New Delhi, July 1 -- A "dome" of extreme heat will send temperatures soaring in the central and eastern U.S. starting on Wednesday. More than 200 million people live in areas where temperatures are expected to exceed 90 degrees. These events can be deadly. They aim-42100508

A similar heat wave in Europe has already had severe impacts on power infrastructure over the past week. France has reduced output at its nuclear reactors, because the rivers where it discharges water used to cool the reactors are already too hot. Discharging more warm water into already-hot rivers is against environmental rules. France gets 70% of its power from nuclear energy, and is a linchpin of Europe's broader electricity grid, exporting power to countries throu...