Alphabet, Microsoft, and Salesforce today pledged $500 million to new climate tech that’s supposed to pull carbon dioxide out of the atmosphere to keep it from heating up the planet. It’s the latest move by Big Tech to propel the emerging technology forward while painting themselves as global leaders when it comes to taking action on climate change.

Regardless, these companies have a lot of work left to do to deal with their own emissions. Carbon dioxide removal (CDR) isn’t the solution for Big Tech’s own pollution.

To be sure, the climate crisis has gotten so bad that the United Nations’ leading climate experts acknowledge that reducing greenhouse gas emissions from fossil fuels won’t be enough anymore. We’ll also have to find ways to draw down tons of CO2 that industry has already pumped into the atmosphere, says a major United Nations climate report published in April.

The UN report, which pulls together the consensus of hundreds of experts across the globe, emphasizes pretty specific, limited uses for CDR. It’s primarily intended to address the legacy of pollution that has piled up since the Industrial Revolution and address a small portion of current emissions that are still really difficult to get rid of using clean energy sources.

Specifically, the UN report says, “CDR to counterbalance hard-to-abate residual emissions is unavoidable” in scenarios that limit global warming to a more manageable level of 1.5 degrees Celsius. In climate policy jargon, “hard-to-abate residual emissions” typically come from just a handful of sectors. That includes heavy industry that manufactures things like cement, steel, aluminum, and chemicals. It also extends to heavy-duty transportation like shipping and aviation.

There’s just as much pressure on those industries to decarbonize as there is on Big Tech. But there are special considerations for heavy industry because it’s still much more difficult to fire up a kiln or fuel a plane with renewable energy. Batteries aren’t advanced enough to power large, electrified ships and planes for long distances without weighing them down. Cement is responsible for a significant chunk of global carbon dioxide emissions, but some of that CO2 comes from a chemical reaction in the manufacturing process — not from burning energy. That’s why those types of industries, compared to other sectors, might rely more on technologies that remove CO2 after it’s already been emitted.

The World Economic Forum launched an initiative last year called the First Movers Coalition — which Microsoft, Salesforce, and Alphabet are members of — that aims to tackle those hard-to-abate emissions.

But for every other polluter outside of those hard-to-abate sectors, including Big Tech, the expectation is that they should prevent the vast majority of — if not eliminate — their emissions. Tech companies might have some residual emissions, perhaps from heavy industry in their supply chains, that they might like to draw down after it’s already in the atmosphere. But for tech companies with much of their business and related emissions in data centers, there’s little excuse for them not to prevent much of their pollution in the first place.

Tech giants that are hyping up carbon removal say that they’re setting up the fledgling CDR market to make it easier for other companies to jump aboard. Getting more backers at this early stage is supposed to make carbon removal more affordable so that it can scale up dramatically.

Back in April, Stripe, Alphabet, Meta, Shopify, and other companies made a $925 million joint commitment to purchase captured carbon this decade. In 2020, Microsoft promised to remove more carbon dioxide than it emits by 2030. Microsoft will “serve as an expert partner by sharing lessons from its carbon removal auctions,” the World Economic Forum says of the new $500 million commitment Big Tech made in Davos.

Yet, despite the cascade of new climate pledges from Big Tech, the emissions of many companies continue to grow. Microsoft’s emissions, for example, rose from about 11.6 million metric tons of CO2 in the 2020 fiscal year to about 14 million metric tons in its 2021 fiscal year. As its business grew, so too did pollution from the use of Microsoft’s devices and cloud services. Salesforces’ planet-heating pollution has similarly grown along with its business in its 2022 fiscal year to the equivalent of over 1 million metric tons of CO2.

Largely through carbon offsets, both companies pay to cancel out enough of their emissions so that they can say they’re carbon neutral. But offset projects, like forest conservation and tree planting, don’t have a good track record of actually permanently removing CO2 from the atmosphere.

Plans to build up the carbon removal market include efforts to try to make it more reliable than traditional offsets. But, for now, the only guaranteed way to stave off the climate crisis is by preventing pollution in the first place. And Big Tech is still responsible for creating a lot of pollution; much of which could be avoided by moving more quickly to clean energy. That deserves as much attention, if not more, as it’s giving to CDR.

“We’re proud of the strides we’ve made but we also rely on a global system that needs to change,” Max Scher, senior director of sustainability at Salesforce, said in an email to The Verge. “We’re focused on what science tells us we must do to limit warming to 1.5C,” Scher said, pointing to renewable energy, nature-based solutions, and “carbon removal that we’ll need in future decades.” Salesforce committed to purchasing $100 million in carbon removal credits as part of the larger pledge today.

Microsoft did not immediately provide comment to The Verge. Neither did Google, whose greenhouse gas emissions have fallen slightly since 2018.