Hello and welcome to more or less on the BBC World Service. We your guide to newsworthy

numbers around the globe and I'm Tim Harford. In June of this year, the Pacific Northwest

region, including regions of Canada and the United States, saw record-breaking temperatures.

But these temperatures didn't just break records. They smashed them.

It has been extremely hot, temperatures very challenging, a new all-time record of 49.5

degrees Celsius. That's just over 121 Fahrenheit was set on Tuesday. In the US as well, it's

been hot in the Pacific. That all-time Canadian record was an astonishing

4.6 degrees Celsius higher than the previous record. The situation was a serious one, with reports

of many heat-related deaths. Unfortunately, record-breaking temperatures is a phrase you've probably

become used to hearing in recent years. It's certainly familiar to loyal listener John

Shaw, who's been thinking about the effect of climate change on the probability of record

temperatures occurring. Having seen the devastatingly high temperatures

in the Pacific Northwest and pondering how long these record temperatures can go on for,

I started thinking, how many temperature records would we expect to be broken in a given

year? Can we show the difference between how many records we'd expect to fall due to

natural variation and how many records actually do fall due to the warming climate?

Interesting questions, John, and so I spoke to Professor Peter Stott, an expert in climate

attribution at the UK's Meteorological Office, the Met Office, to ask him how to think about

the relationship between climate change and record-breaking weather. Professor Stott uses

computer models to compare the probability that a record would have been set under so-called

natural conditions, that is, a world without man-made greenhouse gas emissions, and the

probability of a record being set in our modern world as it is. He and his colleagues run

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