In the 1990s, U.S. Navy submarines reported a shocking loss of thickness in Arctic sea ice. Over the past decade, satellite altimetry readings confirmed this.
In the summer of 2012, the level of ice in the Arctic Ocean dropped to its lowest on record, according to the National Snow and Ice Data Center. To make matters worse, this ice melt came faster than earlier climate models had predicted.
From year to year, the amount of ice continues to change, some years higher and some years lower. Nevertheless, the long-term trend indicates a dramatic and startling loss of sea ice.
The loss of this ice in the Arctic is a direct result of warming temperatures there. In fact, average temperatures have increased at about two to three times faster relative to the midlatitudes. This enhanced amount of warming in the high northern latitudes is referred to as Arctic Amplification.
It’s interesting to note that some climatologists and scientist suspect that this condition could be the culprit behind the big and persistent ridge of high pressure over California that has produced unprecedented dry conditions and record-breaking temperatures throughout the state.
For example, just this past Thursday, Cal Poly, home of climatology for San Luis Obispo, reported an all-time January maximum temperature of 89 degrees, breaking the old monthly record of 88 degrees set back in 1976. San Luis Obispo County Regional Airport reached 91 degrees.
On the other hand, a seemingly everlasting trough of low pressure has plagued the eastern part of the country with bone-chilling cold and endless rain and snow.
So how could warmer temperatures over the Arctic affect the country’s weather pattern?
Jennifer Francis of Rutgers University gave a persuasive presentation, “Wacky Weather and the Disappearing Arctic Sea Ice: Are They Connected?” at the Weather and Climate Summit in Breckenridge, Colo., last year.
Her hypothesis is that Arctic Amplification is producing more persistent and stronger ridges of high pressure and deeper and longer-lasting troughs of low pressure as the amplitude of the polar jet stream increases.
The jet stream is typically a tubular ribbon of high-speed winds flowing in wavelike patterns for thousands of miles from west to east some 18,000 to 40,000 feet up.
Most of the time, the peak or the northern part of the wave pattern indicates ridges of high pressure and fair weather, while the trough or southern part of the wave is associated with low pressure and unsettled conditions.
The amplitude, or the distance between the peaks and troughs of these waves, can stretch for hundreds of miles from Baja California northward to Washington state. Typically, the higher-amplitude wave pattern changes at a slower rate, meaning that both drought events and rain events will last longer in a particular area.
As the Arctic continues to warm, the thickness of the atmosphere over that region will continue to reach higher in altitude, like a hot air balloon. On average, half of the atmosphere’s weight lies between the Earth’s surface and an altitude of about 18,000 feet.
Meteorologists determine the thickness of the atmosphere by analyzing 500-millibar upper-level charts. In other words, this chart will tell you how high the pressure is 3 or 4 miles above the Earth’s surface.
The atmosphere is at its thickest near the equator and gradually narrows toward the poles.
Francis theorizes that as the polar regions become warmer and the atmosphere thickens, the downward slope between the equator and the poles will lessen. This condition may result in greater amplitude of the wave of the jet stream.
Consequently, droughts could become more prolonged and precipitation events, especially combined with ever-increasing amounts of water vapor that a warmer atmosphere can hold, could produce floods.
If you would like to learn more about climate change and how to deal with it, the group Lifelong Learners of the Central Coast is offering a series of courses in March at the PG&E Energy Education Center. Please visit http://www.lifelearnerscc.org to sign up.
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If you are interested in applying, please visit http://www.pge.com/about/community/education.
John Lindseys column is special to The Tribune. He is a media relations representative for PG&E and a longtime local meteorologist. If you have a question, send him an email at firstname.lastname@example.org.