Polar heatwaves sound global climate alarm bells

Polar heatwaves are, as you would imagine, rare events, but in March, simultaneous heatwaves were recorded at both poles, an event without precedent in the instrumental record. I wrote the following Opinion piece for the Irish Examiner discussing the phenomenon and its wider implications.

AT NEARLY 14 million square kilometres in area, Antarctica is a gigantic landmass, around one and a half times the size of the continental United States. The ice shelves perched on top of this vast southern continent contain an almost unimaginable 26 million cubic kilometres of frozen water. A single cubic kilometre of ice weights one billion tonnes.

In recent days, scientists have reported that temperatures in parts of eastern Antarctica have risen by 40C above normal for three consecutive days. The Vostok research station, located close to the south pole at an elevation of nearly 3,500 metres, is the coldest place on the planet, having recorded a temperature of minus 89.2C in 1983.

However, in recent days, Vostok experienced an almost balmy minus 17.7C, an astonishing 15C warmer than ever recorded at that location. Computer simulations and observations across Antarctica indicate that in some locations, temperatures may have risen by up to 50C above normal.

Heatwave in March

To visualise how dramatic a shift this is, consider that in Ireland, the average March temperature range is from 5.2–10.7C. Now, try to imagine a March heatwave in Ireland with temperatures above 50C.

“Wow, I have never seen anything like this in Antarctica”, remarked Ted Scrampos, ice scientist at the University of Colorado, who has recently returned from a research expedition to the region.

Isolated from the world’s continental landmasses by oceans and in continuous darkness for its four to five month winter, Antarctica to a large extent generates its own weather systems.

Except for its vulnerable western Antarctic peninsula, which has shown worrying signs of ice shelf collapse, the main continental shelf hasn’t been considered to be at significant risk of warming. In fact, it has been warming more slowly than the world as a whole.

Polar scientists believe the recent heatwave event is linked to a giant atmospheric “river” that has drawn in masses of warm, wet air from the Pacific ocean. “The moist air has trapped heat over the continent, resulting in the warm surface temperatures…this is an extraordinary event”, said Australian climatologist Prof Julie Arblaster.

Reliable long-term temperature records in the Antarctic only go back as far as the late 1950s, making it difficult to assess just how unusual the current heatwave really is. Weather systems on the frozen continent are notoriously fickle; in 2021, the south pole recorded its coldest ever April-September, yet last month, the level of sea ice surrounding Antarctica fell to its lowest on record.

While attributing a specific meteorological event to climate change is especially challenging in Antarctica, the warming global climate is “loading the dice” to make extreme instances like this ever more likely, according to Jonathan Wille, a French polar meteorology researcher. Temperatures like this, he added, “are never supposed to happen”.

As scientists were pinching themselves in disbelief at the extreme and unprecedented heatwave racking Antarctica, at the other end of the world, weather stations in Greenland and Norway recorded temperature spikes in the Arctic region 27C higher than normal for this time of year.

Warming fast

Overall, the Arctic is heating three times faster than the global average, with temperatures in the region having increased by a full 1C in just the last decade. This in turn is leading to a sharp rise in extreme events. Temperatures deep in the Russian Arctic hit 38C during the summer 2020 heatwave. Unlike the Antarctic, almost all the Arctic ice cap is floating on open ocean, but sea ice has been thinning precipitously as temperatures in the region increase.

A phenomenon known as the ‘ice albedo effect’ explains why Arctic temperatures are rising so quickly. An intact ice sheet reflects almost all incoming sunlight back into space. However, as soon as it begins to thin and expose the ocean beneath, up to 90 per cent of incoming solar energy is absorbed by the dark waters, causing ocean temperature to begin to rise. As this happens, more ice melts, and so the cycle of warming accelerates.

A so-called “blue ocean event” is where the Arctic ocean is virtually ice-free during the summer, something that has not occurred in at least two and a half million years. Scientists now believe this could happen within the next 10-12 years, with profound consequences for the climatic system in the entire northern hemisphere.

Loss of polar ice cover across the entire Arctic region would be the equivalent of shutting down a gigantic air conditioning system that helps regulate both temperatures and weather patterns across the northern hemisphere, with profound consequences scientists are only beginning to fully grasp.

NASA’s former chief scientist, Prof James Hansen and colleagues have researched the likely effects of ice melt on ocean currents and weather systems. The giant Greenland ice shelf is losing an average of one million tonnes of ice per minute. In 2019, this amounted to 600 billion tonnes of ice melt.

Catastrophic consequences

This massive influx of cold freshwater into the North Atlantic could potentially trigger the shut-down of the Gulf Stream, the warm current that transfers huge amounts of heat energy from the tropics and keeps north-western Europe several degrees warmer than its latitude would suggest.

Such an event would have catastrophic consequences for Ireland, causing our temperatures to plummet and our grass-based agricultural system to fail. In addition, a sudden increase in the temperature gradient between the tropics and the northern hemisphere would, according to Prof Hansen, “fuel super-storms stronger than any seen in modern times. All hell would break loose in the north Atlantic”, he added.

The profound energy imbalance that is causing these seismic events at both poles is driven by the annual emission of around 40 billion tonnes of heat-trapping greenhouse gases into the global atmosphere, mainly as a result of fossil fuel burning.

A shut-down of the Gulf Stream, as a result of melting ice caps, would cause our temperatures to plummet and our grass-based agricultural system to fail.

A shut-down of the Gulf Stream, as a result of melting ice caps, would cause our temperatures to plummet and our grass-based agricultural system to fail.

To understand just how dramatic these changes are, scientists estimate that the world’s oceans are heating at the rate equivalent to the energy released by five Hiroshima-sized nuclear bombs per second, or nearly 160 million Hiroshimas a year.

A small reminder of just how rapidly the Arctic system is changing occurred in November 2020, when a time capsule was washed up on the coastline at Gweedore, Co. Donegal. The capsule had been embedded deep in the sea ice at the North Pole just two years earlier, in August 2018. Sometime later, due to rapid thawing, it had come adrift and floated over 3,700 kilometres on the currents before arriving in Ireland.

The seemingly remote Arctic and Antarctic regions are intimately connected with the very waters that lap our shores and the atmosphere above us. What happens at the poles profoundly affects all life on Earth.

At the COP26 climate conference in Glasgow last November, UN secretary-general Antonio Guterres warned that humanity is “digging our own graves” through failing to tackle the climate emergency. “Our addiction to fossil fuels is pushing humanity to the brink. We face a stark choice: either we stop it, or it stops us”.

The only question remains: will we choose to act, or cling to denial as we stumble towards a climate apocalypse?

John Gibbons is an environmental journalist and commentator

ThinkOrSwim is a blog by journalist John Gibbons focusing on the inter-related crises involving climate change, sustainability, resource depletion, energy and biodiversity loss
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