What’s behind the heatwaves impacting the United States?

Climate change caused by the burning of fossil fuels is a global phenomenon that is certainly playing a role in what the US is experiencing, scientists say [Nathan Howard/AP]

Virtually all of the United States has experienced above-normal temperatures in the past week. More dangerously hot weather is in the forecast this week.

More than 85 million Americans are under excessive heat warnings or heat advisories issued by the National Weather Service. Excessive heat, severe storms and flooding are all expected this week.