How Melting Ice Once Cooled Europe — and What It Means for Us

Arctic ice melt 100,000 years ago disrupted ocean circulation and cooled Europe — what might it mean for today’s warming world?

Last weekend, we took our kids outdoor climbing. This is a hobby that their dad and I used to enjoy almost every weekend and vacation when we met, and that we are trying to bring back now that they are old enough to behave.

However, outdoor climbing with kiddos isn’t the same as adult climbing. First, we can’t do certain types of climbing such as multi-pitch (other climbers wouldn’t be happy about watching them for hours). Second, some climbing areas are dangerous for them, so we have to plan ahead to make sure we go to a kid-friendly spot. Third, you need to carry a lot of extra “stuff.”

Among this stuff, there are lots of snacks.

As little T was wandering around with his container of Gold Fish, I warned him to sit down because he’d spill them all over. Of course, he didn’t listen, and we ended up with fish all over the dirty floor.

After talking to him about what happened and how to prevent it from happening again, I told him I had split the Gold Fish into two different containers because I knew this was going to happen.

He looked at me in disbelief. How could I possibly predict this was going to happen?

— Experience, kiddo, experience…

I reminded him that mom is a paleontologist. Studying the past gives us the opportunity to anticipate what could happen in the future.

In the same way, we know that climate change and ice melting occurred in the past. And we can use this information in our future predictions. Only, there is much more at stake than a few fallen fish snacks.

The Arctic has always been a key player in our climate story. Recent research in Nature Communications by Dr. Mohamed Ezat and his team has taken a deep dive into the past.

Arctic freshwater outflow suppressed Nordic Seas overturning and oceanic heat transport during the Last Interglacial – Nature Communications

The team explored how melting Arctic sea ice changed how the Nordic Seas circulated during the Last Interglacial period — over 100,000 years ago. Surprisingly, this ancient ice melt may have triggered a regional cooling pattern that stretched across northern Europe, flipping the script on what we usually expect from a warming climate. Yes, global warming can lead to catastrophic freezing. See:

Could Global Warming Lead To Catastrophic Freezing?

In response to global climate change, other systems, such as global oceanic circulations, could collapse, with devastating consequences.

With the Arctic warming faster than ever and projected to see ice-free summers by 2050, these findings carry new relevance. “This reminds us that the planet’s climate is a delicate balance, easily disrupted by changes in temperature and ice cover,” says Dr. Ezat.

Indeed, it is a delicate balance, especially as we consider what might happen if modern Arctic ice follows a similar melting path.

Dr. Ezat’s team worked with samples from sediment cores extracted from the Nordic Seas. Think of these cores as time capsules of the ocean, recording past sea temperatures, ice conditions, and even freshwater inflows.

Then, the team used a blend of biological and chemical markers to piece together a story of the sea surface conditions from that ancient warm period. By tracking microscopic organisms, specific chemical signatures, and layers of sediments, they built a detailed picture of how sea ice and freshwater inputs shifted the currents.

Their multi-proxy approach (meaning that they used several lines of evidence) allowed them to identify changes over time in ocean temperature, salinity, and even the speed and depth of water mixing in the Nordic region.

And what did the researchers find?

The research revealed three main phases of sea surface conditions during the Last Interglacial.

1. In the early part (around 128,000–126,500 years ago), the sea surface temperatures were unusually cold, with sea ice covering parts of the Norwegian Sea during winter.
2. The second phase (126,500–123,500 years ago) saw temperatures climb, though they were still lower than what’s typical of today’s Nordic Seas.
3. By the third phase, roughly 123,500 years ago, the waters reached conditions similar to those we know now. But what’s interesting is how these cold early stages might have been caused by increased Arctic sea-ice melt.

What do they mean by this?

When this sea ice melted, it released a flood of freshwater into the ocean, especially into areas like the Greenland and Norwegian Seas. This made the surface waters less salty and, therefore, less dense.

Normally, cold, salty water sinks, which is a crucial part of deep-water formation and, by extension, the global heat conveyor belt we call the Atlantic Meridional Overturning Circulation (AMOC).

But with all this extra freshwater, the process slowed down, changing the flow of heat northward and potentially cooling the region. As you can see, a series of cascading effects.

So, what does this all mean for us today?

Dr. Ezat’s study is a timely reminder of how interconnected our climate systems are and how the Arctic plays a unique role in global temperature and weather patterns.

“Our finding that enhanced melting of Arctic sea ice likely resulted in significant cooling in northern Europe in the Earth’s past is alarming,” Dr. Ezat commented.

It’s a piece of the climate puzzle that many wouldn’t expect — melting ice causing cooling. But the reason is clear: by stalling that warm-water conveyor, we’re left with an icy ripple effect that could chill even warm periods.

The researchers hope these findings provide a solid foundation for climate modelers to better predict future outcomes. While today’s Arctic is different, with climate change accelerating sea-ice loss, there are valuable parallels.

Scientists are already concerned that a rapid increase in Arctic freshwater from melting ice could disturb the AMOC, a system we rely on for stable climate patterns.

Recently, a group of scientists signed an open letter about the potential risks of AMOC slowing down, citing “devastating and irreversible impacts.” Dr. Ezat’s study backs up these concerns, showing that changes in Arctic ice could have extensive consequences.

Ultimately, the research highlights the Arctic’s influence on keeping our global climate engine humming. If ice melt continues to pour fresh water into the Nordic Seas, we may face similar disruptions to those of the Last Interglacial.

Whether these effects will mirror the past or take new forms, the study gives us a glimpse of the Arctic’s critical role in maintaining a balanced climate. It’s an invitation to pay close attention to what’s happening in our northernmost seas because, as this ancient story shows, even slight changes can set off global-scale shifts.

Will humans change their behavior in time? Or have we already spilled all our Gold Fish, just like little “T” did last weekend? Although, he learned from his mistake — which gives me hope that we can, too.