Rain Rain go away

The Met Office recently blogged that we were heading for the wettest June on record (since 1860)  – that was before yesterday’s downpours which hit Northern Ireland particularly badly. I can well believe we’ll have record June totals – here in Dorchester I’ve recorded over 156mm so far with more rain in the forecast.

What an increasingly bizarre year we are having with the weather – well bizarre is one word, awful is another. The first quarter of the year was exceptionally dry with only 116mm  –  remember the drought? This has been followed by an amazing 191.75mm in April, an average May with 49.5mm, and this drenching June. The total so far for the second quarter is 397.5mm. That’s nearly 4 times as much as in the first quarter. Let’s hope the third quarter doesn’t follow the same pattern.

Meanwhile the Arctic sea ice is disappearing more rapidly this year than any of the previously recorded years in the satellite era (ie given how difficult it is to record sea ice accurately it’s only since satellites have been recording it that there is any degree of accuracy). This is a particularly good website to follow its fortunes and here’s the latest image showing that 2012 has seen a dramatic drop in sea ice cover in the past month (the yellow line), way beyond even last year or the record 2007 melt.

Sea Ice Extent courtesy of the Polar Research Group University of Illinois Urbana-Champaign

Are the two correlated? It seems a shift in the jet stream which brings low pressure systems across the Atlantic is causing the rain to hit England and Wales, and missing its usual path which is further north. North West Scotland has been unusually dry as all the rain passes by further south. The question is whether the jet stream is moving because arctic sea ice summer cover has reduced so much. There’s also some suggestion that the Jetstream is getting stuck in particular positions for much longer than occurred previously – so when its stuck in a “dry” place it causes long term drought, and when it’s in a “wet” place it never stops raining.

Some think there is a correlation – here’s some evidence in support on the arctic methane emergency group website. It looks like evidence is still being collected and it doesn’t look like there is undisputed causal evidence yet.

If it is the case though it has severe implications for the UK, for agriculture, for the wider economy and for society. Wetter summers with increasing flood events, coupled with drier winters, will make arable farming increasingly expensive as more fungicide is needed to control the growth of moulds on the crop. Grass will grow more, good for grazing and silage, but hay making will become even more difficult, which isn’t good news for the few wildflower meadows that still survive. In Dorset, sharp-flowered rush does seem to be increasingly common in wildflower meadows, and this may be a signal that the soil is getting wetter because of a change in the climate.

Artificial nitrogen fertiliser and other inputs will be more vulnerable to being washed out (into water courses) by heavy spring and summer rain, which could in theory drive more sustainable approaches to maintaining soil fertility, such as using legumes. Soil structure will also be affected as heavy rainstorms erode soil and contribute to compaction especially where soils have already lost their structure through compaction by vehicle use or heaving grazing.

The impact of climate change could actually force UK agriculture to adopt more sustainable approaches to arable and livestock production – but, call me a cynic, but it seems more likely that actually more money will be spent developing new fungicides, a new era of land drainage and more investment to engineer crops to cope with the changing climate.

Hopefully a combination of the best from the two approaches will enable agriculture to reduce its impact on the environment and adapt to the changing climate.

Putting all that to one side, how are the rest of us going to cope with rainy flooding summers for the foreseeable future?

Miles King (sitting in a mouldering west Dorset)

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The Grasslands Trust is the only national UK charity that focuses entirely on saving grasslands that are valuable because they are rich in wildlife, history, or for other reasons.
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4 Responses to Rain Rain go away

  1. Filbert Cobb says:

    Re-wetting of soil after a dry period causes problems, even when the soil is not compacted. I believe much of current flood problems are rooted in widespread agricultural soil compaction, particularly on improved grassland. The cause is not clear – livestock numbers are declining, so grazing intensity seems unlikely. Number one candidate for me is the increasing weight of farm machinery, and the increased use of contractor services – which puts pressure on the timing of operations and increases the likelihood of compaction under permanent agricultural grassland.

    A couple of points to ponder: The highest flood markers on the Watergate at Worcester Cathedral, in order of severity are 1770, 1947, 1886, 2000. Percentage of UK under concrete – 2.27%, according to UKNEA (as reported by Mark Easton on the Beeb today).

    So I think any notion that recent inland flooding is unprecedented, or that the spread of the built environment is to blame, can be discounted and the answer lies in the soil (Fallowfield, A; Hornerama etc, 1958-68).

    • Thanks very much Filbert. I agree that farm machinery is definitely a contributing factor to soil compaction. Driving across fields to check stock is part of the impact of grazing on soil structure, as is fertiliser and herbicide application to grazed land and silage fields, and of course maize crops, which all feed livestock.

      • Filbert Cobb says:

        I was think rather more in terms of the hammering that soil gets from silage harvesting machinery, even where inputs are low. And maize as you point out. We could expect maize – a C4 species – to become more popular if the climate warms.

        But it’s not all bad – if it gets as warm as the Medieval Warm Period the Vikings could entertain us by re-invading Greenland.

  2. Emily Heath says:

    This wet weather has been awful for bees, they can’t get out to forage and flowers don’t produce as much nectar in wet, cool conditions anyway. Also queen bees can’t mate when it’s raining. I’ve seen less bumble bees about this year.

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