The Times Australia
The Times World News

.

How Arctic warming can trigger cold waves in North America – a new study makes the connection

  • Written by Mathew Barlow, Professor of Climate Science, University of Massachusetts Lowell

In February 2021, in the midst of rapidly warming global temperatures[1], an exceptionally severe cold wave hit large parts of North America, from Canada to Northern Mexico. It left 10 million people without power. The impact was particularly severe in Texas[2], which alone had more than 125 deaths associated with the event.

In the U.S., it was the coldest February in more than 30 years[3]. The cold wave became the nation’s costliest winter storm on record[4].

The freezing temperatures were associated with a dip southward in the jet stream[5], a band of strong winds about eight miles above Earth’s surface associated with the boundary between colder and warmer air.

The jet stream flows from west to east, but that’s not the only direction in which atmospheric waves can move – they can also move up and down over large distances, and that can link the weather and climate in one region, like the Arctic, with regions elsewhere, like Texas.

How Arctic warming can trigger cold waves in North America – a new study makes the connection Surface temperatures on Feb. 15, 2021, at 6 a.m. in Texas. The black lines show the jet stream, and the white line indicates the extent of freezing temperatures. Mathew Barlow/University of Massachusetts Lowell, CC BY-ND[6]

When you throw a rock in a pond[7], you see ripples – waves – expand away from the initial disturbance. While ripples on a pond are a different type of wave than dips in the jet stream, both types of waves can transmit the effects of a disturbance to faraway areas.

How Arctic warming can trigger cold waves in North America – a new study makes the connection Water ripples in response to a disturbance. Forance/Shutterstock.

In this case, the atmospheric waves transmitted the influence of climate change in the Arctic to parts of North America and Asia.

In a study released Sept. 2, 2021[8], in the journal Science[9], we show how that happened and how, counter to what one might expect, events like the February cold wave can actually become more likely with global warming.

What happens in the Arctic doesn’t stay there

The Arctic is warming more rapidly than any other region, at a rate more than twice the global average[10].

This is causing large changes in the region’s climate, including melting sea ice and, in the late fall, increasing snow cover over Siberia.

Ice and snow provide an insulating layer and are highly reflective, so their changes strongly alter the amount of energy and moisture moving between the surface of the Earth and the atmosphere. The atmosphere is sensitive to changes in energy and moisture, so substantial changes provide a “kick” to the atmosphere that results in upward moving waves rippling away from the area.

These waves move upward into the stratosphere and disrupt the stratospheric polar vortex[11], another band of fast winds that circles closer around the pole in the middle stratosphere, around 18 miles up. In response, the vortex weakens and stretches.

How Arctic warming can trigger cold waves in North America – a new study makes the connection Two circulation patterns of the stratospheric polar vortex: strong (left) and stretched (right). Blue curves indicate approximate edge of the vortex; shown at about 9.3 miles, or 15 kilometers, above the surface. Mathew Barlow, University of Massachusetts Lowell

Not only can the stratospheric vortex be changed by the waves, but the vortex can also change how the waves move, because the waves are influenced by the wind and temperature fields they move through, and the vortex helps determine those winds and temperatures. What differentiates a vortex stretching event from larger vortex disruptions is that upward-moving waves are reflected back down to the surface, where they can influence lower-altitude weather patterns.

How Arctic warming can trigger cold waves in North America – a new study makes the connection A schematic shows wave activity reflecting off the stretched stratospheric polar vortex. Mathew Barlow, University of Massachusetts Lowell

As these downward moving waves collect at lower altitudes over North America, they create a southward dip in the jet stream, bringing cold air farther south than usual. So, the upward and downward movement of atmospheric waves over long distances – like ripples moving across a pond – can link the Arctic to other regions.

Testing cause and effect

We took two different approaches to identifying and examining these relationships.

First, we used a machine learning, a technique in which a computer essentially trained itself to group similar events from the historical data. We then analyzed the stretched vortex events to show that, for those cases, there was a typical sequence of events: first surface temperature changes in the Arctic, then changes in the stratospheric polar vortex, followed by cold waves in North America and Asia – with vertically moving waves providing the connections over the span of a few months. The identified surface temperature changes in the Arctic are similar to those associated with the melting sea ice and increasing Siberian snow cover of Arctic climate change.

We then used a computer model of the atmosphere to evaluate cause and effect and directly test how the atmosphere responds to those Arctic changes. We found that the model reproduced the observed sequence of events.

The machine learning analysis of observations and the computer modeling experiments provide two independent lines of evidence supporting a pathway of influence – from Arctic climate change at the surface up to changes in the stratospheric winds, and finally back down to cold waves in North America and parts of Asia.

Three globes show the timeline of changes through the year. A timeline shows the pathway from Arctic climate change to cold temperatures in North America. Red and blue in the third panel indicate differences from average conditions. Mathew Barlow/University of Massachusetts Lowell, CC BY-ND[12]

Implications of these results

Our research reinforces two crucial lessons of climate change: First, the change doesn’t have to occur in your backyard to have a big effect on you. Second, the unexpected consequences can be quite severe.

In this case, large changes in the Arctic are not just a local concern – they also have wide-ranging impacts across North America and parts of Asia. And those impacts are not always what people are expecting. The results highlight another reason to rapidly reduce the greenhouse gas emissions that are driving global warming and at the same time the need to develop better strategies for managing extreme weather events, both hot and cold.

[Get our best science, health and technology stories. Sign up for The Conversation’s science newsletter[13].]

References

  1. ^ rapidly warming global temperatures (www.ipcc.ch)
  2. ^ particularly severe in Texas (theconversation.com)
  3. ^ the coldest February in more than 30 years (www.usatoday.com)
  4. ^ costliest winter storm on record (www.ncdc.noaa.gov)
  5. ^ jet stream (www.weather.gov)
  6. ^ CC BY-ND (creativecommons.org)
  7. ^ throw a rock in a pond (theconversation.com)
  8. ^ study released Sept. 2, 2021 (science.sciencemag.org)
  9. ^ Science (www.science.org)
  10. ^ more than twice the global average (doi.org)
  11. ^ stratospheric polar vortex (journals.ametsoc.org)
  12. ^ CC BY-ND (creativecommons.org)
  13. ^ Sign up for The Conversation’s science newsletter (theconversation.com)

Read more https://theconversation.com/how-arctic-warming-can-trigger-cold-waves-in-north-america-a-new-study-makes-the-connection-166550

Times Magazine

Headless CMS in Digital Twins and 3D Product Experiences

Image by freepik As the metaverse becomes more advanced and accessible, it's clear that multiple sectors will use digital twins and 3D product experiences to visualize, connect, and streamline efforts better. A digital twin is a virtual replica of ...

The Decline of Hyper-Casual: How Mid-Core Mobile Games Took Over in 2025

In recent years, the mobile gaming landscape has undergone a significant transformation, with mid-core mobile games emerging as the dominant force in app stores by 2025. This shift is underpinned by changing user habits and evolving monetization tr...

Understanding ITIL 4 and PRINCE2 Project Management Synergy

Key Highlights ITIL 4 focuses on IT service management, emphasising continual improvement and value creation through modern digital transformation approaches. PRINCE2 project management supports systematic planning and execution of projects wit...

What AI Adoption Means for the Future of Workplace Risk Management

Image by freepik As industrial operations become more complex and fast-paced, the risks faced by workers and employers alike continue to grow. Traditional safety models—reliant on manual oversight, reactive investigations, and standardised checklist...

From Beach Bops to Alpine Anthems: Your Sonos Survival Guide for a Long Weekend Escape

Alright, fellow adventurers and relaxation enthusiasts! So, you've packed your bags, charged your devices, and mentally prepared for that glorious King's Birthday long weekend. But hold on, are you really ready? Because a true long weekend warrior kn...

Effective Commercial Pest Control Solutions for a Safer Workplace

Keeping a workplace clean, safe, and free from pests is essential for maintaining productivity, protecting employee health, and upholding a company's reputation. Pests pose health risks, can cause structural damage, and can lead to serious legal an...

The Times Features

The Role of Your GP in Creating a Chronic Disease Management Plan That Works

Living with a long-term condition, whether that is diabetes, asthma, arthritis or heart disease, means making hundreds of small decisions every day. You plan your diet against m...

Troubleshooting Flickering Lights: A Comprehensive Guide for Homeowners

Image by rawpixel.com on Freepik Effectively addressing flickering lights in your home is more than just a matter of convenience; it's a pivotal aspect of both home safety and en...

My shins hurt after running. Could it be shin splints?

If you’ve started running for the first time, started again after a break, or your workout is more intense, you might have felt it. A dull, nagging ache down your shins after...

Metal Roof Replacement Cost Per Square Metre in 2025: A Comprehensive Guide for Australian Homeowners

In recent years, the trend of installing metal roofs has surged across Australia. With their reputation for being both robust and visually appealing, it's easy to understand thei...

Why You’re Always Adjusting Your Bra — and What to Do Instead

Image by freepik It starts with a gentle tug, then a subtle shift, and before you know it, you're adjusting your bra again — in the middle of work, at dinner, even on the couch. I...

How to Tell If Your Eyes Are Working Harder Than They Should Be

Image by freepik Most of us take our vision for granted—until it starts to let us down. Whether it's squinting at your phone, rubbing your eyes at the end of the day, or feeling ...