London (CNN) The scorching heat wave that broke records across Europe last month was made more likely, more intense and up to three degrees Celsius hotter by climate change, a study has found.

Scientists found that the event would have been a once-in-a-millennium occurrence without a changing climate, but was made up to 100 times more probable because of the process.

The UK, Germany, Belgium and the Netherlands all recorded their highest temperatures ever in the July heat wave, with the mercury topping 40 degrees in much of mainland Europe.

Without climate change, temperatures would have been between 1.5 and 3 degrees lower, according to the report from the World Weather Attribution group , an international alliance of meteorological researchers.

The group have analyzed every heat wave in Europe in the 21st century (in 2003, 2010, 2015, 2017, 2018, June 2019 and July 2019), and found that each one was made more likely because of climate change.