Man-made warming

Let’s be clear: man-made global warming is real. As a result of all the carbon dioxide, methane, soot, and other substances that we human beings pump into the atmosphere every year, global average temperatures have been rising over the past half-century.

By Alan Robock (Climate Change)

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Published: Sat 29 May 2010, 9:14 PM

Last updated: Mon 6 Apr 2015, 8:43 AM

While some northern countries relish the prospect of extracting minerals from an ice-free Arctic Ocean and using the Northwest Passage, global warming is not good for most of the planet. After all, it means continued sea-level rise, stronger storms and more frequent flooding, drier and longer-lasting droughts, enhanced heat-stress episodes, ocean acidification (destroying corals and other sea life), and the northward migration of malarial mosquitoes and pine beetles. Moreover, fundamental threats to the food and water supply - especially food in the tropics and water in the subtropics - are coming if we continue business as usual.

Unlike the questions surrounding climate change and its consequences, all of which can be answered by scientists, what we want to do about it depends on values - that is, what is important to us. The choices, singly or in combination, are: 1) nothing (the current response); 2) mitigation (reducing emissions of greenhouse gases); 3) attempted adaptation to the ongoing climate changes; and 4) geo-engineering.

If you are a big oil or coal company, your choice will be nothing. You would choose to continue to make as much money as possible, while the consumers of your products use the atmosphere as a sewer, with no sewerage charge. And you would spend money on public-relations firms and charlatans to try to confuse the public about the science so that you could continue this as long as possible, just like tobacco companies did recently about the safety of smoking. (Indeed, you would use some of the same firms and charlatans.)

But if you are like me, and want to minimise the damage to people and all other living things on Earth, then you choose mitigation and, where necessary, adaptation. As for geo-engineering, we do not yet have enough information to decide, but preliminary studies show that it presents more problems than it solves.

There are basically two quite different and separate types of actions that have been labeled geo-engineering. One, carbon dioxide reduction (CDR), involves removing from the atmosphere the main gas that is causing global warming. In general, this is a good idea, but so far it seems rather expensive, and nobody has yet designed a system to then sequester the carbon and keep it out of the atmosphere.

CDR proposals include artificial trees that use chemicals to capture the CO2, and then pump it underground or under the ocean; planting fast-growing trees and then burying them; and fertilising the ocean with iron to make plankton grow faster, hoping they will fall to the ocean bottom. This last idea has not been shown to work, and may severely damage the entire ocean ecosystem, but the first two are being worked on.

What if Russia and Canada wanted Earth to be warmer, and sinking islands in the Indian Ocean and Pacific want it to be cooler? What if the technology was used for military purposes, or a big multinational corporation had a large role? ll this underscores the need for further study. We have to be able to quantify the benefits, risks, and costs of geo-engineering, and compare them to the benefits, risks, and costs of our other options, so that we can make an informed decision. SRM might be needed in a planetary emergency - say, if continued warming rapidly accelerates ice-sheet melting and sea-level rise, or if it accelerates methane and CO2 emissions from thawing tundra, which would then accelerate the warming itself.

But geo-engineering is not a magic solution to global warming. Right now, it looks even more dangerous. So we must redouble our efforts to shift our economies to a post-carbon world, while still allowing the billions of people without adequate food, water, and education to improve their lives.

This offers tremendous economic opportunities, if we can just put a price on the dangers to the planet of current carbon emissions. So long as governments begin to push the world in this direction, we have a good chance to save our planet without geo-engineering.

Alan Robock is Professor of Meteorology and Associate Director of the Center for Environmental Prediction in the Department of Environmental Sciences at Rutgers University.© Project Syndicate

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