Climate Truth Blog

While some of us climate cynics have difficulty imagining humanity saving itself from its own insatiable oil addiction before it produces terminal levels of atmospheric CO2, there are pragmatic optimists like economist Jeffrey Sachs, a professor and director of the Earth Institute at Columbia University, who can always be counted upon to devise plausible escape scenarios from the dark woods of global heating. In his Sustainable Developments column in the March, 2008 issue of Scientific American, Sachs, the Special Advisor to United Nations Secretary-General Ban Ki-moon, once again draws us a useful map.

Basic science and math tell us that too little CO2 in the air around us would lead to a frozen, dead planet. Too much of the critical gas and we burn up. The magic numbers are well known and for millennia have hovered between 180 and 280 parts per million (ppm). This is the equivalent of 20 to 30 people in a community of 100,000. Small numbers! As we have relentlessly burned fossil fuels for the last 200 but especially the last 30 years, the level of CO2 in the atmosphere has steadily climbed.

In 2008 it has risen to 383 ppm or nearly 40 people in our metaphorical town of 100,000. Still a small number and yet the higher it climbs, the more likely all life on Earth suffers and begins to die. Sachs tells us that in the next year we will pump another 36 billion tons of CO2 into the atmosphere and will watch the ppm climb fron 383 to 385 and beyond.

We are already in unchartered territory—the atmosphere has never seen this much CO2 in the human era—but many scientists are guessing it may not be lethal or dangerous yet (and it is a guess—we don’t really know). Every one agrees we are accelerating toward the cliff’s edge but most experts think there is still time to alter our course. Where is the point of no return? No one knows for sure but some, including Sachs, have suggested the stop sign is 440 ppm. This is the equivilent of adding six or seven people to our town of 100,000.

Others like James Hansen, head of the Earth Sciences Division of NASA’s Goddard Space Institute propose a much bleaker view. In a December 7, 2007 National Geographic article Hansen estimated that the CO2 tipping point for many parts of the climate is around 300 to 350 ppm, exits we missed on the climate highway at least 30 to 60 years ago. Following a presentation at the American Geophysical Union conference Hansen said, “The evidence indicates we’ve aimed too high—that the safe upper limit for atmospheric CO2 is no more than 350 ppm.”

Environmentalist author Bill McKibben writing in the Washington Post on December 28, 2007 referred to these critical thresholds and said, “The last time the Earth warmed two or three degrees Celsius—which is what 450 parts per million implies—sea levels rose by tens of meters, something that would shake the foundations of the human enterprise should it happen again.”

According to Sachs, a 440 ppm limit will allow us to “safely” plow another 900 billion tons of CO2 into the air for another 40 years. Even with this approach we would need to immediately end tropical deforestation, which accounts for seven billion tons of CO2 each year and reduce our current annual fossil-fuel-based emissions by one-third from 36 billion to 21 billion tons. Anyone want to bet that will happen?

But let’s suppose we want to follow Sach’s map to climate stabilization. What roads will he take us down? Sachs suggests that we derive our electricity by emission-free technologies “through the mass mobilization of solar and nuclear power and the capture and sequestration of carbon dioxide from coal-burning power plants.”

Of course it sounds good but there are two problems. The first is that we don’t really know if Hansen or Sachs is right. If Hansen is right, it might not matter what map we use. It may be too little too late. The second problem is that even if Sachs is right and the atmosphere is forgiving of our continuing abuse of it; even if the map he’s drawn will get us to the promised land of climate stabilization, there’s not a shred of evidence that the political will or courage exists among our leaders to take us there.

Two final points we can all concede. Time is running out and we have not yet begun to act. And what good is a map, even an accurate one, if we fail to use it?

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