"Because of the complexity of the Earth's system, things are not as simple as "one ton of CO₂in, equals one ton of CO₂out," says Kirsten Zickfeld, a distinguished professor of climate science in SFU's Department of Geography, and lead author of a new paper published this week in the journalNature Climate Change. "CO₂emissions are more effective at raising atmospheric CO₂concentration than CO₂removals are at lowering it."

According to Zickfeld, this "asymmetry" implies that a larger amount of CO₂removal is required to compensate for a given amount of CO₂emissions if the atmospheric CO₂concentration is to remain unchanged.

Researchers used a series of climate model simulations to test whether the change in climate resulting from CO₂emissions and removals is asymmetric. Their results showed that the rise in the atmospheric CO₂concentration following an emission is larger than the decline following a removal of the same magnitude.

Findings of the study infer that balancing a given amount of CO₂emissions with an equal amount of CO₂removals could lead to a different climate outcome than avoiding the CO₂emissions.

"Our study suggests that assuming exact balance between CO₂emissions and an equal amount of CO₂removals in a net-zero framework risks blowing climate targets," she says.

While Zickfeld says that balancing emissions with CO₂removals of the same magnitude could lead to different climate outcomes, further study is needed to learn more about the extent of this effect.