Tony Juniper: Conditions for life on Earth are changing

On the first day of the new Millennium, 1 January 2001, the first record in the log book at Wicken Fen nature reserve in Cambridgeshire was from my nine-year-old daughter: she wrote "large white butterfly".

This kind of unusual sighting in the depths of winter is becoming more and more commonplace and is of more than passing interest to naturalists.

It is a sign of basic changes taking place in the conditions for life on Earth. A blurring of the seasons with warmer winters and longer summers might seem attractive, but it is in truth the thin end of a long wedge that could take us towards a nightmare scenario: displacing many hundreds of millions of people; precipitating food shortages, water crises and conflicts between countries.

Gordon Brown was quite right yesterday to add climate change into his statement about national security. But unfortunately what he didn't mention was the screaming urgency of reducing the greenhouse gas emissions that are causing global temperatures to rise. The latest science tells us that we have only the narrowest window of opportunity through which to gain a good chance of avoiding temperatures dramatically rising during this century.

We have already invented enough technologies to make a really good start tomorrow in making cuts in the pollution causing our planet to warm rapidly. The missing ingredient remains leadership. If the overriding priority is to protect the security of citizens, as Mr Brown claims, then dealing with this threat has to be top of any list of priorities for politicians.

Sadly, however, last week's Budget – and the continuing resistance of the Government to include international aviation and shipping in the climate-change legislation passing through Parliament – suggest that our political leaders are asleep on the job.

Governments have also lost more than two decades in failing to act decisively, to halt the loss of the world's tropical rainforests – an avoidable tragedy that has commanded a level of political attention that in no way reflects the scale of the crisis that is unfolding. So, while governments invest enormous political capital in making the case for military conflict and sustaining vast military budgets, they seem utterly incapable of making the case to the public of the overriding need to cut emissions from fossil fuels and deforestation.

While our children might make observations about the unusual timing of the emergence of butterflies, their children and grandchildren might have much more serious matters on their minds, as our civilisation is impacted by pollution that we are releasing today.

Tony Juniper is the director of Friends of the Earth