Reblogging to show the temperature maps that are featured in the original study (and the Guardian article about it), because the visual difference really is so striking and so encouraging.
As you look at these maps of forests vs. temperature trends, remember that the temperature map is showing large-scale, very long-term averages, especially on the temperature map. Because of that, the map data doesn't reflect how very, very big a difference it can make on a local scale, e.g. those 9°F summer temperature conditions. And those local scale changes are the changes that people actually live in.
Forest Age vs. Warming Maps
Pictured: Guardian graphic. Source: Barnes, et al, 2024, ‘A Century of Reforestation Reduced Anthropogenic Warming in the Eastern United States.’ Note: Forest age data from North American Carbon Program. Age estimates as of 2019 at 1km resolution. Temperature data from Delaware Air Temperature & Precipitation Dataset.
Source: The Guardian, February 17, 2024. And the original study is here, from the journal Earth's Future, first published February 13, 2024.
(Also, btw, for any non-US and/or non-geography people, don't worry about the fact that there aren't any forests in the middle of the country. That's the Great Plains. Like we definitely did turn most of it into cropland, but it's not supposed to have forests.)
Even the small pockets of new reforestation elsewhere in the country are usually correlated with small pockets of cooling. (And of course correlation by itself does not equal causation, but that's what the rest of the study is for.)
This is genuinely strong evidence that the massive tree planting campaigns of the last 25 years are going to pay off dramatically much sooner than we thought.
The study found that the coolest forests were ones planted planted 20 to 40 years ago.
That means that trees planted in the 90s through 2004 are in that stage and causing the most cooling right now.
It also means that the ongoing, absolutely massive recent reforestation efforts are going to pay off a lot between now and 2050.
That means campaigns like China's 2022 pledge to plant or conserve 70 billion trees by 2030. Or India's annual tree-planting drive, which in 2021 saw 250 million trees planted in just one day. Or Kenya's new tree-planting holiday, started in 2023, to plant 100 million trees each year.
This study also gives strong evidence that newer forests don't have vanishingly few benefits compared to old growth forests - they do have benefits (if not as many), just different ones. It also, I would argue, suggests that tree planting efforts don't have to be ecologically perfect to make a real difference. They certainly were not nailing native plant biodiversity and ecological best practices in the US in the 1930s!
And as we learn (and actually implement) more and more about how to do reforestation right - more biodiversity, native plants only, actual forests and not just tree plantations - the benefits of reforestation will only increase.
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