Tech companies think they can reverse climate change with fancy new tools to take carbon dioxide out of the atmosphere. But new research throws cold water on the idea that cooling the planet after it has already heated beyond a key turning point can avoid serious damage. Much of the toll climate change takes — from rising seas to lost homes — can’t be undone, recent research published in the journal Nature warns.

That makes it all the more urgent for governments and companies with climate goals to slash pollution from fossil fuels now, rather than offsetting or capturing their greenhouse gas emissions after the fact.

“Climate change comes with irreversible consequences. Every degree of warming, or every point of a degree of warming … comes with irreversible consequences,” Carl-Friedrich Schleussner, lead author of the paper and head of the integrated climate impacts research group at the International Institute for Applied Systems Analysis, said in a call with reporters before the paper was published.

Startups are developing a whole suite of technologies to try to help big polluters capture their carbon dioxide emissions — from filtering CO2 out of the air or ocean to trapping CO2 in rocks or concrete. These technologies still have to prove whether they’ll be able to scale up to a level that would make a meaningful impact on climate change.

Tech giants like Microsoft and Google have been among the biggest supporters of these emerging carbon removal tactics. They’ve made commitments to eventually reach net zero or net negative emissions, but their carbon footprints have grown in recent years as they expand data centers for AI. And there isn’t enough renewable energy installed yet to run these companies’ operations without still generating greenhouse gas emissions. Increasingly, tech companies are inking carbon removal deals to try to reverse the impact their pollution has had on the climate.

Globally, emissions need to reach net zero around 2050 to keep the planet from heating up much more than it already has. Nearly every nation on Earth has signed onto the Paris climate agreement of stopping global average temperatures from exceeding roughly 1.5 degrees Celsius above temperatures before the Industrial Revolution. The world is quickly approaching that threshold — having warmed by around 1.2C already, which is supercharging climate-related disasters like monster storms and wildfires.

One of the hopes with carbon removal is that it can potentially reverse climate change, bringing temperatures back down if we overshoot that 1.5-degree target. But things won’t just go back to normal, the new research conducted by 30 scientists shows. Melting ice from glaciers would continue to raise sea levels “for centuries to millennia,” for example, a phenomenon that has already pushed people from their homes along vulnerable coastlines. And even if the globe’s average temperature comes back down, it’s hard to say exactly what outcome to expect from region to region.

The recent devastation caused by hurricanes Helene and Milton — disasters exacerbated by climate change — shows what’s at stake if we wait to take action. The number of lives and homes lost to these kinds of catastrophes keeps growing the longer we fail to stop climate change. And repeated disasters take a compounding toll on the communities that are most at risk. Florida barely had any time to recuperate from Hurricane Helene before Milton hit less than two weeks later.

Overshooting climate targets “entails deeply ethical questions of how much additional climate-related loss and damage people, especially those in low-income countries, would need to endure,” the paper says.

There’s also the possibility that the planet could heat up more than anticipated. Scientists calculate carbon “budgets” to figure out how much carbon dioxide humans can release before missing climate targets like holding warming at 1.5 degrees. But those estimates aren’t exact. The pollution “budget” we think we have left could, in reality, lead to more severe climate change than expected.

In that case, we might also need more carbon dioxide removal than expected to stabilize the climate. But scaling up carbon removal to that level might not be feasible. If greenhouse gas emissions raise temperatures higher than expected, it could take several hundred gigatons of carbon removal to prevent more severe climate impacts, according to the paper.

“Although this concept is interesting, it assumes that there will be a reserve of [carbon dioxide removal] capacity that can be deployed rapidly world-wide — an assumption that I would consider overly optimistic,” Nadine Mengis, a research group lead at the GEOMAR Helmholtz Centre for Ocean Research, writes in a separate Nature article commenting on the research.

Existing facilities that can filter carbon dioxide out of the air only have the capacity to capture 0.01 million metric tons of CO2 globally today, costing companies like Microsoft as much as $600 per ton of CO2. That’s very little capacity with a very high price tag.

“We cannot squander carbon dioxide removal on offsetting emissions we have the ability to avoid,” study coauthor Gaurav Ganti, a research analyst at Climate Analytics, said in a press release. The priority needs to be preventing pollution now instead of cleaning it up later.