How we can limit Earth's warming to 1.5 degrees Celsius — if we act fast

How we can limit Earth's warming to 1.5 degrees Celsius — if we act fast

Updated: 2 months, 2 days, 10 hours, 34 minutes, 16 seconds ago





Good morning and welcome to The Climate 202! Today we’re mourning the legendary singer-songwriter Christine McVie, who died yesterday, and listening to Fleetwood Mac’s “Don’t Stop” on repeat. But first:


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The Post looked at 1,200 possibilities for the planet’s future. These are our best hope.

The 2015 Paris agreement established the world’s most important climate goal: limiting the Earth’s warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit) above preindustrial levels.

Keeping warming this low will help avert the most catastrophic consequences of unchecked climate change, such as dramatic sea-level rise that could inundate some small island nations, destruction of the Arctic’s protective sea ice layer, and the death of the world’s coral reefs.

But achieving this target is now in grave doubt. Already, the planet has warmed by more than 1.1 degrees Celsius (2 degrees Fahrenheit) above preindustrial temperatures, while Russia’s invasion of Ukraine has complicated efforts to curb the use of fossil fuels, a primary driver of global warming.


To see what hope remains, The Washington Post examined more than 1,200 scenarios for climate change over the coming century, drawing on models considered in a key report by the U.N. Intergovernmental Panel on Climate Change and working with experts from the Potsdam Institute for Climate Impact Research in Germany.

The results reveal a world that keeps inching closer to climate catastrophe. But they also show that a safer future is still possible if humanity takes urgent, sweeping actions to phase out fossil fuels, electrify energy systems and remove carbon dioxide from the atmosphere, The Post’s Chris Mooney, Naema Ahmed and John Muyskens report this morning.

If you have time, you can read our colleagues’ full story here. But if you’re in a hurry this morning, here’s a quick recap of how The Post crunched the numbers to determine what we can still do to meet the 1.5C goal:

Filtering out frightening scenarios

Our colleagues began by filtering out hundreds of scenarios that would not keep the 1.5C goal within reach.

However, some of these remaining 230 scenarios rely on unrealistic assumptions, such as a dramatic decline in greenhouse gas emissions by 2025 or a massive build-out of nuclear power plants by 2030.


That leaves just 112 paths that would keep the planet below 1.5C of warming by 2100. But some of these paths involve a “high overshoot,” in which warming soars above 1.5C before coming back down again.

Scientists say high overshoot is an unsettling prospect. It raises the possibility, for instance, of the Earth experiencing dangerous tipping points and even calamities such as the irreversible loss of the West Antarctic ice sheet, which by some estimates could increase global sea-level rise by about 3 feet.

Therefore, our colleagues zoomed in on 26 scenarios that involve a “low overshoot” or none at all. To assess how realistic these 26 paths are, they used a method developed by the Potsdam Institute researchers to rate the scenarios as “speculative,” “challenging” or “reasonable,” in order of increasing plausibility.


Many of the speculative scenarios rely on unreasonable expectations about the amount of carbon dioxide that will be pulled from the air by carbon capture technology , which has yet to be implemented at scale.

The challenging scenarios assume that the world will make speedy progress on removing carbon from the atmosphere and building out more clean energy.

The reasonable scenarios rely on relatively safe assumptions about the world’s pace of progress on deploying carbon capture technology, sequestering carbon in trees and land, slashing carbon emissions from energy production, curbing overall methane emissions, and reducing global energy demand.

However, when our colleagues looked at only reasonable scenarios, they found that none of the paths would have low or no overshoot, while 16 of the paths would have a high overshoot:

By contrast, when our colleagues looked at only challenging scenarios, they found 11 paths that involved low or no overshoot:

Ultimately, these results suggest that the world has probably run out of easy options to stay below 1.5C or have low overshoot. But governments and corporations can still take steps that are more challenging — both scientifically and politically — to ensure a safer, cooler future.

At the U.N. Climate Change Conference in Egypt last month, world leaders reaffirmed their commitment to “keep 1.5 alive.” Outside the conference venue, however, climate activists staged a demonstration where they pretended to resuscitate Earth.


It was an apt metaphor for a goal that is on life support but still reachable with dramatic action.

Pressure points

U.S. gas prices fall toward $3 a gallon as demand drops worldwide

Gasoline is now as cheap as it was in February, before Russia’s invasion of Ukraine sparked a global energy crisis, offering American drivers an unexpected gift for the holidays, The Post’s Evan Halper reports. 

On Wednesday, AAA reported that the average nationwide price of a gallon of regular gasoline was $3.50, while gas price tracking company GasBuddy projected that it could drop below $3 by Christmas. 

Prices are falling because demand for oil and gas is dropping as nations brace for a recession, coronavirus outbreaksin China threaten major financial disruption, and drivers cut back on gas-guzzling as they try to save money to cover other costs.


However, Patrick De Haan, head of petroleum analysis at GasBuddy, warned that several geopolitical and economic events could send gas prices rebounding. In particular, he pointed to the European Union’s looming price cap on Russian oil, which could take effect as soon as Monday.

Possible rail strike could strain energy industry

The House on Wednesday voted to force a contract between rail workers and carriers, a controversial move aimed at averting a rail strike that could hurt the economy, The Post’s Rachel Lerman, Lauren Kaori Gurley, Hamza Shaban and Jaclyn Peiser report. 

While the bill passed the House, it still needs to clear the Senate. A rail strike could occur as early as Dec. 9 after some unions rejected a contract deal brokered by the White House.

A rail strike could bring dramatic disruptions to the energy industry, with several industry groups warning that a strike would severely curtail deliveries of energy commodities such as coal and ethanol, which can’t be transported via pipelines, Zack Budryk reports for the Hill. 


More than 70 percent of ethanol produced in the United States is transported by rail, and the ethanol plants themselves also rely on rail for about 25 percent of the grain used in production. A strike could cut off ethanol supply to heavy-use states such as Texas and California.

Agency alert

Biden pledges millions to help relocate tribes vulnerable to climate change

President Biden announced Wednesday that the federal government will give three Native American tribes $75 million to move away from coastal areas or rivers that face a growing threat from sea-level rise and other effects of climate change, Christopher Flavelle reports for the New York Times. 

Two communities in Alaska and one in Washington state will get $25 million each to move their key infrastructure onto higher ground and away from the coast, with the expectation that homes will follow. Eight additional tribes will get $5 million each to plan for relocation away from climate risks — sometimes called “managed retreat” by experts who study climate adaptation.


“There are tribal communities at risk of being washed away,” Biden said during the White House Tribal Nations Summit on Wednesday, adding that the funding will help tribes “move, in some cases, their entire communities back to safer ground.”

The funding will come from the $115 million given to the Interior Department from the bipartisan infrastructure law and the Inflation Reduction Act, with additional support from the  Federal Emergency Management Agency.

Extreme events

Whirlpools, blackouts, predator fish: What happens on the Colorado River’s descent to ‘dead pool’

As a prolonged drought parches the American Southwest, the federal government is warning that as soon as July, waters could drop so low in Lake Powell that the surface could reach the tops of underwater openings that allow water to reach the hydroelectric dam, creating a sort of drain, The Post’s Joshua Partlow reports. 


If that happens, the eight massive turbines that generate electricity would shut down and more than 4.5 million people could lose power. This whirlpool scenario is one step removed from the much more devastating threshold known as “dead pool,” which could throw the entire ecosystem into turmoil and disrupt the nation’s electricity grid. 

At one point it would have been considered taboo to talk seriously about planning for such a dire scenario. But now, Tom Buschatzke, director of Arizona’s Department of Water Resources, said in an interview that “the critical part about what’s been happening and what climate change is forcing us to do is: we have to look more at the extremes.” 

In the atmosphere


Fritz showing us his smile... and new teeth coming in!— Cincinnati Zoo (@CincinnatiZoo) November 30, 2022

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