As carbon offsets, tree planting can be shady

There is nothing like a tree. It is one of nature’s most generous multi-taskers, providing food, fiber, fuel, shade and habitat for humans and wildlife alike. Forests are a vital part of the Earth’s water and carbon cycles. The planet’s 3 trillion trees provide some of the last wild places on Earth.

However, one benefit of trees is now getting particular attention. Trees inhale and store carbon dioxide (CO2), the gas most responsible for climate change. We produce most of it when we use fossil fuels. Other natural “carbon sinks” absorb it, too, including oceans, wetlands and soils. Protecting, restoring and conserving them is the least-expensive and most readily available hope for stabilizing the planet’s climate.

Nations have agreed to reduce their fossil-fuel pollution but not to end it. In 1997, an international treaty codified the idea of “carbon credits.” By 2050, nations are supposed to put no more CO2 into the atmosphere than they are taking out. However, they don’t have to eliminate all their pollution; they can take credit for paying others to reduce theirs.

For example, a coal-fired power plant could cut its CO2 emissions by 50 percent and offset the rest by paying somebody else to reduce emissions. The idea was to encourage polluters to help fund clean-energy projects in the developing world. The downside, however, is that the world can keep using fossil fuels, although fewer.

Yet, we will not stop climate change by throwing a lifeline to polluters. The cheapest, most immediate and fool-proof way to confront climate change is to leave fossil fuels in the ground. That’s what climate scientists say. They advise that most of the world’s underground coal, oil and natural gas reserves must stay there.

In most places today, solar and wind energy can generate electricity at a lower cost than fossil fuels while improving air quality and public health. Governments should shift their trillions of dollars of energy subsidies to the world’s rapid transition to these clean and inexhaustible resources.

Fossil energy supporters say new technologies will keep CO2 out of the air and take out the CO2 already there. But no cost-effective technology is on the drawing board or the near horizon to do these things. While we wait, pollution continues — and climate change becomes harder to reverse. There is no substitute, natural or otherwise, for retiring fossil fuels from the world economy.

The international community has defined the path to climate stability in three stages. The first is net-zero carbon, the goal described above, where we offset CO2 going into the atmosphere with the amount we and nature remove. That’s to be accomplished by 2050. The second stage is “net-negative carbon,” where we remove more CO2 from the atmosphere than we put in. That’s supposed to happen in the second half of this century.

The ultimate goal is to bring the carbon concentration in the atmosphere down from its present level of nearly 420 parts per million (ppm) to 350 ppm, generally considered safe. Success gets more complicated and expensive every day we keep dumping greenhouse gases into the atmosphere.

The United Nations reports more than 70 countries accounting for 76 percent of global emissions have committed to achieving the first step. In addition, more than 3,000 businesses and financial institutions have set science-based targets for emission cuts, while more than 1,000 cities, 1,000 educational institutions and 400 financial institutions have joined a “Race to Zero.”

Since an effective and affordable technical fix is unavailable, restoring and conserving nature’s carbon sinks is critical — and tree-planting pledges are proliferating. For example:

• Shell says it will spend $300 million over three years to plant planting more than 5 million trees and ultimately plant and conserve 1 billion trees through 2030.
• The World Economic Forum spearheads a campaign to protect or plant 1 trillion trees by 2030.
• China has committed to planting and conserving 70 billion trees by 2030. The goal for U.S. cities, states and non-Profits is 51 billion trees this decade. India already mobilized 800,000 volunteers who planted 50 million trees in one day, while 23 million volunteers in Ethiopia planted 350 million saplings in 12 hours in 2019.
• President Biden has ordered federal agencies to plant 1.2 billion trees by 2030 to restore national forests destroyed by wildfires and insects.
• An international initiative called the Bond Challenge aims to restore 350 million hectares of deforested land.

Republicans in Congress, many of them climate deniers in the past, have jumped on the tree-planting bandwagon. Reuters reports they feel pressure from voters to do something about climate change and prefer measures that will keep America’s drilling boom going. Apparently, it’s the view that we can have a pleasant climate and ruin it, too.

Similarly, allowing polluters to buy the right to keep polluting is like trying to quit smoking by paying someone else to stop. Instead, we should restore the polluter-pays principle and stop emissions at their source. Carbon offsets are problematic because they contain many uncertainties, especially when they involve dynamic systems like nature.

Reforestation is an example. “The truth is much more complicated than assuming more trees can cancel out emissions,” as MIT Professor Charles Harvey points out. Consider:

• The Carbon Community, a British organization specializing in the climate benefits of trees, notes that despite 30 years of research, “there are big gaps in the science of which trees and how to plant them to most effectively capture carbon.”
• There are more than 73,300 species of trees with different carbon sequestration characteristics. Time is of the essence for preventing climate tipping points. But a forest needs a minimum of 10 years, sometimes up to 25, to achieve its carbon-capture potential.
• Studies reach significantly different conclusions about the potential of afforestation and reforestation. Not all locations are suitable for trees, even where land and water are available. One model shows the planet can accommodate about 500 billion more trees without conflicting with urban habitat and food production. Another study found we could plant 1 trillion trees and offset the last 10 years of greenhouse gas pollution. Either way, the tree-planting goals announced to date may exceed available land.
• Carbon offsets must be permanent, verifiable, quantifiable and enforceable. It’s difficult for carbon offsets to meet those standards. Will future generations protect trees from commercial logging, wildfires, diseases, drought, insects, urbanization and farmland to feed the 10 billion people by mid-century? What should happen if carbon offsets don’t produce the CO2 reductions they promised?

Again, there are hundreds of reasons to protect forests and create new ones — but allowing the world to keep burning fossil fuels isn’t one of them. As the old truism points out, the way to get out of a hole is to stop digging. This generation’s job is to end the fossil-fuel era, not save it.

William S. Becker is a former U.S. Department of Energy central regional director who administered energy efficiency and renewable energy technologies programs, and he also served as special assistant to the department’s assistant secretary of energy efficiency and renewable energy. Becker is also executive director of the Presidential Climate Action Project, a nonpartisan initiative founded in 2007 that works with national thought leaders to develop recommendations for the White House as well as House and Senate committees on climate and energy policies. The project is not affiliated with the White House.