Research from the World Meteorological Organisation (WMO) has found that there is a 66 per cent chance of Earth recording a global average temperature of more than 1.5°C above pre-industrial levels by 2027.
There is also a 98 per cent chance of the hottest year on record being broken within the same timeframe.
WMO secretary-general Professor Petteri Taalas said: “This report does not mean that we will permanently exceed the 1.5°C level specified in the Paris Agreement which refers to long-term warming over many years.
“However, WMO is sounding the alarm that we will breach the 1.5°C level on a temporary basis with increasing frequency.”
What is the significance of 1.5°C?
When the Paris Agreement — the global treaty on climate change — was negotiated in 2015, there was a strong and ultimately successful push by nations such as low-lying islands to include the 1.5°C target in the deal because they felt letting temperatures go any higher would threaten their survival.
As a result countries pledged to keep global temperature rises to well below 2°C above pre-industrial levels and pursue efforts to limit warming to 1.5°C over the long-term.
Will limiting temperature rises to 1.5°C really make a difference?
Yes, according to a special report by the UN’s climate science body, the Intergovernmental Panel on Climate Change (IPCC), in 2018.
It found a 2°C rise would lead to more heatwaves, extreme rainstorms, water shortages and drought, greater economic losses and lower crop yields, higher sea levels, and greater damage to nature.
In one of its most sobering findings, the report said coral reefs would decline by 70-90 per cent with global warming of 1.5°C, but would all but vanish in a 2°C world.
A report from the IPCC previously warned that every additional 0.5°C temperature rise leads to clear increases in the intensity of heatwaves, rainstorms and flooding, and droughts in some regions.
With the world already experiencing more damaging climate extremes at 1.2°C of warming, 1.5°C is not seen as a safe level, but things get much worse if it goes above that.
Is it game over if the world warms by more than 1.5°C?
No. Scientists say the 1.5°C or 2°C thresholds are not cliff edges that the world will fall off, but that every bit of warming makes a difference, so it is important to curb temperature rises as much as possible.
As Professor Richard Betts, from the Met Office Hadley Centre, puts it: “Like the speed limit on a motorway, staying below it is not perfectly safe and exceeding it does not immediately lead to calamity, but the risks do increase if the limit is passed.
“Limiting warming to 1.5°C clearly needs much more urgent emissions cuts than is currently happening but, if the target is still breached, we should not assume all is lost and give up — it will still be worth continuing action on emissions reductions to avoid even more warming.”
Are we off track to meet a 1.5°C limit?
Yes, way off track. The 2018 IPCC report said to limit temperature rises to 1.5°C, the world would have to cut carbon emissions by 45 per cent on 2010 levels by 2030, and to net zero — with any remaining pollution absorbed by measures such as planting trees — by 2050.
An assessment from the UN showed the national plans for cutting emissions put forward by countries under the Paris Agreement would lead to a 16 per cent increase in emissions on 2010 levels by the end of the decade.
Other analysis suggests that, even with the latest pledges and targets, we are heading for around 2.4°C of warming.
