The Press and Journal (Inverness, Highlands, and Islands)
Record heat ‘unprecedented’
Recent recordshattering temperatures in the US and Canada which caused deaths and wildfires would be “virtually impossible” without climate change, analysis has found.
A rapid study of last week’s heatwave in parts of North America by an international team of climate scientists found global warming driven by human activity made it at least 150 times more likely to happen.
The scientists also warned of the possibility the climate system may have crossed a threshold where a small amount of warming was causing a faster rise in extreme temperatures, posing the risk of more deadly heatwaves.
In the heatwave, parts of the Pacific north-west saw temperatures that broke records by several degrees Celsius.
The village of Lytton in British Columbia saw a new Canadian record high of 49.6C (121.3F), well above the country’s previous national record of 45C (113F), and was shortly afterwards largely destroyed by wildfire.
And hundreds of deaths have been attributed to the sweltering temperatures which soared above 40C in many cities in Oregon and Washington states in the US and the western provinces of Canada.
Scientists said the temperatures were so extreme they lie far outside the range of historically observed temperatures, making it hard to tell just how rare the event was.
But statistical analysis suggests the temperature highs to be a one in a 1,000-year event in today’s climate, which has seen 1.2C of human-induced global warming since preindustrial times, making it still a very rare event.
Without warming driven by greenhouse gas emissions from sources such as burning fossil fuels, it would have been at least 150 times rarer, or virtually impossible, the scientists said. Friederike Otto, from the Environmental Change Institute, Oxford University, said: “What we are seeing is unprecedented.
“You’re not supposed to break records by four or five degrees Celsius (seven to nine degrees Fahrenheit).
“This is such an exceptional event that we can’t rule out the possibility that we’re experiencing heat extremes today that we only expected to come at higher levels of global warming.”