The link between climate change and Britain’s winter storms

This article originally appeared in the February 16th 2020 edition of The Sunday Times, and was co-written with Shingi Mararike.

Every winter Britain gets hit by a series of storms. Ciara and Dennis are just the latest — but with two key differences.

The first is their strength. Our storms get their energy from temperature gradients in the atmosphere over north America. Recently that gradient has been much greater than normal.

The second is good PR. In 2015 the Met Office decided to start naming storms, which gave them a much higher media profile.

In 1993 Britain had the powerful Braer storm. In 2013-14 we faced about 12 of these weather systems. But in other years there are hardly any, which is why this year might be feeling so extraordinary to people coping with flooding, high winds and lots of rain.

A key question: why does the number vary so much?

Part of the answer lies in the jet stream, the powerful westerly wind blowing about six miles above us which, driven by that steep temperature gradient, has accelerated and got bigger. That energy feeds into our storms.

On their own, Ciara and Dennis are not symptomatic of climate change or a global weather crisis. What climate change does is to alter the likelihood of such events. Computer models of the impact of climate change predict an increase in winter rainfall for the UK, along with warmer atmospheric temperatures and changes to the tracks followed by storms across the north Atlantic. This year may not be a sign of things to come, but we will probably see more severe winter flooding in future.

January 2020 was the warmest or second warmest on record in every global temperature dataset. It was rivalled only by 2016, when there was a strong El Niño event in the Pacific that temporarily raised global temperatures. Given that there is no El Niño this year, these record global temperatures — up to 1.5C above pre-industrial levels — are a cause for concern.

It emphasises the rapid warming of the planet. These record temperatures are consistent with recent events such as the Australian wildfires, the rising temperatures in the Antarctic and the unprecedented lack of ice and snow in parts of Europe.

What does this mean for Britain’s weather? So far the world has seen warming of about 1C. That is going to continue and the best guess is that the world could be — in a worst-case scenario — 4C-6C warmer by 2100.

That may not sound much – but multiplied by the area of the planet it means that the atmosphere will hold an enormous amount more energy.

That energy will not only be felt as heat. It will also power our weather like never before. That means more and bigger storms, stronger winds and changes in the temperature of the oceans, which will make the sea levels rise. If our weather is exciting now, it may soon be overwhelming.

An earlier version of the article implied a greater likelihood of 4-6C of warming. This is at the very top-end of climate projections, following the extreme RCP8.5 scenario, and is not the most likely outcome now – but still possible.

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