Browning Newsletter on Climate: Shifting into Autumn
My thanks to Alex Seagle of Fraser Management Associates, publishers of this fascinating letter written by Evelyn Browning Garriss. Here is part of a section detailing the effect of volcanic activity on weather conditions:
The Volcano Effect
A third natural factor will add to the combined cooling effect of the cool PDO and La Niña - the impact of stratospheric volcanic debris. As discussed thoroughly in previous issues of the Newsletter, there have been multiple high level volcano eruptions in Polar Regions over the past three years: Alaska's Mt. Redoubt and Russia's Sarychev Peak in 2009, and, during this year, Iceland's Grímsvötn and Chile's Puyehue-Cordón Caulle
Another volcano, Mt. Sheveluch on Russia's Kamchatka Pennisula, may have joined these ranks. The volcano is currently erupting 8.6 km (5.3 miles) high. This is high enough that it is forcing airlines to reroute their circumpolar flights, particularly those to Japan and Northern China. It has been erupting all month and, off and on, all year. The mountain is remote and hard to observe so some of the eruptions may have been high enough to enter the stratosphere. At a minimum, the debris is drifting down wind and raining out over North America.
If eruptions are big enough for their columns to enter the stratosphere, the debris can linger for years. This has multiple effects on the weather including:
o The ash and chemicals block out incoming sunlight, cooling the air.
o Water collects around the aerosols (solid and liquid particles) forming clouds, which also block incoming sunlight.
o When the clouds finally precipitate out, the rains and snows are unusually heavy.
o The cooler air changes air pressure which changes wind patterns.
In the case of volcanoes near the Arctic and Antarctic, this means the changed air pressure weakens the circumpolar winds. These are winds that circle around the poles, trapping most of the frigid air over the Arctic or Antarctic. If the winds are weak, these frozen air masses can escape. We saw this last winter when the Arctic air masses escaped south and buried 48 of the 50 states in snow, brought European Christmas travel to a standstill and inundated Asia.
We are currently seeing this in the Southern Hemisphere. The Chilean government declared an official "catastrophe" after heavy snows that the nation's Interior minister called a "white earthquake." The nation's capital had rare snow and southern regions have as much as 9 feet (2.7 meters). South Africa, which usually receives a dusting about once or twice a year, has been hit with storms that have dumped up to 60 cm (2 feet) in some areas. New Zealand was hit by a freak winter storm with heavy snow and bitterly cold weather two weeks ago, snowing on Wellington for the first time in decades.
This is a warning for the Northern Hemisphere. In summertime, the polar air masses are trapped north. Europe, Asia and North America have been more affected by balmy tropics. As fall evolves, the polar air masses will spread south, bringing a cold wet harvest season, particularly for Europe, China and the US. This will be followed by a frozen winter.
David Fuller's view The cold winter forecast would presumably
keep energy prices firm. Additionally, enough weather turbulence is predicted
to ensure that farming remains a challenging profession in many regions of the
Subscribers will be able to meet Elizabeth Browning Garriss at the 49th Annual Contrary Opinion Forum next month. I look forward to it.