm since 1960, with the rate increasing to about 3mm towards the end of the century. Sea ice is thinning; permafrost is melting; glaciers are in world-wide retreat; El Nino events are becoming more frequent, persistent and intense; and on and on.

The changes to our planet are already having disastrous effects on the lives of many plants and animals. It’s not just the poster boys for climate change, polar bears and mountain gorillas, which are in danger. According to a report in Nature, anything between 15 to 37 percent of all plant and animal species could be locked into extinction by 2050 as a result of climate change. We know from the fossil record that we are now living through the 6th major extinction event in our planet’s history. The last one did in the dinosaurs.

Human beings, too, are suffering and will continue to suffer. The Red Cross argue that as of 2001 there were as many as 25 million environmental refugees, people on the move away from dry wells and failed crops. It’s larger than the number they give for people made homeless by war. One sixth of the world’s population gets its water from the melting snow and ice tricking down from mountains, a source which looks set to dry up in the years to come. Industry, agriculture and homes on coasts will be adversely affected by the rising sea.

It’s worries associated with human beings which raise moral problems for me. There is a lot of unnecessary human suffering in our future if we do not make certain choices now. Those choices ultimately depend on what we think is right, on justice, on responsibility, on what we value, on what matters to us. You cannot find that sort of thing in an ice core. You have to think your way through it. We’ll make a start on that in the next post.