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We recently told you about a study that looked at how may more trees could grow on Earth and how much carbon they could absorb from the atmosphere. The answer: The planet has room for about 2.5 billion acres of forest, and all those trees could suck up an additional 200 gigatons of carbon. While that wouldn’t solve climate change, it would be a huge help.
That kind of reforestation would be a monumental global undertaking, but every single tree still counts. They all sequester carbon.
So, if you plant a tree, what kind should it be?
Peter Del Tredici, senior research scientist emeritus at the Arnold Arboretum at Harvard University said that, for trees to sequester a lot of carbon, they need to live long and healthy lives. “You want a tree that is going to survive in your climate with the minimum amount of maintenance,” he said.
To have a meaningful effect, he said, a tree must live at least 10 to 20 years. “It takes that long for a tree to build up enough foliage so that it can have a substantial impact on the environment,” Dr. Del Tredici said.
With that in mind, oaks can be great in the Northeast, while ficus trees might work better in Southern California. In the Northwest, just about everything does well. Nonnative, noninvasive species like the ginkgo tree are good options, too.
Getting your tree to reach its full potential requires plenty of soil volume and ample room to grow, Dr. Del Tredici said. He discouraged fast-growing trees like poplars because they have a shorter life span. Medium-growth trees like pin oak are better from a carbon perspective.
Considering how climate change might shift conditions like temperature and water availability over time is also really important, said Emily Nobel Maxwell, the cities program director for The Nature Conservancy in New York.
Careful placement of a tree can bring additional climate benefits, she added, which could possibly be even more significant than carbon sequestration.
“There are ways to locate tees to maximize energy efficiency benefits,” Ms. Maxwell said. A tree that casts shade on your house in the summer or helps insulate in the winter can lower utility bills and, quite likely, carbon emissions. “You can strategically plant.”
The Arbor Day Foundation has a plenty of tools — like a best-tree finder and a hardiness zone look-up — to help identify the right tree for the right place. The Department of Agriculture’s I-Tree lets you design your optimal tree placement. Another useful exercise is simply to walk around an arboretum or botanical garden to get a sense of what you like. A nursery can be a great resource as well.
But both Dr. Del Tredici and Ms. Maxwell pointed out that putting the tree in the ground is only the first step in a decades-long process. “As important as planting a tree,” Ms. Maxwell said, “is taking care of a tree.”
Fat bears and climate change
Fun fact: There’s a thing called Fat Bear Week and I’m a huge fan.
The event, organized every year in Katmai National Park and Preserve in Alaska, is something like March Madness. Only the players are brown bears and the championship goes to the fattest bear seen at a spot in the preserve called Brooks Falls.
There’s a live stream of the hungry bears and the National Park Service creates an online bracket in which 12 of the preserve’s biggest are pitted against one another. Anyone can vote for a favorite bear online.
Alaska also holds a lottery for roughly 170 viewing permits at a separate site in the McNeil River game sanctuary, a state refuge. It’s roughly 70 miles northeast of Brooks Falls and boasts one of the largest assemblages of brown bears in the country. This year, I won a permit.
So, over the Fourth of July holiday, I watched while as many as 40 brown bears assembled at a time. They gather to catch some of the estimated 50,000 salmon that swim up the McNeil River every summer to spawn. The bears mated, fought, skinned fish and delicately maneuvered bodies that can weigh more than a thousand pounds. There are no fences or other physical separation from the bears — they’ve had decades to get habituated to the presence of humans.
On a trip like this, the weather is a pretty important part of planning. The extremely detailed McNeil Sanctuary website made clear that I should expect rainy weather and low temperatures of 40 degrees Fahrenheit (about 4 degrees Celsius) that would reach highs around 60 Fahrenheit (16 Celsius) if I was lucky.
But, during my whole stay, daytime temperatures hovered in the 80s Fahrenheit. The day I arrived at the sanctuary, Anchorage, roughly 160 miles away, broke its high-temperature record when it hit 90 degrees Fahrenheit. (Normal temperatures for Anchorage at that time of year peak around 65.)
Despite the heat, we had to wear long pants and long sleeves on our hikes to and from the viewing spot. That’s because of cow parsnip, a common weed in Alaska. If it rubs against bare skin that is then exposed to direct sunlight, you can get a nasty rash.
The bears arguably had it worse — they had to endure the same unusually high temperatures wearing fur coats.
The sanctuary was also experiencing a drought, which my guides said was probably reducing the number of salmon heading upriver. Salmon, apparently, rely on smells to navigate their way back home to the tributary of their birth. With the water levels lower, the salmon weren’t getting the message to head home.
The bears I saw didn’t look hungry, but they weren’t yet so well-fed that they could afford to be picky about which parts of the salmon they were eating. When they get really stuffed, they only eat the fatty parts.
Two other things we saw were beautiful but worrisome.
The wildflowers were weeks ahead of schedule. Especially noticeable was the brilliantly pink Alaska fireweed. They were halfway bloomed. According to local lore, their final blooms are a sign that summer is over. And the sunsets were amazing. That’s because the light was filtered through a haze of smoke from wildfires burning across much of Southwest Alaska. In the seven-day period between July 3 and July 10, more than 600,000 acres burned across the state.
Weather, it’s worth repeating, is not climate. But none of the guides could recall temperatures ever being that high. And the pattern of earlier spring, increased wildfire risk, and more severe temperatures is in line with what we expect to see from climate change, according to the National Climate Assessment.
This is the happiest place on Earth for a brown bear, the guides told us over and over. It’ll be interesting to see if it stays that way.