The latest report by the UN’s climate advisory panel has once again highlighted the need for urgent action against human-induced climate change, noting that the tools to prevent climate catastrophe already exist. While hopes of limiting global warming at 1.5C are rapidly fading, climate experts stress that “every additional tenth of a degree matters” to mitigate the already dire consequences of our planet warming.
The 36-page “summary for policymakers”, a synthesis of nine years of research by the Intergovernmental Panel on Climate Change (IPCC), is a stark reminder that the devastating impacts of climate change are hitting faster than expected – and that failure to take decisive action could make some of those consequences irreversible.
“Humanity is on thin ice – and that ice is melting fast,” UN Secretary-General Antonio Guterres warned on Monday as he presented the report’s key findings. “Our world needs climate action on all fronts – everything, everywhere, all at once.”
The IPCC report says our planet is on course to reach 1.5 degrees Celsius above pre-industrial levels – considered a safer limit to global warming – in little over a decade. Its dire warning comes just eight years after the COP21 climate summit in Paris made the 1.5C threshold a beacon for climate policies.
“Since the Paris Accord, the stated objective of states has been to keep global warming well below 2C above pre-industrial levels – and to step up efforts to limit it to 1.5C,” says Wolfgang Cramer, a research director at the Mediterranean Institute of Marine and Terrestrial Biodiversity and Ecology (IMBE).
“This overall objective provided a horizon and a specific target for climate policies,” adds Cramer, who co-authored the IPCC’s last major report in 2022. “But when you look at the current trajectories and the poor efforts mustered by governments, it does indeed appear highly unlikely that we can meet that second target.”
The figures speak for themselves. The IPCC says greenhouse gas emissions would need to be slashed by 45% by 2030 for there to be any chance of capping global warming at 1.5C. That would mean annual cuts equivalent to the one witnessed at the height of the Covid-19 pandemic in 2020, when the world’s economies ground to a halt.
As things stand, humanity is well off the mark. According to the IPCC’s projections, our planet is on course for global heating of 2.5C by the end of the century if governments stick to their emissions pledges – and 2.8C if they stick to current policy.
The planet’s ‘fever’
While the outlook is dire, it should not be cause for fatalism and inaction, experts caution.
“Our actions right now will determine the extent of global warming in the long run. The objective is to ensure it remains as low as possible,” says Cramer, for whom the 1.5C target “is already too high” to avert major consequences for the planet.
“We’re currently at 1.2C and already we are bearing the consequences, with an increase in heatwaves, droughts and flooding,” he explains.
To understand the significance of each fraction of a degree, Cramer draws a parallel with a human suffering from fever. Add one degree Celsius to the normal body temperature of 37C and the person will feel unwell and have headache. Add 2C and the suffering increases. At 3C it becomes dangerous, particularly if the person is vulnerable.
The same goes for our planet, Cramer adds.
“The consequences will differ at each degree and in different parts of the world: they will be most severe in places that are most vulnerable,” he says. “1.5C will always be better than 1.6C, which will always be preferable to 1.7C. Every tenth of a degree matters.”
Biodiversity under threat
The consequences of this global “fever” are increasingly evident, starting with the extinction of biodiversity.
In 2015, the year of the Paris Accord, the Bramble Cay Melomy, a small rodent that lived on a speck of land off the coast of Papua New Guinea, became the first known mammal to go extinct as a result of human-caused climate change.
“Scientists have shown that its disappearance was caused by rising sea levels submerging its habitat,” Camille Parmesan, a climate and biodiversity expert at the CNRS research centre, told FRANCE 24 in an interview in December.
“We have also documented the disappearance of 92 species of amphibians, killed because of the proliferation of a fungus that developed as a result of climate change modifying ecosystems,” Parmesan added.
Corals are another obvious casualty. At 1.5°C, 70% to 90% of reefs could disappear. At 2°C, the figure rises to 99%.
Experts at the UN-backed biodiversity agency IPBES say more than a million species are currently threatened with extinction, with climate change becoming the “most significant” menace. “The more it increases, the more ecosystems are disrupted, with consequences for wildlife,” an agency report stated in 2021.
“Each additional degree will translate into increasingly frequent and severe weather events, with ever greater consequences for the 3.3 billion people who live in vulnerable areas,” adds Cramer.
For several years now, scientists have been investigating links between climate change and extreme weather events, a field known as “attribution science”. Their findings confirm that heatwaves, floods and hurricanes are increasing in intensity, magnitude and frequency as a result of global warming. Research has thus established that climate change made the devastating heatwave that hit India and Pakistan in March and April last year thirty times more likely.
In this context, “decision makers should also focus their efforts on slowing down global warming” – in addition to curbing it, says glaciologist Gerhard Krinner, one of the authors of the latest IPCC report.
“The faster climate change takes place the less time people will have to adapt,” he explains. “This in turn will increase the risk of severe shortages, famines and conflicts.”
Both experts flag the danger of reaching “tipping points” that would be extremely difficult to reverse, such as a destabilisation of the Antarctic ice cap.
While the likelihood of catastrophic ice-sheet melting is currently still low, “it increases as the planet warms and there is a real risk of the rise in sea levels accelerating dramatically at between 1.5C and 2C”, Cramer warns.
Should the Antarctic’s permafrost come to melt, it would release vast amounts of greenhouse gases trapped under the ice, in turn further warming the planet and accelerating ice melt. Other examples of tipping points include the Amazon rainforest turning to savannah and Greenland’s ice cap melting.
Each of these scenarios can be avoided, the experts insist, provided there is a political will to do so.
“We now have multiple solutions that are readily available to slow down and limit climate change,” says Cramer, for whom “the obstacle is no longer innovation – but politics”.
“Today’s efforts will make all the difference in the long term,” adds Krinner. “We can still spare ourselves those extra tenths of a degree.”