The “official” hurricane season in the Atlantic ended November 30, 2016. If you believe climatologists and the media, it was an active season. But was it? There was a vicious fire in a resort town next to America’s Great Smoky Mountains, and on the other side of the world Australia’s Great Barrier Reef had a historic coral die-off. As always, there’s news concerning climate change: Birds and whales find more food in the warming arctic — if they get there in time.
The Paris climate agreement has been ratified by a sufficient number of countries and is in effect, but the UN warns that promises made to curb CO2 emissions are insufficient to prevent catastrophic climate change.
For now, it’s cold in the northern hemisphere — in fact, it’s winter.
Or is it? Let’s go Around The World.
Atlantic Tropical Storm Season Ends
Many forecasters are patting themselves on the back for a successful 2016 Atlantic hurricane season forecast. But the numbers, when properly analyzed, indicate that the forecasts were not that good. Most forecasters predicted an active season. Hurricanes and major hurricanes (category 3 or greater) were right on the averages of six and three respectively. Only named storms exceeded average, 15 to 12. But the fifteen should have an asterisk, or at least an explanation.
First there was Hurricane Alice in the early days of January. Alice was more a part of the 2015 season, which ended just a month earlier, than part of the 2016 season which wouldn’t start for another five months.
Then there’s the matter of naming storms based on satellite observations. The historical record goes back well before the use of satellites, and in those days if there didn’t happen to be a ship nearby nobody would have known there was a tropical storm. Six of this year’s tropical storms never had winds over 50 miles per hour, and two didn’t hold tropical storm classification for more than a day.
Of more interest than who got it right is the question of why the season was more-or-less normal. The average season appears to have been caused by a balance between relatively strong wind shear left over from El Niño and warm water associated with the general rise in worldwide air and sea temperatures.
In one way, 2016 was definitely not a normal hurricane year — it was the longest on record from first storm to last. Alice started things off in January, and Hurricane Otto, the southernmost hurricane ever to hit land, ended the season in November.
Otto was memorable for more than just its date and extreme southern location. Over Thanksgiving weekend, Otto hit Nicaragua with 100 mile per hour winds, crossed Central America, and became a rare trans-oceanic tropical cyclone, wandering through the eastern Pacific as a tropical storm before dissipating.
Extreme Drought Leads To Wildfires In Tennessee
Water, water, nowhere. Until the last few days, that’s been the theme in the inland southeast US, with eastern Tennessee at the epicenter of wildfires courtesy of a historic drought.
Winds from the Great Smoky Mountains (living up to their name) pushed fires into the resort town of Gatlinburg in late November before a cold front brought helpful rain. At least thirteen people were killed in the fires and 14,000 were evacuated from their homes.
Precipitation is highly variable from month to month and season to season — even from one side of a mountain to the other. In this case the persistent winds from the east and southeast blocked rain from reaching the west side of the Smokies.
When winds blow down a mountain, they can accelerate to hurricane force, carrying blazes quickly into the valley below. The fires, as they literally flew from ridge to ridge on burning embers, caught Gatlinburgers by surprise.
Dry downslope winds on the lee side of a mountain are called chinook in the US and föhn (a German word; that’s an umlaut over the o) in Europe. In many places they are a regular occurrence, and some have local names such as the Santa Ana wind on the west side of the Coastal Range in southern California. Chinook winds don’t occur regularly enough on the west side of the Smokies to have attained a name, but everyone is calling this one BAD.
It would certainly be premature to assign the cause of the Tennessee fires to climate change. However, there is mounting evidence that the weather patterns now favor greater extremes — of hot, cold, wet, and dry. The several-year drought in California may be a confirmation of this idea.
Australian Coral Reef Dying
One of the well-known results of global warming is the bleaching and ultimate death of coral reefs.
This past year saw the greatest die-off to date on the Great Barrier Reef of Australia. The warming associated with El Niño had something to do with worldwide bleaching of coral, which leads to die-off. But with the oceans getting warmer on average, the future of coral reefs is precarious.
On the northern part of the Great Barrier Reef, 67% of coral died this year.
More Global Warming News
Recent studies show that the arctic, as it warms, is changing in terms of supporting an ecosystem. The base of the food chain is algae, which has flourished with the warmer temperatures. Birds, fish, and whales come to feast on the krill, which eat the algae. So what could be bad about an increase in food at the bottom of the chain?
For one thing, the bloom is coming much earlier in the spring, and there is a question of whether the animals at the top of the food chain can respond adequately. They may arrive too late to get in on the bonanza.
Not all effects of global warming will be bad. The warm arctic will be a boon to shipping as the ice coverage shrinks. But as even well-intentioned individuals have found, messing with Mother Nature can have unexpected results. As an example, two species of mosquito which formerly didn’t interbreed, are now thought to be producing a super-mosquito in Florida, where their breeding seasons now overlap.
In other climate news, the Paris agreement (COP21), having been ratified by the requisite number of signatories, is now in effect. But the UN says the promises from 146 countries to cut carbon dioxide emissions fall way short of the main goal — to limit the global average temperature increase to 2 C (3.8 F).
Winter: We Know It When We See It
There has been a dispute about the actual dates of winter for a long time. One side wants to use calendar months; the other side wants to use astronomical events. Neither side is right.
Dictionaries define winter as the coldest part of the year, coming between fall and spring. But they differ on the exact time period that constitutes winter.
One definition (the meteorological one) uses the calendar months of December, January, and February. The other uses the astronomical occasions of the winter solstice and the vernal equinox.
Decoded Science has once before waded into the controversy, with the opinion that winter should be defined as the 91 coldest days of the year statistically. This means that winter will differ slightly from place to place, but will generally run from around December 10 to March 11. That just about splits the difference between the meteorological and astronomical definitions.
In many places in the northern hemisphere, winter has arrived, weatherwise. With arctic temperatures warming much more than the average of the entire globe, somebody has to have less warming, maybe even cooling. The current pattern favors colder than normal temperatures over the northern tier of the US, western Asia, and Japan.
Tell Decoded Science what the weather is like where you live.