Also posted on Medium.

​Plant a tree, save humanity. Or rather, plant untold millions of trees and give humanity a fighting chance against climate change. That’s the bottom line of a lot of talk lately about a high-profile Science study, which broke the news that massive global reforestation could solve climate change. Many outlets spread the news, providing a glimmer of hope in the ceaseless bad news about climate. 

Despite all the press, the notion of reforestation to fight climate change isn’t particularly ground-breaking. E.O. Wilson had some global-scale thoughts about this “rewilding" some time ago. Data for Progress’s Green New Deal calls for reforesting forty million acres of the US in the next fifteen years. At the city level, making a warmer world more livable involves trees, to reduce heat island and ground-level ozone, make non-car transportation more appealing, and improve resilience to massive rain events. Cities like Los Angeles have new reforestation efforts  - 90,000 trees in two years! - and newly-created positions to oversee these efforts. Lots of people have this “more trees for climate action” idea because it’s a good idea: reforestation is not only effective, but nearly foolproof. An urban tree might die, but it can’t really backfire otherwise, and those trees that live provide a whole host of additional benefits beyond climate. Compared to any kind of new technological solution, planting trees is tried and true, and relatively cheap per tree. 

What does this look like, though?

​What about the people among all those trees? 

A future with a lot more trees could look a bit like the present in in the re-forest that already covers Connecticut, and to some extent, the rest of southern New England, as I mentioned in this previous post. As a refresher, European settlement and its attendant clear-cutting began in the 1630s in Connecticut. By 1820, only about 25% of Connecticut was still forested, but due to the opening of much more fertile farmland further west, Connecticut’s farm fields and pastures began to revert to forest starting around 1870. This tiny state is now around 60% forested. Yet with 3.6 million people, it’s certainly not wilderness - Connecticut is one of the most densely populated states. Lots of people, but also lots of trees. If you want to know about living alongside trees, this is the place to learn. 

This brings us to some math helpfully provided by the state of Vermont. They reckon an average acre of forest stores 107 metric tonnes of carbon (MtC). That’s pure carbon, not carbon dioxide, and not emissions like your car creates. By that more real-world measure, an average forested acre stores 393 MtCO2e, which is the annual emissions from 83 cars. 

One acre = 83 cars isn’t bad, but it’s also really simplistic. A forest isn’t just a forest - the kind of trees growing in the forest matters, as well as how old they are, how large they are, and most particularly, what’s in the soil around them. Generally, the best trees for storing carbon are those with heavy, dense wood, like oaks, for example. Just as logically, the larger the tree, the more carbon it stores, giving older, larger trunk-diameter (aka caliper) trees the edge as well as those with a larger ultimate size. In measures of annual carbon storage, the growth rate of trees matters, which is a little contradictory, since softer-wooded trees often grow more quickly. Confused yet?

Consider this, too: the management of the forest matters quite a bit, too, maybe as much as what’s growing there, because carbon remains stored in fallen leaves and branches, too. Organic matter in the soil may be the largest carbon sink in our hypothetical acre of forest, but to get that organic matter, the branches, leaves, and other tree detritus must be allowed to accumulate and decay naturally, not raked or removed. Fallen trees contribute to this total, too. 

The trees matter. The soil matters. What’s under the trees matters. The management (or lack of it) of the forest matters. And all these things matter tremendously, because climate change is a real, present, existential threat to humanity. 

As we dig into it, the details of our forest acre end up making all the difference in terms of its climate action benefit. There’s plenty of unanswered questions about the forest itself, but those questions multiply when we add people into the mix and start asking about what, if any, benefit we get from the trees in places closer to us - not an acre of forest, but a single red maple in the yard or a lone honey locust along the street. 

Can we fit some of this needed reforestation into places people live?

What’s the best way to do that, for climate and for those of us living in the Re-Forest?

What can we learn from the reforested places, like Connecticut, we already have?

 

Take a look at this picture. Where is this trail? Oregon? The Boundary Waters? Maybe Shenandoah? Nope, it’s just an ordinary trail in Connecticut. My state of residence for two years now is a surprisingly superlative trail state, with the venerable Blue-Blazed Trails comprising 825 miles packed within the third-smallest state. How does a tiny state that’s #4 in population density manage to have so much trail? 

The answer is in the picture, too: all those trees. There’s a lot of trees among the subdivisions and golf courses here. New England is the most heavily forested region in the US, which might surprise you if you know that the southern part of New England, including where I am, is also one of the mostly densely populated regions. There’s a lot of people, but there’s also a lot of trees. [Even if there’s a little less than there used to be, as reported here. ] Today around 60% of Connecticut’s land area is forested, plus a bit more than 60% of its urban areas are covered with tree canopy. That’s the highest percentage of canopied urban land in the nation. 

If you want to know about trees + people, this is the place. 

What’s really remarkable is that Connecticut is not just forested - it’s re-forested. European settlement started early here - the 1630s - so native forests had about two centuries of being transformed into a patchwork of agriculture and settlement stitched together with those famous stone walls. By 1820, only about 25% of Connecticut was still forested, but all those stones make better walls than farmland, especially compared with nearly everywhere to the west. As farming moved to more promising locations, the forest began to return. Re-forestation began around 1870 - a long time ago.  

What that means is that the Re-Forest outside my window wasn’t born yesterday. It’s century-old forest, at least in many places, giving it a maturity and richness that the relatively young forests of, say, the Midwest, just can’t match. If you’re used to these pale copies, the New England forest can be a little…spooky. It’s the hush of leaf mold underfoot. It’s the constant whisper of mountain laurel leaves. It’s the sheer size of forested areas and their single-track labyrinths. But most importantly, it’s the wildlife. Century-old forests, especially when they are large, are good habitat not just for birds and squirrels, but for bears and bobcats and the large coyotes of the East. 

You’re never really alone on that trail.

The wildlife of the Re-Forest lives among countless relics of this land’s  pastoral past. You can’t miss the stone walls, but there are building foundations, abandoned roads, and the occasional lost cemetery, too. It’s a Life After People vibe that reminds you, on your solitary hike, that lots of other people were here, and now they are gone. It’s easy to let your mind drift to colonists and settlers and start to hear faint footsteps behind you.

That’s ridiculously Euro-centric, of course. For every dead colonist in the Connecticut woods, there’s countless dead Native Americans, which is a morbid way to say that this land was home to humans for millennia before the Puritans landed. Where I live was Quinnipiac land, so you could meditate upon that while you hike, and the apocalypse of epidemic and genocide that followed first European contact. 

Millennia of human occupation surely left sign everywhere, but I lack the perspective to see it. In places, indigenous Americans altered the composition of the forest itself, crafting a massive permaculture garden of sorts. Did that happen here? One of the best permaculture candidates in the forest here would have been American chestnut (Castanea dentata), its grand canopy now long gone, reduced to saplings sprouting from ancient roots. Ashes (Fraxinus spp.) are joining the chestnut as I type this, due to the predation of emerald ash borer. This missing forest, these ghosts in the woods, includes the extinct and extirpated, too: the passenger pigeon, the Eastern elk.(There are reintroduced elk in other places in the East, but they are not the Eastern elk (Cervus canadensis canadensis), which has been extinct since 1880.) Gray wolves and cougars once hunted here. 

You’re never really alone on that trail, yet you’re more alone than you would have been, once.

You could think time began here with the arrival of white colonists from England (mostly), a false idea but an easy habit of long standing. It’s harder to see it from a different perspective, with not the men with muskets but the continent-blanketing trees in the foreground. The US Forest Service estimates that before Europeans arrived, about 46% of the land that would become the US was forested, around a billion acres. We’ve since lost about 256 million acres of that, and as of 2012, around a third of the US was forested land. Without even getting into the quality of virgin forest vs today’s woods, that’s a lot, an inconceivable amount, of forest that exists only in memory, with some of those memories a century-plus old. Ghost forest.  

Along with housing bobcats and passenger pigeons and memories, that forest stored carbon, and of course, it could again. The Green New Deal report by Data for Progress estimates that reforesting 40 million acres by 2035 could offset a whopping 600 million tons of carbon dioxide equivalent by 2050. 

Forest quality and composition matters in this, but notice that 40 million acres, while a lot, is quite a bit less than that 256 million acres we’ve lost since Europeans arrived. Reforesting 40 million acres would entail restoring forest vegetation to around one in six of every acre that’s not forest now but was in 1630. That seems much more doable. 

Would that reduction in emissions make a difference? In a word, yes. Six hundred million tons is about 8.5% of 2017 US greenhouse gas emissions. For reference, the 2025 target set for the US in the Paris Agreement was/is 16% below 2016 emissions. People in the know generally agree that the Paris Agreement’s goals were too little, and of course, it’s anyone’s guess whether the US will ever honor those too-little goals. But still: it’s about half the 2025 targeted reduction, from trees. 

Don’t let anyone tell you climate change is hopeless. One answer is right there in the numbers. North America would re-forest itself if we humans got out the way. It tries to do it constantly, in old fields and vacant lots and maybe your unmowed yard. Some forest, missing chestnuts, missing ashes, probably missing lots of other species, could retake the rest of the range of pre-settlement woods, like it has in New England. The trees would inherit the earth.

Imagine that Re-Forest, and ask yourself what other relics might rest beneath that canopy of leaves, like the colonial stones outside my window. Maybe this house. Maybe your house or your street. If we don’t find an answer, through re-forestation or otherwise, to our manmade climate catastrophe, this forest could be haunted by the passenger pigeon, the Eastern elk, and… us.