Over the past week, the world marked the hottest week on record, with the hottest June on record also being measured in the UK. The impact of these rising temperatures is not just being witnessed in Europe, India, or the USA – where extreme heat is causing danger to life – but also, critically, in the polar regions.
Sea ice in Antarctica has reached its lowest extent since satellite observations began, at 17% below average, leaving scientists concerned about the impact of rising sea levels if glaciers weaken. Daily records from 2023 are tracking well below previous lows and the mean over the last 40 years. Put another way, the current extent of the ice is almost a million square miles (2.5 million square kilometres) less than the average. To put this data into an understandable perspective, this loss is approximately nine times the size of Britain.
Sea ice: emerging tipping points in Antarctica
Professor Nerilie Abram, climate scientist at the Australian National University, was interviewed by the Climate Crisis Advisory Group about her recent expedition to Antarctica. She described the situation there as worse than she’d imagined: “We knew it was bad, but it’s even worse than we thought.”
Professor Abram highlighted the anomalies in Antarctic sea ice, relative to the time of year, and pointed out that almost everywhere it is well below the extent it would normally be. Sea ice is growing but at a much slower rate than it normally would. Reversing a steady increase in ice cover from 1981 to 2014, the period since 2014 has seen a sharp and noticeable decline. This creates the potential for further warming to happen, especially with the darker ocean absorbing the sun’s energy rather than reflecting it back into space, as the lighter ice surface would do.
Abram told me:
“While the Northern Hemisphere swelters under record-smashing heatwaves, the dramatic loss of sea ice around Antarctica is another symptom of our rapidly warming global climate. Antarctic sea ice is off the charts this year. Normally at this time of year the sea ice would be rapidly expanding around Antarctica, but this year that ice is struggling to form.
“Over the last decade the area covered by sea ice around Antarctica has reduced by around two million square kilometres. That far exceeds the total Arctic Sea ice loss over the last 40 years. The loss of Antarctic sea ice is yet another demonstration of the profound ways that we are altering our planet. We need to urgently reduce greenhouse gas emissions to reach net zero, and then below zero emissions.”
Why should we be concerned about low sea ice levels?
It can be difficult for some to make the connection between events in Antarctica and the impact on their lives in the UK. Climate scientist Professor Katherine Hayhoe describes this challenge as being one of “psychological distance” and observes that although people are worried, their concern tends not to turn into action, as they often don’t know what to do.
Hayhoe has long advocated that talking about the changing climate is the most important thing to do. Perhaps it is worth talking to neighbours, family, and friends to see if they are even aware of the sea ice anomaly in Antarctica. In short, we need to answer the questions: “Why should we care that the sea ice has reached its lowest extent?” and “How does it affect me?”.
The Woods Hole Oceanographic Institution puts it this way: warmer ocean temperatures lead to changing weather patterns. “Higher sea surface temperatures increase evaporation and add additional moisture to the atmosphere over the oceans. This extra water vapor boosts the precipitation dumped by rainstorms and blizzards on coastal areas and inland locations.”
In the UK then, we would expect to see more flooding, and those who have suffered a flooded property will understand what a lengthy process that is to solve. It will also mean a warmer atmosphere, bringing heatwaves and droughts – both scenarios that the UK is not prepared for. Europe as a whole is not prepared for extended heatwaves, as we are seeing with the current situation in Spain, Italy, and Greece.
Scientific evaluation of events
Dr Zack Labe, an atmospheric climate scientist from Princeton University, told me that there were inherent complexities within the Antarctic system and that the impact on marine ecosystems can also be an overlooked issue:
“Scientists are now trying to understand the causes of this large sea ice anomaly, which is likely related to both unusual atmospheric and oceanic conditions occurring at the same time. For example, strong winds associated with a weather phenomenon called the Amundsen Sea Low have prevented sea ice from forming as quickly in some areas compared to normal.
“The phase of a climate pattern called the Southern Annular Mode is also an important driver of sea ice extremes in the Antarctic due to its influence on regional winds and storminess. It is also very likely that ocean heat in the Southern Ocean may be inhibiting some of the sea ice growth. In other words, even if the air temperatures are well below freezing, a warmer ocean can still inhibit the formation of sea ice.
“We are still trying to understand the role of human-caused climate change for this ongoing extreme event, and each data point is another new clue for scientists. The reason that this question is so complex is related to the fact that natural climate variability is a very large factor that influences weather and oceanic conditions across Antarctica and the Southern Ocean.
“In the short-term, the lack of sea ice is very much influencing local weather conditions, such as through the anomalous warmth observed over large parts of the Weddell Sea this year. It is also impacting marine and terrestrial ecosystems, such as for animals which rely on the annual formation of sea ice for their habitat. One impact of a long-term lack of sea ice is related to reducing the barrier between ice shelves/coastal glaciers and warmer ocean waters.
“To put in another way, without Antarctic sea ice acting as a buffer, more ice sheet melt is possible due to the intrusion of deep ocean heat waters.”
“There will always be scope for surprises”
Dr Rob Larter, marine geophysicist with the British Antarctic Survey and winner of the Polar Medal, also highlighted the impact on marine species when he told me, “The negative anomaly in sea ice extent around Antarctica this year has reached an unprecedented level. If this turns out to be more than an exceptional excursion it is likely to lead to a range of adverse climatic and ecological effects through albedo change, decrease in dense bottom water production, impacts on the timing and location of primary production in the oceans, and direct impacts on species that depend on sea ice”.
Dr Larter helpfully outlined short-term and long-term possibilities:
“In terms of the short-term outlook for the West Antarctic Ice Sheet (WAIS) there is some good news: Recent modelling studies do not support the worst case scenarios of very rapid ice loss resulting from marine ice cliff instability. Another recent study concludes that the remaining ice shelf in front of Thwaites Glacier is doing little to buttress the glacier, which means that a large increase in ice flow rate is not expected when the ice shelf disintegrates.”
He cautioned however that once we move beyond the short-term, the assessment changes. “The outlook for the longer term (say beyond this century) remains bad for the WAIS and therefore for its contribution to sea-level rise. Further bad news for the longer-term outlook comes from a pair of independent ocean modelling studies, both of which show incursion of increasing amounts of relatively warm water from the deep ocean onto the shelf later this century. This can be expected to accelerate ice sheet loss.”
Larter concluded by acknowledging that scientific caution was needed when predicting future circumstances and that this caution can conflict with desire from the public for action. “However, the caveat to all modelling studies is that nobody has ever observed the demise of a marine-based ice sheet, so however skilled we think the models are, there will always be scope for surprises.”
Government response to climate warnings
The often-mocked government response of ‘sit tight and assess’ from the recent satirical film Don’t Look Up, sadly appears to be what is happening just now. Scientists, commentators, and the public are watching and waiting to see how bad the impact is going to be; meanwhile, the UK government fails to mobilise and put contingency plans in place. In recent days, the government’s plan to cope with the climate crisis has even been condemned as “very weak” by experts, who say not enough is being done to protect lives and livelihoods.
In the UK, Grant Shapps, the secretary of state for energy security and net zero, continues to double down on continued fossil fuel expansion, emphatically declaring “I am not just stopping oil”. With this statement, it seems unclear how the UK can meet its legal obligations to achieve net zero under the Paris agreement – the government simply seem to be playing politics with the climate.