Another thing to fear about climate change is how much scientists still don’t know.
BY KARL MATHIESEN AND ZIA WEISE
MARCH 20, 2023 3:30 PM CET
But a sprawling assessment of tens of thousands of scientific papers on the state of the planet, released Monday, pointed to another unsettling truth: Scientists still don’t have answers to many of the questions that will define how well the world copes with the worst of climate change.
In its latest report, the Intergovernmental Panel on Climate Change (IPCC) describes a world of long-foreseen impacts arriving now with shocking power. Human suffering — especially among the poor — will increase rapidly in the coming decades. The symbolic limit of 1.5 degrees Celsius will almost certainly be breached.
There is still an opportunity to avert the very bleakest scenarios, with the shift toward clean energy moving faster than expected, the report also notes.
But in many critical areas, IPCC scientists say the world is flying blind into the storm.
By the time they publish their next report — at the end of this decade — there will be more clarity about where global temperatures will peak. Green policies will have triggered social and economic transformation, with major benefits — and major upheaval.
That means there are still far too many unknowns to say with certainty how and when the most devastating impacts will hit.
“Generally, science is still lagging policy,” said Piers Forster, an IPCC author and director of the Priestley International Centre for Climate at the University of Leeds.
“We need a living laboratory mentality to test ideas in open and transparent ways to really learn about how to transform society. Otherwise, we’ll be going with technologies according to who shouts loudest rather than the best.”
How extreme will the extremes get?
Extreme weather events of the past few years — including the 2022 heat wave that sent temperature records tumbling across much of Europe, and the floods that devastated Pakistan last year — have surprised some of the world’s top climate scientists with just how far they sat outside the normal range.
Experts still know relatively little about when and where these types of extreme climate events will happen. Or what happens when two events, like a drought and a heat wave, hit one place simultaneously. That’s because scientists have tended to look at broader averages across regions, rather than the most intense extremes in specific locations.
“We haven’t asked the models [to] come up with an outrageously high temperature number, like 50 degrees in Canada » — a mark reached during a heat wave in 2021 — « and work out how likely that is or if that’s possible,” said Friederike Otto, an author of the IPCC report and senior lecturer at Imperial College London. “And I think that’s why these are surprises.”
Who are the vulnerable people?
As leaders look to contain the worst impacts of global warming, knowing where to concentrate efforts will be key.
The IPCC classified between 3.3 billion to 3.6 billion people — almost half of the world’s total population — as being among the most vulnerable, with people in the developing world hit hardest.
Even as the report was released, Mozambique, Malawi and Madagascar were locked in a record-breaking and repeated assault from Cyclone Freddy. The region is still recovering from Cyclones Idai and Kenneth in 2019.
But in rich countries too, the poor, the old, the sick, the young and the marginalized will be less equipped to face the challenges ahead.
Identifying precisely who is most at risk requires a blending of the physical sciences with social, political, economic disciplines. That discussion is only in its infancy.
When are we going to reach scary tipping points?
The IPCC expressed “medium confidence” that an abrupt change in Atlantic currents that could plunge Europe into an ice age would not happen before 2100.
Heartening? Perhaps. But regarding the most dangerous and sudden potential impacts of climate change, scientists’ level of certainty is still disturbingly low.
The field remains full of conjecture. But in a paper last year — which was published too late to be included in the IPCC report — scientists identified 16 of these so-called tipping points, including the collapse of the Earth’s major ice sheets, which would trigger massive sea level rise; and the loss of permafrost, leading to a sudden release of carbon dioxide and methane, further fueling global warming.
What’s clear is that there’s a direct correlation between rising temperatures and the likelihood of changes turning increasingly irreversible. For instance, the IPCC said, with a rise in global temperatures between 2C and 3C, Greenland and the West Antarctic would “almost completely and irreversibly” lose their ice sheets for millennia.
Should we dim the sun?
The stuff of science fiction veered into reality late last year, when a U.S. startup called Make Sunsets launched balloons that may have released reflective sulfur particles into the sky above Mexico.
Solar Radiation Management — as it’s called — is just one of a handful of mooted planet-cooling hacks. But none of them come without downsides. Nor do we even know if they will work. And the fear is that rogue actors will take matters into their own hands.
« There’s not enough science, there’s zero governance, » said Pascal Lamy, the former World Trade Organization chief who chairs the Climate Overshoot Commission.
The IPCC’s finding that there is almost no chance to avoid breaching the 1.5C limit has spurred more interest in fields once shunned as defeatist or worse. The White House has called for researchers to contribute to a new “climate intervention” research plan.
It remains deeply controversial. « The science is divided on this. We have a few scientists with a very high reputation who say let’s look at it seriously. Another small part of science that say: ‘No no! This is Dr. Strangelove and so on,’ » said Lamy. « But what’s for sure, is that if we succeed in a proper governance framework, it will have to be linked to proper science. »
Is the IPCC fit for purpose?
The IPCC’s membership includes many governments that are not thrilled to hear prescriptive views on how to structure their economies. So as the world moves increasingly into questions of transformative change, some scientists and policymakers are questioning whether the institution is fit to deliver the answers needed.
“The IPCC is a little bit like the Catholic Church: a very conservative institution with seemingly immutable rituals, with staying power and carried by an important mission,” German economist and chair of the European Scientific Advisory Board on Climate Change Ottmar Edenhofer told Die Zeit.
“What we don’t know is what kind of governance, what political instruments have to be put in place now. I doubt that the IPCC, with its intergovernmental structure, will be able to help us here,” Edenhofer said.