A Battle For The Jet Stream Is Raging Above Our Heads

A Battle For The Jet Stream Is Raging Above Our Heads The northern hemisphere jet stream crossing Cape Breton Island in the Maritime Provinces of Eastern Canada. NASA/Wikimedia Commons

When prolonged periods of severe weather strike, two things often get the blame these days: climate change and the jet stream. Many have expressed concerns that the rapidly melting Arctic is now disturbing the jet stream, bringing more frequent bouts of wild weather. But potentially even more powerful changes are afoot in the tropics – and the consequences could be severe.

The northern hemisphere’s jet stream is a current of fast-moving air encircling the globe from west to east in the middle latitudes – the zone between the baking tropics and the freezing Arctic. The strongest winds are about ten kilometres high, near the altitudes at which planes fly, but the bottom of the jet can reach all the way down to the ground, forming the prevailing westerly winds familiar to many. The southern hemisphere’s counterpart is what gives rise to the Roaring Forties – similarly treacherous winds between latitudes 40° and 50°.

The jet forms a relatively sharp dividing line between the warm tropical and cold polar air masses. The strongest winds are concentrated in a band several hundred kilometres wide. But this band is not fixed. It meanders and snakes its way around the globe, sometimes touching the edge of the tropics and at other times scraping the polar regions

A Battle For The Jet Stream Is Raging Above Our Heads In November 2019 (top), the jet shifted southwards from its usual position (bottom), leaving the UK on the cusp of its cold side, where storms often intensify. ESRL/NOAA, CC BY

As a result, the jet can have a wide array of impacts across the hemisphere. If it passes over your location, expect to be repeatedly bombarded by the whirling storms that are carried along by it. As a recent example, the severe flooding in the North of England in November 2019 arose in part from a shift of the jet, which put the UK right in the middle of a region where storms tend to grow.

If the jet shifts to pass north of you, you’ll find yourself under the warm, dry zone of the atmosphere which lies south of the jet. This brings generally settled and pleasant weather in summer, but can set the scene for droughts and heatwaves. And if the jet moves south instead, you’ll be on its cold polar side, so you’d better hope this doesn’t happen too much during winter.

Weather worries

The jet has always varied – and has always affected our weather patterns. But now climate change is affecting our weather too. As I explore in my latest book, it’s when the wanderings of the jet and the hand of climate change add up that we get record-breaking heatwaves, floods and droughts – but not freezes.

The coldest weeks of any given winter will occur when the jet brings masses of cold air directly from the polar regions. But severe though this may feel, records show that similar events in past decades were even colder than they are now. While the jet is largely doing the same as it always has, the planet-heating greenhouse gases we’ve added to our atmosphere mean that invasions of polar air these days are just that bit milder.

The flip side, of course, is that when the jet moves north in summer, bringing warm air from the south, we often have to endure temperatures beyond anything in living memory.

A Battle For The Jet Stream Is Raging Above Our Heads Mount Everest (top middle) is so high that it grazes the jet stream, blowing snow off its peak. NASA

It is clear and well understood how climate change and the jet can combine like this to cause truly extreme weather events. But whether climate change is directly changing the jet’s behaviour is a much harder question to answer.

Some have suggested that the rapidly warming Arctic is weakening the jet, by reducing the temperature contrast between the tropical and polar air to either side of it. As a result, the jet meanders more to the north and south, and these meanders can remain fixed over one location for longer – as happened when the “Beast from the East” placed much of Northern Europe under a bitter chill.

There are certainly some interesting ideas here, but many still do not find the logic compelling, and more convincing evidence from observations and computer models will be needed for these theories to become widely accepted.

Scientists are however increasingly confident that important changes are afoot in the tropics. Driven by the vast quantities of energy pouring in from the Sun directly overhead, these are the great powerhouses of Earth’s climate. Indeed, the power of the tropics is evident in the worldwide weather disruption caused by El Niño events – subtle increases or decreases in temperatures in the equatorial Pacific Ocean, that in turn disturb the jet stream.

A Battle For The Jet Stream Is Raging Above Our Heads If El Niño causes equatorial Pacific Ocean temperatures to warm, the jet stream brings stormier weather in winter. climate.gov

Over the past few years, it has become apparent that at high altitudes, the Earth’s tropical regions are heating up more quickly than the rest of the world. At least partly because of this, the tropical regions of the atmosphere have been widening, expanding ever so slightly away from the equator, and impinging more on the jet stream.

Tug of war

We are in the early days of a great battle in the air above our heads between the Arctic and the tropics, for the future of the jet stream. At best, there might be a stalemate, leaving the jet stream distorted but otherwise unmoved.

However, if one of the competitors outweighs the other, regional climate patterns could be severely altered as the climate zones shift along with the jet. It’s too early to say with any confidence which of these will win out, but many computer models predict the jet will shift a little towards the pole, consistent with a greater influence of the tropics.

In this case, we should expect to see the warm, dry regions at the edge of the tropics extend a little further out from the equator. The strongest impacts of this would likely be felt in regions such as the Mediterranean, which are already highly sensitive to fluctuations in rainfall. A northward jet shift would act to steer much needed rainstorms towards central Europe instead, leaving the Mediterranean at greater risk of drought.

So, the jet may not become more erratic as the Arctic warms, but it may well change profoundly. And one thing is clear: the stress of increased temperatures and altered rainfall patterns from our destabilising climate will leave us even more vulnerable to the weather patterns brought by the whim of the wandering jet stream.

About The Author

Tim Woollings, Associate Professor in Physical Climate Science, University of Oxford

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Storms of My Grandchildren: The Truth About the Coming Climate Catastrophe and Our Last Chance to Save Humanity

by James Hansen
1608195023Dr. James Hansen, the world's leading climatologist, shows that exactly contrary to the impression the public has received, the science of climate change has become even clearer and sharper since the hardcover was released. In Storms of My Grandchildren, Hansen speaks out for the first time with the full truth about global warming: The planet is hurtling even more rapidly than previously acknowledged to a climatic point of no return. In explaining the science of climate change, Hansen paints a devastating but all-too-realistic picture of what will happen in our children's and grandchildren's lifetimes if we follow the course we're on. But he is also an optimist, showing that there is still time to take the urgent, strong action that is needed- just barely.  Available On Amazon

Extreme Weather and Climate

by C. Donald Ahrens, Perry J. Samson
0495118575
Extreme Weather & Climate is a unique textbook solution for the fast-growing market of non-majors science courses focused on extreme weather. With strong foundational coverage of the science of meteorology, Extreme Weather & Climate introduces the causes and impacts of extreme weather events and conditions. Students learn the science of meteorology in context of important and often familiar weather events such as Hurricane Katrina and they'll explore how forecast changes in climate may influence frequency and/or intensity of future extreme weather events. An exciting array of photos and illustrations brings the intensity of weather and its sometimes devastating impact to every chapter. Written by a respected and unique author team, this book blends coverage found in Don Ahrens market-leading texts with insights and technology support contributed by co-author Perry Samson. Professor Samson has developed an Extreme Weather course at the University of Michigan that is the fastest-growing science course at the university. Available On Amazon

Floods in a Changing Climate: Extreme Precipitation

by Ramesh S. V. Teegavarapu

9781108446747Measurement, analysis and modeling of extreme precipitation events linked to floods is vital in understanding changing climate impacts and variability. This book provides methods for assessment of the trends in these events and their impacts. It also provides a basis to develop procedures and guidelines for climate-adaptive hydrologic engineering. Academic researchers in the fields of hydrology, climate change, meteorology, environmental policy and risk assessment, and professionals and policy-makers working in hazard mitigation, water resources engineering and climate adaptation will find this an invaluable resource. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook-icontwitter-iconrss-icon

 Get The Latest By Email

{emailcloak=off}

LATEST VIDEOS

Tiny Plankton Drive Processes In The Ocean That Capture Twice As Much Carbon As Scientists Thought
Tiny Plankton Drive Processes In The Ocean That Capture Twice As Much Carbon As Scientists Thought
by Ken Buesseler
The ocean plays a major role in the global carbon cycle. The driving force comes from tiny plankton that produce…
Climate Change Threatens Drinking Water Quality Across The Great Lakes
Climate Change Threatens Drinking Water Quality Across The Great Lakes
by Gabriel Filippelli and Joseph D. Ortiz
“Do Not Drink/Do Not Boil” is not what anyone wants to hear about their city’s tap water. But the combined effects of…
Talking About Energy Change Could Break The Climate impasse
Talking About Energy Change Could Break The Climate Impasse
by InnerSelf Staff
Everyone has energy stories, whether they’re about a relative working on an oil rig, a parent teaching a child to turn…
Crops Could Face Double Trouble From Insects And A Warming Climate
Crops Could Face Double Trouble From Insects And A Warming Climate
by Gregg Howe and Nathan Havko
For millennia, insects and the plants they feed on have been engaged in a co-evolutionary battle: to eat or not be…
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
To Reach Zero Emissions Government Must Address Hurdles Putting People Off Electric Cars
by Swapnesh Masrani
Ambitious targets have been set by the UK and Scottish governments to become net-zero carbon economies by 2050 and 2045…
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
Spring Is Arriving Earlier Across The US, And That's Not Always Good News
by Theresa Crimmins
Across much of the United States, a warming climate has advanced the arrival of spring. This year is no exception.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
A Georgia Town Gets Half Of Its Electricity From President Jimmy Carter's Solar Farm
by Johnna Crider
Plains, Georgia, is a small town that is just south of Columbus, Macon, and Atlanta and north of Albany. It is the…

LATEST ARTICLES

Hurricanes And Other Extreme Weather Disasters Prompt Some People To Move And Trap Others In Place
Hurricanes And Other Extreme Weather Disasters Prompt Some People To Move And Trap Others In Place
by Jack DeWaard
If it seems like extreme weather disasters such as hurricanes and wildfires are becoming more frequent, severe and…
If All Cars Were Electric, UK Carbon Emissions Would Drop By 12%
If All Cars Were Electric, UK Carbon Emissions Would Drop By 12%
by George Milev and Amin Al-Habaibeh
The COVID-19 lockdown has led to reduced pollution and emissions in the UK and around the world, providing a clear…
Brazil’s Jair Bolsonaro Is Devastating Indigenous Lands, With The World Distracted
Brazil’s Jair Bolsonaro Is Devastating Indigenous Lands, With The World Distracted
by Brian Garvey, and Mauricio Torres
The Amazon fires of 2019 drove the greatest single year loss of Brazilian forest in a decade. But with the world in the…
Why Countries Don't Count Emissions From Goods They Import
Why Countries Don't Count Emissions From Goods They Import
by Sarah McLaren
I would like to know if New Zealand’s carbon emissions of 0.17% include emissions produced from products manufactured…
Green Bailouts: Relying On Carbon Offsetting Will Let Polluting Airlines Off The Hook
Green Bailouts: Relying On Carbon Offsetting Will Let Polluting Airlines Off The Hook
by Ben Christopher Howard
The coronavirus pandemic has grounded thousands of aircraft, contributing to the largest-ever annual fall in CO₂…
Longer Growing Seasons Have A Limited Effect On Combating Climate Change
Longer Growing Seasons Have A Limited Effect On Combating Climate Change
by Alemu Gonsamo
Climate warming is leading to early springs and delayed autumns in colder environments, allowing plants to grow for a…
Both Conservatives And Liberals Want A Green Energy Future, But For Different Reasons
Both Conservatives And Liberals Want A Green Energy Future, But For Different Reasons
by Deidra Miniard et al
Political divisions are a growing fixture in the United States today, whether the topic is marriage across party lines,…
How The Climate Impact Of Beef Compares With Plant-based Alternatives
How The Climate Impact Of Beef Compares With Plant-based Alternatives
by Alexandra Macmillan and Jono Drew
I am wondering about the climate impact of vegan meat versus beef. How does a highly processed patty compare to…