Study Says Recent Heat Wave in North America Likely Linked to Global Climate Change

A record-breaking heat wave that hit the western United States and Canada at the end of June would have been "virtually impossible" without human-caused climate change, according to an analysis by a group of leading climate scientists.

The World Weather Attribution group said that global warming, caused by greenhouse gas emissions, made the heat wave at least 150 times more likely to happen.

To investigate whether climate change played a role, the scientists analysed historical observations and computer simulations to compare the climate as it is today, after about 1.2 degrees C of global warming since the late 1800s, with the climate of the past.

They found the observations were so extreme they lie far outside the range of historically observed temperatures. But with the climate of today, it was estimated the event could take place once in a thousand years.

Looking into the future, if the planet were to warm by two degrees Celsius - which could happen as early as the 2040s at the current rate - heat waves like these would occur every five to ten years and be around a degree Celsius hotter.

This meant that adaptation plans need to be designed for temperatures well above the range witnessed in the past, the team warned./msn