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Caldeira Lab

The Great Climate Experiment: How far can we push the planet? Ken Caldeira [Scientific American]

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The editors of Scientific American asked me to write a piece on what would happen if we didn’t curtail CO2 emissions and we burned all of the fossil fuels available and dumped that CO2 into the atmosphere.

This was quite challenging because I had to write something at a level that the intelligent non-scientist could read, but also it had to be something that my scientific colleagues would find to be sound science. And since nobody can really foresee the future with great accuracy, I had to say something that was fairly robust. And so I think one of the things we can say is that climate is going to get a lot warmer and that it’s going to get more similar to what it was like when the dinosaurs were around 100 million years ago, which is high CO2 levels and a very warm planet.

So then the question comes to us, well, is this going to be a catastrophe or is this just something we’re going to deal with? And I think we can say with a pretty high degree of certainty that it’s going to be catastrophic for at least some ecosystems. I think the clearest is probably coral reefs are severely challenged by both ocean acidification and global warming. Arctic ecosystems are probably in big trouble, and it might also be places like rainforests and so on might also be in big trouble.

Now, what about humans? I think there’s a few things. One is that, obviously, if you’re a poor subsistence community depending on coral reefs, you’re probably in trouble. Maybe also if you’re a similar subsistence society depending on growing food in a place where you’re going to have big droughts that you’re also going to be in trouble. But it might be that for the middle classes of the industrialized world that climate change is really a secondary issue, and that they’ll still have their TV sets and their McBurgers and McNuggets to eat and that life will go on.

That said, we don’t really know that that’s true. If we look at the 2008 subprime mortgage crisis, there you had perturbations in some financial markets that led to a 5% loss in GDP throughout the world. And so our economic system can take some regional perturbation to amplify it into a global crisis. Also, these days, you have countries where you have nuclear arm nations, and if they feel they have an existential threat, there’s potential for war and so on.

So one issue is, since most catastrophic effects of climate change are likely to show up regionally, in some sort of regional drought or storms or floods or something else like that, are these social and political systems going to amplify these regional crises and form a global crisis out of it? And I think we don’t really know the answers to these questions. We know that our continued emissions of CO2 is increasing our levels of environmental risk, but it’s really hard to quantify exactly how much risk we’re facing.


Caldeira, K. (2012) The Great Climate Experiment. How far can we push the planet? Scientific American, September 2012, pp. 78-83.


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