As most in the Princeton area could not help but notice, June went out and July came in with heat in the 90s and humidity. But the nagging question for many was: Is this just fluctuating summer weather, or is it an indication of global warming?
Fortunately for us, cooler temperatures returned this last week. But looking at reports from across the country and around the world, “cooler” was not the prevailing pattern.
Temperatures in San Diego reached 115. Heat and dry conditions produced forest fires in California and Colorado. Thirty-three died in Montreal from extreme heat. And according to a report in the Washington Post, a massive dome of intense heat and humidity settled over the eastern two-thirds of the United States and southeast Canada for close to a week.
Denver; Mount Washington, New Hampshire; Burlington, Vermont; Montreal; and Ottawa all set records highs or the highest low temperatures ever recorded.
And this record heat reached elsewhere around the globe. In the British Isles last week, stifling heat caused roads and roofs to buckle, as multiple all-time highs were recorded in Scotland, and Shannon and Belfast, Northern Ireland.
Record high were also experienced in parts of Eurasia, including Tbilisi, Georgia, which endured highest-ever temperatures; in Yerevan, Armenia, which tied its all-time record for July; and in southern Russia, which matched its warmest late-June levels.
Over the past several years, rising arctic temperatures have resulted in both warmer winter temperatures and summer temperatures, which in turn, have reduced the amount of arctic sea ice, allowing the increasingly blue arctic ocean to absorb more heat, rather than have the ice reflect it back up into space or the atmosphere.
This change has earned its own name, Arctic amplification. And it has its own impact on the region, namely, an abrupt weakening of the polar jet stream over the past two decades. This change, or weakening, has caused the polar jet to become much wavier, with greater wave “breaks” and blocking patterns where waves sit in the same place for weeks and promote extreme weather patterns (extreme cold relative to normal as well as extreme heat, very wet and drought conditions).
The year 2018 has seen these effects on both the jet stream and the polar ice, as unfortunately each reinforces the changes to the other.
These record changes, as well as the melting of the Antarctic ice, should serve to warn the world that significant alterations to our fossil fuel energy systems are necessary as soon as possible, if we want to avoid more record heat and the repercussions.