Short Wave Podcast Summary: Sea Camp – Why Are Ocean Currents Shifting?

Published on July 7, 2025

Hosts: Emily Kwong and Regina Barber
Producer: Hannah Chen
Special Guests: Matt Luongo (Climate Scientist and Physical Oceanographer), Lynn Talley (Professor at Scripps Institution of Oceanography), Shangfeng Xie (Climate Scientist and Oceanographer)

Introduction to Sea Camp

In the premiere episode of "Sea Camp," a special series from NPR’s Short Wave, hosts Emily Kwong and Regina Barber embark on an eight-week exploration of the ocean's depths. This inaugural episode, titled "Why Are Ocean Currents Shifting?" sets the stage by examining the intricate relationship between the ocean and the atmosphere and the profound implications of shifting ocean currents in the context of a warming planet.

Understanding Ocean Currents

Hannah Chen, the episode's producer, introduces the fundamental concepts of ocean currents:

“Ocean currents are the continuous movement of water within the ocean along a particular path... they affect fish migration, distribute heat and nutrients which support ecosystems, help drive weather, and shape human travel.”
(04:04)

Matt Luongo elaborates on how the ocean moderates climate, particularly along the U.S. west coast:

“Anyone who lives along the west coast of the U.S. for instance, knows that we have really mild winters, and that's a result of the fact that we have the ocean kind of mediating the weather there.”
(01:15)

Regina Barber reflects on the personal connection to this phenomenon:

“Yeah, I mean, I grew up in Washington State and California. And he's right. Like, we do have very mild winters, but I never, like, put together. It's because of the Pacific Ocean.”
(01:38)

Historical Insights: Benjamin Franklin and the Gulf Stream

Hannah Chen introduces Lynn Talley, a professor at the Scripps Institution of Oceanography, who shares a fascinating historical perspective:

“One of the oldest ocean current maps we have comes courtesy of Benjamin Franklin.”
(04:42)

The discussion reveals how Benjamin Franklin’s cousin, a whaling captain, leveraged knowledge of the Gulf Stream to expedite mail delivery across the Atlantic:

“He noticed that his cousin in Rhode island, who was a whaling captain, could get across the Atlantic Ocean a whole lot faster than the British official postmaster ships. And that's because his cousin in Rhode island knew about the Gulf Stream.”
(05:22)

Emily Kwong highlights the significance of the Gulf Stream:

“Because the Gulf Stream... it's like, a perfect route if you want to cross the Atlantic.”
(05:49)

Remarkably, a 1978 discovery showed that Benjamin Franklin's map of the Gulf Stream remains accurate today, underscoring the stability of these surface currents over centuries:

“The map was so accurate, and it was exactly where it is now.”
(06:33)

Hannah Chen summarizes:

“These surface currents remain so consistent over time... the main envelope, she called it, that Benjamin Franklin drew, is basically the same map as what we use now.”
(06:40)

Driving Forces Behind Surface Currents

The conversation shifts to the mechanics that sustain ocean currents. Hannah Chen outlines several factors:

“There's temperature, there's salinity, coastlines, overall, global wind patterns... even the rotation of the Earth can drive these currents because of something that's called the Coriolis effect.”
(07:12)

Regina Barber further explains the Coriolis effect:

“Because the Earth is spinning, it affects air currents. So, like, this makes air flow, like, slightly deflect to the right in the northern hemisphere, and it slightly deflects to the left in the southern hemisphere, and it makes these, like, curved paths of air. And this, in turn, like, affects the ocean currents.”
(07:24)

Matt Luongo emphasizes the dominance of wind-driven surface currents:

“The surface currents are primarily driven by winds... the Gulf Stream, the California Current, the Kuroshio... these kind of wind driven surface currents.”
(07:49)

The Impact of Climate Change on Ocean Currents

Hannah Chen introduces Shangfeng Xie, who discusses recent research on how a warming climate is influencing ocean currents:

“In a warming climate, surface currents across the globe will significantly accelerate.”
(08:15)

Regina Barber probes further:

“Like, will they speed up everywhere?”
(08:35)

Hannah Chen clarifies:

“In more than three quarters of the world's oceans, yes. But the surface currents specifically, not the deep ocean ones.”
(08:37)

Using the analogy of an outdoor swimming pool, Hannah explains:

“It'll take a really long time for the deep ocean to warm, but the top layer is warming much faster.”
(09:26)

As the surface water warms, it expands and creates greater pressure differences, speeding up the surface currents:

“As this surface water warms, its molecules move faster and further apart. Meaning that it's all going to take up more space. That'll result in intensified pressure differences, basically pushing parts of the ocean, like the currents at the surface, to move faster.”
(09:34)

This acceleration is already observable. For instance, the Antarctic Circumpolar Current has sped up over recent decades:

“...the Antarctic Circumpolar current... it's sped up significantly over the past few decades.”
(09:56)

Consequences of Shifting Currents

Shangfeng Xie discusses the ecological ramifications:

“Fish definitely is going to tell the difference... their migration, spawning and feeding... phytoplankton. And also the fish migration is certainly going to change tremendously.”
(10:22)

Hannah Chen adds that accelerating currents may alter their paths and impacts:

“As these currents speed up, they could end up shifting their location and their effects as well.”
(10:55)

Shangfeng Xie explains:

“When the currents speed up, they're going to move nutrients, they're going to move heat. If you speed a current up, it might not want to stay where it started. It might try to push itself a little farther towards the pole, and it will carry things farther and faster.”
(11:16)

The Atlantic Meridional Overturning Circulation (AMOC) Exception

While most surface currents are accelerating, the AMOC, a crucial system for global heat redistribution, is an exception. Hannah Chen describes AMOC:

“It's a system of surface currents and deep currents, kind of like an Atlantic Ocean current conveyor belt that moves warm water north and cold water south.”
(11:16)

Shangfeng Xie highlights concerns about AMOC:

“It... helps redistribute energy and kind of moderate heat around the world.”
(11:27)

Hannah Chen shares alarming projections:

“For decades, scientists have been worried that it's begun to slow down. And Xiaoping's team's models supported this. They said that along with multiple currents in the deeper ocean, it'll continue to decelerate, which could change a whole host of things... sea level rise along north part of the East Coast, Western Europe and a lot of the Northern Hemisphere way colder or change monsoon season and rainfall near the equator...”
(11:41)

Call to Action: Addressing Climate Change

Emily Kwong underscores the urgency:

“Like a choose your own adventure game, but bad.”
(12:20)

Hannah Chen reinforces the gravity of the situation:

“But unlike a choose your own adventure game where you can restart it whenever, we humans only get one shot.”
(12:22)

Matt Luongo emphasizes the need for immediate action:

“We understand a lot of the basic building blocks. So I think it then becomes kind of a political and social decision on how much we want to not emit CO2, for instance. It's kind of what we decide to do.”
(12:36)

Closing Remarks

Emily Kwong and Regina Barber thank Hannah Chen for her insightful contributions, setting the stage for the subsequent episodes in the "Sea Camp" series. The hosts highlight the importance of understanding and addressing the shifting ocean currents to mitigate potential climate disasters.

Conclusion

This episode of Short Wave's "Sea Camp" provides a comprehensive exploration of ocean currents, their historical significance, the driving forces behind them, and the profound impacts of climate change on these vital systems. Through expert insights and engaging narratives, Emily Kwong and Regina Barber underscore the interconnectedness of the ocean and the atmosphere, emphasizing the urgent need for collective action to preserve the planet’s climatic balance.

Notable Quotes:

• Matt Luongo (01:15): “Anyone who lives along the west coast of the U.S. for instance, knows that we have really mild winters, and that's a result of the fact that we have the ocean kind of mediating the weather there.”

• Shangfeng Xie (10:22): “Fish definitely is going to tell the difference... their migration, spawning and feeding... phytoplankton. And also the fish migration is certainly going to change tremendously.”

• Hannah Chen (09:34): “As this surface water warms, its molecules move faster and further apart. Meaning that it's all going to take up more space. That'll result in intensified pressure differences, basically pushing parts of the ocean, like the currents at the surface, to move faster.”

• Matt Luongo (12:36): “We understand a lot of the basic building blocks. So I think it then becomes kind of a political and social decision on how much we want to not emit CO2, for instance. It's kind of what we decide to do.”

References:

• Sea Camp Series: An eight-week deep dive into oceanography, exploring various aspects of marine science and the critical role oceans play in Earth's climate system.

• Physics Behind Currents: Understanding the Coriolis effect and its influence on both atmospheric and oceanic circulation patterns.

• Historical Maps: The enduring accuracy of Benjamin Franklin’s Gulf Stream map as evidence of the stability of major ocean currents over centuries.

Note: This summary encapsulates the key discussions and insights presented in the "Sea Camp: Why Are Ocean Currents Shifting?" episode of NPR's Short Wave, providing a clear and comprehensive overview for listeners and non-listeners alike.