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Why some scientists are pressing the UN to prioritize climate ‘tipping points’

In this week's issue of our environment newsletter, we look at why some scientists are agitating for more public awareness of climate tipping points and what a pika's poop can tell us about the habitat of this at-risk species.

Also: The heat pump, illustrated

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This week:

  • Why some scientists are pressing the UN to prioritize climate 'tipping points'
  • How a heat pump works
  • Researchers are looking at pika poop to see how climate change is affecting this mountain mammal

Why some scientists are pressing the UN to prioritize climate 'tipping points'

Two people are seen from behind as they walk down an empty road. The sky is orange with wildfire smoke.

While environmentalists are preparing for the COP28 climate summit in Dubai later this month, the UN's Intergovernmental Panel on Climate Change (IPCC) is also meeting to discuss its next assessments of the state of global warming.

After a record-shattering summer — with 2023 on pace to become the hottest year in recorded human history — one of the key decisions for the IPCC is whether to emphasize the prospect of runaway, irreversible global warming by issuing a special report on climate tipping points.

Tipping points are aspects of the climate system "prone to abrupt and or irreversible shifts" driven by positive feedbacks, said Tim Lenton, a climate scientist at the University of Exeter in the U.K. who has been researching tipping points for two decades.

For example, "as the Greenland ice sheet melts, the surface descends in altitude, which brings it into warmer air, which tends to accelerate the melting," he said.

Some of these feedbacks can become so strong they become "self-propelling," Lenton said, increasing warming even without the addition of more greenhouse gases.

The issue of tipping points has been briefly raised in previous IPCC comprehensive reports, but the next set of them isn't due for another five to seven years.

"It's just not adequate risk management or sensible to wait around for a slow cycle of reporting like that," Lenton said. "We have to be more fleet of foot."

While Lenton supports a UN report on climate tipping points, he's convening a group of more than 200 scientists who are producing their own tipping points report, outside the purview of the IPCC, to be released in time for COP28.

Thomas Stocker, a former co-chair of IPCC Working Group I, which studies the physical science of climate change, said the 2012 IPCC special report on managing risks of extreme events motivated him to call for a tipping points report.

He said it would respond to some of the persistent questions that have been around since 2001, when the IPCC first looked at what were then called "surprises" in the climate system.

Luke Kemp, a researcher at the Cambridge Centre for the Study for Existential Risk in the U.K., said one of the "scary" aspects of tipping points is that scientists still don't have clear knowledge of what the early warning signals are. Nor does the scientific community know when exactly "the feedbacks are likely to become self-amplified to the extent where they're difficult to handle."

Kristie Ebi, a professor of global health who studies the health risks of climate change at the University of Washington in Seattle, said addressing worst-case scenarios involving tipping points "helps give our future self a leg up and be in a place where we can be more resilient."

For example, she pointed to the construction of the bridge to P.E.I., completed in 1997, which was built to allow for one metre of sea-level rise. Adding the extra metre didn't cost that much more at the time and retrofitting would have been very expensive, she said.

In 2021, Naomi Oreskes, a professor of the history of science at Harvard University, argued that having thoroughly established the link between human activity and climate change, the IPCC should now focus on issues such as mitigation, adaptation and tipping points.

"Scientific resources are finite … it is really important for the scientific community to be strategic about where the bulk of the effort is placed," said Oreskes, co-author of the 2010 book The Merchants of Doubt: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming.

Stocker noted that climate scientists faced "fierce resistance" from governments in getting the concept of a "global carbon budget" approved in previous IPCC reports. But it has become one of the key pieces of information for measuring progress on emissions reductions.

"Had it not been for our ambition to have that controversial topic in the summary for policymakers, we would not be where we are today," Stocker said. "I think with tipping points, we can make the same arguments."

Oreskes said "the whole point of the tipping point report is to say it's not too late to avoid the worst catastrophes, like the dieback of the Amazon or the collapse of the West Antarctic ice sheet."

Since the IPCC operates on consensus-based decision-making, Canada would need to agree to commission a special report on tipping points.

"We support science, we support the development and the better understanding of climate science and its impact," Environment Minister Steven Guilbeault said in an interview. "And if that means, for example, supporting a special report on tipping points, it's certainly something that I would be supportive of."

Regardless of how the climate community examines the tipping points, the danger of crossing them is clear.

"If you cut off a leg of a starfish, the starfish can grow that limb back," Oreskes said. "But if you cut off the leg of a human, we don't grow legs back. Most of our ecological systems are more like people than they are like starfish."

James Westman


Old issues of What on Earth? are here. The CBC News climate page is here.

Check out our podcast and radio show. This week: Stressed about the plastic packaging you toss? Us, too. A farmer in Nova Scotia asks if there's a better way to package greens. We find out. What On Earth drops new podcast episodes every Wednesday and Saturday. You can find them on your favourite podcast app, or on demand at CBC Listen. The radio show airs Sundays at 11 a.m. ET, 11:30 a.m. in Newfoundland and Labrador.

Watch the CBC video series Planet Wonder featuring our colleague Johanna Wagstaffe here.


Reader feedback

Wendy Thompson:

"What a brilliant idea re: your article on the recycling machines for plastic bottles in exchange for bus tickets, particularly in Rome and in the city of Medellin in Colombia. Sounds like a win-win situation for the environment and an encouragement to the locals to use their transport system more often.

"But reading about Coca-Cola's latest ploy in Toronto to allow the exchange of plastic bottles for a chance to play in the Replay Arcade with the enticement of a free Coca-Cola beverage seems to be a total win-win just for that particular company. Sadly, a lost opportunity for any benefit to the Canadian environment."

Also, following up on our Oct. 26 story about a guy who climbs and fixes wind turbines and plans to open a school to train others, Rick Stomphorst wrote in about some existing training programs. Stomphorst is with the Kitchener, Ont.-based Work-Based Learning Consortium, which helps companies upskill their employees.

"We developed a new training program this year and had over 20 students complete it," he said, adding that wind turbine repair training is also available from Advanced Composites Training in London, Ont., and the Toronto non-profit Relay Education. "Every employer I've spoken with needs more blade technicians," Stomphorst wrote. He added that in Canada, seasonal recruitment starts in February, with field work from April to October.

Write us at whatonearth@cbc.ca.

Have a compelling personal story about climate change you want to share with CBC News? Pitch a First Person column here.


The Big Picture: A heat pump in action

There's been a lot of talk of late — both in political discourse and in this newsletter — about heat pumps, a longstanding low-carbon technology to heat and cool buildings. For those who still don't fully understand the science, we thought we'd provide a handy graphic.


Hot and bothered: Provocative ideas from around the web


Scientists are looking at pika poop to see how climate change is affecting this mountain mammal

An American pika stands in its rocky mountainous environment. It resembles a small rabbit, but has shorter hair and looks closer to a guinea pig.

As the climate continues to warm, scientists say sensitive species like the pika — a small, mountain-dwelling mammal that looks like a mouse — can act as an early warning system for more widespread impacts.

Pikas may be adorable, but their poop doesn't really have the same appeal — that is, unless you're a biologist who knows it may hold valuable information about what climate change is doing to the creature's alpine home.

Researchers at the University of British Columbia's Okanagan campus are developing a genetic monitoring tool that could provide insights on this. By analyzing pika DNA, including from their poop, researcher Kate Arpin and the university's Russello Lab say they could soon track individual pikas, monitor the interconnectedness of different pika populations and record those populations' evolution in near-real time.

The American pika can be found at high elevations throughout parts of the Canadian Rockies and B.C.'s Coast Mountains, in rocky, barren habitats with little soil and vegetation. Hikers in western Canada may be familiar with their characteristic call ("eep!").

Pikas are widely consideredone of the animals most vulnerable to climate change. As temperatures rise, forests climb to higher elevations, reducing the amount of habitat available for pikas, said Tony Einfeldt, an ecologist with Parks Canada.

Warmer temperatures can also make it harder for pikas to find enough food and decrease the winter snowpack, which they rely on for insulation during the winter.

Biologists expect pikas will be forced to move to higher elevations, which could further isolate populations from each other — a common driver of decline among many species.

"One way of catching that process early would be to look at the changes… that would result in these increasingly island-like mountainous regions through genetic tools," said Einfeldt, who says park ecologists are currently monitoring pikas by recording the piles of dried vegetation that the mammals gather as a winter food source.

"They provide us this pulse, this barometer of what's happening in our most sensitive ecosystems," said Erik Beever, a research ecologist with the U.S. Geological Survey and Montana State University.

Limited evidence shows certain U.S. pika populations may have some ability to adapt, but in other areas, pikas are seeing widespread decline. The status of Canadian populations is less well known largely because of a lack of genetic data, said Arpin.

She says she hopes the genetic monitoring tool she and her collaborators have built may soon change that. The tool is already extremely accurate when it comes to analyzing a pika's genetic material from tissue samples, even those dating as far back as 1930.

The more degraded DNA found in their scat is trickier to analyze accurately, with error rates close to 30 per cent. Still, Beever is optimistic.

"I would argue that the rapidity of development and evolution of these molecular tools is pretty mind-blowing, and specifically on the front of non-invasive techniques [like scat sampling]."

Arpin says while this sort of genetic monitoring is very new, there have been breakthroughs for other species.

"Recent work … has developed the same type of genetic monitoring tool for polar bear and for deer [scat] samples," she said. "There's definitely promise in using these sorts of genetic monitoring tools in the future."

If sampling is done over many years, researchers could even potentially watch the species evolve through its poop.

If researchers are able to achieve high accuracy with fecal samples, it would mean a change of approach for the Parks Canada ecologists monitoring pikas — as Einfeldt already knows from Arpin's request for samples.

"Usually, we're trying to avoid touching the poop," he said. "But we donned our rubber gloves and got our forceps out and went digging through their latrines that they form in these rocky environments, looking for the freshest, best poop we could find."

Darius Mahdavi

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