Johann Hari: We're covering our planet with a cloud of space junk

In 1965, the American astronaut Edward White dropped a glove, and it has been orbiting the earth at 17,000 miles per hour ever since. This sounds like a quirky Trivial Pursuit answer – what is the deadliest garment in history? – but it could be about to give us all a galactic slap in the face.

That glove is now joined by so much space trash that scientists are warning it could be poised to take out the satellites we depend on every day – and trap us here on a heating earth.

In just 50 years of exploring space, humans have left 600,000 pieces of rubbish in space, all circling us at super-speed. When it is whirring so fast, a one millimetre fleck of paint hits you as hard as a .22 calibre bullet fired at point-blank range. A hard-boiled pea is as dangerous as a 400lb safe smacking into you at 60mph. And a chunk of metal the size of a tennis ball is as explosive as 25 sticks of dynamite.

We are adding to this junk faster than ever before. There is no international agreement not to leave trash in the skies – and all nations are being reckless. The International Association for the Advancement of Space Safety warns that, at the current rate, the volume of Star Drek will increase fivefold in the next decade. More flights leave more rubbish, and more countries test their fancy new weapons systems by blowing up old satellites – and creating new torrents of trash.

This creates a minor danger, and a major danger. There is a small risk that this rubbish will smack into human beings when minor amounts of it re-enter the Earth's atmosphere. For example, in March 2007, the wreckage of a Soviet spy satellite nearly crashed into a passenger plane over the Pacific. But only one woman has ever been hit by space junk: Lottie Williams from Oklahoma was smacked in the shoulder by a charred piece of space rocket. She was not injured.

But there is a greater danger that an unstoppable chain reaction will begin: the rubbish will crash into other pieces of rubbish, causing it to shatter into smaller chunks that will then crash into each other – and on, and on, until the earth is circled by a haze of impassable metal debris that remains there for millennia. There are (contested) fears that the process began in February this year, when an old Russian satellite crashed into a US satellite high above Siberia.

Dr Marshall Kaplan at John Hopkins University Applied Phyiscs Laboratory says that we face a "coming catastrophic disaster. If we don't clean up this mess in the next 20 years, we're going to lose our access to space". Vladimir Solovyov, Russia's space mission control chief, agrees. He warns: "The clouds of debris pose a serious danger... to earth-tracking and communications satellites."

What would it mean? The super-speed of our globalized world is dependent on satellites. If they are taken out by a barrage of 17,000mph rubbish, you can say goodbye to your mobile phones, GPS, and weather forecasts – and we'll be needing them in this century. We will be trapped here, unable to explore space. Hubble telescope bubble, toil and trouble.

What can we do now? There are some proposals for removing the rubbish, like creating a series of lasers that would sweep the trash back into our atmosphere, where it would mostly burn up. But they are regarded as of dubious scientific plausibility, and a long way off.

The most urgent task is to stop adding to the rubbish – but the 20 governments that have access to space are refusing to do it. They will not agree a deal; they don't want to tell each other where their spy satellites are, or to agree not to blow them up when they feel like it, to test their flashy new weaponry.

This wall of garbage orbiting us all seems like a symbol of the great dilemmas facing humanity in the 21st century. We have become capable of the most stunning technological breakthroughs – but we are sabotaging them by proving ourselves incapable of the most basic forms of self-restraint. At the moment of victory, we regress. The achievements of our frontal lobes are undermined by the backwardness of our adrenal glands.

This story is being played out, with mild variations, again and again, in this century. We have dramatically improved human health – yet now seem poised to cook it under a thick blanket of our own carbon emissions. We have made it possible to fish and farm more efficiently than ever – so we do it till we have taken all the fish and destroyed all the soil.

It doesn't have to be like this. We can restrain ourselves to save our satellites, and our ecosystem. Individuals restrain themselves all the time; why can't we do it collectively? The only alternative is to become a species who heroically reach for the stars – only to smack into a wall of our own trash.

j.hari@independent.co.uk