Worms are on the move, and people are nervous.

That’s because they’re taking over territory in the Far North that’s been wormless since the last ice age. Scientists say the expansion will inevitably change northern ecosystems, with implications for the whole planet, in ways we don’t fully understand and probably can’t undo.

[. . .]For example, by encouraging the growth of certain plants at the expense of others, altering entire food webs and squeezing out rare, native flora that is already threatened by climate change.

[. . .]They can also trigger microbial activity that can help to unlock potent greenhouse gases like carbon dioxide, methane and nitrogen that are stored in the soil.

[. . .]Now, as human-caused climate change raises temperatures and thaws the permafrost, the worms are getting a foothold.

[. . .]Because of changes in the chemistry and physics of the ground, grasses and shrubby plants tend to thrive, taking over from tundra mosses and lichens. That’s good news for the lemmings and voles that favor such plants, according to Hanna Jonsson, an ecology researcher at Umea University. But probably not good for other herbivores that might not adapt easily to a change in available food.

Most importantly, these changes can reduce the amount of snow cover that reflects solar heat back into space from the top of the world. That means the ground can absorb exponentially even more heat.

That makes for a complicated global picture, and scientists still aren’t sure exactly how these earthworm invasions might affect the planet’s ecosystems and overall greenhouse gas levels.

[. . .]Initial research by Klaminder and Jonsson suggests that, depending on vegetation type, the overall impact on the planet’s carbon balance could amount to zero or even a net reduction. That’s because any release of carbon dioxide from the decomposition of organic matter caused by worms could be offset by growing plants that can suck up some carbon from the air.

Other experts, including Frelich and Craven, say any such virtuous effect on the carbon balance could be canceled out by the decline of tree growth in the forests of North America. And any sort of carbon dioxide sequestration that earthworms could be doing in the long-term would be too little, too late.

[. . .]What scientists agree on is that the worm-related changes are definitely significant. They’re happening very quickly in a region that’s warming much faster than the rest of the planet and hosts some of the world’s last untouched ecosystems and some of its most vulnerable species of flora and fauna.

The changes are probably irreversible, because earthworms are very difficult to eradicate. And, we’re very likely going to see settlements expanding as the Far North becomes warmer and more hospitable[. . . .]