Can Global Warming Be Kept Below 2 Degrees Celsius?

World leaders are updating their pledges at COP26 but is there room for hope, or is it too little, too late?

Ruth Schuster
Ruth Schuster
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A coal-fired power station at sunset in Pocerady, Czech Republic.
A coal-fired power station at sunset in Pocerady, Czech Republic.Credit: kamilpetran / iStockphoto via Ge
Ruth Schuster
Ruth Schuster

Can the world as we know it be saved from global warming? No. It’s already not like the world we knew if we’re more than 5 years old. If anything, climate change is apparently accelerating. Nobody is safe.

But can we be spared worse? Is it even theoretically possible at this point to keep the mean global temperature increase below 1.5 degrees Celsius, or even 2 degrees Celsius – a level long touted as catastrophic? (4 degrees is the new 2 degrees, but don’t be fooled.)

LISTEN: Can Israeli climate tech undo decades of neglect?

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Theoretically yes, according to an international team of climate scientists writing in Science, as the 2021 UN Climate Change Conference (COP26) rolls on. But that “yes” is based on the nations meticulously fulfilling their updated pledges and hopefully going even further.

That is an optimistic assumption, since they haven’t so far. Talk is cheap and as John Harris wrote in The Guardian, too few of these world leaders came to Glasgow with a mandate for serious climate action “because almost none of them have tried to get one.”

Indeed, the record on keeping climate promises is abysmal. Even before COP26, the Brookings Institute points out, over 100 countries had joined an alliance aiming for net zero emissions by 2050: “These pledges are powerful, visible, simple … and utterly insufficient,” wrote the institute’s Rahul Tongia.

On Thursday, The Guardian drove home the emptiness of the rhetoric by noting that fossil fuel use and carbon dioxide emissions haven’t declined: they’ve reached record heights

Emissions in Europe have dropped a bit in the last 20 years, but the global trajectory is horrifying, and emissions from giants China and India are slated to keep rising.

Also, big business tends to fudge figures while beating the green drum: As The New York Times reported Thursday, at least some companies claiming to be environmentally woke are ignoring a key component – the emissions of their supply chain, which can be responsible for as much as 95 percent of the companies’ real contribution to greenhouse gases.

It’s tempting to succumb to feel-good distractions, but solar panels or even an eggplant garden on a manufacturer’s roof aren’t going to go far in mitigating production and transport emissions. And increases of 1.5 or 2 degrees Celsius above preindustrial levels, to which we are now reduced to aspiring, means the extreme weather experienced so far is nothing yet.

Five temperature/emissions scenarios (Dec. 2019): No action; current policies; pre-COP26 pledges; pathways to 2C and to 1.5C, if urgent vast cuts are made to emissionsCredit: Hannah Ritchie and Max Roser

Note that the Intergovernmental Panel on Climate Change itself warns that even if emissions are eliminated quickly, it could take 20 to 30 years for temperatures to stabilize. That, by the way, is a guesstimate since temperature and carbon dioxide levels are correlated but at a lag. We don’t know what the lag will be, or its dimensions; we just know that temperature is not “caught up” with the CO2 already emitted.

How it could be done

So, how can warming be curtailed below 1.5 or 2 degrees Celsius, per Yang Ou of the Joint Global Change Research Institute and colleagues? It’s a matter of keeping one’s word and hoping for new technologies.

The authors applaud that 121 parties, which are responsible for 52 percent of global greenhouse gas emissions, updated their pledges at COP26 and most vowed to move fast – meaning, to cut as “soon” as 2025 to 2035. Of course, that leaves the ones responsible for the other 48 percent and the snag that all too many others are lying or just not moving fast enough: the global trajectory of emissions remains sharply upward.

Annual CO2 emissions by region, October 2020Credit: Our World in Data

But Ou et al stress that the COP26 pledges are stronger than the previous lot, and that world leaders are evincing a keener sense of urgency.

There have also been technological advances that have been reducing the cost of renewable energy and electric vehicles, and so on. Apropos, an electric car is only as “clean” as the power station from which it gets its power. If your local power plant isn’t green, neither is your vehicle.

“Collectively, the updated pledges result in lower CO2 emissions from energy and industry in 2030 by 15 percent relative to the 2015 pledges,” Ou et al write. And note, while some are committing to becoming carbon-zero by 2050 – for instance, Shell Oil! – or 2070 (India), none are committing to becoming carbon-negative.

But if the COP26 pledges are sincere, if the countries and Shell Oil and its ilk sustain their actions afterward too, then the probability of “exceeding 4 degrees Celsius is virtually eliminated,” Ou and colleagues claim. They calculate a 34 percent probability of temperature increase below 2 degrees Celsius. There is a 1.5 percent chance that temperature increase can be kept below 1.5 degrees Celsius (note again that 1.5 degrees is considered catastrophic).

Climate activists protesting against the use of fossil fuels, on the sidelines of the COP26 Climate Conference in Glasgow on Wednesday.Credit: BEN STANSALL - AFP

But Ou et al add that if countries step up their mitigation efforts, not only is the probability of exceeding 4 degrees Celsius virtually eliminated, but the probabilities of limiting temperature change below 2 degrees and 1.5 degrees also increase to 60 percent and 11 percent, respectively.

In Israel, meanwhile, the person in the street seems oblivious to the implications of climate change, even though the temperature in the Middle East is rising faster than elsewhere (if we leave the Arctic Circle out of it). The mean global temperature has already increased by 1.1 to 1.2 degrees Celsius; in Israel it’s risen by 1.5 degrees.

To save us, our leaders need our help. It’s not good enough to grouse from the house about useless politicians and their blowhard ways. Earth could be alien to humans by the year 2500 if we don’t change trajectory, The Conversation and Scientific American warn.  Don’t want that? We the people must lead by example, accept that we will have to change our behavior and curb our consumerism, and vote responsibly.

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