We’re Approaching 1.5 Degrees C of Warming, but There’s Still Time to Prevent Disaster
Scientists say it’s likely that at least one of the next five years will exceed an average increase of 1.5 degrees Celsius above preindustrial temperatures
The sun sets behind smoke from a distant wildfire as drought conditions worsen on July 12, 2021 near Glennville, California.
CLIMATEWIRE | The world is careening toward a major planetary milestone, leading meteorological organizations said Wednesday. Nations are striving to halt global warming at 1.5 degrees Celsius — yet global temperatures already are nudging temporarily above that threshold.
A new report from the European Union’s Copernicus Climate Change Service warns that the last 11 months in a row have all seen global average temperatures above the 1.5 C threshold. And the last 12 have all been characterized by record-breaking monthly heat; temperatures last month hovered about 1.52 degrees above Earth’s preindustrial average.
Meanwhile, the World Meteorological Organization said Wednesday that there’s an 80 percent chance at least one of the next five calendar years will exceed a 1.5 C average. Nearly a decade ago — in 2015 — that chance was nearly zero.
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It wouldn’t be the first time a 12-month span has crossed 1.5 C. Copernicus reported earlier this year that the yearlong period between February 2023 and January 2024 averaged 1.52 C above preindustrial levels, marking it the hottest 12 months on record at the time.
Temperatures have continued to inch higher since then. The yearlong period that just ended in May saw global temperatures average about 1.63 C above preindustrial levels, making it the new hottest 12-month span.
Still, temporary fluctuations into 1.5 C territory don’t suggest the threshold has yet been permanently crossed.
The Paris climate agreement doesn’t explicitly outline the definition of when a temperature threshold has passed. But most scientists agree that the 1.5 C target refers to a long-term average. The exact amount of time that defines “long term” is also debatable, but it generally refers to years or even decades.
It’s even possible the world could cross the 1.5 C threshold without realizing it for years.
For now, even a whole year above the 1.5 C threshold wouldn’t push the long-term average over the red line. If scientists look back at the average over the past 10 years, they’ll find that it’s still below the threshold.
It’s a point that United Nations Secretary-General António Guterres raised in a passionate speech in New York on Wednesday for World Environment Day.
“The 1.5 degree limit is still just about possible,” he said. “Let’s remember, it’s a limit for the long term, measured over decades, not months or years. Stepping over the threshold for a short time does not mean the long-term goal is shot — it means we need to fight harder.”
But even if the Paris Agreement’s most ambitious target remains technically feasible, experts are increasingly skeptical the world can achieve it. According to the U.N.’s Intergovernmental Panel on Climate Change, global emissions would need to peak by 2025 — next year — and then fall 42 percent by 2030 in order to keep warming below 1.5 C.
The world then would need to hit net-zero emissions around 2050.
Meanwhile, recent research has suggested the world likely can burn only about 200 billion metric tons of additional carbon dioxide before the threshold is out of reach. Global emissions are still rising, and nations worldwide currently are spewing nearly 40 billion tons of CO2 annually from the burning of fossil fuels alone.
That means the odds of overshooting the 1.5 C target are rapidly rising. And scientists are growing more candid about those risks.
“It is almost inevitable that we will at least temporarily overshoot 1.5,” said Jim Skea, an energy expert at Imperial College London, at a presentation of the third and final installment of the IPCC’s most recent major assessment report in April 2022. Skea was a co-chair of the working group that prepared the report.
In December 2023, leading international researchers presented an annual climate science report to the U.N. warning that overshooting the 1.5 C target is “becoming inevitable.”
It’s possible that world leaders could lower the planet’s temperatures back below a 1.5 C threshold even if they temporarily overshoot, using various technological means to suck CO2 back out of the atmosphere.
But that’s not a guarantee — and some climate impacts are virtually irreversible once they’ve occurred, such as sea-level rise or plant and animal extinctions, making it crucial for world leaders to limit warming as much as possible while they still can.
That means even if an overshoot becomes inevitable, keeping global temperatures as close to 1.5 C is the next step. And that still means reducing global emissions as rapidly as possible.
“Why all the fuss about 1.5 degrees?” Guterres said in Wednesday’s speech. “The difference between 1.5 and 2 degrees could be the difference between extinction and survival for some small island states and coastal communities. The difference between minimizing climate chaos or crossing dangerous tipping points.
“One-and-a-half degrees is not a target. It is not a goal. It is a physical limit.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2024. E&E News provides essential news for energy and environment professionals.
