May 1, 2015, by Alex Kirby
Sunbathing by Tower Bridge on a hot day in central London.
Image: Elfod Nemeth via Flickr
Research using records dating back to 1659 indicates at least a 13-fold rise in the likelihood of human-influenced climate change pushing up temperatures in central England. LONDON, 1 May, 2015 − If you live in England, prepare for a future where distinctly warmer years are the new normal. An international team of researchers says the likelihood of record-breaking warm years is going to increase substantially because of human influence on the climate. Their study shows that the chance of England experiencing a record-breaking warm year, on a par with 2014, is at least 13 times higher. And there are signs that it could be even higher. The study, published in Environmental Research Letters, is based on climate model simulations and detailed analyses of the Central England Temperature (CET) record − the world’s longest instrumental temperature record, dating back to 1659. The results show that human activities have a large influence on extreme warm years in England − which is remarkable, the researchers say, because England is such a small region of the world.
The CET does not cover the whole of England, let alone Scotland or Wales or the rest of the British Isles. It has monthly recordings of average temperatures dating back to 1659, and recordings of average daily temperatures back to 1772. It is designed to represent the climate of the English Midlands, a roughly triangular area bounded by Lancashire in the north, Bristol in the south-west and London in the south-east. The researchers say the CET has undergone thorough and extensive quality control, which makes it an ideal resource for studying long-term temperature trends across the region. The lead author of the study is Dr Andrew King, a researcher at the ARC Centre of Excellence for Climate System Science at the University of Melbourne, Australia.
“It is remarkable that we get such a clear anthropogenic influence on temperatures in a relatively small area across central England”
He says: “When you look at average annual temperatures over larger regions of the world, such as the whole of Europe, there is a lower variability in temperatures from year to year, compared with smaller areas. “As a result of this low variability, it is easier to spot anomalies. This is why larger regions tend to produce stronger attribution statements, so it is remarkable that we get such a clear anthropogenic influence on temperatures in a relatively small area across central England.” The researchers calculated the probability of warm years caused by human influences by first using climate model simulations to calculate the likelihood of very warm years when there are only natural influences on the climate, and then when there are both natural and human influences.
The researchers then studied the CET and picked out the warmest years from the record since 1900. These were plotted onto a graph, which they used to calculate the likelihood of warm years happening now, and a century ago. The model-based method suggested (with 90% confidence) at least a 13-fold increase caused by human influences on the climate, while the observation-based approach suggested at least a 22-fold increase in the probability of very warm years in today’s climate compared with a century ago (again with 90% confidence). “Both of our approaches showed that there is a significant and substantial increase in the likelihood of very warm years occurring in central England,” Dr King says. According to the CET, 2014 was the warmest year on record in central England. During the last 60 years, rapid warming has been recorded in the CET in line with the human influence on the climate, with the highest average annual temperature of 10.93°C recorded in 2014. Dr King says he would expect that other areas near the UK would produce similar results. “We performed a similar attribution study for Europe as a whole and found a 35-fold increase in the likelihood of extremely warm years using model simulations.” − Climate News Network
Alex Kirby is a former BBC journalist and environment correspondent. He now works with universities, charities and international agencies to improve their media skills, and with journalists in the developing world keen to specialise in environmental reporting.