Can you give folks a guide to buying carbon offsets, and do they really work?

Cynthia Ryan, Reno, Nev.

When a company or individual purchases a carbon offset, how do we know if it helps reduce net carbon emissions? Who verifies the claims of the offset providers? Are any tests published?

Patricia, New Orleans

Seven years ago, the University of California set an ambitious goal of becoming completely carbon neutral by 2025. The higher education network contracted with a massive solar farm to power its 10 campuses, replaced buses with electric vehicles and experimented with a new tool that turns food waste into methane. Greenhouse gas emissions are 15 percent lower than they were in 2013 — a substantial change for such a large institution, equal to taking tens of thousands of cars off the road for a year. But it’s still a long way from zero.

The university system’s biggest barriers, according to a 2017 report, were the natural-gas-powered plants that heat and cool its campuses and produce 65 percent of its emissions. Overhauling the plants could cost $3 billion — money the university didn’t have. And even if the plants were made completely electric, the fact remains that California’s electric grid is powered mostly by fossil fuels.

That’s when the University of California turned to offsets.

Without systemic changes in the way society functions — an electric grid powered completely by renewable energy, a food system that generates fewer greenhouse gases, etc. — it is pretty much impossible for a single person or even a large institution to go completely carbon-free.

“The whole purpose of offsets,” said University of California at Berkeley climate policy researcher Barbara Haya, “is to create a way for an individual or a company or a university to pay someone else to reduce emissions to cover emissions that they can’t reduce themselves.”

There are two kinds of offset markets. Mandatory or “compliance” schemes exist in places where the government has limited the amount of greenhouse gases that companies and institutions can emit. These markets allow members to meet some of their targets by paying for sustainability programs that have been independently evaluated to determine the amount of carbon dioxide emissions they save. In California’s cap-and-trade program, for example, companies offset emissions beyond their cap by purchasing carbon credits from forest conservation initiatives or projects that capture emissions from farm animals.

Voluntary offset markets work much the same way, catering to individuals, companies and institutions such as the UC system that want to reduce their carbon footprint. People can buy offsets for emissions from a specific activity, such as an international flight, or buy packages with names like “the green wedding carbon offset” and “balanced living bundle.”

Since there’s no globally recognized cost of carbon, the price of offsets usually depends on the project that produces them — typically between $5 and $10 per metric ton of carbon dioxide. That’s much cheaper than the actual cost of the climate damage caused by each ton of carbon emitted.

Voluntary offsets are the dietary supplements of the climate world — no federal agency regulates them to make sure they deliver the benefits they promise. You have to do your own research to make sure you get what you pay for.

Since sellers usually don’t tell you exactly what your offset purchase is funding, it’s important to examine the projects in their portfolio. If they don’t list all projects and provide certifications, that’s a big red flag. Good projects should be permanent and enforceable. They must also be “additional” — efforts that wouldn’t happen if not funded by the offset, and that don’t simply shift emissions someplace else.

Check to see whether the projects have been approved by a reputable standard — an independent organization that develops instructions, or “protocols,” for various types of projects and lists those that are up to snuff. California’s Air Resources Board, which oversees the state’s cap-and-trade system, recognizes three such standards: American Carbon Registry, Verra and Climate Action Reserve. Many standards also post lists of retailers where their approved offsets can be purchased.

Transparency is a good indicator of whether an offset is legitimate, said Craig Ebert, president of Climate Action Reserve. His organization posts on its website the protocols for every kind of offset it will consider listing, from urban tree planting to reducing emissions from landfills. Projects must also hire an independent auditor to ensure they meet the protocol’s requirements before they can be listed.

Haya is helping University of California evaluate offsets to purchase as part of its carbon neutrality effort. In the meantime, Haya advised the school system to seek opportunities to create its own offsets. Last year, the university solicited ideas and wound up investing in a dozen projects: research on carbon capture, programs to distribute solar lights and efficient cook stoves in developing countries, and experiments in sustainable agriculture.

With any offset, the aim is that the climate benefits of these projects will zero out the emissions from the purchaser. But a ton of carbon dioxide purchased does not necessarily lead to a ton of carbon dioxide saved, Haya said.

Programs that are poorly devised or badly enforced may not deliver the reductions they promise. Initiatives involving forests — which represent about half of offsets offered in the United States, according to Haya — are especially tricky. A 2019 investigation by ProPublica found plots in the Brazilian rainforest that were sold for credits and then cut down anyway. Six years after the program began, half of the forest that was supposed to be protected was gone.

Even when offset projects are well monitored, nature itself can interfere. Drought, storms and invasive insect infestations can weaken trees and reduce the amount of carbon stored. A wildfire can rip through a project area — as happened to a forest in Oregon this month — turning what should have been a tool for storing carbon into a major emissions source.

Critics argue that offsets simply allow the wealthy — who often burn the most fossil fuel — to pay their way out of the climate problem without altering their practices. Meanwhile, those who live at the site of the offset project — often farmers in developing countries — are left with the difficult task of enacting change. To prevent this, most compliance schemes put a limit on how much of a company’s target can be met through offsets; in California, it’s 8 percent.

Another concern is that if purchasing offsets is cheaper than reducing emissions, businesses and big institutions won’t have an incentive to develop greener practices. If, instead of looking at offsets, the UC system went ahead with the heating and cooling plant overhaul, maybe it would discover a brilliant new way to heat and cool buildings without fossil fuels — something that might eventually become the standard for all construction.

After all, the world cannot offset its way to carbon neutrality. All emissions will need to be eliminated eventually. The United Nations Intergovernmental Panel on Climate Change has found that humanity must reach “net zero” by 2050 to avoid the disastrous effects of warming the planet beyond 1.5 degrees Celsius above preindustrial levels.

For these reasons, offsets are not a get-out-of-jail-free card. “You are always going to be responsible for your own emissions,” Haya said.

But offsets can play an important role in fighting warming, Ebert said, particularly when they fund initiatives that are important but not cost-effective. The market for blocks of captured carbon is probably never going to be large, but a company trying to offset its own emissions can help make sequestration viable.

Offsets also provide a way for those most at fault for climate change — such as the United States, which has produced more greenhouse gases in its history than any other nation — to take responsibility for emissions outside their borders.

“It’s not sufficient for us to get to net zero and say we’re done,” Ebert said. “It’s both a moral and ethical obligation for all of us to invest in these other areas.”

Both he and Haya used the word “invest” a lot. And that’s a good way to think about offsets: You’re not canceling out emissions; you’re buying a stake in a more livable world.