Unless measures are taken to curb climate change, summers in the UK and the rest of the northern hemisphere could last for six months come 2100, a study warned.
Researchers from China used historical climate data and modelling to determine how the seasons have shifted in the past, and will likely alter in the future.
Changes could also see winters shrunk down to the span of just two months — with far-reaching impacts on agriculture, human health and the environment.
Unless measures are taken to curb climate change, summers in the UK and the rest of the northern hemisphere could last for six months by 2100, a study warned (stock image of Blackpool in summertime)
‘Summers are getting longer and hotter while winters shorter and warmer due to global warming,’ said paper author and physical oceanographer Yuping Guan of the Chinese Academy of Sciences.
‘More often [now], I read some unseasonable weather reports — for example, false spring, or May snow, and the like,’ he added.
In their study, Dr Guan and colleagues analysed historical climate data on the Northern Hemisphere that was collected daily from 1952–2011 in order to determine how the length and onset of each season has been changing with time.
The team defined the start of each summer as being when temperatures reached the hottest 25 per cent for that year, and winter as the onset of the coldest 25 per cent of temperatures.
Building on this historical dataset, the researchers next used climate change models to predict how the timing of the seasons will likely shift in the future.
Back in the Fifties, the four seasons arrived in the Northern Hemisphere in a predictable and fairly evenly distributed pattern.
However, the team found that, on average, summers grew in length from 78 to 95 days between 1952 and 2011, while winters shrank from 76 days to 73.
Spring and autumn were also seen to decrease in duration — falling from 124 to 115 days and 87 to 82 days, respectively.
As a result of these shifts, the team noted that spring and summer are now starting earlier than they used to, while autumn and winter are beginning later.
The greatest changes in the seasonal cycles, meanwhile, were found in the Mediterranean region and the Tibetan Plateau.
‘This is a good overarching starting point for understanding the implications of seasonal change,’ commented climate scientist Scott Sheridan of the Kent State University in Ohio, who was not involved in the present study.
It is difficult, he said, to conceptualise average temperature increases in the context of climate change.
However, he added: ‘I think realising that these changes will force potentially dramatic shifts in seasons probably has a much greater impact on how you perceive what climate change is doing.’
The full findings of the study were published in the journal Geophysical Research Letters.
Changing seasons will also lead to more severe weather events — including heatwaves and wildfires in summer and cold surges and winter storms on the other side of the year. Pictured: scenes of the impact of Winter Storm Uri on the state of Texas last month
The findings comes as a separate study from the US warns that the climate crisis is pushing some tropical regions to the threshold of human habitability.
The danger comes, the researchers explained, when air temperatures are sufficiently hot and humid and exceed a ‘wet-bulb temperature’ of 95°F (35°C).
The wet-bulb temperature is the lowest temperature that can be achieved under ambient conditions by means of the evaporation of water only.
‘If it is too humid our bodies can’t cool off by evaporating sweat — this is why humidity is important when we consider liveability in a hot place,’ paper author Yi Zhang of New Jersey’s Princeton University told the Guardian.
‘High body core temperatures are dangerous or even lethal,’ he added.
Analysis of historical data and future climate models indicated that temperature extremes in the tropics are increasing in parallel with tropical mean temperatures, the researchers explained.
This means that — to keep wet-bulb temperatures in these regions below an unsafe level — global average temperature increases will need to stop at 2.7°F (1.5°C), the goal set out by the Paris Climate agreement but likely to be broken within a decade.
It is estimated that around 40 per cent of the world’s population lives in the tropics.