Our last hope — geoengineering?

Otago Daily Times

2 days ago

Peruvian farmer Saul Luciano Lliuya, who sued a German energy firm arguing that the company's emissions contributed to the melting of Andean glaciers, standing by Lake Palcacocha. PHOTO: REUTERS
This is the second anniversary of the arrival of the emergency but practically nobody is mentioning it.
Instead people are choosing to worry about more familiar problems like global trade wars, the rise of fascism and genocidal wars.
It's kind of a global displacement activity: if we don't mention it, maybe it will go away.
Two years ago this month (June 2023) the average global temperature jumped by a third of a degree Celsius in a single month.
That shook the climate science world to its foundations, because the orthodox predictions assumed about one-tenth of a degree of warming every five years.
The June 2023 event was "non-linear". Like most major shifts in natural systems, the pressure built up and up, and then suddenly the system flipped into a different stable state.
It took more than another year — until last December — to figure out what actually happened.
Ninety percent of the extra heat in the atmosphere from burning fossil fuels goes straight into the ocean. That heat was bound to affect the ocean currents, and sooner or later one of those currents would start returning very warm water to the surface.
The water gave up its heat to the air — and suddenly, two years ago, the low-level clouds over the eastern North Atlantic started to thin out, letting in much more sunshine to warm the ocean's surface.
This chain of events, where the warming we cause triggers further changes in the climate, is called a "feedback" — and since we didn't cause it directly, we can't turn it off.
So two years ago we got three-tenths of a degree of warming in one huge lurch — from +1.2°C to +1.5°C in June 2023 — and since then about one-tenth of a degree more in slow but steady warming.
The average global temperature has been about +1.6°C for the past year.
Many scientists had hoped that we could hold the warming down to +1.5°C at least until the mid-2030s, but that's already passed.
This means more and bigger forest fires, floods, droughts, cyclones and killer heatwaves, which is bad enough — but it also turns the future into a minefield.
The "never-exceed" limit on warming, set by the Intergovernmental Panel on Climate Change (IPCC) 10 years ago, was +2.0°C.
They chose that limit because they knew we would activate many feedbacks if the warming went past there. Some they knew about (eg melting permafrost), but they also feared that there might be some hidden feedbacks north of +2.0°C.
It's turning out that big hidden feedbacks start kicking in at a much lower temperature.
We already hit one at +1.2°C two years ago, and for all we know there could be another feedback just ahead.
In fact, feedbacks might even come in clusters that cascade and carry us quickly up into much higher temperatures.
Unlikely, but not unimaginable.
So suddenly the absolute priority is to hold the heat down. Greenhouse gas emissions must be stopped far sooner than the "Net Zero by 2050" target the IPCC originally set, but there is no way that can be done in less than 10 or 15 years — and the World Meteorological Organisation says that we could reach +1.9°C average global temperature as soon as 2029.
The only way to hold the heat down in the short term is geoengineering: direct intervention in the atmosphere to reflect more sunlight back into space and thereby cool the planet.
Many people are nervous about it, but we find ourselves in a position where geoengineering is the least bad option.
I am not a climate scientist, but I have been paying close attention to the subject for a long time (two books), and I spent three days in Cape Town last month interviewing many of the leading scientists in the field at the largest ever conference on geoengineering.
None of the men and women I spoke to were ready to deploy geoengineering techniques now, but they could probably begin to deploy within five years if a crash programme was launched right away.
Which governments could finance and direct such a programme?
The United States is no longer a serious contender (although possibly a major obstacle). The Russians have shown no interest in the subject.
But the United Kingdom, the only country committed to open-air research on geoengineering, could lead a European group.
China also has the scientists and is keenly aware of the threat, and India would almost certainly join in such an enterprise.
Developing countries are desperately exposed to climate damage and would also collaborate.
It's a long shot, but that would be the best available outcome.
• Gwynne Dyer is an independent London journalist.