I read with interest the article in Tuesday's Telegraph about the threat to your planet from outer space through collision with an asteroid or comet ('Killer' asteroid threat to Earth, 19 September 2000).

When I first heard of the threat some years ago it seemed quite bizarre to me and my first reaction was to assume that it had been invented or greatly exaggerated by scientists in pursuit of government money. 

I now realise that the threat is quite real, and that it is not a matter of whether a devastating impact will occur, but simply of when. 

It is very reassuring to know that the chances of it happening soon are extremely small. Nevertheless, I hope that our government will take the threat seriously and contribute to the necessary research and to possible counter measures - although it will probably be decades before they become viable.

In the meantime we can hope and be reassured that the laws of probability are on our side, and perhaps turn our attention to a more serious and imminent threat: the emergence on our planet of a species whose exceptional intelligence and abilities have enabled it to develop mass industrial societies, but whose short-sightedness and greed have caused it to disregard or misapprehend the question of finite resources and the burden that can be safely placed on our planet's life-supporting ecosystems.

I ask myself why is it that so few people recognise the danger, and suspect that it is for the same reasons that in the 1930's so few people, whether in Germany itself or elsewhere, recognised the true danger of Hitler and his National Socialism before it was too late. 

For the few who could see, the signs were clear, but no one listened to them, and the reality - the full horror of which Britain was largely spared - turned out to be far worse than even they could have foreseen.

With the benefit of hindsight, one is amazed at just how blind the vast majority of people - including the educated and putatively well-informed - were. 

I have no doubt that we are in a similar situation today, only the threat we are facing is from the non-sustainability of our economy and lifestyles and the damage they are increasingly doing to our planet's life-supporting ecosystems.

Yesterday the temperature in my flat dropped to below 17 °C and I'm beginning to think about turning the heating on. At the turn of a dial I can bring the temperature up to a comfortable 19 - 20 °C. But what are people going to do when then the gas has all gone and when burning the remaining oil and coal is throwing the climate into turmoil?

I suppose I could take the attitude of, "well, I'm all right Jack!", but the thought of my young nieces and nephews and future generations one day cursing me for my selfishness and stupidity prevents me from doing so. 
 

So I've put on my thermal underwear and a pullover and will try not to turn on the heating for a while longer. 

It may not save the world from the horrible fate it is heading towards, but at least it's a step in the right direction.
A bigger step, of course, would be to set myself the goal of heating my flat entirely using renewable sources of energy.

Only if we resolve to achieve sustainability in the shortest possible time (within a generation), in the same way that our parents and grandparents resolved to defeat Hitler, will we succeed in avoiding catastrophe.

As in early 1939, at the moment things do not look good, with the "Chamberlains" still assuring us that everything is going to be alright and that we shall all be able to continue with our lives as before.

When will a "Churchill" appear on the scene promising us nothing but "blood, sweat and tears" until we have achieved our goal - of sustainability - and rid the world of the terrible menace hanging over it, and that still so few recognise?