World to blow past key climate red-line, study finds

World governments have failed to cut emissions sufficiently to avert serious climate disruptions, a new study has found.

Commitments from national governments have made it “inevitable” that average global temperatures will cross the critical threshold of 1.5 degrees Celsius (2.7 Fahrenheit) above pre-industrial levels, according to a landmark paper by the Department of Energy (DOE) published on Thursday in Nature Climate Change.

These findings now shift the focus to trying to limit emissions with the goal of keeping warming as close to 1.5 degrees as possible — while trying to find ways to drag warming back down, the DOE and its research partners at the University of Maryland and the Environmental Protection Agency (EPA) stated.

“Let’s face it. We are going to breach the 1.5 degrees limit in the next couple of decades,” coauthor scientist Haewon McJeon of the DOE’s Pacific Northwest National Laboratory said in a statement.

“That means we’ll go up to 1.6 or 1.7 degrees or above, and we’ll need to bring it back down to 1.5. But how fast we can bring it down is key,” McJeon added.

The study comes on the eve of President Biden's visit Friday to the U.N. Climate Change Conference (COP27) in Egypt, where he plans to tout U.S. progress on clean energy and climate goals, according to the White House. Still, the study found that government actions in the U.S. and other countries have not kept pace with the changing climate.

In climate circles, the concept of passing a key threshold is called “overshoot.” But while passing the global warming threshold is now likely unavoidable, differing degrees of overshoots — and speed of bringing temperatures back down — lead to dramatically different results, the researchers found.

If countries simply upheld their existing climate commitments — which would see the emissions of planet-heating gasses declining indefinitely at about 2 percent per year — carbon dioxide levels in the atmosphere will continue to increase throughout the end of the century, the researchers found.

That scenario leads to “irreversible and adverse consequences for human and natural systems,” lead author Gokul Iyer of the Joint Global Change Research Institute said in a statement.

Even that grim scenario is more optimistic than existing trends would suggest. And despite Democrats’ passage of a sweeping climate bill in late September, the Biden administration has approved new oil and gas wells “at a far faster pace” than the Trump administration did in an equivalent period, Politico reported earlier this month.

“We’re producing 12 million barrels of oil per day and by the end of this year we will be producing 1 million barrels a day more than the day in which I took office. In fact, we’re on track for record oil production in 2023,” Biden bragged in late October.

The burning of fossil fuels is almost universally agreed upon by scientists as the primary driver of climate change.

Over the past two decades, the fossil fuel industry has shifted from outright denial of this linkage to a posture analogous to that of tobacco companies, which blames the damage caused by climate change on society as a whole, according to a 2021 study in One Earth.

In the most ambitious scenarios that the DOE researchers explored, the delay gives way to rapid action. In these models, countries would have to make rapid cuts in their emissions of greenhouse gasses — largely released from the burning of fossil fuels — through 2030.

This path would bring a global net zero of carbon dioxide by 2057 — and with it a drastic slowdown of the processes that drive global heating, the researchers found.

That path would involve a rapid scaling up of emissions-reducing technologies — from electric vehicles to hydrogen and wind power and massive cuts in the use of carbon-based energy, according to the study. It would also require an enormous scaling up of technologies like carbon capture, to pull planet-heating carbon dioxide from the atmosphere, researchers found.

World governments pledged at the 2015 Paris Climate Agreement to stay below 2 degrees Celsius of warming and to remain “as close as possible to 1.5 degrees.” 

That 2-degree figure marks a red-line at which the worst climate impacts could be avoided, but at which severe disruptions begin to emerge — sowing discord, drought and disease far more dramatic than if warming is kept to 1.5 degrees.

Extreme heat waves would also affect more than twice as much of the world population in the 2-degree world than the 1.5-degree world, a U.S. government study found.

At 2 degrees, loss of biodiversity also doubles or triples over the levels expected at 1.5 degrees, as does the number of ecosystems transitioning from one form to another — as from forest to savannah or scrubland, according to the 2018 U.N. study

The higher threshold of warming also leads to markedly more severe declines in yields of key cereal grains and drops in the annual yields of fisheries.

One fact that helps explain that dramatic fall in available fish protein: at 1.5 degrees, coral reefs suffer severe declines, but at 2 degrees they all but disappear.

According to a U.N. report from late October, the world is nowhere near the emissions cuts necessary to keep warming even to 2 degrees Celsius.

To keep warming below 2 degrees, world governments — particularly major emitters like the U.S., China, India and Russia — would have to cut emissions by 30 percent.

The DOE researchers stressed that world leaders much move far more quickly to scale up their plans to reduce emissions.

“Moving fast means hitting net-zero pledges sooner, decarbonizing faster, and striking more ambitious emissions targets,” Iyer said.

“Every little bit helps, and you need a combination of all of it. But our results show that the most important thing is doing it early. Doing it now, really.”