The three months (December 2019 - February 2020) were unusually mild, wet and windy. This was the mildest European winter on record, and February was the wettest on record in England, and not surprisingly that was reflected here in the New Forest.
There were only 10 days with an air frost in the whole winter (compared with 17 last winter), and the winter minimum was -2.6C (compared with -5C last year). Despite that, each of the average monthly temperatures were within a degree of last years, though well above long-term averages for the area. Snow did not fall on any day (except for a few flakes in one particularly vigorous shower in February that also gave hail) in the entire winter this year.
It rained on 52 days(out of 91), with 19 of those having particularly heavy rainfall. Though flooding was less of an issue in our area than in the Midlands, there were some very wet periods for the Forest, with a great deal of surface water.
We were in a pattern, particularly towards the end of the winter, where significant Atlantic Storms seemed to arrive one after another, with very heavy rain, mild temperatures and strong or very strong winds. February had 10 days with peak wind gusts over 40 knots in our garden, by far the windiest month since the weather station was set up here. The peak gust was a mighty 61 knots here in the village, on February 10. The much more exposed Needles Battery station (about 15km from us, but on a cliff above the English channel) regularly recorded gusts over 90mph.
There has been much talk about climate change and whether any particular storm is caused by global warming. There seems to be (what might be deliberate) confusion which does not help the discussion.
Weather is the conditions (temperature, sunshine, rain etc.) at a place at a particular time. Weather is chaotic. That is, tiny changes in starting conditions can evolve quickly to give widely different outcomes, in a system that is too complex to predict with complete accuracy. There are too many variables interacting with each other. This means that statistically, most weather in a place will be close to the “average”, but the weather will normally produce “extreme” events from time to time. It is a matter of frequency. Sunshine in July in the New Forest happens much more often than snow, but snow in July will happen from time to time, just not very often. Very heavy rainfall or strong winds or high temperatures or low temperatures are all going to happen from time to time without that necessarily suggesting that anything particularly unusual is happening.
Climate is the frequency with which particular weather occurs over a period of time in a particular place. It’s often expressed as a series of averages, so we expect arctic regions to have cold temperatures and snow much more often than the equator, and so it will have much lower monthly or annual average temperatures.
So climate change is not having unusual weather, it is about changes in how often unusual weather events occur and how that changes the average weather in a place.
Unusually mild winters are more common now in the South of England than they used to be. Cold weather and snow is reduced in frequency too. This lines up with measured changes in the average temperature here and globally, which shows steady and accelerating increases. Our understanding of the atmosphere says that we would expect to see more storms as average temperature increases, and a higher frequency of more extreme weather events, though any single event might have happened occasionally even if there were no global warming.
Was Storm Ciara proof of global warming? Not directly, but the fact that we have year after year with higher average temperatures and much more frequent storms and floods is simply a way of saying that the climate is changing here and that it is warming.
Given all the evidence is that by far the most likely explanation for this change is the increase in Carbon Dioxide concentrations in the atmosphere, and that these are almost entirely of human origin, reinforces the need for us to take action to reduce emissions, as well as planning more effectively to deal with the impact of a climate that today is already significantly different to the past.