No, we can’t geoengineer our way out of the climate crisis

All across the world, temperatures and weather conditions vary tremendously, as they always have. But if we look to global conditions, by averaging our data about the entire world together, we find that there have been some rapid, even alarming changes happening on a global scale. The biggest changes, overall? They’re threefold.

1. There have been significant changes to the contents of Earth’s atmosphere, largely due to industrial human activity, and those changes have also affected the land, oceans, and clouds as well.
2. There has been a significant rise in the average temperature of Earth: locally in nearly all places, as well as globally, with some places experiencing greater warming than others.
3. And, coincident with those changes, there has been a tremendous decrease in the percentage of Earth’s surface that is wild, versus the percentage that has been used for human (residential, agricultural, industrial, commercial, etc.) purposes.

Although many had hoped that a long-term fix involving the development and global deployment of net-zero carbon emission energy solutions, recommended by scientists since the 1990s, would have been enacted by this point in the 21st century, the reality is that carbon emissions are higher than ever, and that the world isn’t just warming, but that warming has intensified in recent years.

Many have hoped to geoengineer a solution to this problem, with the idea of “reflecting incoming sunlight away” as the leading idea. But those endeavors won’t merely fail in the long-term, they’ll actually make the underlying problem even worse. Here’s why.

Traditional power plants, based on the combustion reactions of fossil fuels, such as the Dave Johnson coal-fired power plant shown here in Wyoming, can generate tremendous quantities of energy, but require the burning of an enormous quantity of fuel in order to do so. The ash produced by this burning sends large quantities of particulate ash into the atmosphere, where it will eventually settle into the soil and onto the ocean bottoms, where it may become incorporated into materials found in the same location, while simultaneously adding long-buried carbon molecules back into Earth’s atmosphere.

For most of the 1990s, 2000s, and 2010s, scrupulous scientists who were studying Earth’s climate came to an incontrovertible conclusion, something that was predicted by climate models way back in 1967: that the Earth was warming due to the greenhouse gas emissions associated with the industrialization brought about by human civilization. The idea was simple:

• with more heat-trapping, infrared-radiation absorbing gases in the atmosphere,
• more of the heat radiated by Earth gets reflected and re-reflected back down toward the surface,
• increasing Earth’s overall energy budget and thereby increasing Earth’s temperatures.

During those three decades — the 90s, 00s, and 10s — global temperatures were seen to increase linearly, or at a relatively constant rate over time. Even as we got better and better at measuring temperatures, especially over the oceans and in sparsely populated regions, and even as greenhouse gas emissions continued to accelerate, two assumptions continued to prevail.

1. First, that there would be an abundance of natural mitigating factors, such as the ocean acting as a heat sink and the greening of previously frozen regions, that would keep temperature rises steady, or even cause it to tail off.
2. And second, that developments in clean, green energy technologies would lead to a rapid decarbonization of the energy grid, globally, allowing Earth to re-regulate itself and return to a stable state.

Although there are seasonal variations in global carbon dioxide levels at about the ±3 parts-per-million level, the long-term trend has been a rise in carbon dioxide concentration in Earth’s atmosphere. Although the average rise has been about 2 ppm per year from the late 20th-century onward, the rate of carbon emissions has increased with time.

Unfortunately, that’s not the reality that we’re dealing with. We’ve been measuring the concentration of carbon dioxide in the atmosphere — long known to be the primary driver of the greenhouse effect here on Earth — for many decades, and we’ve also been measuring and quantifying the total global emissions (including broken down by country) for long periods of time as well. While it is true that the United States has reduced its greenhouse gas emissions from a high of around 6 billion tons of carbon dioxide per year down to a more modest 5 billion tons of carbon dioxide per year, increases elsewhere in the world, particularly in China and India, have more than offset that.

The reality is that back in the early 1990s, when scientists were first sounding the alarm about global warming, global carbon dioxide emissions were just a shade over 20 billion tons per year. As of 2023, the latest year for which cumulative data is available, that budget is now just under 40 billion tons per year: a near doubling of global emissions in less than 35 years.

At the same time, the fraction of planet Earth’s landmass that can be considered wilderness has been diminishing extremely rapidly. Back in 1900, less than 25% of Earth’s landmass was used for human purposes like agriculture; as of 2018, only 23% of Earth’s landmass was still wild in any way.

These graphs show the carbon emissions broken down by the top polluting countries (top) and by global carbon emissions (bottom). Despite an ongoing goal of reducing carbon emissions, humanity has continued to only increase our greenhouse gas output overall.

In other words, even as greenhouse gas emissions rose and rose, without bound, the natural regulating factors present on Earth have been systematically removed by human activity. All of this has led to a predictable but difficult-to-accept result: that not only has Earth’s temperature been continuing to warm, but that the warming we’re observing has been accelerating. Whereas it looked for a long time like Earth’s temperatures were rising by about 0.07 °C (0.13 °F) per decade throughout the 20th century, that rise has been quantified to be more like 0.18 °C (0.32 °F) here in the 21st century. Moreover, the closer we come to the present day, the more severe that warming is.

Many prominent climate scientists have continued to raise the alarm about this. Robert Rohde, the leader of Berkeley Earth, has stated, “The abrupt new records set in 2023 and 2024 join other evidence that recent global warming appears to be moving faster than expected.” Meanwhile, climate scientist Gavin Schmidt, director of the NASA Goddard Institute for Space Studies, noted, “The long-term trends are very, very clear. It’s warming more over the land than it is over the ocean. It’s warming more in the Northern Hemisphere, where there’s more land, than in the Southern Hemisphere, where there is less. And it’s warming most of all in the Arctic regions.”

According to Berkeley Earth temperature data, 24% of the entire planet’s surface, including 32% of land masses and 21% of ocean area, had their warmest year on record in 2024. Many other places experienced top-5 warm years, while nowhere on Earth, even in Antarctica, recorded their coldest year on record in 2024.

On January 10, 2025, three different global temperature assessments — NOAA, NASA, and Berkeley Earth — were released. Compared to the preindustrial baseline period (taken to be 1850-1900), they found, respectively, that global average temperatures were 1.46 °C (2.63 °F), 1.47 °C (2.65 °F), and 1.62 °C (2.91 °F) hotter as of 2024.

They found that 2023 was warmer than all prior years, and that 2024 was hotter still: besting 2023 by a global average of 0.10 °C (0.18 °F).

They found that 32% of all global land areas, along with 21% of all ocean areas, had their warmest year of all-time occur in 2024. This means that 3.3 billion people, across a total of 104 separate countries, experienced their hottest year on record in 2024.

And even though there were several external (i.e., non-human) factors that were at play in 2023 and 2024:

• the 2023 transition from La Niña to El Niño conditions,
• the 2024 peak of the 11-year solar cycle,
• and the continued atmospheric effects of the 2022 Hunga Tonga eruption,

the overwhelming majority of the temperature rise is definitively attributable to human-caused emission of greenhouse gases, primarily carbon dioxide. As Gavin Schmidt put it, “We anticipate future global warming as long as we are emitting greenhouse gases, and until we get to net zero, we will not get a leveling off of global mean temperature.”

This graph shows the global average temperature anomalies relative to the 1850-1900 baseline. The red line shows the multi-year moving average of global temperature, while the dotted green line shows a linear fit to the warming from 1974-2022. As recent years show, the warming trend has accelerated in recent years, with 2023 and 2024 marking severe departures from the late-20th century trend.

So what are we to do in this situation, as a species that’s dependent on our planet for our survival?

There are two paths that are being presented to people: one of which is scientifically sound and the other of which is highly dubious. The scientifically sound solution is to address the underlying causes of climate change, by reducing greenhouse gas emissions (particularly carbon dioxide), maintaining and restoring wild places such as forests and shrubland that serve as carbon sinks, and by transitioning from fossil fuel-using sources of energy like coal, oil, and natural gas to clean sources like nuclear, solar, hydroelectric, and wind power.

Of course, those solutions cost money and take time to implement at large scales, and are violently opposed by industries that rely on fossil fuels such as coal, oil, and natural gas. The dubious solution, often offered as either a “stopgap” measure (i.e., to mitigate warming until we can fully transition away from a heavily carbon-polluting economy) or as a wholesale solution to global warming, is instead to geoengineer a climate solution. These geoengineering solutions are normally focused on one of three avenues:

• carbon capture and storage, which is expensive and, to date, has captured less than a cumulative total 1 billion tons of carbon dioxide,
• launching a series of mirrors or lenses to decrease the total amount of incoming sunlight that strikes Earth, a very expensive and labor-intensive (but temporary) fix,
• or via cloud seeding, which seeks to reflect a large amount of incoming sunlight back into space, keeping the Earth cooler than it would be without clouds.

In 2024, cloud seeding operations were conducted in Malaysia: not to reduce global warming, but to trigger precipitation over a highly populated area with insufficient rainfall and water resources.

That last option, unfortunately, is being seriously pursued by many as a legitimate option for combating global climate change. We have known for decades that it is not. In the aftermath of September 11, 2001, the grounding of airplanes in the U.S. and Canada provided us with a laboratory to measure the effect of cloud seeding directly: by not having airplanes flying through the skies, emitting particulates that seed clouds in the upper atmosphere. What we found, shockingly to many, was that those artificially produced clouds created an effect called global dimming: an effect that masks about 30% of the natural warming we’ve already caused on our planet.

Whenever we stop seeding/producing these clouds, we can acquire a much more accurate measurement for how significant the problem of global warming actually is: about 30% more severe than what we’re currently experiencing. That warming is just “in the pipeline,” and hasn’t been seen yet because we’re already reflecting larger-than-natural amounts of sunlight away from Earth.

However, we can’t just keep on adding more clouds as natural warming intensifies, as that short-term fix is destined to lead to even more severe long-term consequences.

This diagram shows the energy budget of Earth, with incoming and outgoing radiation (values are shown in W/m^2). Satellite instruments (CERES) measure the reflected solar, and emitted infrared radiation fluxes. The energy balance determines Earth’s climate and temperature. When the Sun is directly overhead, atmospheric absorption is minimal, allowing for the best surface measurements of incident solar radiation on Earth.

Naturally, Earth’s atmosphere is composed primarily of two gases:

• nitrogen gas, which makes up about 78% of our atmosphere,
• and oxygen gas, which makes up about 21% of our atmosphere.

There’s a small amount of the noble gas argon, a little bit of water vapor, which varies drastically dependent on other conditions, and then there are lower concentrations of gas that are largely transparent at optical (visible light) wavelengths but that readily absorb infrared radiation: gases like carbon dioxide, carbon monoxide, methane, and other compounds involving atoms like sulfur.

According to Berkeley Earth, “In general, sulfur aerosols are believed to have masked some of the effects of global warming… [we can] anticipate that global warming may continue to accelerate if additional reductions in sulfur air pollution are undertaken.”

So you might think, “Oh, all we have to do is pollute the atmosphere with cloud-seeding particles, such as sulfur aerosols, and we can safely continue to burn fossil fuels for our energy needs, increasing the carbon dioxide content for a while longer without having to reckon with those consequences.” That’s a recipe for the ultimate disaster: unchecked warming that we’re artificially masking through these geoengineering shenanigans. To understand why, let’s take a look at a graph of Earth’s carbon dioxide levels historically: going back hundreds of millions of years.

This graph shows the inferred atmospheric concentration of carbon dioxide (red) and oxygen (blue) as a function of time. A remarkable drop in carbon dioxide concentration coincides with the colonization of continental land by plants, particularly trees, here on Earth, just under 400 million years ago.

In particular, take a look at what the conditions were on Earth prior to the late Devonian period, and contrast that with what happened during the Carboniferous period. Earth’s atmospheric carbon dioxide levels were once astoundingly high: hovering at around 4000 parts-per-million. (For comparison, they were around 270 parts-per-million prior to the industrial revolution, and stand at around 420 parts-per-million today, here in 2025.) But by the time we arrive at the Carboniferous period, those levels have plummeted, and are instead down to just a few hundred parts-per-million.

What happened?

The short answer is simple: trees. While plants had been in existence for hundreds of millions of years, they were largely confined to watery environments for most of their history. The first land plants arrived on Earth roughly 470 million years ago, but remained confined to regions that were near water. When trees arose, however, roughly 385 million years ago, they possessed a number of evolutionary advantages. With woody trunks, they could rise to greater heights than all other plants, gaining a winning advantage for soaking up sunlight. With a rich root system to support that weight, they could burrow into the ground, absorbing water even when there was no rainfall.

So long as there was bare land on Earth, and so long as temperature, precipitation, and soil conditions permitted it, plants and trees could colonize the planet’s surface. And they did so: all over the world.

Carbon emissions under the 5 scenarios considered by the IPCC in their 6th and most recent (2021) report. Emissions are measured in billions of tons of carbon dioxide per year (y-axis). The blue scenarios are dependent on immediate and rapid decarbonization, while the orange line assumes substantial steps occurring in short order to reduce emissions. The redder scenarios are far more troubling, and possibly a more realistic reflection of the status quo. We know that our waste products are poisoning our environment; only the severity and eventual outcome remain to be fully determined.

That’s where today’s “fossil fuels” come from: not from dinosaurs, but from the ~100 million years where trees thrived across planet Earth, but where there were no fungal decomposers to dispose of them. Dead trees fell, were buried, and became today’s fossil fuels: oil, coal, and gas. When we extract them and burn them, we’re taking that long-buried carbon and putting it back into the atmosphere. And the longer we do that, the greater the greenhouse effect is going to be on planet Earth. Employing a stopgap measure such as cloud seeding only gives us a false sense of security: the idea that global warming isn’t as big of a problem as it really is.

Remember: today’s carbon emissions don’t lead to today’s warming; warming lags emissions by several decades, perhaps more like ~50 years. The worst effects of global warming, therefore, are yet to come, and this problem only intensifies the longer we continue to expel carbon dioxide, unchecked, into the atmosphere. Cloud seeding may indeed lower the amount of incident sunlight that strikes the Earth, but it does so at the expense of putting additional pollutants — and more carbon dioxide — into the atmosphere, exacerbating the underlying problem overall. That’s not a solution by any means. A solution would involve capping and ultimately zeroing-out carbon emissions, while reforesting large portions of the Earth. The longer we fail to address those critical needs, the longer global warming will proceed at an accelerating rate, and the hotter planet Earth will get, globally, as a result.