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Geoengineering the Climate

by Kaitlin Alexander | University in Canada

F Posted in: News and Politics P Posted on: November 12, 2010

Climate change would be a whole lot easier to fix if we could immediately see the results of our actions. First of all, we would have recognized the reality of the problem long ago, before very much harm was done. And even if we initially stalled on fixing the problem, we could throw all our weight into reducing greenhouse gases as soon as the floods and droughts and rising sea levels became too much, and stop the warming overnight.

This kind of fantasy scenario is like riding a bike. As soon as you jerk the handlebars to avoid running off the road, the bike responds. The only lag between your recognition of a problem and the subsequent resolution of that problem is your reaction time.

However, the climate system works more like a ship. Remember in the movie Titanic, when the crew first saw the iceberg, and cranked the wheel all the way to the right so they could go around it? The ship didn’t turn immediately. She kept going straight for a while before she responded. Unfortunately, she didn’t respond early enough to miss the iceberg, and you know what happened next.

The climate is very similar. There is a lag time between when we emit carbon dioxide from the burning of fossil fuels and when we see the effects of the subsequent warming. A lot of this has to do with the oceans, which store massive amounts of heat and slowly release it to the atmosphere. The warming we are seeing today is from fossil fuel emissions in decades past, and the actions we take today will not show up until decades in the future. Even if we bring global greenhouse gas emissions down to zero tomorrow, the world will continue to warm.

Because CO2 emissions continue to rise year by year, and because governments have had little to no success addressing this problem, some scientists are beginning to think that we won’t be able to stop climate change in time. Another unfortunate aspect of the climate system is its non-linearity – there are hidden thresholds and “tipping points” which, if crossed, could trigger feedbacks that cause global warming to spin out of our control. The scientific community thinks that, once the world has warmed about 2 C from pre-industrial times, these tipping points and feedbacks will start to kick in. We have already warmed 0.8 C, and at least another 0.5 C is in the pipeline, even if we were to cut off all emissions tomorrow. You do the math. There’s not a lot of wiggle room, especially given the increasingly low chances of climate legislation being passed by the world’s governments.

So what happens if we’ve gone too far? Do we have no choice but to sit back and watch all hell break loose? In fact, there are other choices, but they could easily come with unexpected side effects that make our situation worse. Techniques known as “geoengineering”, in which radical technologies offset our influences on the earth’s climate, fall into two categories:

1) Counteracting the warming. Greenhouse gases such as carbon dioxide trap heat and cause the Earth to warm up, so we could introduce technologies that have a cooling effect on the Earth. By increasing the planet’s albedo (reflectivity), more of the Sun’s rays will bounce right off the Earth’s surface without being absorbed.

One way this could be achieved would be to inject massive amounts of sulfate particles into the stratosphere, blocking sunlight just like a volcanic eruption. However, this could have detrimental effects on the ozone layer, especially around the polar regions. We could end up trading the damaging effects of a warming climate for the damaging effects of too much UV radiation, a problem that we’ve already spent considerable time and energy addressing.

A similar proposal is to put objects in the Earth’s orbit that would reflect sunlight – giant mirrors, lenses, or sunshades in space.

2. Counteracting the CO2. If we can’t stop or even slow down our emissions of greenhouse gases, perhaps we could alter the biogeochemical systems of the Earth so they would absorb the gases and keep them safely out of the atmosphere. CO2 “sinks” already exist – forests, oceans, permafrost – but they’re not big enough to contain all of our emissions. How could we expand them, or add more?

The concept of artificial trees, that will perform photosynthesis anywhere, is intriguing – but the scale of implementation needed is not very feasible. Think of the amount of land that would have to be covered with these machines in order to offset our emissions.

A more widely discussed possibility for expanded carbon sinks involves fertilizing the ocean with iron filings, promoting blooms of phytoplankton that would photosynthesize, absorbing our emissions of CO2. However, as anyone living near the Great Lakes knows, overloading a water body with nutrients can have serious consequences for the ecosystem. Algal blooms can deplete the water of oxygen and block sunlight, killing the other plants and animals that share the habitat. For an ecosystem that covers most of our Earth’s surface, that might not be such a good idea.

All of these propositions have another dimension of questions attached: Who will control them? If we’re going to actively counteract our climatic influences, many careful decisions will need to be made. Who will calculate how much geoengineering, and of what type, to implement? Who will decide when enough is enough?

I have heard geoengineering described as a tourniquet: the worst possible option, except for bleeding to death. Scientists understand that it should be considered a “last resort” – only to be used when we have eliminated fossil fuel use and it still isn’t enough. However, there are certainly politicians and industry leaders out there who see geoengineering as an attractive alternative to cap-and-trade systems or carbon taxes.

Recently, at their Convention on Biodiversity, the UN decided to ban geoengineering – it’s just too dangerous, and we don’t know enough. However, this ban will also restrict large-scale research projects on geoengineering that could give us a clearer picture of what is and is not feasible. Isn’t it more prudent to take small risks now so that we understand our future options, rather than jump blindly into full deployment when the time comes?

Bart Gordon, the outgoing chair of the U.S. Congress Science & Technology Committee, just issued a congressional geoengineering report. He was interviewed by a Chemical & Engineering News article on the subject, and had these words to say:

A research moratorium that stifles science, especially at this stage in our understanding of climate engineering’s risks and benefits, is a step in the wrong direction and undercuts the importance of scientific transparency. If climate change is indeed one of the greatest long-term threats to biological diversity and human welfare, then failing to understand all of our options is also a threat to biodiversity and human welfare.

How many risks should we take in order to secure a safer alternative for possible future use? Will pursuing research into geoengineering distract us from the important task of reducing greenhouse gases, or is the situation already so far gone that preparing for the worst is worthwhile? One thing is clear: If earlier generations had thrown their efforts into fixing climate change as soon as scientists recognized it was underway, we wouldn’t be worrying so much today about the feasibility of giant mirrors in space or oceans full of iron.

Image courtesy of Flickr, Ana_Cotta

Kaitlin Alexander Kaitlin Alexander Kaitlin Alexander is a B.Sc. student and aspiring climatologist from Canada. She serves as NextGen Journal's Climate Correspondent and blogs at http://climatesight.org.

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