‘Shoo-doot-n-shoobie-doo. In the still of the night……’
That thunderous sound you don’t hear is the howling wind and crashing waves of a tropical cyclone.
After a 100-decibel five weeks, tropical nights have gone Five-Satins-like still. But the Atlantic Basin often has a secondary peak of hurricane activity in October, with the action concentrated in the Caribbean, Gulf of Mexico, and western Atlantic.
Shoo-doot-n-shoobie-doo — The Still of the Night will almost certainly be broken again.
Although it doesn’t seem like it if you live in Houston or San Juan, there’s non-hurricane-related weather news. Atmospheric carbon dioxide has now hit its annual bottom and will rise until next spring, as northern hemisphere vegetation hibernates or dies. And a coalition of governors is acting to reduce carbon emissions.
Let’s go Around The World.
Harvey, Irma, Jose, Maria — A Fearsome Four
If you live in Houston, you undoubtedly thought Harvey would be the definitive storm of the 2017 hurricane season, the way Andrew defined 1992. Then came Irma, which left a long path of destruction, the almost-forgotten Jose, and most recently, Maria, which has left Puerto Rico in shambles. The only name that could properly define this hurricane season would be Wicked.
Everyone is talking about these hurricanes in relation to global warming, and — other things being equal — warmer atmosphere means warmer water, and warmer water means more and stronger hurricanes. But hurricanes need an additional factor to thrive: low vertical wind shear (change of wind with height).
This summer graced the tropical Atlantic with almost no shear. No one knows if this is the start of a large-scale shift in the general circulation of the tropics caused by global warming. 2017 could be a taste of things to come. But it is also possible that some feedback mechanism triggered by global warming will increase vertical shear over parts of the tropics and in the end dampen hurricane activity.
Maria And Lee Depart With A Flourish
After brushing the North Carolina Outer Banks, Maria sped off to the northeast just as Hurricane Lee, which had the good manners to steer clear of North America, was moving north. The two joined forces and the unified entity brought stormy weather to parts of the British Isles.
Technically this weather was non-tropical, deriving its energy from juxtaposition of warm and cold air masses rather than tropical, acquiring energy from warm water, but this is a distinction without a difference. Wind is wind and rain is rain. The moisture that fell as rain in London had a tropical origin, even if it was a non-tropical process that caused it to fall.
Carbon Dioxide Kisses 400 Goodbye
Atmospheric carbon dioxide, a powerful greenhouse gas, is measured in parts per million (ppm) of the atmosphere. In 1880, the start of accurate observations and roughly the beginning of the industrial revolution, the number stood at 280. On August 30, 2016, the last daily reading below 400 was reported at Mount Mauna Loa in Hawaii. The 402.27 reported on September 27, 2017 was likely the bottom for this cycle. In the past month, a few hourly readings below 200 ppm have been noted. But as the northern hemisphere’s summer vegetation dies, less CO2 will be absorbed. In a couple of months, the atmospheric concentration of carbon dioxide, now rising at a rate of about 2 ppm per year, will have kissed 400 goodbye for the foreseeable future.
Round numbers always attract attention, so 400 should be considered a milestone. Up next: 420, which would represent a 50% increase from pre-industrial times. There is considerable evidence that a doubling of atmospheric carbon dioxide in a short time span causes major extinctions.
State Governors Can Do What the U.S. Federal Government Won’t
A 14-Governor coalition is taking action that is in accord with the Paris climate agreement. The fact that the United States is withdrawing as a member of the international panel does not prevent individuals, local groups, corporations, cities, and states from acting on their own to reduce carbon emissions.
California has historically taken a leading role in environmental laws. Because of its history of air pollution problems, the state has a waiver which allows it to enact stricter laws than those of the Federal Government. In the past, automakers have objected to the state’s higher standards, and have made dual models of many cars. This is expensive, and the automakers are complaining again about new California car emission standards. This time I’m betting some enlightened automaker will roll out a complete line of cars that meet the new standards ahead of the deadlines, and other car manufacturers will quickly follow when they see that customers are not only willing but anxious to pay a little more to help fight global warming.
Jet Stream Transitioning To Northern Hemisphere Winter
Summer’s jet stream is relaxed; winter’s is more active. The northern hemisphere is now in the autumnal transition from summer to winter, and the jet stream is changing. The stronger jet stream is a reflection of more pronounced differences in temperature at the surface. Winter weather in the United States and Europe will be affected by the strength, position, and wave amplitude of the jet stream. No guesses here yet on what those might be. Check Weather Around The World on November 7, 2017 for an update on winter weather projections for 2017-18.