Answers From Chris Smith!
By Paul Homewood
The saga continues!
To quickly recap, Lord Smith, Chairman of the Environment Agency and formerly Labour MP Chris Smith, was interviewed by the Sunday Telegraph in February. Discussing floods, he told the Telegraph:-
“We are experiencing a new kind of rain.
Instead of rain sweeping in a curtain across the country, we are getting convective rain, which sits in one place and just dumps itself in a deluge over a long period of time. From the point of view of filling up the rivers and the drains, that is quite severe.”
This attracted much criticism from experienced meteorologists, such as Bill Giles, who wrote to the Telegraph to complain:-
“There is nothing new about convective rain. Perhaps next time he should get a meteorologist to check his answers so that he doesn’t appear so ignorant of simple straightforward facts.”
Meanwhile, a spokesman for the Environment Agency tried to suggest that Smith had been trying to explain that convective rain was becoming increasingly common.
I decided to follow this up, and ask the Agency under FOI for the evidence used to support Smith’s claims.
Their first reply did not answer my specific questions, and simply referred me to the Met Office 2012 summary, which pointed out how wet the year had been but made no mention of convective rain, while claiming that he had been “misquoted”. I saw this as an attempt to fob me off, so I refused to accept their reply.
My persistence paid off, and I received their second reply yesterday. Their “evidence”, it seems, centres around a briefing document sent to them by the Met Office, when officials from the latter attended the September Board Meeting at the Agency. As far as I can see, this document has never been in the public domain.
As well as addressing the specific issue of convective rain, the document also goes into some detail on two other matters of significance. I will be discussing these in a separate post.
But on the original issue, the Met have this to say (my bold):-
However, when the jetstream dips to the south of the UK, the distribution of rainfall is skewed away from the climatological average, and southern areas can see periods of significantly above average rainfall and associated higher risk of river and surface water flooding. Not only do the low pressure systems steer across southern areas, but the following factors act to increase the risk of heavy rain and flooding:
· different prevailing wind direction means that different windward slopes will be subject to enhanced rainfall
· the frequent southerly to easterly component to the airflow means that warm, thundery air from the near Continent may be drawn towards the UK, increasing the potential for heavy rainfall
· fronts are more likely to become slow-moving, giving persistent rain in some areas
· between the low pressure systems themselves, the dominant low-pressure (‘cyclonic’) environment is conducive to formation of heavy showers during summer. Again, these may be slow-moving, with an increased risk of intense downpours and surface water flooding.
Low pressure systems of this nature are unusual in summer and because the atmosphere is warmer it can hold more water than in other seasons resulting in significant amounts of rainfall
It is really the last point that has relevance. What the statement boils down to is this.
1) Convective rain, or heavy showers, tend to form in a “low pressure environment”, which is unusual in summer.
2) The atmosphere is warmer in summer, and therefore can hold more water, resulting in heavy rainfall.
3) Last summer, the movement of the jetstream to the south resulted in persistent low pressure systems across southern areas.
And that’s it! No evidence, or even speculation, that any of the factors were affected by climate change, or that such events are on the increase.
There is absolutely nothing in the document to support either Smith’s claim of “a new kind of rain”, or the subsequent one that convective rain was increasing.
For a politician like Chris Smith, the message is everything, whether supported by facts or not. But, in future, perhaps he might like to ponder Bill Giles’ advice “to get a meteorologist to check his answers so that he doesn’t appear so ignorant of simple straightforward facts”.