Countries all over the world are counting on a net-zero strategy to eliminate carbon to offset equivalent emissions to help them achieve their climate goals. But a new study by researchers in British Columbia suggests that mathematics may not be that simple.

What does net zero emissions mean?

Net zero emissions or carbon neutrality means that any greenhouse gas emissions produced are “offset” Or offset by removing emissions.

It can be through natural methods (such as tree planting and wetland restoration) or technical methods (such as: Direct air carbon capture(It does not include carbon capture at the source, such as power plants, which only reduces emissions.)

Removal of carbon is seen as a way to deal with the following issues:

Who promises to achieve net zero emissions?

According to the Paris Agreement on Climate Change, the world will Achieve carbon neutrality between 2050 and 2100.

In fact, according to the United Nations, 131 countries have now or are considering the goal of reducing emissions to net zero By 2050, and many companies, cities and financial institutions.They include Canada with Canadian Oil Sands Producer.

Watch | Canadian oil producers aim to achieve net zero emissions by 2050:

Canadian oil sands producers are pooling funds to reduce carbon emissions-but they hope to help fill this gap through taxation, and environmental groups are crucial. 1:50

How do countries and companies calculate net zero?

The lead author of a new study, Professor of Climate Science at Simon Fraser University in Burnaby, British Columbia, said: “Assuming that one ton of carbon dioxide entering the atmosphere is balanced by one ton of carbon dioxide emitted from the atmosphere. Published in the journal Nature Climate Change last week.

Zickfield suspected that this might not be the case. So she and her colleagues did some climate modeling experiments to test this idea.

Why do researchers think that a reduction of one ton may not offset one ton of emissions?

Because they know that many processes in the Earth’s climate system are “non-linear,” Zickfeld said. E.g:

  • With the increase of carbon dioxide, the growth of plants will also increase. However, no matter how much additional carbon dioxide is added, plants can only accelerate their growth before they stabilize.

  • The ocean can absorb some of the extra carbon dioxide emitted into the atmosphere. But as atmospheric concentrations increase, the ocean’s ability to absorb additional carbon dioxide decreases.

Scientists have seen hints that this may mean that carbon emissions and removals are asymmetric—that is, they may have different effects on the same amount of carbon dioxide.

In June 2019, in the World Environment Day announcement at the Ottawa Dominion Botanic Garden, saplings were displayed on the table. Tree planting is another way to remove carbon from the atmosphere. (Justin Tang/Canada Press)

However, because this is not what they are specifically looking for, there are many factors that make it impossible to get a clear answer. David Keller, a scientist at the GEOMAR Helmholtz Center for Marine Research in Kiel, Germany, said who did not participate in this new research, but Do related research.

He said that Zickfeld’s study is the first to truly determine whether carbon emissions and removal of the same amount of CO2 actually offset each other.

How do researchers do it?

To get a clear answer, the researchers used a “medium complexity” climate model.

Keller said that this is the appropriate model they are looking for to make things simple enough to have clear answers to the questions they are asking.

Researchers added and deleted 100 billion buckets (approximately Global annual emissions in 2020) And 1 trillion tons of carbon dioxide emissions. Zickfield said this is approximately the range of emissions we expect to need to remove to achieve Paris’s lower temperature target, which is 1.5 degrees Celsius higher than the pre-industrial period.

Then, they studied the climate impact for the next 1,000 years.

What did they find?

Studies have shown that if you remove and emit the same amount of CO2, you will end up with a higher atmospheric CO2 concentration than if you did not emit CO2. In other words, the result is not net zero.

“And this asymmetry will increase as the number of our emissions and removals increase,” Zickfeld said.

It will not change over time-this difference will still exist after 1,000 years.

On June 22, in Newport Beach, California, a man waded into the sea at sunset. The study found that one ton of carbon removed from the atmosphere and one ton of carbon emitted add up to not zero. This is because natural processes, such as the ocean’s ability to absorb carbon, change as more carbon is added. (Jae C. Hong/Associated Press)


Zickfield said that the two aforementioned “non-linear” processes—changes in plant growth and ocean uptake with increasing carbon dioxide—are the culprits.

The researchers found that the temperature changes associated with adding and removing the same amount of CO2 are also different from the situation where CO2 is never emitted, but the difference is smaller.

Zickfield said the researchers were also unable to determine which case had a higher temperature. In this experiment, it looks like there is no emission, but the preliminary results of other experiments are contrary.

“This is the first step,” Zickfield said. She added that more research is needed to determine details, such as how much removal is needed to offset a given amount of emissions.

What does this mean for net-zero commitments and calculations?

Zickfeld said that we need to be more cautious when considering the removal of carbon dioxide to offset emissions, because the earth is complex and we have not considered many geophysical systems.

“The risk is that we will eventually encounter an unstable climate, and if we do not consider these effects, we may risk exceeding the temperature target,” she said. “My opinion is that because of all these uncertainties in the system, I think the focus should really be on reducing carbon dioxide emissions.”

Keller said that Zickfeld’s research is important because it showed what it was for the first time, but more work needs to be done on this topic. In fact, he is currently conducting similar experiments with different models.

Although this particular study may not be relevant to policymakers, Keller said they should be aware that carbon removal is not the exact opposite of adding carbon dioxide to the atmosphere.

Holly Buck, assistant professor of environment and sustainability at the State University of New York at Buffalo, said these findings are related to discussions about how to implement policies to achieve the net-zero goal.

She foresaw that such research would allow for mathematical corrections in the future to match a certain amount of emissions with a certain amount of removals to ensure they cancel each other out.

“This is the first step, and policymakers should pay attention to this,” Buck said.


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