hambach forest -- 4/15/2026

15 Apr 2024

hambach forest -- 4/15/2026

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Today's encore selection -- from The Power of Trees by Peter Wohlleben. The cooling effect of trees.

“Hambach forest shows just how much even a small remnant of forest can benefit the local climate. It is one of the most famous forests in Germany because it has become a symbol of changing energy policies. The forest’s fate seemed sealed when excavators digging for lignite in the neighboring open-pit mine chewed their way to within a few yards of the forest’s edge. From what was once about 15 square miles (40 square kilometers) of trees, only three-quarters of a square mile (2 square kilometers) remained. The clearing of a last miserable remnant of forest was halted by an injunction from the Munster Higher Administrative Court after the federal and state governments came to an agreement following protests by environmental organizations and activists.

“But is it too late to save Hambach Forest? The gaping maw of the enormous, nearly 1,000-foot (300-meter)-deep mine lies at its feet. In summer, hot winds rise from the mine’s depths, creating a powerful vortex that sucks away the cool, moist air the ancient trees have put so much effort into creating. Storms sweep over the mine unobstructed, toppling trees at the forest’s edge and slowly but surely reducing the size of Hambach. Hambach lies in an agricultural wasteland that heats up in summer almost as much as the open-pit mine. There are hardly any other forests around that could bring their influence to bear and help create a local microclimate more friendly to trees.

“So is there any chance the ancient forest can survive? To answer this question, Greenpeace asked a team led by PierreIbisch to undertake a local climate study. You already know the main method they used: measuring the temperature of different land surfaces via satellite and coloring them in on maps. There were other ecological investigations as well. They study found that in the extremely hot summer of 2018 the difference in temperature between the forest and the open-pit mine was up to 36 degrees Fahrenheit (20 degrees Celsius). You cannot help but be seriously impressed that such a small but reasonably intact, forest exerts such a strong cooling effect.

Aerial view of Hambach Forest from the south, October 2018

“Despite the results of the study, the future of the old trees in Hambach is, unfortunately, not particularly rosy. The excavators continue to chew their way closer and closer, and trees around the edge of the forest are dying from the heat as winds from the mine act like a gigantic hair dryer, blowing away the cooling effect of the forest. At the same time, large quantities of moisture are being removed, or, to stay with the same metaphor, Hambach Forest is constantly being blow-dried.

“The severity of the situation becomes even clearer when we remember that every day a mature beech releases up to 130 gallons (500 liters) of water into the air via its leaves — water that is hard to find in the ground because of the proximity of the lignite mine. To add insult to injury, the open-pit mine is being emptied of water by giant pumps because the bottom of the mine lies far beneath the water table and, without the pumps, the enormous hole in the ground would flood.

“Experts have recommended planting a buffer zone around the ancient forest to save it. At the very least, young trees could reduce temperatures around Hambach Forest a little bit and humidify the air to relieve some of the stress now plaguing the ancient forest. Images taken by Greenpeace show that bugger zones planted around human communities would be a blessing for us too. Members of the environmental group took photographs of Cologne using a thermal-imaging camera. This large city in the Rhine Valley is about an hour’s drive from out forest lodge. The results were similar to those from Berlin and Hambach Forest. Buildings and asphalt glowed red in the summer heat. In contrast, the deep blue of trees in city parks made the parks look like lakes, and their temperatures showed they did indeed act like lakes. The green giants reduced the temperatures by up to 36 degrees Fahrenheit (20 degrees Celsius). That’s a strong argument for adding more green to cities.

“The forest offers us another benefit in addition to its cooling effect. It delivers more rain, as we’ll see in the chapter on rivers in the sky. Before we move on, however, there’s a glimmer of hope that there might be some movement in the views of state foresters who spend their time felling trees in nature’s cooling systems. Ulrike Hofken, then minister of the environment for the German state of Rhineland-Palatinate announced a temporary moratorium on logging in ancient beech forests to the end of 2021.”