Natural ‘carbon sinks’ not enough to achieve net-zero emissions targets

Two Victoria scientists are among a group of international climate researchers urging policymakers to be more realistic when determining net-zero carbon emissions targets.

The local climate scientists co-authored a study recently published in Nature, outlining the need for reduced fossil fuel emissions to achieve net-zero emissions targets.

The study says many policymakers and corporations rely too heavily on “carbon accounting,” pointing to carbon offsets and natural carbon sinks, such as forests, as a way to balance carbon outputs. The paper argues that these carbon sinks are not enough to keep up with the level of emissions and that ending fossil fuel reliance is the only effective way to reach net-zero emissions.

Andrew Weaver, UVic climate scientist—and former Oak Bay-Gordon Head MLA and BC Green Party leader—told Capital Daily that the study, which he co-authored, was an update to research papers he and fellow UVic scientists put out in 2007-2009. These papers defined the need for ‘net-zero’ global emissions to achieve climate targets. But policymakers, according to Weaver, misinterpreted what was meant by that.

“We were very clear as to what ‘net zero’ met back in 2007, 2008,” Weaver said. “But as policy deliberations and negotiations continued forward over the next 15, 16, 17 years at the international negotiating level, the definition of ‘net zero’ started to creep in terms of beginning to allow countries to take credit for natural sinks of carbon as a somehow negative emission.”

Weaver says that by hiding behind this “carbon accounting,” we falsely equate actions like funding a kelp farm or protecting forests to cancelling out carbon emissions from fossil fuels. “It doesn’t work that way,” he said.

“We as a community—the 25 scientists involved in this—basically the people who defined this area, this whole field, put this paper together to clarify what ‘net zero’ meant because of the kind of carbon accounting that was occurring.”

Political timelines don’t match the science

He says the big issue is “a timescale mismatch.”

Millions of years ago, the atmosphere had significantly more carbon present and the planet’s temperatures were far hotter. Over those millions of years, plants slowly captured the carbon and stored it. As these plants and animals died and were buried within the earth, they turned into coal and oil. As we burn these fossil fuels, we release this ancient carbon back to the atmosphere.

“We're putting up the carbon that was in the atmosphere hundreds of millions of years ago, back into the atmosphere on the time scale of a few decades,” said Weaver.

It would take the earth millions of years to recapture it naturally, making it impossible to prevent global warming with passive solutions alone. The study argues that the concept of "net-zero" emissions must be interpreted as “geological net zero”—the planet’s natural ability to capture carbon in the earth.

When it comes to fighting global warming, time is of the essence. This year is on track to be the first to breach the global warming limit of 1.5C since pre-industrial levels, a target seen as paramount to prevent the worst effects of climate change. The Paris Agreement, signed by 196 countries including Canada, aimed to keep warming to below 2C, with the ultimate goal of preventing an increase past 1.5C.

Local co-author of the study, Nathan Gillett from the Canadian Centre of Climate Modelling—a sector of Environment Canada that conducts research in Victoria—says that while it’s “pretty much impossible” to keep warming below the 1.5C threshold, there’s still hope to keep it below 2C.

“But certainly, it would take strength in climate action internationally to achieve that,” he said.

Canada’s reliance on natural sinks not enough to offset emissions

Canada has relied on its forests as a natural carbon sink—in 2019, Prime Minister Justin Trudeau tweeted a promise to plant 2 billion trees by 2030 to help the country reach its climate goals. But last year, an audit of the program found that it was unlikely to even get one-tenth of those trees planted within the 10-year timeframe. Within the first two years, it had only achieved 0.4% of its goal.

Natural gas companies like LNG Canada have pointed to offset projects like creating wetlands and biodiversity initiatives as being able to reduce its carbon footprint, a tactic that Weaver calls misleading.

As the climate shifts, Canada’s wildfire seasons have also intensified—last year’s fires were the worst on record for the country, making Canada a top carbon emitter and decimating forests across the country. Not only do these fires create more atmospheric carbon, but they also destroy these natural carbon sinks the government has based its policies on.

“If you're going to plant a billion trees, how are you going to stop them from burning and dying? You're not,” Weaver said.

While both Weaver and Gillett say these natural carbon sinks remain important in the fight against global warming, they say they’re simply not enough to solve the problem without other strategies. The most effective solution, according to both researchers, is to stop the reliance on fossil fuels.

‍ Carbon capture technologies could be a solution, but remain in early stages

Another potential solution, says Weaver, would be to invest in carbon capture technology. Carbon capturing systems, like the one in Squamish can capture a higher amount of carbon from the atmosphere, making it a far more effective offset than planting trees.

“Rather than spending all our time trying to figure out how we can game the system, what we should be doing is enhancing our research and development in that particular area,” Weaver said.

Furthermore, he said, pushing for investment in this technology is necessary if BC is going to continue to rely economically on various fossil fuel projects.

“The new government in BC has to deal with the elephant in the room, which is the fact that they cannot make their legislative greenhouse gas reduction target of a 40% reduction of emissions by 2030,” Weaver said. “They're just not going to be able to make it, because nobody is going to accept the fact that LNG Canada's massive growth in emissions can somehow be offset by preserving a forest.”

Gillett says that while carbon capture technology is great in theory, implementing it at the scale needed poses a challenge. In the timeframe we have, ending fossil fuel emissions is likely the only effective approach, he said.

“If you look at IPCC assessments, you look at this study, or any other studies, you'll find that to get to net zero, you really have to get fossil fuel emissions to pretty close to zero,” Gillett said.