Our Understanding of How to Modulate Climate Change is Ballooning

As our climate continues to warm, torrential rains, ferocious winds, and deadly storm surges like those of recent hurricanes Helene and Milton are becoming increasingly likely occurrences in the Southeastern United States. We can expect these storms more often if we continue to burn fossil fuels for energy.

Helene and Milton illustrate perfectly the reasons for the trend. Hurricanes require several conditions to materialize, but the one ingredient that stands out is ocean heat.  Waters in the Gulf of Mexico started to break all-time temperature highs this summer, and recent weeks have seen an additional uptick in temperatures -- a “marine heat wave” that provided additional fuel to the storms.

In addition to hurricanes, floods, droughts, and tornados are all thought to be worsened by global warming, which is currently at nearly 1.5 degrees C above pre-industrial times. This may not sound like much but consider that 20,000 years ago the temperature was only 8-9 degrees C lower than now and that gave rise to an ice age with most of North America covered by a giant glacier. That illustrates that a few degrees of temperature change can have dramatic effects. 

It is now a virtual certainty that we will blow through the 1.5 degree C goal suggested by the 2015 Paris Climate Agreement in hopes of keeping temperature “well below 2 C above pre-industrial levels.” Unfortunately, that aspiration runs counter to reality: Global temperature this past year has already broken the 1.5 degree threshold and shows no signs of abating. A Washington Post article quotes Columbia University climate scientist James Hansen, “The 1.5-degree limit is deader than a doornail.”

Yet many large activist groups cling to the illusion of a 1.5-degree cap. The Climate Action Network, a huge group of 1,900 organizations, still states, “We hold governments accountable to the promise of the Paris Agreement to deliver ambitious climate targets to keep global warming below 1.5 C.” The COP 28 Global Youth Statement says, “We are the last generation that can take decisive action to keep 1.5 C within reach.”

So much for following the science. These are the new “deniers.”

What can we do to minimize the current rise? Spoiler alert: More wind turbines, solar panels, and electric cars cannot reduce temperatures. To understand why, let us review the factors determining the Earth’s average or aggregate temperature.

They are:

• The amount of light (which becomes heat) from the sun that reaches Earth;
• The amounts of “greenhouse gases,” such as carbon dioxide (CO2) and methane, that are produced and released – because they absorb the heat that radiates back from the Earth’s surface trap it in the atmosphere and prevent it from escaping into space. They keep Earth’s temperature warmer than it would otherwise be, much like a blanket.
• Our ability to effectively remove and sequester greenhouse gases

CO2 is emitted in huge volumes every year – roughly 36 billion tons and those amounts will increase with a surge in demand for energy to power artificial intelligence data centers. 

The U.S. is no longer the biggest emitter, having been far surpassed by China. Other large contributors are the European Union, India, and Russia. The U.S. and EU are slowly bringing their emissions down, but increases in Russia, India, China, and most of the rest of the world are swamping those reductions. A long-term solution requires that these emissions must be greatly reduced. However, until greenhouse gas emissions are reduced significantly worldwide, a goal that currently seems unachievable, CO2 will continue to accumulate, and the world will continue to warm.

To actually reduce the amount of CO2 within a meaningful timeframe, one approach would be massive “geoengineering” projects to actively remove it. This could take various forms, including reforestation and other biological approaches, but these are very slow (centuries) and prone to setbacks such as forest fires, the combustion products from which create more CO2. A much faster and more efficient approach is direct air capture, in which air is pulled into large structures that use a chemical process to remove the CO2, which is then stored underground or incorporated into a product such as concrete.

This sequestration approach is currently being attempted at various facilities, but the scale is nowhere near what is needed. As of 2022, roughly 8,000 tons of CO2 were removed at various facilities. A 1-million-ton plant is supposed to begin operating in the American Southwest this year, but it would take nearly 40,000 of these plants to simply balance out yearly CO2 emissions, much less reduce the overall balance. Thus, unless a massive technical breakthrough occurs, CO2 levels will climb for the foreseeable future, and temperatures will continue to rise.

But consider the first of the bullets above – the amount of heat from the sun that reaches Earth, which can be altered by an approach called “global shading.” This approach, which can take various forms, derives its plausibility from the well-known effects of significant volcanic eruptions, which propel ash and sulfur dioxide particles into the stratosphere and cause a small reduction in the sunlight reaching Earth’s surface.

It turns out that Earth’s temperature is very sensitive to small changes in sunlight. The eruption of Mount Pinatubo in 1991 resulted in global temperature reductions of about half a degree for the subsequent year or two. The much larger eruption of Mount Tambora in 1815 resulted in “the year without a summer,” including snow in Virginia on July 4, 1816. In the opposite direction, as many countries have reduced air pollution, the amount of the sun’s heat reaching Earth has increased and contributed to warming.

Scientists have investigated mimicking volcanic effects by injecting massive amounts of sulfur dioxide into the upper atmosphere. But this has serious environmental effects and is likely unfeasible. There is also an experiment currently under way to spray massive amounts of seawater into the clouds in an attempt to whiten them and cause higher reflectance of sunlight back into space. But because this raises the likelihood of salty rain, which would be disastrous to agriculture, this approach is probably a non-starter as well.

A New York Times article earlier this year described a conceptual project of NASA to build a giant solar shield to reflect heat. It would be located nearly a million miles away from Earth in space and would be huge, roughly the size of Argentina. It would block enough sunlight to reverse the current level of global warming, but it would be prohibitively expensive, and since the amount of future global warming is unknown, it is difficult to say exactly how large it would need to be and whether it would need to expand to account for future warming.

However, there is a more down-to-earth approach (pun intended) to accomplish the same thing in a more flexible and less expensive way: An array of numerous large balloons in the stratosphere to provide shade. They could be deployed in a belt near the equator to mimic the effect of the solar shield but with much quicker deployment, greater flexibility, and probably at far lower expense.

Unfortunately, all these approaches have one irredeemable flaw: They would require virtually unanimous consent of all the nations on Earth, which seems unlikely.

Is the situation hopeless?

Not necessarily. A Google X effort called Project Loon demonstrated the ability to navigate and hover high-altitude balloons over a spot on Earth. It should be possible, therefore, for an array of balloons to hover over the American Southwest that would reduce the temperature within parts of this country and would require no international agreements. We calculate that an array of 2 million balloons, each about 100 meters in diameter, would reduce temperatures in the Southwest by 1 to 2 degrees C and, as the cooler air traveled eastward, would provide some benefit to other parts of the nation.

These balloons would be so high that they would barely be noticeable from the ground and well above aviation altitudes. They would act like a thermostat: If you want it cooler, add more balloons. They would be recoverable and environmentally benign. And if they were successful in the U.S., other nations, and possibly even an international agreement, might follow.

If you think it’s hot now, stay tuned: It is going to get even warmer in the years ahead. We need ways to quickly reduce the worst effects of global warming. Balloon arrays may seem unorthodox, but what better alternative is there?

A previous version of this article was published by Issues & Insights.

Tom Hafer developed systems for neutralizing rockets and drones. He currently coaches teenage robotics teams. Henry I. Miller, a physician and molecular biologist, is the Glenn Swogger Distinguished Fellow at the American Council on Science and Health. Hafer and Miller were undergraduates together at M.I.T.