Johann Hari: Planting trees won't offset jetting to the sun

If you fly one way, one time to Miami, you emit more greenhouse gases than the average SUV driver in a year

After yet another Hottest Year Since Records Began, the symptoms of our planetary fever are so great even George Bush is reaching a tipping point. As the Greenland ice shelf thaws ever-closer to total collapse, there are whispers from Washington that the forthcoming State of the Union address will include an admission by the President that global warming is caused by man.

But while Bush's denial is finally melting - albeit six years too late and with far too little action to come - there are subtler forms of denial persisting even here, among environmentally aware Europeans. As we run from this disaster, many of us are clambering on to lifeboats full of holes. Let's look at two of the most popular: the carbon offsetting scam, and the EU's flailing carbon trading scheme.

For most of us, the biggest contribution we make to destabilising the planet's climate is through flying. If one person flies one way, one time to Miami, you emit more greenhouse gases than the average SUV driver in a year. You could cycle, recycle and use energy-saving light bulbs for the rest of your life, and it's all cancelled out by a single weekend break by the beach.

So it is deliriously tempting to believe in the slew of websites that promise to wipe your conscience clean after every flight. You emitted four tonnes of greenhouse gases flying to Rio? Fine, we'll plant enough trees to absorb four tonnes back - just click here.

But a report this week by the US green group Clean Air-Cool Planet is an icy reminder that it just ain't so. They found that the £15bn-a-year carbon-offsetting market is "like the Wild West - full of cowboys". In an unregulated market, there is no guarantee that the cash you give will plant anything, anywhere.

But the picture is even worse than this report suggests. It's not only the practice of carbon sinks that is in error. It's the whole concept. In order to compensate for Britain's annual carbon emissions, we would have to cover the whole of France, Germany, Spain and Italy in trees - and make sure they literally never decay or die.

As an analysis in the New Internationalist magazine showed recently, to understand this you have to draw a distinction between the two different pools of carbon on our planet. There's the "active carbon pool" - the carbon dioxide that is always circulating between forests, the atmosphere and the oceans, in a complex natural rhythm. Then there's the "fossil carbon pool", which is locked away in coal, oil and gas deposits built up over millennia. When we dig up the fossil pool and burn it - to power planes, trains and automobiles - its gases join the active carbon pool, sending it out of balance.

It's pretty much a one-way process: once carbon comes out of the ground, it stays out of the ground for a very long time. And as the biologist Tim Flannery puts it: "There is so much carbon buried in the world's coal seams [alone] that, should it find its way back to the surface, it would make the planet hostile to life as we know it."

Paying to put some trees in the middle doesn't make much difference. Trees can store only some carbon - we don't even know how much, with estimates varying by 1,000 per cent - and for a limited period of time. Sooner or later, they die. Oliver Rackman, the Cambridge University botanist, explains it starkly: "Telling people to plant trees [to prevent global warming] is like telling them to drink more water to keep down rising sea levels." The water - or gas - will come out in the end.

But the other life raft many of us are swimming towards - the EU's Emissions Trading Scheme (ETS) - is sinking just as fast. In principle, "cap and trade" is a simple, sound idea. Every relevant corporation is given by the Government a maximum amount of carbon they are allowed to belch into the atmosphere each year. If they improve their efficiency and emit less than their quota, they can sell their surplus carbon emissions to another company. The benefit? It provides polluters with a profit motive to become greener.

Yet when the Public Accounts Committee of the House of Commons studied the new system designed to achieve this, it described it as "bullshit" and "an outrageous waste of public money". What went wrong?

There are two big flaws. Every European government grossly overestimated their initial carbon emissions, so any cut in the greenhouse gas pumped out seemed more impressive - and brought in more cash. This led to the farcical situation where they found the scheme appeared to have paid £96m to BP and three other corporations "for keeping emissions down to levels they had already achieved before they joined".

And it gets worse. The emissions of each corporation are supposed to be measured by an agency called the Integrated Pollution Prevention and Control System. But as Carbon Trade Watch puts it, "the whole system increasingly relies upon the goodwill of corporations to report their emissions honestly".

More than 40 per cent of sites don't have any adequate monitoring procedures, and government inspections have halved since Labour came to power. It's as though teachers wrote their own Ofsted reports, and received more cash if they rated themselves excellent.

In our panicked response to the disaster of global warming, it turns out we have been furiously swallowing placebos. I wish these painless solutions worked. I wish global warming could be wished away with a click and an accounting trick. Too often, environmentalists can sound as if we think people deserve global warming as a punishment for their "greed" or their "rape of the planet". I don't. When I hear the deniers speak, I would give anything to live in their reality. I love the world that is passing. I love cheap flights. I love the fact working-class people can holiday in exotic places for the first time. I love weekends in Prague. But I love having an inhabitable planet more, and I can't deny the science.

We are going to have to move beyond these delusion-solutions, and the Tory MP Tim Yeo is right (and was swiftly slapped down by fake-green David Cameron for it): for starters, we have to ban short-haul flights. It is obscene that the most popular destination from Heathrow is Manchester, when it can be reached by train, which is 10 times less polluting. Yes, I know it costs far less to fly. That's why the Government needs to end the £9bn tax break it gives the aviation industry by refusing to tax their fuel, and use the cash to bring train fares crashing down. And for long-haul flights? There is no easy solution, except that we will all have to fly much less.

Until we start facing these sad, nasty facts, we are barely one step ahead of George Bush as he prepares to step out of his long, long denial.