As Londoners prepared for the 2012 Olympics, the UK has experienced unseasonably wet and cool weather. The months of April, May and June were unusually rainy, cloudy and cold in Great Britain (and July hasn’t proven much better!). Even ping-pong ball-sized hailstones were part of the mix in June.
The average rainfall in Wales and England during June was more than double the normal amount, and precipitation levels in Scotland and Northern Ireland were high as well. With skies full of storm clouds, hours of sunshine have also been fewer than normal across the country. What's more, flooded streets made driving hazardous in some areas, while a landslide even caused a freight train to derail.
Weather forecasters have attributed the downpours to a weather pattern known as the Spanish plume. Rain occurs when a warm, humid air mass encounters a cold air mass. During a Spanish plume, the warm front comes from the UK's south, while the cold front sweeps in from the west.
In addition to the Spanish plume, the jet stream has also been blamed by meteorologists for the dreary weather. The jet stream is a major current of air in the upper atmosphere. In recent months, the jet stream was further south than it is normally.
Yet while the Brits have endured cold, wet weather, America has suffered the opposite extreme, a heatwave. During June, temperatures reached the mind 90s °F (30s °C) in New York City. Neighborhoods in the outer boroughs experienced brownouts (reduce power voltage) due to weather-related energy demands.
Electricity conservation programs and the prospect of higher electricity prices encouraged northeasterners to reduce electricity consumption while the temperatures soared. A program compensates New York customers who save energy by turning off air conditioners, slowing down elevators, and dimming lights. Program participants can lower their strain on the energy grid by firing up their own onsite power generators.
What caused the damaging heat wave in America? Some put all the blame on global warming, but the reality is more complex. Multiple factors contribute to any record-breaking weather event.
Although experts concluded that climate change makes extreme weather events more likely, the contribution from climate change is only part of the picture. Meteorologist Martin Hoerling said headlines oversimplify events when they describe extreme weather as a consequence of climate change. He explained that natural causes bring weather close to the brink, and climate change adds an extra bit to push weather into record-breaking territory.
Another effect of the heatwave is the stress it has put on American farms. Cattle, hay and forage suffered from heat and drought, putting a burden on cattle ranchers. Grain, soybean and alfalfa fields will also produce less than normal this year.
Still, Australian grain and beef exporters are poised to pick up some of the slack from decreased USA production. Considering how difficult it is to retroactively reach consensus on the causes of extreme weather, much less prevent it, perhaps humanity should be thankful for a flexible global agriculture sector that can respond to changing climate.