Experts struggle to explain how rises in sea-surface temperatures have accelerated so quickly. Photograph: PPAMPicture/Getty Images
Rapid ocean warming and unusually hot winter days recorded as human-made global heating combines with El Niño
February is on course to break a record number of heat records, meteorologists say, as human-made global heating and the natural El Niño climate pattern drive up temperatures on land and oceans around the world.
A little over halfway into the shortest month of the year, the heating spike has become so pronounced that climate charts are entering new territory, particularly for sea-surface temperatures that have persisted and accelerated to the point where expert observers are struggling to explain how the change is happening.
“The planet is warming at an accelerating rate. We are seeing rapid temperature increases in the ocean, the climate’s largest reservoir of heat,” said Dr Joel Hirschi, the associate head of marine systems modelling at the UK National Oceanography Centre. “The amplitude by which previous sea surface temperatures records were beaten in 2023 and now 2024 exceed expectations, though understanding why this is, is the subject of ongoing research.”
Humanity is on a trajectory to experience the hottest February in recorded history, after a record January, December, November, October, September, August, July, June and May, according to the Berkeley Earth scientist Zeke Hausfather.
It’s official: 2023 was Earth’s hottest year ever recorded, beating the previous record set in 2016 by a huge margin. Last year was also the first in which the world was close to 1.5°C (1.48°C) hotter than the pre-industrial average (1850-1900). We are brushing against the threshold scientists urged us to limit long-term warming to.
Some scientists, including former Nasa climatologist James Hansen, predict 2024 will be humanity’s first year beyond 1.5°C. As what were once dire warnings from climate experts become our shared reality, what can you expect?
The 1.5°C temperature target, enshrined in the 2015 Paris agreement, is not shattered on first contact. Most of the climate tipping points scientists fear could send warming hurtling out of control are not expected until Earth is consistently warmer than 1.5°C. The global average temperature is likely to dip down again once the present El Niño (a warm phase in a natural cycle focused on the equatorial Pacific Ocean) dissipates.
Instead, 2024 could be our first glimpse of Earth at 1.5°C. Here’s what research suggests it will look like for people and nature.
Ecosystems on the brink
Tropical coral reefs are in hot water. These habitats comprise a network of polyp-like animals (related to jellyfish) and colourful algae encased in calcium carbonate. The complex forms they build in shallow water around the Earth’s equator are thought to harbour more species than any other ecosystem.
“Corals have adapted to live in a specific temperature range, so when ocean temperatures are too hot for a prolonged period, corals can bleach – losing the colourful algae that live within their tissue and nourish them via photosynthesis – and may eventually die,” say coral biologists Adele Dixon and Maria Beger (University of Leeds) and physicists Peter Kalmus (Nasa) and Scott F. Heron (James Cook University).
Coral bleaching, once rare, now occurs on an almost annual basis. Damsea/Shutterstock
Climate change has already raised the frequency of these marine heatwaves. In a world made 1.5°C hotter, 99% of reefs will be exposed to intolerable heat too often for them to recover according to Dixon’s research, threatening food and income for roughly one billion people – not to mention biodiversity.
Coral reefs will earn their reputation as the “canaries in the coal mine” for climate change’s impact on the natural world. As global heating ticks up towards 2°C, the devastation already seen on reefs will become evident elsewhere according to an analysis by biodiversity scientist Alex Pigot at UCL:
“We found that limiting global warming to 1.5°C would leave 15% of species at risk of abruptly losing at least one third of their current geographic range. However, this doubles to 30% of species on our present trajectory of 2.5°C of warming.”
Heat beyond human tolerance
Above 1.5°C, humanity risks provoking heatwaves so intense they defy the human body’s capacity to cool itself.
Intense heat and humidity have rarely conspired to create “wetbulb” temperatures of 35°C. This is the point at which the air is too hot and humid for sweating to cool you down – different from the “drybulb” temperature a thermometer reports.
Earth’s rising temperature could soon change that according to climate scientists Tom Matthews (Loughborough University) and Colin Raymond (California Institute of Technology).
“Modelling studies had already indicated that wetbulb temperatures could regularly cross 35°C if the world sails past the 2°C warming limit … with The Persian Gulf, South Asia and North China Plain on the frontline of deadly humid heat,” they say.
But different areas of the the world are warming at different rates. In a world that is 1.5°C hotter on average, temperatures in your local area may have actually risen by more than that.
To account for this, Matthews and Raymond studied records from individual weather stations worldwide and found that many sites were closing in much more rapidly on the lethal heat and humidity threshold.
“The frequency of punishing wetbulb temperatures (above 31°C, for example) has more than doubled worldwide since 1979, and in some of the hottest and most humid places on Earth, like the coastal United Arab Emirates, wetbulb temperatures have already flickered past 35°C,” they say.
For a chance to avoid these horrors, we must eliminate the greenhouse gas emissions heating Earth and that means rapidly phasing out coal, oil and gas, which account for 80% of energy use worldwide.
How fast? According to the latest estimate, published in October, very fast indeed.
“If humanity wants to have a 50-50 chance of limiting global warming to 1.5°C, we can only emit another 250 gigatonnes (billion metric tonnes) of CO₂,” say climate and atmospheric scientists Chris Smith at the University of Leeds and Robin Lamboll at Imperial College London.
The US economist William Nordhaus claimed as early as the 1970s, when scientific understanding of climate change was still taking shape, that warming of more than 2°C would “push global conditions past any point that any human civilisation had experienced”. By 1990, scientists had also weighed in: 2°C above the pre-industrial average was the point at which the risk of unpredictable and extensive damage would rapidly increase.
Two years later, the United Nations Framework Convention on Climate Change (UNFCCC) was established to stabilise the amount of greenhouse gas in the atmosphere at a level that would “prevent dangerous interference with the climate system”. At the first summit in Berlin in 1995, countries began negotiations for the global response to climate change which continue to this day.
Halting global heating at 2°C remained the horizon to which negotiators strived for nearly two decades. And yet, you’re more likely to hear about the rapidly approaching 1.5°C temperature limit nowadays. At the most recent UN summit, COP27 in Egypt, leaders clinched an agreement to keep the target at 1.5°C, though they achieved little that would put the world on track to meet it.
So why did 1.5°C became the acceptable limit to rising temperatures? That story reveals an essential truth about climate change itself.
Acceptable for who?
Global temperature rise is just one measure of how the climate is changing. Scientists also track concentrations of CO₂ in the atmosphere, sea-level rise and the intensity of heatwaves and flooding. But taking the Earth’s temperature is the simplest way to predict the global consequences of warming.
At Copenhagen’s 2009 climate summit, the world still lacked an official temperature goal, nor had there been a full scientific assessment of what was “safe”. But a formation of island nations known as the Alliance of Small Island States (AOSIS) was already urging countries to draw the line at 1.5°C.
Scientific research had started to reveal the devastation that awaited many of these countries at 2°C, with coral bleaching, coastal erosion and erratic weather expected to become more frequent and severe. Worse still, new estimates indicated that sea levels would rise faster than earlier assessments had predicted, threatening the very existence of some islands.
Low-lying islands in the tropics are among the most vulnerable places to climate change. Rich Carey/Shutterstock
Only stopping global temperature rise well below 1.5°C would head off this catastrophe, AOSIS argued. As Mia Mottley, prime minister of Barbados, would later put it: “2°C is a death sentence”.
At a summit in Cancún, Mexico in 2010, governments agreed to keep global average temperature rise below 2°C while scientists reviewed the proposal for 1.5°C. The review, when published in 2015, found that the “concept, in which 2°C of warming is considered safe, is inadequate”. The idea that a “safe” level of warming could be achieved was subjective: current levels were already unsafe for those on the sharpest end of climate change.
Although the science on the effects of 1.5°C was, at the time, less robust than for 2°C, the review concluded that limiting warming to 1.5°C would minimise risks compared to a warmer world.
Coral reefs, for example, which millions depend on for food and income, are already being damaged by climate change. At 1.5°C, few reefs will escape harm. But at 2°C, virtually all reefs throughout the tropics are thought to be at severe risk. Halting climate change at 1.5°C would slow the rate of sea-level rise by roughly 30%, preserving cultures and communities that could disappear at 2°C.
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This insight fed into negotiations that ultimately produced the Paris Agreement in 2015, which committed countries to:
holding the increase in the global average temperature to well below 2°C above pre-industrial levels, and pursuing efforts to limit the temperature increase to 1.5°C.
A scientific assessment in 2018 confirmed the relative advantages of limiting warming to 1.5°C. In essence, the benefits of halting warming at a lower temperature are always relative to the costs of allowing warming to continue, which will continue to mount for as long as action is delayed. The only “acceptable” limit is that which humanity collectively decides.
Campaigning by AOSIS forced the rest of the world to acknowledge (in principle at least) that 2°C was unacceptable for many. But more recent research suggests that even 1.5°C of warming could carry unforeseen risks, such as the West Antarctic ice sheet collapsing at current levels of warming.
The world has already warmed by around 1.2°C. By the time COP27 ended in late November 2022, only 30 out of nearly 200 countries had strengthened their national pledges for reducing emissions. No country has a pledge compatible with limiting warming to 1.5°C. And with temperatures increasing more than 0.2°C a decade, some suggest that 1.5°C is already out of reach.
The latest scientific assessments indicate that achieving the 1.5°C limit is still technically and economically feasible, but fossil fuels must be rapidly phased out, and CO₂ emissions halved by 2030 and reduced to net zero by mid-century. This is a huge, but not impossible, task.
We will, however, need a little luck on our side. Staying within 1.5°C also depends on how the climate responds to the emissions we put into the atmosphere in the meantime. Although limiting warming to 1.5°C becomes increasingly unlikely with every year of delay, giving up on it now would play into the hands of those determined to preserve fossil fuel revenues indefinitely.
Limiting warming limits the consequences of climate change, particularly for the most vulnerable people and communities. And even if the world does pass 1.5°C, it doesn’t remove any pressure. 1.5°C became the goal because exceeding it was deemed unacceptable. The increasing likelihood – but not certainty – of passing 1.5°C demands even more urgent action to avoid every additional fraction of a degree of warming, minimising the impacts, risks and costs of climate change for everyone, everywhere.
Don’t have time to read about climate change as much as you’d like?
NSW, Queensland and Tasmania experienced hottest winters with spring likely to deliver hotter than average temperatures too
Image of a kangaroo.
Australia’s winter of 2023 was the warmest since official records began in 1910, with average daily temperatures 1.53C above the long-term average.
According to data from the Bureau of Meteorology released on Friday, the 2023 winter beat the previous record of 1.46C above the average set in 1996. Every winter since 2012 has been warmer than the 30-year average calculated from 1961 to 1990.
Global heating and weather conditions that delivered sunny days were behind the record, scientists said.
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Dr Andrew King, a climate scientist at the University of Melbourne, said the winter warmth was “pretty consistent with the trend towards warming that we have already seen and expect to continue as we keep emitting greenhouse gases”.
King said the high-pressure systems that brought the extra warmth were “part of the story”, adding “we would not get the temperatures that we have seen this winter really happening without human-caused climate change”.
Carrying blood-red ribbons to represent the crucial red lines already crossed by Cop26 negotiations, hundreds of representatives of global civil society walked out of the convention centre in Glasgow on the final morning of the summit in protest.
The audience at the People’s Plenary in the conference blue zone heard speakers condemn the legitimacy and ambition of the 12-day summit before walking out to join protesters gathered on the streets beyond the security fencing.
“Cop26 is a performance,” the Indigenous activist Ta’Kaiya Blaney of the Tla A’min Nation told the meeting before the walkout. “It is an illusion constructed to save the capitalist economy rooted in resource extraction and colonialism. I didn’t come here to fix the agenda – I came here to disrupt it.”
A recent analysis of the lifestyles of 20 billionaires found that each produced an average of over 8,000 tonnes of carbon dioxide: 3,500 times their fair share in a world committed to no more than 1.5C of heating. The major causes are their jets and yachts. A superyacht alone, kept on permanent standby, as some billionaires’ boats are, generates around 7,000 tonnes of CO2 a year.
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I’ve come to believe that the most important of all environmental measures are wealth taxes. Preventing systemic environmental collapse means driving extreme wealth to extinction. It is not humanity as a whole that the planet cannot afford. It’s the ultra-rich.
The fossil fuel industry benefits from subsidies of $11m every minute, according to analysis by the International Monetary Fund.
The IMF found the production and burning of coal, oil and gas was subsidised by $5.9tn in 2020, with not a single country pricing all its fuels sufficiently to reflect their full supply and environmental costs. Experts said the subsidies were “adding fuel to the fire” of the climate crisis, at a time when rapid reductions in carbon emissions were urgently needed.
