summer weather and food production

It can’t have escaped anyone’s notice that summer 2012 has seen some pretty unusual conditions. In the UK its officially been the second wettest summer (June, July and August) since records began with only 1912 being wetter. The only exception was the NW of Scotland with somewhat drier than average conditions. This of course followed a winter and early spring in which we were being warned of possible water shortages over the coming summer thanks to a couple of drier than normal winters.

The wet conditions this summer have had a major impact on cereal, fruit and vegetable crops. In England the National Farmer’s Union estimates that wheat production was down 15% from the 5 year average (http://www.bbc.co.uk/news/uk-19890250). Wet weather around harvest time made the headlines with floods, particularly in the north-east, meaning that some crops couldn’t be harvested at all. The grain that was brought in often had to be dried artificially, substantially adding to production costs. The Scottish strawberry crop was also reported to be decimated, and cold wet weather around apple blossom time in April and May meant that there were less pollinating insects flying and so apples have experienced reduced yields this year.

However, personal experience suggests it hasn’t all been bad news. The raspberry crop in my garden was the biggest I’ve ever seen as long as I could pick them fast enough before they started to mildew. Raspberies are a British native plant growing on woodland margins and have evolved to do well in cool damp conditions. Hence they were quite happy with this summer’s weather. My sweetcorn yield was also up on previous years and potatoes seemed to do pretty well. Tomatoes growing ouside came to very little though. I’ll be starting to dig up the parsnip crop this weekend so we’ll see how well they’ve done fairly soon.

My own apple tree produced only two edible apples, but talking to the farmer at Cross Lanes Orchard (www.users.waitrose.com/~crosslanes/index.htm) just outside Reading suggests that it hasn’t all been bad with apples either. Whilst yields were significantly down for some varieties others have done very well. Cross Lanes is an orchard that grows over 40 different varieties of apples, as well as plums and pears, and so this highlights the importance of diversity in the crop with earlier and later blossoming varieties meaning that there’s a good chance that some varieties will do well.

Over in the USA its been a drought summer, with some big wheat producing states such as Kansas and Nebraska experiencing “exceptional” drought conditions – the most extreme drought category according to the US Drought Monitor at the University of Nebraska-Lincoln (droughtmonitor.unl.edu). As some of our undergraduate students reported in Weather and Climate Discussion last week, this has had an impact on local food production but also potentially on global food prices. Whilst US wheat yields are actually up, corn yields have been down and the quality of pasture for cattle is also very poor (US Department of Agriculture). Reduced grain yields lead to increased prices and because a  lot of grain is used in winter feed for livestock production the impact goes beyond the grain price itself.

These stories all highlight our dependence on the weather for maintaining food production, an issue that has concerned mankind since the earliest civilizations. In ancient Egypt for instance the fertility of the fields along the Nile was dependent on the annual floods, which were themselves dependent on rainfall many hundreds of miles south around the river’s headwaters. These days we have more sophisticated agricultural methods and are able to develop varieties of crops which are more tolerant of particular weather conditions. However, we still have some way to go in our ability to make weather predictions on the seasonal timescale that will allow farmers to make decisions on what crop varieties to plant ahead of time.