Earth just had its warmest May on record amid startling Siberian heat waveAstonishing warmth in Siberia helped propel global average surface temperatures to a record high during May, according to the Copernicus Climate Change Service, a science division of the European Union. In addition, the January through May period was the second-warmest such period on record since at least 1979, scientists found. This is likely to be confirmed in coming days by other science agencies whose data extends back to the late 19th century, such as NASA. Globally, May was 1.13 degrees (0.63 degrees Celsius) above average compared with average May temperatures from 1981-2010, beating the previous record set in 2016. The past 12-month period (June 2019 through May 2020) was close to 1.3 degrees (0.7 Celsius) above average, matching the warmest 12-month period that was set during October 2015 through September 2016. This is significant because 2016 was the warmest calendar year on record, boosted to the No. 1 spot by both human-caused global warming and a strong El Niño event in the tropical Pacific Ocean. Such events, which feature above-average sea surface temperatures and altered weather patterns across large parts of the globe, are associated with temporary increases in global average temperatures. Copernicus reports that the 12-month period is about 2.3 degrees (1.3 Celsius) above preindustrial temperatures, which is of importance to policymakers who are working to limit global warming to well below 3.6 degrees (2 Celsius) above the preindustrial average, with an aspirational goal of holding warming to 2.7 degrees (1.5 Celsius) above preindustrial levels. Scientists have shown that steep and urgent emissions cuts would be required to meet both of these goals. The regions of the globe that were most above average during May include the areas you'd expect to be cold, even at that time of year, namely...