Intense heatwaves like the one that blasted the US Midwest and northeast recently are likely to be increasingly common because of human-induced climate change, the UN World Meteorological Organization (WMO) said on Thursday. As if that warning wasn’t bad enough, climate scientist Alvaro Silva at the WMO told me that dangerous pollutants like ozone are also common features of extended periods of heat. Here he is now, discussing the recent heat alert in the US, as well as the scorching temperatures in the Middle East that caused so many reported deaths at the annual Hajj pilgrimage in Saudi Arabia.