Forests across Europe, the US and Canada have been hard hit by drought, fires and bark beetles. Now scientists fear the northern hemisphere’s greate

The end of the great northern forests? The tiny tree-killing beetle wreaking havoc on our ancient giants

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2024-06-05 13:30:05

Forests across Europe, the US and Canada have been hard hit by drought, fires and bark beetles. Now scientists fear the northern hemisphere’s greatest carbon sink is nearing a tipping point

T he giant sequoia is so enormous that it was once believed to be indestructible. High in California’s southern Sierra Nevada mountains, the oldest trees – known as monarchs – have stood for more than 2,000 years.

Today, however, in Sequoia national park, huge trunks lie sprawled on the forest floor, like blue whale carcasses stranded on a beach. Many of these trees were felled by a combination of drought and fire. But among the factors responsible for the rising toll is a tiny new suspect: the bark beetle.

Along with wildfires and rising temperatures, scientists fear that the insects could contribute to the breakdown of Earth’s northern conifer forests, including the potential dieback of the taiga, the vast ecosystem that stretches across Canada, Scandinavia, Siberia and Alaska.

The boreal forest spans 11.3m sq km (2,800m acres) and stores about 272 gigatonnes of carbon. Its possible collapse is considered a climate tipping point: the moment when an ecosystem that was previously a carbon store flips over to releasing huge amounts of carbon instead – through a forest fire, or the gases released by decaying trees and eroding soil.