Why even a fraction of a degree can escalate climate change impacts
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fraction → escalate → impacts
Countries have gathered at the annual climate change negotiations at the COP31 summit in Turkey to discuss how to achieve a goal that is increasingly unachievable.
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that → gather → goal
A decade ago, countries agreed to limit climate warming to 1.5 degrees Celsius (2.7 degrees Fahrenheit).
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countries → agree → degrees
Heat-trapping emissions from burning fossil fuels are still rising in the atmosphere, and most countries are not on track to meet their climate pledges to cut emissions by transitioning to cleaner energy.
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countries → trap → energy
The best-case scenario for the planet is now 1.7 or 1.8 degrees Celsius of warming (roughly 3 degrees Fahrenheit), according to a recent United Nations study.
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scenario → warm → study
If fossil fuel emissions stay on their current path, the world would be around 2.8 degrees Celsius (5 degrees Fahrenheit) hotter by the end of the century.
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world → stay → century
While the difference between 1.5 and 2 degrees Celsius may seem tiny, scientific research shows those increments can produce dramatically different outcomes for the planet.
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increments → seem → planet
More warming raises the risk of extreme weather globally and could lead to the collapse of some of the planet's most sensitive ecosystems.
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warming → raise → ecosystems
"The crucial point is that every fraction of a degree matters," says Tim Lenton, climate professor at the University of Exeter.
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Lenton → matter → Exeter
"Every fraction of a degree that we avoid is really able to do a huge amount of limiting harm.
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we → avoid → harm
As they grow, they create the framework that supports vast numbers of other species, making reefs biodiversity hotspots.
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reefs → grow → species
They're also vital to hundreds of millions of people who depend on them for food and livelihoods.
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who → depend → food
Prolonged marine heat waves cause corals to bleach, turning them white, which can eventually kill corals.
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which → cause → corals
With a historically strong El Niño now raising water temperatures, scientists say the fifth global bleaching event is likely unfolding.
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event → raise → temperatures
Even before the previous bleaching event from 2023 to 2025, researchers found that 44% of coral species globally are at risk of extinction.
"These are incredibly worrying statistics, but they also emphasize that time matters," says David Obura, director of the coral research organization CORDIO East Africa, who worked on the study published last month in the journal Nature.
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who → find → journal
"Every ten years, every five years counts.
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years → count → ?
Given their susceptibility to heat, the survival of most coral reefs depends on the difference between 1.5 and 2 degrees of warming.
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survival → give → warming
The Intergovernmental Panel on Climate Change found that beyond 2 degrees Celsius of warming, 99% of corals would be lost.
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% → find → corals
"At 2 degrees of warming, we anticipate most corals just won't survive, not in functional ways to build a reef ecosystem," Obura says.
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Obura → anticipate → ecosystem
"So you might still find some of the species, but many of them may be so rare or so compromised that they will have gone extinct by then."
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they → find → them
With the dire forecasts for the future of coral, conservation groups and coastal communities are working to make reefs as healthy as possible in many areas so they can better withstand climate change.
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they → work → change
That includes restoring corals, reducing water pollution and even breeding more heat-tolerant corals.
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That → include → corals
"Most people around the world don't have the luxury of giving up on degraded ecosystems, because that's where they live," Obura says.
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they → have → ecosystems
"That's all they have.
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they → have → ?
So we have to work out how to make them function again.
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them → have → ?
Millions more exposed to extreme heat
The goal of 1.5 degrees Celsius is an average temperature, measured across the planet.
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goal → expose → planet
What it masks is the increasingly extreme heat events that are raising the average.
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that → mask → average
Researchers have found that for every tenth of a degree of warming, an additional 140 million people are exposed to dangerous levels of heat.
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people → find → heat
Heat waves are already causing heavy death tolls, like in Europe, where an estimated 50,000 people died of heat-related causes this past summer.
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people → cause → causes
The real toll of heat waves is often hidden, since many heat-related deaths are undercounted.
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deaths → hide → waves
"You could think of it a bit like a tipping point for the human organism or body," Lenton says.
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Lenton → think → organism
"At some point, our physiology kind of reaches a tipping point and the worst tipping point is death.
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point → reach → point
Every degree of climate change also affects the intensity of storms.
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degree → affect → storms
Warmer air can produce heavier downpours because it holds 7% more water vapor for every degree.
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it → produce → degree
Rainstorms are already getting more intense in most of the U.S.
Scientific research also shows higher levels of warming could lead to other risky tipping points, like the collapse of Antarctic glaciers.
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levels → get → glaciers
If they destabilize, the melt would add vast volumes of water to the ocean, raising sea levels globally.
"We're never exactly sure where the tipping point is until we cross it, but we can be 100% confident that, for most of them, more warming is a bigger likelihood of crossing them," Lenton says.
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Lenton → destabilize → them
"Less warming is controlling that risk and that's why we should fight for every fraction of a degree that we can stave off.
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we → control → that
At the ongoing climate negotiations in Turkey, countries are not expected to make major new commitments to cut climate emissions.
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countries → expect → emissions
Discussions are focusing on a new goal for electrification, meaning more cars and homes would run on electricity instead of fossil fuels.
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cars → focus → electricity
That would help reduce overall emissions, since a growing share of the world's electricity comes from cleaner sources, like solar and wind.
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share → help → solar
The Aporia
