In the lead up to Copenhagen, much of the conversation is centering around cap-and-trade and the deployment of expensive new energy generation and efficiency technologies. But according to the latest report by the McKinsey Institute on global CO2 abatement, the most immediate solution to global warming is, surprisingly, trees.

Above is my interview with Carter Bales of the McKinsey Institute. In 2007 he co-authored a groundbreaking study which examined every possible method for reducing greenhouse gas emissions and their implementation costs. The curve proved that in the U.S., energy efficiency is the real winner:

But when you do that same exercise for global greenhouse gas emissions, you get a different result. REDD (Reduced Emissions from Deforestation and Degradation) and AR (Afforestation & Reforestation) are essential in mitigating the climate problem.

In order to stabilize the climate, we need to abate 17,000,000 tons of CO2 emissions by 2020. This would keep atmospheric CO2 to 450 PPM (parts per million) just enough to limit the mean global temperature rise to 2 degrees, according to McKinsey.

If we exceed 2 degrees for a sustained period of time, scientists now agree this would likely create a catastrophic biofeedback loop that could dramatically impact everything from weather patterns and water supplies to flu outbreaks and soil stability.

The problem is, according to McKinsey’s math, if you add up all the promises made by all the global super powers you only come up with HALF that amount needed to get there. So where is the other half going to come from?

Forest and land management.

As Bales says, “Without looking to forestry and land use there is no way, No WAY at all, you will ever get on the intended curve to top at 450 PPM of CO2… If the negotiators don’t get this, there is no solution.”

Here’s McKinsey’s global CO2 abatement curve:

The real problem right now is that the idea of allowing companies to buy carbon offsets (essentially by paying a foreign country NOT to cut down its trees) is at loggerheads with climate activists who want those companies to start cleaning up their act by using (and making) cleaner energy.

It’s a bit of a conundrum, but one thing is for certain, we cannot afford to let the rainforests disappear and the Copenhagen treaty needs to provide some mechanism that would allow industrialized nations to fund their protection.

Report: Forests hold the key to solving climate change
The McKinsey Institute has run the numbers and one thing is clear – stopping deforestation is the fastest way to get the climate back on track. But will it b