Climate change made the May flooding in Canterbury more severe - researchers
Climate change made the rainfall that led to Canterburys flooding in May more severe, researchers have found. Researchers studying the effects of climate change on severe weather events in New Zealand have found that the extreme rainfall that brought flooding to Canterbury in May was 10 to 15 per cent more intense as a result of human influence on the climate system. Canterburys extreme rain event in May led to a regional state of emergency and hundreds of evacuations, including the entire town of Springfield. Ten state highways and 52 schools were closed at the storms peak. Farmers fled for their lives, with some describing heart breaking scenes of lost stock and a wall of water that caused significant damage to their properties. Broken bridges cut both road and rail services, effectively splitting the South Islands east coast in two, including the Ashburton/Hakatere River Bridge, which closed after significant damage . READ MORE: * New climate change targets put future of West Coast coal mines in limbo * 'Atmospheric rivers' drive New Zealand's wet and extreme weather * Scientists' estimate of rising costs of climate change could improve planning The Ministry of Business, Innovation and Employment-funded research project is looking into the role of climate change on the severity and frequency of extreme weather events. It involves researchers from Bodeker Scientific, MetService, the National Institute of Water and Atmospheric Research, Victoria University of Wellington, and the University of Canterbury. They examined the extreme rainfall in Canterbury from May 29 to 31, which produced historic flooding and prompted MetService to issue a rare red warning. The Insurance Council of New Zealand lists the insured losses from the event at $43.8 million. MetService senior meteorologist Chris Noble said the event was caused by a slow-moving low near central New Zealand that directed an easterly flow onto the South Island, with a subtropical feed of moisture delivering prolonged heavy rain. Rainfall totals of 200 millimetres in two days were widespread along the Canterbury foothills, peaking at an overall total of 540mm at Mt Somers in the headwaters of the Ashburton River. Noble said the research team used MetServices ensemble forecast system and found that compared to a climate system unaffected by human activities, between 10 and 15 per cent more rain fell. Using a large collection of global climate model simulations, taken from the weather@home project, they also found that these events are at least 20 per cent more likely to occur today than in preindustrial times when the atmosphere was about one degree colder. Climate change did make it wetter and climate change also means we can expect more frequent and more severe weather events. The findings were consistent with climate science expectations that the intensity and frequency of severe precipitation events would increase as the atmosphere warms and is able to hold more moisture, he said. Research like this will help us understand what might happen as we go forward and what impact climate change is having on weather systems and how much can we as humans do to stop this happening in future.