Dozens of countries have pledged to achieve net-zero carbon emissions within the next few decades.
But the strategies — critical to halting climate change — are missing key details. Namely: how much leftover emissions will need to be sucked out of the air to meet the net-zero goal.
A new study finds that most countries haven’t predicted how much pollution they will need to offset to hit net zero by 2050. The estimates that do exist range anywhere from 5 percent to 52 percent of a country’s peak carbon emissions.
It’s the latest finding in a growing body of research on countries papering over the obstacles to achieving net-zero emissions. Carbon removal is still far from being deployed on a large scale, meaning many countries are counting on an untested technology to offset a big chunk of their emissions and meet climate goals.
Instead, world leaders should strive to achieve net zero with as few residual emissions as possible, experts say, and plan accordingly.
“If you’re planning for infrastructure that has a lifetime of decades, you want to make sure you are investing in the right things,” said Holly Buck, a climate policy expert at the University of Buffalo. “So you don’t want to invest in, for example, new fossil fuel infrastructure if you want those residual emissions in 2050 to be low.”
But most nations around the world don’t yet have detailed long-term plans in place.
While 195 countries ratified the Paris Agreement, only 72 submitted voluntary long-term strategies that lay out how they plan to achieve a low-carbon economy by 2050. Of those, just 26 include an estimate of future residual emissions, according to a study published this month in One Earth journal.
“We were surprised at how few countries report these emissions,” said lead author Harry Smith, a doctoral student at the University of East Anglia in England.
The ones that do report residual emissions vary in their predictions. Most wealthy countries — which have historically emitted the most planet-warming emissions — project residuals in the 5 to 15 percent range in 2050, meaning they aim to decarbonize most of their economies.
But Canada presents a range of possible future scenarios, including residuals totaling anywhere from 17 to 44 percent of the country’s peak emissions. Australia’s scenarios range from 36 to 52 percent.
These higher-end estimates suggest that some countries don’t plan to decarbonize everything possible. Instead, they might choose to continue emitting carbon in some sectors — even ones that could be easily decarbonized — while buying carbon offsets from other countries or using carbon removal technology to counterbalance the pollution.
Canada’s long-term strategy, for instance, explicitly states that “fossil fuel production and consumption could remain higher” if carbon removal technologies become viable at large scales.
That’s a big gamble. While carbon removal is swiftly growing in popularity, it isn’t yet happening at the scales necessary to meet the Paris climate targets, and it’s unclear how quickly the technology will advance in the coming decades.
The study highlights other causes for concern as well.
The long-term strategies identify agriculture as the single largest contributor of residual emissions. But the ways countries could cut down on their agricultural emissions, like reducing the amount of meat they consume, are complex and politically difficult to achieve.
These kinds of demand-side interventions are “quite off the table for many governments,” Smith pointed out.
The long-term strategies also tend to omit aviation and shipping emissions from their residual estimates. Those sectors, however, are widely regarded by experts as among the most difficult to decarbonize, making them obvious sources of future residual emissions.
That means even the few countries that have come up with residual emission estimates are likely still underestimating them.
Vague promises
The new study isn’t the first to raise these concerns.
Beck published a similar paper last year in Nature that also found that most long-term strategies don’t address residual emissions, and those that do tend to be vague about where such emissions originate and exactly how they might be counterbalanced with carbon removal.
The study looked mainly at long-term strategies with the lowest residual emission estimates. Even in those best-case, most ambitious scenarios, it found that countries expected their leftovers to amount to an average of 18 percent of their current emissions.
Other research groups are tracking the net-zero timelines that countries around the world have announced in recent years, whether or not they’ve been formally described in a long-term strategy.
Many of them, including the U.S., are striving to achieve a net-zero economy by the year 2050. That’s in keeping with guidance from the U.N.’s Intergovernmental Panel on Climate Change on how to meet the Paris Agreement’s most ambitious target of keeping global warming below 1.5 degrees Celsius.
Yet many of these timelines fall short when it comes to long term strategy, research groups have found.
The Climate Action Tracker, an independent scientific consortium that monitors government climate efforts, evaluates countries’ net-zero targets. The project has found that most net-zero strategies are vague and don’t comply with the best practices encouraged by scientists for long-term planning.
CAT’s guidelines suggest that countries include transparent assumptions about future carbon removal. They also discourage countries from cleaning up their residual emissions with offsets purchased from other places, recommending that leftover emissions be counterbalanced within a nation’s own borders.
“The more comprehensive and transparent a country is with its net zero target, the better the CAT will evaluate the country’s target,” Sarah Heck, a climate policy analyst with the nonprofit Climate Analytics and a team member at the Climate Action Tracker, said in an email.
So far, the organization has awarded an “acceptable” rating to only a handful of net-zero strategies, including ones from Chile, Colombia, Costa Rica, the United Kingdom and the European Union.
‘PDFs that sit in a folder’
Experts agree that countries should develop detailed, long-term plans for achieving net zero — and dealing with residual emissions is key to those strategies. But that’s still easier said than done.
There’s no indication that long-term strategies will become mandatory under the Paris Agreement anytime soon. And making them a requirement could become a burden for countries with limited resources or political buy-in for long-term economic modeling and detailed policy planning.
Making long-term strategies a bigger priority under Paris would require more resources for countries to invest in their planning, Buck said.
“To me, the story is that we’re not doing a serious planning effort and we need a lot more resources devoted to that,” she said. “Not just technological modeling, but stakeholder and public engagement and buy-in to make these real plans rather than PDFs that sit in a folder.”
Meanwhile, the international community could also develop more detailed, standardized guidance for what acceptable long-term strategies should look like, Buck added.
Many experts suggest that countries should have separate targets for reducing emissions and counterbalancing with carbon removal. The emissions reduction targets should be ambitious, they say, decarbonizing everything except the sectors that are difficult or impossible to mitigate. Only then should countries begin mopping up with carbon removal.
The split targets would help discourage countries from continuing to burn fossil fuels and assuming that carbon removal — with all of its uncertainties — will solve the problem down the road.
Countries should also make residual emissions a focus of their innovation efforts, Smith said, striving to develop new technologies and new policies specifically designed to reduce these future leftovers.
And countries shouldn’t just assume that some residuals are inevitable, Buck added. Technology is evolving all the time, meaning sectors that are difficult to decarbonize today might be easier to clean up in the future.
“The expectations of residual emissions change as technology matures,” she said. “It’s important that we continually update these projections and assumptions.”
