[The articles below were first published during the winter of 2015]
“Everyone loves to talk about the weather, and this winter Mother Nature has served up a feast to chew on. Few parts of the US have been spared her wrath.
Severe drought and abnormally warm conditions continue in the west, with the first-ever rain-free January in San Francisco; bitter cold hangs tough over the upper Midwest and Northeast; and New England is being buried by a seemingly endless string of snowy nor’easters.
Yes, droughts, cold and snowstorms have happened before, but the persistence of this pattern over North America is starting to raise eyebrows. Is climate change at work here?
One thing we do know is that the polar jet stream – a fast river of wind up where jets fly that circumnavigates the northern hemisphere – has been doing some odd things in recent years.
Rather than circling in a relatively straight path, the jet stream has meandered more in north-south waves. In the west, it’s been bulging northward, arguably since December 2013 – a pattern dubbed the “Ridiculously Resilient Ridge” by meteorologists. In the east, we’ve seen its southern-dipping counterpart, which I call the “Terribly Tenacious Trough.”
These long-lived shifts from the polar jet stream’s typical pattern have been responsible for some wicked weather this winter, with cold Arctic winds blasting everywhere from the Windy City to the Big Apple for weeks at a time.
We know that climate change is increasing the odds of extreme weather such as heatwaves, droughts and unusually heavy precipitation events, but is it making these sticky jet-stream patterns more likely, too? Maybe.
…We do know… that the Arctic is changing in a wholesale way and at a pace that makes even Arctic scientists queasy. Take sea ice, for example. In only 30 years, its volume has declined by about 60%, which is causing ripple effects throughout the ocean, atmosphere, and ecosystem, both within the Arctic and beyond. I’ve been studying the Arctic atmosphere and sea ice my entire career and I never imagined I’d see the region change so much and so fast…”
-- Jennifer Francis (Research Professor at Rutgers University), “A melting Artic and weird weather,” The Conversation (theconversation.com), February 18, 2015
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“Last year was the hottest in earth’s recorded history, scientists reported on Friday, underscoring scientific warnings about the risks of runaway emissions and undermining claims by climate-change contrarians that global warming had somehow stopped.
Extreme heat blanketed Alaska and much of the western United States last year. Several European countries set temperature records. And the ocean surface was unusually warm virtually everywhere except around Antarctica, the scientists said, providing the energy that fueled damaging Pacific storms.
In the annals of climatology, 2014 now surpasses 2010 as the warmest year in a global temperature record that stretches back to 1880. The 10 warmest years on record have all occurred since 1997, a reflection of the relentless planetary warming that scientists say is a consequence of human emissions and poses profound long-term risks to civilization and to the natural world.
Of the large inhabited land areas, only the eastern half of the United States recorded below-average temperatures in 2014, a sort of mirror image of the unusual heat in the West. Some experts think the stuck-in-place weather pattern that produced those extremes in the United States is itself an indirect consequence of the release of greenhouse gases, though that is not proven.
Several scientists said the most remarkable thing about the 2014 record was that it occurred in a year that did not feature El Niño, a large-scale weather pattern in which the ocean dumps an enormous amount of heat into the atmosphere.
Longstanding claims by climate-change skeptics that global warming has stopped, seized on by politicians in Washington to justify inaction on emissions, depend on a particular starting year: 1998, when an unusually powerful El Niño produced the hottest year of the 20th century.
With the continued heating of the atmosphere and the surface of the ocean, 1998 is now being surpassed every four or five years, with 2014 being the first time that has happened in a year featuring no real El Niño pattern. Gavin A. Schmidt, head of NASA’s Goddard Institute for Space Studies in Manhattan, said the next time a strong El Niño occurs, it is likely to blow away all temperature records.
…February 1985 was the last time global temperatures fell below the 20th-century average for a given month, meaning that no one younger than 30 has ever lived through a below-average month.”
-- Justin Gillis, “2014 Breaks Heat Record, Challenging Global Warming Skeptics”, The New York Times, January 16, 2015
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“We have seen a quantum jump in extreme weather events in the Northern Hemisphere in the last several years. Droughts, deluges, and heat waves are increasingly getting “stuck” or “blocked,” which in turn worsens and prolongs their impact beyond what might be expected just from the recent human-caused increase in global temperatures.
A growing body of research ties that unexpected jump to a weakening of the jet stream -- in particular to “more frequent high-amplitude (wavy) jet-stream configurations that favor persistent weather patterns,” as a new study puts it.
…Reinsurer Munich Re has the most comprehensive database of global natural catastrophes Their 2010 analysis, “Large number of weather extremes as strong indication of climate change,” concluded “it would seem that the only plausible explanation for the rise in weather-related catastrophes is climate change. The view that weather extremes are more frequent and intense due to global warming coincides with the current state of scientific knowledge…”
… the evidence is mounting that we have entered a new regime of extreme weather thanks to our as-yet unrestricted emissions of greenhouse gas…”
-- Joe Romm, “Global Warming Linked To More Extreme Weather And Weaker Jet Stream, January 15, 2015, Climate Progress website (thinkprogress.org)
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It’s common knowledge that we’re in an era of Climate Change (with the unfortunate footnote that millions of Americans have been miseducated to disbelieve science and the proven phenomenon and threat of global warming).
Weather records have periodically been broken for years, but that used to be an occasional event, whereas now “unusual weather” is practically the norm. Anyone who pays minimal attention to weather patterns is sure to be aware of that fact.
The winter that officially ended yesterday is a good example. Warm spells during winter have been increasingly common over the years, whereas they used to happen once or twice, if at all. This year the temps jumped up into the 50s or 60s several times.
That happened most often in February, when winter heat records were repeatedly broken. Then the first two weekends of March we had some of the coldest temperatures ever on our hikes (near zero in the mountains on at least 3 mornings).
As you probably know, global warming doesn’t mean that it’s warmer all the time, although average temps are higher. It also means unstable weather, with extreme temperature swings and more powerful storms, which can include big snowstorms.
Can we learn to live with such extremes? We’re actually more able to adjust and adapt than many plants and animals. After flowering, some plants may freeze and die, or their fruit may fail to develop. Migrating birds can be caught unprepared.
Fortunately those of us who are hikers can always don our warm layers and still get out on the trails – and thoroughly enjoy ourselves for a few hours -- which is exactly what we did during the bouts of bitter cold that greeted us on a few hikes.
Yes, it’s a bit of a shock to our system, and psychologically disorienting, to be walking around in a T-shirt one day and then, after a 50-degree drop, bundling up in thermals and other warm clothing the next. Fortunately we can still go hiking.
For those who are concerned about the environment and the state of our planet, the biggest potential problems lie in the long run if our ecosystem is destabilized.
As to the present, there are no real safety risks in going out even when it’s bitterly cold, of course, as long as we wear enough protective clothing. And as many of you know, the healthy exercise of hiking keeps us warm while we’re moving.
Actual outdoor danger is thankfully rare at any time of year (gale force winds, icy roads, powerful storms, etc.). At such times our trips will usually be cancelled, since it makes sense to stay home rather than put ourselves at unnecessary risk.
For now, let’s get ready to enjoy and celebrate spring (!), whatever weather it may bring. Are you open to the idea of enjoying the lovely season that lies ahead???
-- Charlie Cook