There's no doubt whatsoever that the earth's environment is in a terrible state. Even Al Gore accepts that global warming is a reality. Devastating extreme weather (such as drought, floods, cyclones and hurricanes) is becoming more frequent, and scientists predict that this century will be worse. Polar icecaps are melting, and according to research carried out by Thomas R. Knutson of the US National Oceanic and Atmospheric Association, global warming will cause the frequency of Category 5 hurricanes (the most powerful type) to double this century.

The environment is a crucial question for socialists. It's crucial because workers and the poor will suffer the most as the environment worsens - witness Hurricane Katrina for proof of this. And it's crucial because many of the strategies proposed to save our planet serve only to defend the system that is killing it - the system of capitalism.

So why is our planet in such a sorry state? One of the most common arguments is that there are simply too many people on the planet for nature to handle - that with six billion people on the planet, the environment cannot be saved. However, the last 200 years have shown two crucial facts about the overpopulation argument - firstly that it is a conservative argument that leads to racism, and secondly that it is just plain wrong.

The "overpopulation" argument is much older than most realise. It was first advanced by Thomas Malthus, who argued over 200 years ago that increasing world population would cause scarcity, starvation and environmental devastation within the 19th century, and that the world couldn't possibly produce enough food for one billion people. Malthus's "solution" was for efforts to be made to reduce birth rates and living standards - but only those of the poor and/or "undesirable".

In other words, rich whites could consume all they liked, while those poor or coloured enough to earn Malthus's contempt would suffer. Today, theories of overpopulation cause people to blame populous countries like China for environmental destruction - when the USA, with 78 per cent fewer people than China, uses 78 per cent more energy, and, according to the International Energy Agency, creates over 60 per cent more greenhouse gases.

If you follow the overpopulation argument to its logical conclusion, the solution to environmental crisis is one of two things - at best keeping countries like China in underdeveloped poverty, or at worst, advocating genocide.

The overpopulation argument, however, is simply wrong. It ignores the fact that environmental damage is caused not in meeting human needs, but in maximising profits. Under capitalism, production is based upon profit, not the needs of humanity. As a result, corporations often ignore the environmental impact of their actions - and the competitive nature of capitalism forces them to do just this, or to be undercut by less scrupulous competitors.

Even as early as the 1800s, obvious environmental damage was being caused by unsustainable farming methods used to squeeze every possible dollar out of the land. To quote Marx's collaborator Frederick Engels:

"What cared the Spanish planters in Cuba who burned down forests on the slopes of the mountains and obtained from the ashes sufficient fertiliser for one generation of very highly profitable coffee trees - what cared they that the heavy tropical rainfall afterwards washed away the unprotected upper stratum of the soil, leaving behind only bare rock!"

During the 20th century, this drive for profit at any cost led to car companies (famously General Motors in America) purchasing public transport systems and running them into the ground - to boost car sales and profits. The same logic leads today to oil and coal power being used instead of clean, but less profitable alternatives like solar and wind power. And in the recent war in Lebanon - a war caused by the logic of capitalism - Israeli bombs caused the biggest oil slick since the Exxon Valdez disaster of 1989.

The world isn't dying, it's being killed. Not by people like you and me, but by a mad economic system that puts the relentless quest for profits above everything else. As long as the quest for short-term profit is the most important driving force in society - as long as we live under capitalism - the environment will suffer. And arguments about overpopulation merely serve to defend this system, by telling ordinary people to blame ourselves and each other, rather than fighting back against the system that is destroying our planet and our future.