Have weather patterns really been unusual?
There’s been much in the press in recent days following the widely publicised ‘Unusual weather’ conference held at the Met Office.
The Independent headline was similar to others in the media, advising readers to ‘Stand by for another decade of wet summers’, continuing that the UK was in the midst of a ‘rare’ weather cycle.
This cycle, scientists announced, was the Atlantic Multidecadal Oscillation (AMO).
But as it turns out, there’s nothing rare or unusual about it at all.
The AMO was first identified by researchers nearly 20 years ago, incidentally when I had just begun my career as a forecaster at the Met Office, and describes a natural, cyclical warming and cooling of the North Atlantic Ocean over time.
This cycle is known to affect temperatures and rainfall, and alter North American and European summer climate.
In the UK, it leads to an increased risk of summers that are wetter than average.
It’s also linked with changes in the frequency of Atlantic Hurricanes, and of North American droughts.
The 1930’s and 1950’s in North America are dominated by heat records and correlate almost perfectly with a warm AMO.
The AMO has a cycle of approximately 70 years and would mean the current warm AMO is likely to last into the next decade.
But talk of another decade of wet summers is misleading.
If as expected the warm AMO continues then there’s a higher risk of wet summers – but it certainly doesn’t mean every summer will be a washout.
It’s worth remembering that one of the warmest, sunniest summers on record happened in 1959 – during the previous warm AMO cycle.
The return to much colder winters discussed at the conference has coincided with another natural phenomena – that of low solar activity - which has been shown to be associated with weather patterns that encourage cold winters across the UK and Europe.
It goes to show that at a time when it seems that every weather event or climate pattern is linked in some way to man-made climate change, natural weather cycles like the AMO can offer a more straightforward, natural, explanation.