by The historic Paris climate agreement started a mantra from developing countries: “1.5 to stay alive.” It refers to the international aim of keeping global warming below 1.5 degrees Celsius (2.8 degrees Fahrenheit) compared to pre-industrial times. But the world is likely to pass that threshold within a decade, and global warming shows little sign of slowing.
The world is already facing natural disasters of epic proportions as temperatures rise. Heat records are regularly broken. Wildfire seasons are more extreme. Hurricane strength is increasing. Sea level rise is slowly submerging small island nations and coastal areas.
The only known method capable of rapidly arresting this temperature rise is climate engineering. (It is sometimes called geoengineering, sunlight reduction methods or solar climate intervention.) This is a series of actions intended to deliberately change the climate.
These actions include mimicking the cooling effects of large volcanic eruptions by sending large amounts of reflective particles into the atmosphere, or brightening low clouds over the ocean. Both strategies will reflect a small amount of sunlight back into space to cool the planet.
However, there are many unanswered questions about the effects of deliberately changing the climate, and there is no consensus on whether it is a good idea to find out.
One of the biggest concerns many countries have regarding climate change is national security. That is not the same as wars. Risks to food, energy and water supplies are national security issues, as are climate-induced migration.
Could climate engineering help reduce the national security risks of climate change, or would it make things worse? That question is not simple to answer, but researchers who study climate change and national security like us have some idea about the risks we face.
The huge problem of climate change
To understand what climate engineering will look like in the future, let’s first talk about why a country would want to try it.
Since the industrial revolution, humans have put about 1.74 trillion tons of carbon dioxide into the atmosphere, mostly by burning fossil fuels. That carbon dioxide absorbs heat, warming the planet.
One of the most important things we can do is to stop putting carbon into the atmosphere. But that won’t make things better quickly, because carbon stays in the atmosphere for centuries. Only reducing emissions will keep things from getting worse.
Countries could pull carbon dioxide out of the atmosphere and lock it up, a process known as carbon sequestration. Currently, carbon dioxide removal projects, including growing trees and direct air capture devices, are pulling about 2 billion tons of carbon dioxide out of the atmosphere per year.
However, humans are putting over 37 billion tons of carbon dioxide into the atmosphere annually through fossil fuel use and industry. As long as what is added exceeds what is taken out, droughts, floods, hurricanes, heat waves and sea level rise, among the many other consequences of climate change, will continue to worsen .
It may take a long time to reach “net-zero” emissions, the point where humans are not increasing the concentration of greenhouse gases in the atmosphere. Climate engineering could help in the meantime.
Who would try climate engineering and how?
Different government research arms are already running different scenarios, looking at who might decide to undertake climate engineering and how.
Climate engineering is expected to be cheap compared to the cost of achieving greenhouse gas emissions. But it would still cost billions of dollars and take years to develop and build a fleet of planes to transport megatons of reflective particles into the stratosphere each year. No billionaire thinking of such a venture would have money quickly, despite what science fiction suggests.
However, one country or a coalition of countries that saw the harms of climate change could make a cost and geopolitical calculation and decide to start climate engineering on its own.
This is the so-called “free driver” problem, meaning that at least one country of average wealth could unilaterally affect the world’s climate.
For example, countries with increasingly dangerous heat waves may want to induce cooling, or countries that depend on monsoon precipitation may want to restore some dependence that has been disrupted by climate change. Australia is currently investigating whether the Great Barrier Reef could be rapidly cooled to prevent it.
A conflict alarm is raised when risks are created for neighbors
The climate does not respect national boundaries. Therefore, a climate engineering project in one country is likely to affect temperature and rainfall in neighboring countries. That could be good or bad for crops, water supplies and flood risk. It can also have far-reaching unintended consequences.
Some studies show that a modest amount of climate engineering is likely to have far-reaching benefits compared to climate change. But not all countries would be affected in the same way.
Once climate engineering is implemented, countries may be more likely to blame climate engineering for extreme events such as hurricanes, floods and droughts, regardless of the evidence.
Climate engineering can fuel conflicts among countries, leading to sanctions and demands for compensation. Climate change can leave the poorest regions vulnerable to harm, and climate engineering should not make that harm worse. Some countries would benefit from climate engineering and thus be more resilient against geopolitical confrontations, while some countries would be harmed and thus left more vulnerable.
No one has done large-scale climate engineering yet, which means that much information about its effects depends on climate models. But while these models are excellent tools for studying the climate system, they are not good at answering questions about geopolitics and conflict. Furthermore, the physical effects of climate engineering depend on who is doing it and what they are doing.
What lies ahead?
Currently, there are more questions than answers about climate engineering. It is difficult to say whether climate engineering would create more conflict, or whether it could ease international tensions by reducing climate change.
But international decisions on climate engineering are likely to come soon. At the United Nations Environment Assembly in March 2024, African countries called for a moratorium on climate engineering, urging all precautions. Other nations, including the United States, have pushed for a formal scientific group to study the risks and benefits before making any decisions.
Climate engineering could be part of a fair solution to climate change. But it also comes with risks. Simply put, climate engineering is a technology that cannot be ignored, but more research is needed so that policy makers can make informed decisions.
This article is republished from The Conversation, a non-profit, independent news organization that brings you facts and analysis to help you make sense of our complex world.
It was written by: Ben Kravitz, Indiana University and Tyler Felgenhauer, Duke University.
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Ben Kravitz receives funding related to this work from the National Oceanic and Atmospheric Administration and the National Science Foundation.
Tyler Felgenhauer receives funding related to this work from the National Science Foundation and Resources for the Future.
