Weird weather: Can computers solve UK puzzle?on June 4, 2020 at 11:17 pm

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Met Office

A top climate scientist has called for more investment in climate computing to explain the UK’s recent topsy turvy weather.

Prof Tim Palmer from Oxford University said there were still too many unknowns in climate forecasting.

And in the month the SpaceX launch grabbed headlines, he said just one of the firm’s billions could transform climate modelling.

Short-term weather forecasting is generally very accurate.

And long-term trends in rising temperatures aren’t in doubt.

But Prof Palmer says many puzzles remain unsolved: take the recent weird weather in the UK, with the wettest February on record followed by the sunniest Spring.

• Forecasters set for ‘billion pound’ supercomputer
• May was sunniest UK month on record

Weather somersault

Meteorologists were astounded by this unprecedented weather somersault – and especially by the amazing amount that May sunshine exceeded the previous record.

This year’s figure was 13% higher than the previous record – that’s like the winner of the 100 metres leaving opponents over 11 metres behind.

Some place the blame on climate change, but the Met Office says, as yet, there’s no strong evidence for that.

Prof Palmer told BBC News: “It would be really valuable for us to have more knowledge of how climate change is affecting weather patterns like this.

“Was climate change implicated in the recent weird weather? We don’t know.”

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PA Media

He agrees that space observations have massively improved our understanding of the climate.

But he complains: “It is very frustrating to see space get quite so much attention when we can’t be sure what will happen to the climate on Earth.

“If only we could secure one of their billions for computer modelling that would be a big help.”

So what do we know so far about recent British weather weirdness?

Jetstream locked

Well, here’s what’s clear: the strong jetstream to the south-west of England through the winter locked in place the succession of Atlantic storms that drenched the UK.

The Met Office successfully predicted the wet winter in its seasonal forecast, but failed to predict the sudden leap to a dry spring when the jetstream was looped over the UK, holding the sunny weather in place.

In a global climate chicken-and-egg debate there’s the question of why the jetstream behaved this way.

Some scientists believe it’s being affected by conditions in the Arctic, which is warming faster than anywhere on the planet, because of greenhouse gases. But this is disputed.

Prof Palmer said the jetstream appeared to be influenced by a climate phenomenon known as the Indian dipole – an irregular oscillating current in the Indian Ocean. This was also blamed for the wildfires in Australia.

But what’s influencing the Indian dipole? Or is it completely natural?

Scientists know ocean currents on the other side of the world can influence our weather – but did water round the Chagos Archipelago really prompt a “barbecue spring“ in grateful lockdown Britain?

“There are very strange things going on in the tropics,” Prof Palmer added. “The question is, ‘is it natural?’ and we’re not yet sure.”

Scientists are now planning to re-run UK climate models over recent years and remove the heating element of CO2 emissions from the mathematical puzzle. That should offer a better understanding of British weather at least.

Unlocking secrets

Prof Palmer admits it’s surprising this exercise wasn’t done sooner. But of all the uses of extra cash for climate research, he thinks the most useful spending on climate research might be to unlock the secret of clouds – one of the most intractable climate mysteries.

If warmer weather leads to more low-level clouds, that will bounce out radiation and cool the Earth. If it leads to more high-level clouds, that will trap in heat.

In fact, Prof Palmer said, one recent cloud modelling exercise suggested that if we’re unlucky, global temperatures may rise by 5C after CO2 levels are doubled – a level utterly inhospitable to humans. The conclusion was previously ruled out under different analysis.

“We need to understand these processes better,” he says.

“Normally in science you learn about the system under study by doing laboratory experiments. With Earth’s climate, there is no lab experiment you can do.

“The climate model is the only tool we have to understand what future is in store for humanity as a result of climate change.

“Space observations tell us what is happening now, but climate models tell us about what will happen next year, next decade, next century.”

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