Are Earth’s species really doomed? This study has a hot new take.

When it comes to human-driven species slaughters, there’s
(new) good news and there’s (old) bad news.

The bad news, as those of you who read that 2019
United Nations biodiversity report
remember, is that experts
predicted we are on track to wipe out 1 million species as a result
of polluting, clearing forests for agricultural purposes, expanding
cities and roads, overhunting, overfishing, mucking up water
resources, spreading invasive species, and generally microwaving
the planet. But take heart! A new paper shows some critters may be
more resilient than scientists thought, and we still have a sliver
of time to ensure that we don’t wipe out all the Earth’s
animals (the bar is set so high these days).

Why the (slightly less awful) adjustment? Past studies on
climate-driven extinction and biodiversity loss tended to lump a
bunch of different factors under the climate change umbrella. But
this paper, published Monday in the Proceedings of the National
Academy of Sciences, parsed some of the factors driving extinction
in order to determine which aspects of climate change have the
biggest impacts on species loss.

By looking at 581 sites around the world and 538 species across
those sites, researchers found that the best predictor of a local
extinction event was an increase in that location’s maximum
annual temperature: when the hottest days of the year got hotter.
“If it gets too hot, [some species] basically can’t live there
anymore,” study co-author John Wiens told Grist. Surprisingly,
the average increase in temperature in a given place over the
course of a year — what we typically think of when we talk about
climate change — didn’t appear to have much to do with
extinction events at all. In fact, the researchers found local
extinctions were happening more often in places where the mean
annual temperature hadn’t increased a lot.

In short, it’s really those record-breaking hot days — the
kind that has all of Paris splashing in fountains, or force
normally temperate Washington state to open cooling centers —
that spell doom for at-risk species.

How that actually plays out depends a lot on what, if anything,
humans do to stem the climate crisis. The study found that if the
hottest days of the year (the maximum annual temperature) increase
0.5 degrees C, half of the world’s species will go extinct by
2070. If those maximum temperatures increase by 3 degrees C, that
is, if we continue to produce emissions business-as-usual, then 95
percent of species will go extinct. “That’s really bad,”
Wiens said.

But if humanity can keep a handle on those uncharacteristic heat
waves, plants and animals may still have some wiggle room for
survival. That’s because a given plant or animal may be able to
do something called a “niche shift,” which means the species
can change the range of temperatures in which it is able to
survive.

That versatility may buy some critters a little time, but
experts caution it’s not an excuse for complacency about the
climate crisis. “At some point,” Wiens said, “it’s going to
get too hot.”

Here’s the good news: if we stick to the only global climate
agreement we have — an agreement that aims to keep temperatures
from increasing more than 1.5 degrees C. — those species loss
numbers could be much, much lower. “We have to talk about the
Paris Agreement,” Wiens said. “If we’re able to stick to
that, then it might be a loss of only 15 percent or so.”

This story was originally published by Grist with the headline
Are Earth’s species really doomed? This study has a hot new
take.
on Feb 10, 2020.

Source: FS – All – Science – News
Are Earth’s species really doomed? This study has a hot new take.