Ian Morse writes:

Scientists are clear: the number of plant and animal species on Earth is declining. The climate crisis, habitat loss, pollution and the illegal wildlife trade are all pushing species toward extinction. Researchers especially worry that losing too much biodiversity could push the earth past a tipping point into irreversible change, and on into a new paradigm in which humanity and other life can’t survive.

Which partly explains humanity’s self-interest and urgency in understanding and maintaining global biodiversity. But there’s a catch: most of Earth’s biomass isn’t composed of plants and animals, but rather of microscopic organisms found almost everywhere — in soil, the upper atmosphere and deep ocean trenches. Microbes help us grow food on our farms and to process it in our gut; they give us diseases and help cure them.

An ominous question looms: how will climate change, along with other human-destabilized planetary boundaries — ocean acidification, deforestation and land use change, ozone depletion, nitrogen and plastics pollution, and maybe worse — alter the microbial world?

According to a new paper, “we have no idea” whether diversity among microbes is growing or shrinking, whether we could be walking blind toward microbial extinction cliffs — or soon be living in a world more dominated by microbes.

“We’re pretty clear that macro-biodiversity is in decline, but whether micro-biodiversity is going the same direction, we’re not sure,” says David Thaler, a microbiologist at the University of Basel and study author. [Continue reading…]