When Slowing Global Warming Means Cutting Down Trees: Hard Choices in the Climate Crisis

May 18, 2021 | 1:57 pm
Brookhaven National Laboratory/CC
Kate Cell
Senior Climate Campaign Manager

President Biden recently announced that the US would cut carbon dioxide (CO2) emissions to 50–52 percent of 2005 levels by 2030. While there are many reasons why even this level of ambition isn’t sufficient, it’s still an enormous shift from where we are today, and an important milestone toward where we need to be.

The world needs to remove more CO2 from the atmosphere than we emit by midcentury to meet Paris goals—this is called “net-negative emissions.” This is critical—not only to slow the pace of climate change, but to reduce the staggering number of deaths from fossil fuel air pollution—more than 8 million people in 2018 alone. Right here in the US, moving to net-negative emissions would be a huge step toward addressing the grave and racially unjust health burdens of our energy choices.

What is this wholesale transformation going to look like? How will it play out across our communities and landscapes? It’s hard to envision fully, but it’s bound to involve some complicated calculations and difficult choices. It will cause tension—even among likeminded environmental allies. In fact, it already has. Here’s one glimpse, from my own small town in the forested hills of Western Massachusetts.

Small town, big solar

In my little town, there are fewer than 1,800 people, but lots of trees: forested areas cover approximately 90 percent of the landmass. There’s also lots of wildlife. Bears lumber in and out of our yards so often we’ve given them nicknames, and we see deer, coyotes, and the occasional moose. Bald eagles fish at the lake. On summer nights, I hear barred owls in extensive conversation. Most roads into town wind alongside year-round brooks and it takes 20 minutes to get to the nearest traffic light, two towns away. A satellite view of my neighborhood looks like this:

Satellite view of Massachusetts forest

The 60-acre proposed solar site behind my house.

That red arrow points to 60 currently forested acres of the 190 a company is proposing to use to build the largest solar installation in the state, on land leased from the largest private landowner in the state. The total installation would generate 20 megawatts of power (alternating current, or AC), enough electricity for about 3200 homes, four times as many houses as we have in town. The 60 acres near my house alone would generate 5 megawatts.

Already, the discussions are heating up among townspeople on social media sites and during outdoor get-togethers. Lots of us are deeply concerned about the climate crisis. And many of us do not want these acres clear-cut, even for solar generation. My work has made me hyperaware of the impacts of climate change (including hotter temperatures, higher seas, and fiercer wildfires) and the racially unjust burden of serious disease caused by burning fossil fuels, and I have developed pretty strong opinions about the urgency and scale of the climate problem. Some of my neighbors don’t always like my answers to their questions.

Barred owl perched on a tree branch with a green leafy background.

A barred owl near where I live.

Talking to my neighbors

Here are some of the conversations I’ve had with neighbors so far.

Our forests are so special. Yes, they are. They are beautiful and they are valuable. They provide varied habitats for the animal species I mentioned above and many more. While they’re busy taking CO2 out of the air, they’re also providing all of us with oxygen. Our woods include wetlands (it’s really swampy behind my place, I can attest) which means that installing solar there may damage those ecosystems. The solar sites would take up about 1 percent of the town’s total landmass, and there may well be sound environmental reasons to oppose them. But they aren’t primarily climate change reasons, and here’s why.

Don’t we need trees to fight climate change? Most folks here know that trees store carbon. Second-growth New England forests store approximately 77 metric tons per acre in trees and their roots, and in dead trees, litter on the forest floor, and the soil. (All my figures are in metric tons; one metric ton equals 2,205 pounds.) The amount of stored carbon that preparing to install the solar project would release into the atmosphere will depend in part on how the wood is used after harvest. If it’s chipped or burned, the 38 percent of forest carbon that’s stored in trees above ground will be released as CO2 right then. For 190 acres, that’s 5,559 tons. Yikes. But if it’s used to build houses or furniture, that carbon will stay locked up in the wood products for a long time.

Forests also absorb CO2. A recent paper by researchers studying the Harvard Forest, just 30 miles away, found that it absorbs (or sequesters) approximately 4.4 tons of CO2 per acre annually, so 190 acres sequester 836 tons a year. That’s the annual CO2 emissions of about 181 cars.

836 tons sounds like a lot of carbon sequestered, and it is, but then some colleagues helped me figure out that the output from the 20 megawatts of solar on that same land could mean more than 6,000 tons per year in avoided CO2 emissions (i.e., CO2 we don’t put into the air). The landowner also owns a timber company and won’t burn all the wood, but even if she did, within one year after construction the solar panels would offset more CO2 than burning would produce. After that, every year, the solar panels would avoid emissions of 5,146 tons more CO2 per year than the 190 acres of forest could sequester. Those 5,146 tons represent the annual CO2 emissions of about 1,123 cars.

Here’s another way to think about the relative CO2 benefits of forests and solar. My husband and I put a solar system on our house in January 2017, soon after we moved in. According to our solar monitor, that one small, 6.6-kilowatt power residential system avoids the emissions of an average 4.3 tons of CO2 per year, almost as much as one acre of forest can sequester.

But these forests could sequester CO2 for hundreds of years. Yes, that’s how I was thinking too, before I did all the above “carbon math.” This math necessarily includes assumptions: I’ve assumed no loss of forest acres to wildfire or pests, and a relatively constant electricity generation mix in Massachusetts over a conservative 25-year lifespan of the solar project. Under those conditions, it will take nearly 180 years—seven human generations—for the forest to sequester an amount of CO2 equivalent to the panels’ avoided emissions. We don’t have 180 years. Remember, President Biden’s proposed 50–52 percent reduction target is for 2030, nine years from now.

With less than 30 years to become carbon neutral to limit warming to only a further 0.5° Celsius (we’ve already warmed more than 1°C since 1880), avoiding emissions now is simply crucial.

We also don’t know what will happen to the forests in the future. The Harvard Forest has been sequestering more carbon in recent years, and the good news is that the study authors expect that “forests across the region are likely to accrue [sequester] carbon for decades to come.” They warn, though, that Massachusetts forests are under stress from pests including the hemlock wooly adelgid, the emerald ash borer, and the Asian longhorn beetle. We don’t know what the effects of these pests, or climate change itself, will be on long-term forest health and survival.

A bull moose browsing shrubbery.

Some of my neighbors are moose.

Can’t we just use less electricity? Sure, we can turn the lights and electronics off when we don’t need them and use efficient appliances and lighting. We can weatherize our homes; we can develop more efficient manufacturing processes. There’s a lot we can—and should—do, and as my colleague John Rogers says, “the best electrons are the ones we don’t use or generate.”

Unfortunately, we can’t come close to the required emissions reductions just by using less electricity. Being carbon-neutral means burning no oil or gas, so we’re going to need to electrify our transportation, cooking, and heating and cooling, and we’re going to want that electricity to be generated by renewable sources, including solar.

Can’t we put it somewhere else? Like many of my neighbors, I would also like solar on the roof of every suitable home, big box store, municipal building… I would like to see parking lots sheltered by solar, landfills topped with solar arrays, powerline easements with solar beneath the towers. Because we’ve waited so long to act, at this point it’s not either-or. It’s both/all. The incentives in Massachusetts are encouraging solar, as they should—and some of that encouragement points to putting solar on land cleared for that purpose.

Won’t our property values be affected? There’s not a lot of research on the implications for home value from solar built on previously forested land, but yes, they might be. One recent study finds that house prices in Massachusetts and Rhode Island within a mile of a solar installation have declined, on average, 1.7 percent.

Clean energy deployment isn’t the only thing that can affect property values—climate change can too. Take, for instance, climate change-exacerbated sea level rise and tidal flooding in coastal Massachusetts. In just one seaside town, Revere, 1,105 of today’s homes are at risk of becoming chronically inundated in the next 15–30 years. That’s nine percent of Revere’s houses, home to 2,575 people. Those people, and tens of thousands of others along the US coastline, are going to need a place to go. Under these circumstances, I can easily imagine housing prices increasing in inland communities like mine.

I don’t want our town to change! I sympathize with this, but things are going to change no matter what. We’ve been used to about five days a year with a heat index (temperature plus humidity, or the “feels like” temperature) over 90°F. Without strong action on climate, our county should expect to see 26 more such days in the next 15 – 45 years. We’ve never had heat indexes above 100°F before, but we’ll see seven such days by mid-century and three weeks by end of century, without strong action. Even with strong action, temperatures will rise swiftly through mid-century and then start to level off.

A map figure showing how Massachusetts' climate will change under various carbon emissions scenarios.

The red arrows track what summers in Massachusetts could feel like over the course of the century under the higher-emissions scenario. Yellow arrows track what summers here could feel like under the lower emissions scenario. You can see that we’re already “heading south.” If we keep emitting at current rates, by the end of the century we’ll have the summers of the Carolinas.

Harder choices ahead

Renowned economist John Kenneth Galbraith is famous for, among many other things, saying that “Politics is not the art of the possible. It is the art of choosing between the disastrous and the unpalatable.” This describes our moment precisely. We have left it so late to act on climate, to reform our profligate ways with our planet and our atmosphere, that many choices will be complex, and fraught, and painful, from here on out. But here’s the thing: the climate we have today, with its stronger storms and heavier downpours, its hotter heatwaves and fiercer wildfires, its rising seas and melting glaciers, is as good as it’s going to get for a very long time.

Living near the state’s biggest solar installation instead of in a healthy, beautiful, and fairly contiguous forest is unpalatable to many of my neighbors. So is losing acres of trees and possibly wetlands, which are highly efficient at sequestering and storing CO2. But the ways the US has produced energy in the past have been disastrous. Some of us, including the people in my town, including me, have benefited from that production happening far away, with the burden of its pollution falling most heavily on Black and brown people. Just take one health impact, asthma: Black Americans are 42 percent more likely than whites to have it and two to three times more likely to die from it.

I am proud to say that we have “Black Lives Matter” signs all over town, including a large banner over the entrance to Town Hall. Participating in the swift transformation of our energy system would be one way to show we mean it.

About the author

More from Kate

Kate Cell is the Senior Climate Campaign Manager for the Climate & Energy program at the Union of Concerned Scientists. In her role, she manages the UCS Climate Campaign, leading a multi-disciplinary team of scientists, policy analysts, legislative affairs staff, and outreach and communication experts working to achieve policies that can reduce global warming emissions and increase resilience to climate change impacts. Her team is focused on demonstrating and alleviating the disparate burdens climate change poses to environmental justice communities, low-income communities, and communities of color.