The major study of global diurnal temperature range (DTR), the most complete standalone study of DTR in over a decade, found clear evidence to support the conclusion that most global land areas analysed have experienced significant warming of both maximum and minimum temperature extremes since 1950.
The study also found Europe has experienced a greater decrease in DTR — the measure of the gap between the highest and lowest daily temperature — than either North America or Australia which could make it more difficult to survive heatwaves.
Prof Peter Thorne of Maynooth University’s department of geography, who led the study, said the findings have serious implications for human health and agriculture, particularly in Ireland.
DTR is the daily maximum temperature, minus the daily minimum temperature in a given area.
It is one of the 27 key indicators studied by scientists for the detection of climate change but its study has, for various reasons, been neglected by climatologists over the years.
In this latest study, Prof Thorne and his researchers found since the mid 1950s, daily minimum temperatures rose by 0.24C per decade while daily maximum temperatures rose by 0.19C per decade.
With the daily minimum temperatures rising faster than the daily maximum temperatures, they established that DTR has decreased by 0.04C per decade in that time.
The reduction in global DTR resulting from daily minimum temperatures warming faster than daily maximum temperatures is an indicator of shifts caused by climate change, the research team said.
“A change in an area’s DTR alters the thermal stress on local ecology and places pressure on the overall resilience of its natural environment,” said Prof Thorne.
“Research has shown that, despite Ireland’s temperate climate, its mortality rates are effected by temperature.
“In heatwaves, it is not the daily maximum temperatures that prove dangerous — rather it’s when the minimum temperature at night does not go low enough to allow the body to recover.
“Similarly, crops and livestock require low minimum temperatures in order to recover from excessive daytime temperatures.
“With the agri-food sector worth an estimated €24bn, changes in such aspects of the thermal climate could have extremely significant consequences for Ireland’s economy.”
Meanwhile, the Environmental Protection Agency (EPA) published guidelines yesterday, prepared by scientists at UCC’s Environmental Research Institute, to make it easier for local authorities to plan for the consequences of climate change.
The EPA director general, Laura Burke, said that last winter’s devastating flooding shows just how vulnerable we are to extreme rainfall events which are projected to increase.
“Simply cleaning up after flood and storm events is no longer enough,” she said.
“We must now plan to adapt our economy, society and environment to deal with the reality of climate change and to manage the risks it poses to our way of life, livelihoods, and wellbeing.”