IT MAY seem premature to talk about last-ditch measures to deal with runaway climate change, but Ben Lieberman has it right. Lieberman, an energy expert at the Heritage Foundation, a Washington think-tank, responded to the news that the US Senate will not pass any climate legislation this year by saying: "It's pretty clear that no post-Kyoto treaty is in the making -- certainly not in Cancun, and maybe not ever."

The Cancun meeting next December is where the optimists hoped to untangle the mess left by last December’s abortive climate summit in Copenhagen and create a new treaty to replace the Kyoto accord, which expires in 2012. It was always a slim hope, but the US Senate has decisively crushed it. Big Coal and Big Oil win again.

The US Senate is one of the more corrupt legislative bodies in the Western world, so this comes as little surprise.  Few senators take direct bribes for personal use, but very many believe that they will not win re-election unless they accept cash donations from special interests like the fossil fuel industries. Taking the cash obliges them to vote in defence of those interests. Pity about the public interest.

As Senate majority leader Harry Reid put it: “We know that we don't have the votes." The Democrats control fifty-nine out of a hundred seats in the Senate, but some of their more vulnerable members have been picked off by the fossil fuel lobby, so there will be no serious climate legislation in the United States before the mid-term Congressional elections in November. And it’s not going to get better after November, on current forecasts.

The likelihood that the Democrats will emerge from the November Congressional elections with a bigger majority in the Senate is approximately zero. The probability is that the balance will tilt the other way, perhaps a little, perhaps a lot. Either way, that means that there will be no climate legislation in the United States until after the next Congressional election in November, 2012.

Maybe President Barack Obama will be back in office in early 2013 with a bigger majority in the Senate, but that’s the earliest that we can hope for any legal US commitment to cut its emissions – and it’s far from sure even then. Until the United States makes that commitment, you may be sure that none of the rapidly growing economies like China, India and Brazil will make it either. So the climate goes runaway.

Not right away, of course. We won’t actually reach the point of no return (+2 degrees C higher average global temperature) until the late 2020s or the early 2030s. But we will be ‘committed’ to that outcome much sooner, because with every year that passes, the cuts that we would need to make to hold the temperature below that level become deeper.  Eventually, in practice, they become impossible to achieve.

Before the current recession, global emissions of greenhouse gases were growing at almost 3 percent per year, and they will certainly return to that level when the recession ends. To come in under +2 degrees C of warming, we need to be reducing global emissions by at least 2 percent by 2012: a total cut of around 5 percent each year, assuming that economies grow at the same rate as before.

That would be hard to do, but not impossible. However, as the years pass and the emissions continue to grow, it gets harder and harder to turn the juggernaut around in time. On the most optimistic timetable, there might be US climate legislation in 2013, and a global climate deal in 2014, and we really start reducing emissions by 2015.

By then, we would need to be cutting emissions by 5 or 6 percent a year, instead of growing them at 3 percent a year, if we still want to come in under +2 degrees C. That’s impossible. No economy can change the sources of its energy at the rate of 8 or 9 percent a year. So we are going to blow right through the point of no return.

Plus two degrees C is the point of no return (and every government has recognised it as such) because after that the additional warmth triggers natural processes that speed the warming. The permafrost melts and emits enormous amounts of greenhouse gases. The warming oceans lose their ability to absorb carbon dioxide. After that, just cutting human emissions won’t stop the warming. Runaway.

The only way to avert that disaster that currently offers any hope is geo-engineering: direct intervention to hold the actual global temperature increase below 2 degrees C, no matter what happens in the short term to the concentration of greenhouse gases in the atmosphere.

There are various suggestions on the table. Maybe we could create a kind of sunscreen in the stratosphere by putting some sulphur dioxide gas up there. Maybe we could thicken up the clouds over the ocean so they reflect more sunlight. Maybe, maybe, maybe. But nobody has done serious field trials of these techniques, and it’s high time that they started. We are probably going to need them.

Welcome to the last ditch.

Gwynne Dyer is a London-based independent journalist whose articles are published in 45 countries.