Tuesday, June 12, 2018

Cascading consequences: Atmosphere - Jetstream - Cyclones - Hydrological cycle

There’s a new study that comes as no surprise, still since it's such an excellent example of Cascading Consequences, to say nothing of fascinating for the added dimension in understanding it offers, I want to share it over here.
The evidence is in and since about the 1950s the speed at which hurricanes travel across oceans and land has been slowing down appreciably.  It’s no surprise because as the Arctic warms the air column above it increases in height relative to the slower warming tropical atmospheric column.  This decreasing gradient of course impacts all natural vectors and oscillations that flow through it. 

Rossby waves and cascading consequences.   It’s the same phenomena that’s causing our jet stream to become more sluggish and erratic these past decades.  Jennifer Francis is an expert and I want to share what she has to explain since it offers an introduction to the concepts at work here.  

Jennifer Francis - Understanding the Jetstream

Published by George Morrison on Feb 26, 2013

A short review of how the jetstream and Rossby waves work, and some emerging indications that the dynamics may {???} be changing in a warming world. 

This 5 minute excerpt from a longer presentation by Dr. Francis, original available here: 

For further info, see this blogpost for a good primer, followed by a discussion of the Francis and Varvus paper from last year:   Stuart Staniford "Slowing Rossby Waves Leading to Extreme Weather?" 

Of course there's a big difference between Cyclones and Hurricanes, but the thing is, they both inhabit our changing atmosphere and are being significantly modified from a regime humanity has know its entire existence.

Tropical cyclones have slowed over the last 70 years
BY Carolyn Gramling , June 6, 2018

… The fierce, swirling storms move 10 percent slower, on average, than they did nearly 70 years ago, a new study finds. Such lingering storms can potentially cause more damage by dumping even more rainfall on land beneath them.

Atmospheric scientist James Kossin examined changes in how quickly tropical cyclones, known as hurricanes in the Atlantic Ocean, moved across the planet from 1949 to 2016. ... Kossin reports in the June 7 Nature.

Over that same time period, the average temperature of Earth’s surface rose by about half a degree Celsius. Scientists already predict that average wind speeds will increase in tropical cyclones as ocean waters warm due to global warming (SN: 6/27/15, p. 9). The new study suggests that climate change is also altering how quickly these tropical cyclones travel across land or water.  The effect was even more pronounced as storms moved over land, …

The new study makes an important link between the atmospheric effects of global warming to its effects on tropical cyclones, says atmospheric scientist Christina Patricola of the Lawrence Berkeley National Laboratory in California, who also wrote a commentary that accompanies the new paper. “Tropical cyclones tend to move along with larger-scale [atmospheric] circulation around them,” she says. ...

J.P. Kossin. A global slowdown of tropical-cyclone translation speed. Nature. Vol. 558, June 7, 2018, p. 104. doi:10.1038/s41586-018-0158-3.
C.M. Patricola. Tropical cyclones are becoming sluggish. Nature. Vol. 558, June 7, 2018, p. 36. doi:10.1038/d41586-018-05303-w.

Further reading
C. Gramling. ‘Killer Hurricanes’ reconstructs the past to predict storms of the future. Science News. Vol. 192, October 28, 2017, p. 29.
C. Gramling. Intense storms provide the first test of powerful new hurricane forecast tools. Science News Online, September 21, 2017.
T. Sumner. Titanic typhoons are in the forecast. Science News. Vol. 187, June 27, 2015, p. 9.
S. Perkins. ‘Storm Surge’ revisits Sandy, looks to future hurricanes. Science News. Vol. 187, January 10, 2015, p. 29.

Of course no contemplation of our atmosphere is complete without considering water and the hydrological cycle.  There's another more recent Jennifer Francis talk on YouTube that's worth listening to if you want to know more about it.

Scientist Reveals 7% More Water Vapor Fuels Storms Today

Published on Mar 10, 2018

Jennifer Francis, Ph.D., Research Professor I, Department of Marine and Coastal Sciences, Rutgers University, speaks about weather changes. And how are those related to climate change? 

In this presentation, Dr. Francis will explain new research that links increasing extreme weather events with the rapidly warming and melting Arctic during recent decades. Evidence suggests that Arctic warming is causing weather patterns to become more persistent, which can lead to extremes such as droughts, cold spells, heat waves, and some flooding events.

Learn about future free lectures at the New England Aquarium at

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