The temperature of the Earth is too damn high. Unless we can get our planet to halt its warming trend, and soon, our species continued existence here is very much in jeopardy. Sure, we've implemented countless climate change remediation schemes in recent decades but the fact remains that our window of opportunity for addressing this issue is quickly closing. It might come a time in the very near future that we stop farting around with half-measures and pull out the proverbial big guns, namely geoengineering and terraformation.
In Breaking Boundaries: The Science of Our Planet, Stockholm Resilience Centre researchers Owen Gaffney and Johan Rockström walk readers through the scope and scale of environmental challenges we currently face, explore the concept of "planetary stewardship," and in the excerpt below, discuss what we might have to do if what we're doing doesn't work.
Excerpted from Breaking Boundaries: The Science of Our Planet reprinted by permission of DK, a division of Penguin Random House LLC. Copyright © 2021 Owen Gaffney and Johan Rockström.
If all else fails, can we restabilize Earth using extreme technological fixes? In the worst-case scenarios, protecting billions of people will take unprecedented feats of engineering. Geoengineering aims to address climate change using deliberate and large-scale technological interventions. Think terraforming our own planet. To be honest, most of these ideas come straight from the pages of science fiction. But many are now getting serious scientific attention. By 2030, we should know which ones are our best bets.
Geoengineering comes in two flavors. The first option is to block sunlight from reaching Earth. The second is to suck greenhouse gases out of the atmosphere. Both are insanely high-risk interventions in a complex system.
There are several ways to block sunlight, starting at a cosmic level. Erecting giant sunshades between Earth and the sun would do the job nicely, by potentially stopping about 2 percent of incoming heat from the sun. The numbers have been crunched. We would need hundreds of thousands of 10-foot-square (1-meter-square) sunshades weighing approximately 20 million tons (18 million metric tons). In total, it would cost a few trillion dollars and last about 50 years. But this does not help ocean acidification, because carbon dioxide will still be building up in the atmosphere. If we keep emitting, even if we block incoming solar radiation, then the ocean will get steadily more acidic—one of the major causes of past mass extinctions. In addition to the cost and engineering challenge, giant sunshades are likely to bring unexpected consequences: for example, changing weather patterns around the globe.
Retro futuristic sci-fi concept of planetary terraforming.
Probably the most talked-about geoengineering solution is to dump millions of tons of tiny particles high into the atmosphere in order to reflect heat back to space. We know this works. Every major volcanic eruption ejects ash into the upper atmosphere. This has a measurable effect on climate. When Mount Pinatubo erupted in the Philippines in 1991, the planet cooled a little for a few years after the initial eruption, but this impact was short-lived because these particles dissipate in the upper atmosphere within a few years. The scale of this type of intervention would need to be immense: some 3.3 to 5.5 million tons (3 to 5 million metric tons) of sulfur ejected every year.
Cloud seeding or whitening is another option. Churning up large tracts of the ocean can throw salt particles into the atmosphere that help cloud formation. More clouds will reflect more heat back to space and perhaps cool the planet. This idea could be used quite locally to protect coral reefs, for example. On a global scale, though, this would take vast armadas of autonomous ships plying the ocean forevermore.
We could also simply paint our roads, roofs, and cities white to reflect heat. Locally, this effect could keep towns and villages cooler. A similar proposal is to grow genetically modified crops that are better at reflecting heat from the sun, for more widespread cooling. There is a dangerous thread running through all of these geoengineering ideas, though. Once we start we cannot stop. If we are forced to stop a geoengineering project for whatever reason—the money runs out, geopolitical strife, catastrophic unforeseen consequences, for example—then Earth’s temperature would rocket abruptly.
Several ideas for sucking carbon dioxide out of the atmosphere have also been proposed. The most commonly talked about is carbon capture and storage. There are two main ways to do this. The first is to pull carbon out of the atmosphere using some kind of machine. The second is to grow and burn plants for energy. Burning the plants releases carbon dioxide, but this would then need to be trapped and put somewhere safe, away from the atmosphere. The most common proposal is to pump it back into used oil reservoirs, deep beneath the sea, for safekeeping. However, if we rely on plants to capture the carbon, the scale needed will interfere with global food production, and we will struggle to provide enough food for our growing population.
Ultimately, some of these technological solutions will be required, even if the world makes massive emissions cuts because we are so close to unmanageable risks. When geoengineering becomes essential, we should plan for a smorgasbord and deep systematic assessments of risks. Carbon capture and storage seems the most promising option: it is economically viable and appears relatively safe. In the next decade, we need to start scaling it up, so that we are ready to pull 5.5 to 11 billion tons (5 to 10 billion metric tons) of carbon dioxide out of the atmosphere every year. We will need this even if the world follows the Carbon Law. Going further than this, though, really is in the realm of science fiction.
Finally, researchers have also proposed a way to stabilize parts of the Antarctic ice sheet. It would take about 12,000 wind turbines to generate the power, but giant snow machines could be employed to suck up seawater and turn it into snowfall to rebuild the ice sheet and protect the world from several yards of sea-level rise. Our assessment is that ideas like this are, for now, interesting projects on paper and in the minds of brilliant colleagues. While they highlight the sheer scale of the challenges we face, they are perhaps unrealistic at the moment. Ten years from now, we might be revising this opinion. These are the extremes we are being forced to consider.