February heatwave: is the UK climate changing?
February's sudden warm weather broke records, but whether it was climate change isn't an easy question.
Spring has sprung! The days are lengthening, the flowers are blooming, and the UK broke its record for the warmest-ever February day two days in a row. Temperatures passed 20°C in Wales and the London area, in stark contrast to the plunging temperatures and deep snow brought by the Beast from the East at the same time last year.
Is this the inevitable result of climate change? And what are the effects of such warm weather so early?
Is this weather so unusual?
The recent warmth was very unusual, both here and across western Europe and Scandinavia, according to Dr Dann Mitchell, climate scientist at the University of Bristol. “Records have definitely been broken everywhere, and we’re in a part of the world where we have very long temperature records,” he explains. “We can look back to, say, 1880 or even 1850 in some cases, so we really can tell that this is a very extreme February temperature.”
Can we say it’s the result of climate change?
It’s important not to confuse weather with climate: we can’t judge the entire climate on the events of a few days. “Weather is what we experience on a day-to-day timescale, and climate is what we experience over a much longer timescale,” says Mitchell. “We generally say that climate is what you expect and weather is what you get.”
What’s more, unusual weather events in isolation are difficult to pin on climate change. For example, Mitchell suggests that there are three main factors that brought the February heatwave: the dry weather for much of early 2019 making it easier for the Sun to heat dry soils, high pressure air over the UK and Europe drawing in warm air from equatorial regions such as the Canary Islands, and the atmosphere absorbing more energy because of the increased carbon dioxide that we’re putting into it. “The absorption of energy by carbon dioxide is a very strong contributor," he says, "which is why I think climate change is making these sorts of events more frequent.”
Such warm weather so early in the year, while still very unusual, is becoming much more likely. Most recent estimates suggest that it would happen, on average, once in 100 years. “In our non-altered climate state, it was probably closer to 10,000 years. In that sense, climate change has probably increased the frequency so that it’s gone from a one-in-10,000-year event to a one-in-100-year event,” Mitchell says.
Why is this weather so different from last year’s 'Beast from the East'?
While this year’s weather came from the south, last year’s cold snap was the result of a system of high pressure over Scandinavia which drew cold air from Siberia over the UK.
What are the immediate effects of the warm weather?
In the immediate aftermath of the heat came fires. Ashdown Forest in East Sussex, Marsden moorland in West Yorkshire, and Arthur’s Seat in Edinburgh all suffered from outbreaks of fire. Early 2019 has seen less rain than usual and, according to firefighters tackling these blazes, the addition of the warm spell dried out the soil enough to make fires of this sort more likely.
In addition, the early emergence of warm, sunny weather could prove perilous to wildlife, especially if it doesn’t stay. Many types of species take cues from the weather around springtime: insects and mammals come out of hibernation, flowers bloom, some birds start to nest, and others even return from migration. According to the Portland Bird Observatory, swallows and house martins have both been spotted in the UK already, despite usually returning from Africa around April.
If the weather turns cold again, this could have a knock-on effect on the availability of food. A substantial drop in temperature would leave insects and flowering plants struggling, leaving hedgehogs, awoken from their hibernation, and early broods of baby birds without access to sufficient food to make it through until spring.
What can I do?
The RSPB has published advice on how to help wildlife which could suffer the consequences of a cold snap. First of all, you can provide a food source, such as meal worms and fat balls, and fresh water. You could also consider putting a bird house in your garden, or even planting pollen-rich plants as a source of nectar.
Listen to our interview with Dr Dann Mitchell about last summer's heatwave in the Science Focus Podcast below. Make sure you subscribe and rate it wherever you get your podcasts from.