‘Gobsmackingly bananas’ record temperatures are dividing scientists

Aerosols have historically served to mask human-induced climate change by reflecting some of the sun’s heat back into space.

“Surprising. Astounding. Staggering. Unnerving. Bewildering. Flabbergasting. Disquieting. Gobsmacking. Shocking. Mind boggling.”

That’s not really what you want to hear from one of the world’s preeminent climate scientists in response to the latest global air temperature data, but that was the reaction of Ed Hawkins, professor of climate science at the University of Reading and creator of the iconic “warming stripes” visualisation. Zeke Hausfather, a researcher at nonprofit group Berkeley Earth, described it more succinctly: “Gobsmackingly bananas.”

Last month was the hottest September on record by a wide margin: almost a full 1C (33.8F) above the 1991-2020 average, and 0.5C higher than the previous record in 2020. It comes after the warmest June ever recorded. And the toastiest July. The same was true for August. And it will likely be followed by a warmer-than-average October.

Last month’s shocks continue if you delve a little deeper into the figuresprovided by the Copernicus Climate Change Service, known as C3S:

* Globally, it was 1.75C warmer than the pre-industrial average for September (1850-1900)

* The year through September is 1.4C higher than the pre-industrial average

* 2023 is looking like it will be the hottest year on record

* Europe was 2.51C higher than the 1991-2020 average

Berkeley Earth analysis, published on Wednesday, suggests a strong likelihood that this year will exceed 1.5C of warming for the first time.

It’s not just air temperatures sending out SOS signals: Surface ocean temperatures are also at unprecedented highs, and sea ice around Antarctica is at an extreme low for the season. That’s not just bad for marine life and penguins — the ocean covers 70% of the planet, and Antarctic ice plays a key role in regulating the earth’s temperature, sometimes referred to as the planet’s refrigerator.

It’s not clear what’s caused the temperature spike. Samantha Burgess, deputy director of C3S, told me that roughly two-thirds — or 1.2C — of the 1.75C of warming above pre-industrial temperatures seen in September is due to human-induced climate change. The remaining 0.5C or so is due to a combination of different factors, for which it’s much harder to assign specific levels of blame.

For example, we are in an El Nino season, a naturally-occurring climate pattern that warms global temperatures. El Nino conditions are still developing, meaning we haven’t yet seen the peak and don’t know how strong it will be. In January 2022, Hunga Tonga-Hunga Ha’apai, a large underwater volcano in the Pacific Ocean, erupted and hurled an immense plume of water vapor — a greenhouse gas — into the atmosphere, enough to temporarily elevate global temperatures for a few years.

And while new regulations have greatly reduced sulphur emissions from ships and industry, aerosols have historically served to mask human-induced climate change by reflecting some of the sun’s heat back into space. Now, with fewer reflective clouds, more solar radiation reaches the earth’s surface. A similar effect is caused by reduced sea ice at the poles: The more dark sea that’s exposed, the more heat gets absorbed.

Does the recent data demand increased urgency in the climate fight? That’s a debate climate scientists are having, says Ryan Katz-Rosene, associate professor at the University of Ottawa’s school of political studies. He notes two broad camps that, although they’ve existed for years, are becoming increasingly divided. The first group is dubbed “accelerationists” by Katz-Rosene and includes figures such as researcher Leon Simons and Physics Professor Emeritus Nick Cowern. They say that warming is accelerating faster than climate models predicted and focus on the effects of aerosols. The models do take into account reduced aerosol pollution, but researchers expected fossil-fuel consumption to fall in parallel.  Instead, it hasn’t even peaked yet. Some, including Cowern, are worried enough to call for geoengineering — essentially emitting aerosols on purpose — to mask the warming again.

The other side — who Katz-Rosene calls “observationists” — reckon that this year’s heat is in line with the models and that the spike can be attributed to short-term variability. As Burgess notes, we can’t yet pinpoint the exact factors behind September’s increase, but the temporary effects of the volcano and El Nino likely contributed. Indeed, year to year, the warming we’ve seen hasn’t been linear. As scientist Andrew Dessler points out, climate denialists will sometimes pick a hot year and a cold year to argue that global warming has paused or reduced.

Of course, there’s some overlap in opinion. The rate of warming has increased slightly and some models do predict an acceleration. But I think, for now, the observationists have a good point: We’re looking at a handful of data points and trying to reveal long-term trends. A pattern will emerge over time, but currently, the summer’s record-breaking temperatures don’t mean that the climate fight is doomed or that we need to leap to something as extreme as geoengineering. Likewise, if the historical trend continues, we might see a spate of years which aren’t quite so warm. It’s important to not view that as a win: Until we stop burning fossil fuels, the planet will continue to get hotter.

Besides, both groups of scientists agree on this: The gap we really should be worried about isn’t the one between the records, or the observed trend and the models, but the fissure between science and political will. We need to be decarbonising with far more urgency. According to the Climate Action Tracker, not a single country in the world is taking action that’s compatible with limiting warming to 1.5C. Yet the UK has rolled back some net zero targets, Germany has approved bringing coal-fired power plants back online over the winter and US oil production is running at an all-time high. That’s really gobsmackingly bananas.

Lara Williams is a Bloomberg Opinion columnist covering climate change. Views are personal and do not represent the stand of this publication.

Credit: Bloomberg