Reality Check: No Evidence That Recent Winters Have Been Wetter Than In Earlier Decades
There is no evidence that recent years have been unusually wet, compared to earlier decades.
I have been waiting to update the situation with regard to the flooding of the Somerset Levels. I had hoped to include the rainfall data for the local station at Yeovilton, but the Met Office still have not issued them yet. I have chased, but they say, understandably, they are too busy at the moment.
However, we can look at the numbers for the region, SW England & S Wales.
Let’s just recap the background. The problems started with heavy rainfall in the 2nd week of December, after a much drier than normal November. (The Levels are marked on the map below in red – to the best that my limited artistic talents allow!)
At the local station of Yeovilton, about 20 miles south, Met Office figures show that rainfall in November was 23% lower than normal. Given this, and the dry summer, river levels should have pretty low as December started.
During December and January, rainfall over the region amounted to 450mm, which is 165mm above the 1981-2010 average.
At Yeovilton, in December, rainfall was 43mm above normal. Although, as I say, January data is not yet available, rainfall maps don’t suggest that Somerset has been wetter than the rest of the region and indicate between 150mm and 200mm, against a normal of 67mm.
This would imply that December and January’s rainfall combined was probably about 120mm and 170mm above normal. This is all a long way round way of saying that the regional pattern looks pretty representative of Somerset.
If we look at 2-month precipitation numbers during autumn and winter in the region, we find that this latest period of December/January has been exceeded on eight occasions since 1910. (There are multiple events in two years, 1929/30 and 2001/01, which means that these eight occasions are spread over five years).
In other words, it is, on average, an event that happens pretty much every decade or so.
The graphs below show the three combinations – Oct/Nov, Nov/Dec and Dec/Jan. These are typically the wettest months of the year. Note that on all three graphs, I have shown the latest Dec/Jan plots in red, for comparison purposes. I would also point out that the year shown on the X-Axis is the “January year”. So, Dec 2013 to January 2014 is shown as 2014. This also applies to October to December – October 2013 to November 2013 is labelled as 2014. (A bit confusing, I know,but it keeps things consistent).
A couple of points stand out:
- 1929/30 stands well above the rest, and on all three graphs. More on this later.
- There is no evidence that recent years have been unusually wet, compared to earlier decades.
Comparisons with 1929/30
It already looks as if February will end up being another very wet month in the South West, so we may very well find that the 3-month total, for Dec-Feb, exceeds most other years since 1910.
Whatever the outcome, though, it does not look likely that the latest Dec-Feb figures will come any where close to the Nov-Jan period in 1929/30. If current trends remain, my guess would be for another 200mm this month, which would leave a total for the three months of about 650mm. This is well below the 812mm recorded from Nov 1929 to Jan 1930.
It would also come in lower than Oct – Dec 2000.
So what should we learn from all of this?
1) While it has been an exceptionally wet winter in the South West of England, it is far too early to be talking about it being unprecedented, or to be looking for links to “climate change”.
2) As the graph below shows, precipitation during the “six winter months” has actually been at historically normal levels in recent years, and the trend looks to be a declining one. If nothing else, this rather makes a nonsense of the theory that global warming is leading to wetter winters.
3) Whilst the continuing wet weather is prolonging the agony for the Levels, the situation in December and January was not an unusual one. I will leave others to judge what effect the lack of dredging and other maintenance work has had on the floods.
4) If any year was “unprecedented”, it was 1929/30. (And as I have shown previously, the wet winter of that year affected the whole country.) I find it incredible that the Met Office have not carried out a detailed analysis of that winter, and indeed some of the other wet years, to see what they have in common with this winter.
There is little doubt that scientists such as HH Lamb would have done precisely that. Instead, we see a desperate attempt to find a link to “climate change”.
Surely, to do science properly, you should first look for natural causes for events such as these. And to do that, you have to learn from the past. Only then can we hope to understand the present and the future.
5) We have been bombarded with claims of record rainfall months, and forecasts of record winters. Meanwhile, David Cameron describes the Somerset floods as “biblical”. Am I the only one that cannot remember being told that 1929/30, or other years, were much wetter?
At least the media have an excuse – they are trying to sell newspapers. The Met Office have no excuse at all.