Studies of the link between heat and health matter, especially because the past decade in North America has been confirmed as the hottest in 11,000 years.
Sea ice has hit record lows for this time of year, data also show. "It's just crazy, crazy stuff," says a scientist who has been studying the polar region since 1982.
Think of it as down-to-earth geoengineering. Some simple actions could make a big difference to city life in the long, hot summer.
Researchers are painting a dark picture. One new study involves warming of the planet, another deals with heat extremes and a third underlines what will happen if we do not reduce carbon emissions.