An updated road map for combating climate change pours cold water on the idea that unproven technologies can play a major role in averting disaster.

Today, the International Energy Agency (IEA) updated its road map for the energy sector to reach net-zero greenhouse gas emissions by 2050. It doubles down on the need to swiftly switch to renewable energy while minimizing the use of technologies that are still largely in demonstration and prototype phase today, including carbon capture and hydrogen fuels.

The IEA, initially created to safeguard the world’s oil supply, debuted its landmark road map in 2021 with a stark forecast for fossil fuels: calling for no more investment in new oil, gas, and coal projects. It laid out steps every country on Earth needs to take in order to meet the goals of the Paris climate accord, which seeks to limit global warming to roughly 1.5 degrees Celsius by reaching net-zero emissions. But the planet is still heating up, reaching 1.2 degrees Celsius — triggering more extreme weather and climate disasters and pushing the IEA to revise its global road map to address new realities.

The biggest difference in this new report is that emerging technologies that have gotten a lot of hype as high-tech fixes to climate change now play a significantly smaller role than expected in 2021. Those technologies, which include hydrogen fuel cells for heavy vehicles and devices that filter CO2 emissions from smokestacks or ambient air, now account for 35 percent of emissions reductions rather than nearly 50 percent.

Why? They just haven’t lived up to the hype, the report says pretty plainly.

“I think that some realism has kicked in from this, and I wonder how that realism from this report will kind of perforate through those industries,” says Dave Jones, global insights lead at energy think tank Ember.

Today, “hydrogen production is more of a climate problem than a climate solution,” the report says. Hydrogen as a fuel is nothing new, but most of it is still made using gas. Some countries, including the US, are investing in ways to make hydrogen more sustainable by using renewable energy or fossil fuels paired with carbon capture. If it takes off, it could create cleaner fuel for planes, ships, or trucks.

But building out the infrastructure to transport hydrogen is proving to be a bigger barrier than anticipated, Jones says. On the other hand, electric charging infrastructure, while still limited, is growing much more rapidly. The IEA’s updated road map shrinks the share of fuel cell electric heavy-duty vehicles on the road in 2050 by up to 40 percent compared to its initial 2021 forecast.

The road map similarly cuts down the role of carbon capture technologies by around 40 percent in emissions reductions from power generation. “So far, the history of [carbon capture] has largely been one of unmet expectations,” the IEA’s new report says. The US Department of Energy (DOE) has wasted hundreds of millions of dollars on failed carbon capture projects mostly because of “factors affecting their economic viability,” according to a 2021 report by the Government Accountability Office.

“Removing carbon from the atmosphere is very costly. We must do everything possible to stop putting it there in the first place,” IEA executive director Fatih Birol said in a press release. If pollution doesn’t fall fast enough and the planet warms beyond 1.5 degrees, countries can attempt to use carbon capture technologies that are “expensive and unproven at scale” to try to reverse some of that warming, the press release says. But relying on those technologies would come with heightened climate risks.

Renewable power capacity globally needs to triple by 2030 in order to stop generating planet-heating pollution in the first place, the report says. Spending on clean energy would need to more than double from $1.8 trillion this year to $4.5 trillion by early next decade. Energy efficiency also has to double within the same timeframe, and the world’s wealthiest countries need to reach net-zero emissions years ahead of the global 2050 target.

The timing of this updated road map is important. It follows the United Nations’ first global report card on how well countries are tackling climate change. In short, they’ve fallen behind, as emissions continue to rise despite the need to limit warming to 1.5 degrees.

The UN held a climate summit in New York last week to push countries to ramp up their clean energy commitments, but heads of state from the countries with the biggest carbon footprints — China and the US — didn’t participate. They’ll have another shot during a larger UN climate conference that starts in Dubai in November.