August 4, 2013

Changing climate changes the jet stream, which changes weather


---- — So what is going on with the weather?

North Country humor frequently involves comments such as, “if you don’t like the weather, wait a minute, it will change,” or “we get three seasons in a single day,” or some other variation of these.

But really, what is going on with our recent weather? A colder than usual May, record amounts of rain in May/June, and now in July a major heat wave concurrent with a record level of water in Lake Champlain. 

If you go to the National Weather Service site in Burlington, you will find that the rainfall amounts in May and June were high. Indeed, they set a two-month record of 18.6 inches for that time period over the entire data set of 127 years. 

What is happening elsewhere with the global nature of weather? There were devastating floods in Calgary, Alberta, also at this time. June temperatures in Talkeetna, Alaska, hit 96 degrees Fahrenheit, and it was warmer than Miami; Valdez, Alaska, hit 90 degrees, breaking the record of 87 set in 1957. 

In late June 2013, in Phoenix, US Airways canceled 18 flights because the maker of its jets did not have performance data greater than 118 Fahrenheit. At 119 degrees, it was not known for sure how much runway the planes would need to safely take off. 

Climate scientists are aware of these local happenings and the global extreme events, as well. It has become a major study as to why, with climate change, these extreme events occur and last so long. Research is beginning to shed some light on possible reasons. 

What scientists do is to collect and interpret data. There is no room for opinion. There is no justification for guesswork. The process of science is slow and meticulous, with time to shape ideas, challenge those ideas and formulate an explanation that fits. 

Globally, recent data released by NASA and NOAA show record heat for June. This data extend to 340 months where each month was warmer than the long-term 20th century average for that month.

A person under age 28 has never experienced a month where the average temperature was cooler than the 20th century average for that month. 

One area that climatologists are concentrating on is the albedo effect. This is a measurement of how much of the incoming sun’s radiation or energy is reflected back to space.

Snow and ice have high albedos, as they reflect a large portion on the incident radiation. See the illustration here showing the percent reflected for a variety of different Earth surfaces.

For example, fresh snow reflects 80 to 95 percent of incident light whereas water bodies reflect only 10 to 60 percent of incident radiation. The balance of the energy is absorbed.

Due to global warming, we are seeing record amounts of sea ice loss in the Arctic Ocean; both a loss of ice in Greenland and a surface ice melt of its glacier that reduces its albedo; and finally, significant decrease in mountain snowline.

All of these decreased albedo changes increase significantly the amount of heat energy in Earth’s atmosphere. (See three-part diagram that illustrates the decreasing albedo.) This change in the energy balance of our planet has a big effect on our weather and therefore the climate. 

So now what happens with all of this increased energy? Data are now showing that the jet stream is changing in a major way.

The jet stream, which dictates our weather, is a river of air three or more miles above the Earth’s surface that moves rapidly from west to east. It generally has a gentle, wavy pattern, as shown on the map of United States and Canada. 

However, in recent years it has taken on a new shape (see illustration “January Pattern So Far”) with deep troughs and peaks. This then brings cold air farther south than usual, and/or warm humid air much farther north than usual, for extended periods of time.

This accounts for the recent weather patterns we have seen, but it will take more data and time to firmly establish what is happening here. 

Stay tuned!

The scientific career of Raymond N. Johnson, Ph.D., spanned 30 years in research and development as an organic/analytical chemist; he is currently founder and director of the Institute of Climate Studies USA ( Climate Science is published the first Sunday of every month.