Net Zero targets promise to reduce greenhouse gas emissions as much as possible and “offset” the remainder in one of two ways: first, paying someone else, somewhere else, to reduce emissions on your behalf; second, by storing carbon in “carbon sinks”—for example, by planting trees or restoring wetlands—that reduce carbon dioxide concentrations in the atmosphere.
Countries, cities, and companies from around the world have set Net Zero targets for years between 2040 and 2050. President Biden announced that the United States aims to reach Net Zero by 2050, the same target set by Massachusetts, California, New York, Hawaii, and the District of Columbia. Since it is not possible to reduce global emissions to zero with today’s technology, Net Zero targets provide wiggle room to meet some portion of emission reduction targets with carbon offsets: outsourcing emission reductions to other states or countries.
The Net Zero debate centers around one question: What “counts” as an offset? Ultimately, carbon offsets are only truly beneficial for the climate when they are:
Real—carbon sequestration has actually occurred;
Verified—carbon sinks are recorded, monitored and tracked by a reputable, impartial entity;
Permanent—carbon that is sequestered does not get re-released into the atmosphere later (for example, if you plant a tree, it should not be later cut down); and
Additional—carbon being sequestered would not have been stored without the incentive provided to enact this measure.
The final requirement for offsets to be beneficial for the climate—that the offset is “additional” to what would have been done otherwise—is particularly contentious.
For example, in May, the Boston Globe published the results of a collaboration between ProPublica and MIT Technology Review that demonstrated how complicated issues around “additionality” can become. California’s Air Resources Board oversees a statewide forest offset program that has allowed conservation organizations—like Mass Audubon society—to earn carbon credits for preserving trees (rather than logging them). They can sell these offsets to polluting companies, giving them the right to emit more than permitted by California law. In theory, these transactions “net” out any increase in emissions from polluters by preserving forests. However, this would only be true if the trees preserved by Mass Audubon were ever really at risk of being logged—if the trees were never truly at risk of being logged, then the carbon stored by preserving them was not “additional” to what would have happened in the absence of the credit trading system. On the flip side, the sale of carbon credits has generated millions of dollars in revenue for Mass Audubon to acquire more land to preserve, and the representatives from California’s Air Resources Board point out that it would be “unrealistic and impractical” to create criteria to demonstrate or refute “additionality”—an intention to cut down a tree or not.
This example points to some problematic side effects of combining emissions reductions and carbon offsets together into a single target of reaching Net Zero. Every emission credit that does not lead to a true reduction in net emissions not only fails the “additionality” test, it also has the effect of delaying emission cuts until later. Recent research by the Lancaster Environment Centre suggests a different approach: first reduce emissions as much as possible and then, separately to match remaining recalcitrant emissions to carbon sinks. Treating emission reductions and emissions offsets separately helps to ensure that carbon offsets are truly additional and beneficial for the climate.
