Wetter winters and more hot summers

ESKDALE faces a future of hotter, drier summers and warmer, wetter winters, according to a new report by the Met Office.

Rainfall will be heavier and more intense and the amount of rain to fall in any one day could rise by nearly half in the summer and a quarter in the winter.

Western Scotland is already one of the wettest areas of the UK and the effect of higher rainfall will be strongest here.

In the past 30 summers in Eskdale there were no days above 25C a month on average. If global temperatures rise by 2C, there could be one day and with a 4C rise, there could be four days.

The hottest summer day of the past 30 years in Eskdale was 30.1C.

If global average temperatures rise by 2C above pre-industrial levels, the hottest summer day could be about 32C. If they rise by 4C, it could be about 35.8C.

In the past 30 years there were 14 rainy days on average a month in summer. If global average temperatures rise by 2C, this could be 13 days a month. At a 4C rise it could be about 11 days.

On the wettest summer day of the past 30 years 52mm of rain fell in this area. At a 2C rise, this could be about 55mm and at a 4C rise it could be about 74mm, which is 43 per cent more than now.

The warmest winter day of the past 30 years was 16.8C. If global average temperatures increase 2C above pre-industrial levels, the warmest winter day could be about 17.3C. If they rise by 4C, it could be about 17.7C.

On the wettest winter day of the past 30 years 58mm of rain fell in Eskdale. At a 2C rise this could be about 71mm and at a 4C rise it could be about 72mm, which is 24 per cent more than now.

The Met Office climate projections for the UK indicate significant temperature rises in the decades ahead for both winter and summer, with the greatest increases in the already warmer south.

Extreme weather could become more frequent and intense.

Not every summer will be hotter than the last but temperature records are expected to be regularly broken, while heatwaves are likely to be longer and happen more often.

Human activity has increased carbon dioxide (CO2) emissions and caused rising temperatures worldwide since the growth of industrialisation in the 19th century, says the report.

If global average temperatures rise by 2C above pre-industrial levels, days at least as hot as the 2019 record could be more frequent and widespread.

With a 4C rise, parts of the UK could experience temperatures above 42C.

Urgent cuts in emissions are needed to keep the rise in global average temperatures in check.

Governments, which signed the Paris Agreement in 2016, pledged to cut emissions and keep temperatures well below a 2C rise by the end of this century but the Intergovernmental Panel on Climate Change (IPCC) says even a 1.5C rise could be devastating.

Currently, more than a quarter of the UK has 20 or more days without rain each summer month. This could grow to more than half the country if it reaches 4C global warming.

In warmer winters the heaviest rains are likely to get more intense. If global average temperatures rise by 4C above pre-industrial levels, half the country could expect at least 20 per cent more rainfall on the wettest winter days.

Summer rains may also become heavier in many places, although total rainfall is expected to decline.

Currently, the wettest areas of the UK dominate the west coast, with nearly all of Wales and western Scotland receiving most rain in winter.

So how much will change in future winters? With a 2C rise, very little compared to what we’ve seen recently.

But winters over the past 30 years have been rainier on average than previously, and the pattern of wetter winters could continue.

The exact amount of change in rainfall at 2C global warming will vary around the country. Most places could have slightly wetter winters than in the 20th century.

If global average temperatures were to rise by 4C, more than half the country could see at least 10% more rain over the winter months.

The UK climate projections suggest increases in winter rainfall in most parts of the country, as well as drier summers.

Rainfall measurements fluctuate from year to year, making projections challenging.

Not every winter will necessarily be rainier than the one before, and not every summer will be dry, but both trends could have big impacts.

In warmer winters the heaviest rains are likely to get more intense. If global average temperatures rise by 4C above pre-industrial levels, half the country could expect at least 20% more rainfall on the wettest winter days.

Summer rains may also become heavier in many places, although total rainfall is expected to decline.

Of course, not all of the heaviest rains will necessarily fall in these two seasons. The current wettest day on record was 3 October 2020, when enough rain fell across all four nations to fill Loch Ness.

Currently, the wettest areas of the UK dominate the west coast, with nearly all of Wales and western Scotland receiving most rain in winter months.

So how much will change in future winters? With a 2C rise, very little compared to what we’ve seen recently.

But winters over the past 30 years have been rainier on average than previously, and the pattern of wetter winters could continue.

The exact amount of change in rainfall at 2C global warming will vary across the country. Most places could have slightly wetter winters than in the 20th Century.

If global average temperatures were to rise by 4C, more than half the country could see at least 10% more rain over the winter months.