Is the weather of the past 8 months likely to be the "new norm" due to climate change?

[Summer8906]

It's well known that the past 8 months have been typified by dull, wet weather with more southwesterlies than normal plus very mild nights at all seasons and very mild days in the autumn and winter (though less so in the summer due to high cloud amounts).

Meanwhile, the same setup (which seems to be anomalously southwesterly, i.e more southwesterly than normal) is delivering extremely dry and warm weather to southern Europe: after a dangerously hot summer, many Mediterranean countries have the opposite problem to us, i.e. not enough rainfall in the winter. They are sharing in the silly mild temps though, but mild and dry rather than mild and wet.

We've had a lot of unsettled summers of late (I know some disagree, but this is certainly my perception) with 2020 and 2021 featuring three unsettled months and 2019 and 2023 two unsettled months and one settled one.

I know many climate change predictions have featured a higher incidence of 1976- or 1995-style summers but hot summers (as in, typified by long spells of hot sunny weather) remain relatively infrequent, occurring perhaps every 4 years on average.

Other trends include spring and early summer being by far the most settled period of the year, with the best chance of prolonged anticyclonic weather occurring usually sometime between mid March and late June.

Wondering if this is likely to be typical of "the new normal" or whether the last 8 months remain an aberration?

While obviously we are being spared the worst effects of climate change compared to places further south, I'm not liking the signs so far of anomalously southwesterly conditions, high cloud amounts and the one settled season of the year - spring - also being negatively impacted by the spring flowers coming out too early, while the mild, dull and unsettled meteorological winter is still ongoing.

Edited February 24 by Summer8906

[reef]

It's likely as the climate warms the land will warm more quickly than the ocean so it means continental flows in summer will be more extreme. This is what we are sort of seeing in recent years.

Apart from that, for the other 90% of the time in the UK, higher SSTs mean more intense storms, heavier rainfall, more flooding and in winter more moderation of cold sources so less snow. The jury is out whether it influences synoptics and makes westerlies more likely, but it seems that way. In winter at least. Overall, patterns seem to get stuck in place more now.

For summers, it generally doesn't change the weather on the ground. 13C and raining in July just becomes 15C and raining, with overnight mins proportionally higher. However hot spells will be more extreme, though not necessarily more frequent at first.

I dont think we'll know if this is the new normal for a few years yet. It could be a blip in an otherwise gradual change, much like the 2007-2012 period.

[*Stormforce~beka*]

Last 12 months more like! The persistent cloud started last March. That for me is when it started going tits up!

[Thundery wintry showers]

I think the cloud and rain is largely a consequence of anomalous synoptic setups - we've often had the jet stream coming across Britain, sandwiched between blocking highs over Greenland and south-western Europe, bringing wet weather and warmth, especially to the south, assisted by the high SSTs in the eastern North Atlantic. This did indeed set in starting around mid-March last year. I'm not sure if these setups are likely to become more frequent with climate change, but one thing that is highly likely is that, because warmer air can hold more moisture, as the climate warms, heavy rain events and associated flooding will tend to get more extreme. Also, with increased evapotranspiration, we can expect droughts to become more extreme too.

I agree with Reef regarding hot continental air getting hotter as the continents warm faster than the oceans. In particular, north Africa has warmed at at least twice the global average rate in summer, which has contributed to extreme hot days warming faster than the summer mean temperature.

[sundog]

Think the weather the last yr is   down to climate change and  El Niño . Perhaps worth mentioning the Hunga Tonga eruption from December 2021.Perhaps all 3 have led to a perfect storm for the last while. So dont know if its the new normal. I doubt it . I would hope things will get a bit better in the next yr or so. But it is clear the overall direction of travel we are heading. 

[WYorksWeather]

I don't think a pattern as anomalously wet as this will become the norm, in short. But future rainfall trends are very complex, so for the more general question of whether things will get wetter or drier, I've posted a more detailed answer below.

The biggest difficulty in climate models at the moment is future precipitation patterns. The consensus at the moment seems to be wetter winters and drier summers are a likely long-term UK trend. But whether we actually see that or not is quite uncertain, as it depends on a large number of factors. It's not as simple as temperature, where any idiot can tell you that a warmer Earth means a warmer UK, along with virtually everywhere else.

In essence there are plenty of reasons to think we might get wetter - warmer SSTs mean more evaporation, warmer air can hold more moisture. Certainly extreme precipitation events when they do occur will likely result in greater rainfall totals.

However, there are also perfectly good reasons to think the UK might get drier. A weakening jet stream due to reduced equator-pole temperature differentials may make it more vulnerable to buckling or splitting, allowing more blocked patterns. We also have the expanding Azores high, which may mean that we take part more in warm dry summer spells that affect much of mainland Europe.

In short, the consensus is that the balance will be on the drier side in summer and the wetter side in winter, but it is all very uncertain.

Major uncertainties are generally around the triggers for climate tipping points. For those unaware, a tipping point in this context is essentially when some major component of the climate system as we know it moves to a new state, in a way that is irreversible on a human timescale. We know this has happened in the past. Probably the best known example affecting the UK is a potential AMOC collapse. Of course as is well known, this would lead to colder winters for the UK. Less well known, however, is the fact that this would probably lead to hotter summers. Most disastrously though, it would massively reduce rainfall during the growing season, which would devastate agriculture.

Other past changes that could happen again include an ENSO cycle breakdown. During the Pliocene about 3-5 million years ago, a permanent El Nino existed, and there was no ENSO cycle as we would recognise it. Other factors include runaway ice sheets losses that become self-sustaining, the loss of the Amazon rainforest, and various others.

And that's not even considering character of rainfall, which is yet another consideration. That's probably even harder to predict - e.g. for a given amount of rainfall, will we have more rain days, or less rain days but more severe downpours and flash flooding risks?

In short, predicting UK temperature is pretty easy. Short of an AMOC collapse (and possibly even not then, depending on how much the Earth has warmed prior), UK temperatures in 30 years will be warmer than they are now. But rainfall is much, much harder to predict, as it depends on how the rest of the climate system changes in a way that is much more complicated than just warmer Earth = warmer UK.