As the effects of climate change become impossible to ignore, it’s a good time to consider the actions needed for us to minimize future harms from unchecked warming. Specifically, our need to install at least 27 gigawatts (GW) of solar capacity by 2050, as outlined in the Massachusetts Clean Energy and Climate Plan. This is a magnificently ambitious goal. If we succeed, not only will we reduce the emissions of heat-trapping carbon dioxide, we’ll improve our air quality, uncouple our economy from destructive fossil fuel industries, and keep more of our energy dollars in the commonwealth. But we should be clear-eyed about what it will take to achieve these overwhelmingly beneficial outcomes.

To build this much solar capacity within the next 24 years will require we use a small fraction of our forested lands. This is not abdicating our responsibility to be good environmental stewards. To the contrary, the careful siting of solar on some forested parcels will help avert much more widespread and severe environmental harms in the future.

As background, consider that Massachusetts has not provided for its own energy needs since the early-1800s, when we relied on the power of draft animals, flowing water, and firewood. By the middle of that century, we had cleared almost all of our forests for crops, pasture, firewood, and timber. But as agriculture waned and we became more reliant on imported fossil fuels for energy, our forests largely recovered. The commonwealth is now about 60 percent forested, the highest since colonial times. However, this “greening” is somewhat an illusion. We have merely exported most of the environmental costs of our energy use to other regions where fossil fuels are extracted and processed. While our forests regrew other regions suffered, and continue to suffer, the direct harms from providing the fossil fuels we rely on. But with advances in solar technology, we now have the ability to produce most of the energy we need right here in Massachusetts. We can take direct responsibility for the energy we use.

But herein lies the dilemma. Without using a small fraction of our (re)forested lands for solar, we will most likely fail to meet our renewable energy goals and not realize the greater benefits described above. To be clear, rooftops, parking lots, landfills, and other disturbed sites are the most appealing (and incentivized) locations for installing solar and we must continue to pursue these opportunities. But these types of projects are relatively costly and their development potential is limited, both in ultimate capacity and because of the time required to realize it. With more than a decade of clean energy action, falling costs, and the incontrovertible evidence of global warming, we have still only installed about 4.7 of the 27 GWs of solar capacity needed, according to the Solar Energy Industries Association. Alarmingly, since 2021, the pace of solar development has declined, with a precipitous drop in large-scale projects. This is partly due to the misperception that large ground-mount solar projects are unnecessary and pose an excessive threat to our forests. But actual land-use projections and other supporting studies don’t support this.

In 2023, Mass Audubon projected that solar development might cause the conversion of about 1.3 percent of our existing forested land. This was their worst-case scenario and characterized as “too high a cost” to pay. Fundamental to this conclusion was the presumption that because trees sequester carbon, clearing them to build solar is counterproductive for mitigating climate change. But this is a deeply flawed premise. Studies from a variety of researchers, including from the Harvard Forest (the institution that co-produced Mass Audubon’s work), indicate that by offsetting fossil fuel use, the net carbon benefit of a solar facility far exceeds the climate mitigation benefit provided by any forest it replaces.

The uncomfortable truth is that our fossil fuel carbon emissions greatly exceed the sequestration capacity of our forests. Each year, our three million acres of forest (again, 60 percent of our land area) can only sequester about 10 percent of our emissions. This is the fundamental imbalance driving climate change. And counterintuitively, as our forests continue to mature, their ability to mitigate fossil fuel emissions will actually decrease. This is because old forests reach a state of “carbon equilibrium,” where the carbon released to the atmosphere from the death and decomposition of large old trees roughly balances the carbon sequestered by younger trees that grow to take their place; this is the natural cycle. But the carbon from fossil fuels is from ancient geological formations and it is excess to this system. Thus, until we stop burning fossil fuels, atmospheric carbon levels will continue to rise regardless of how well we conserve, or even (implausibly) expand, our forests.

None of this should be taken to imply that forests aren’t important for many other reasons or that we shouldn’t work hard to protect them from indiscriminate loss. But when balanced against the overall benefits of displacing fossil fuels, and always keeping in mind the dire consequences of failing to mitigate climate change, the wise use of a small fraction of Massachusetts’ forested land in order to help meet our urgent need for affordable renewable energy is a sensible path to a better future.

Keith Hastie is a retired environmental scientist, lifelong environmentalist, member of the Shutesbury Planning Board, and contributor to the Western Massachusetts Clean Energy Network. Supporting information can be found at: wmcen.org.