One of the pretty faces of fjords: the surface of Alaska’s Three Saints Bay—protected ocean waters within a fjord—reflects the picturesque mountains like a mirror. ©Robin Corcoran/USFWS, flickr

Long, deep and usually surrounded by breathtaking cliffs, a fjord begins as a U-shaped trough, gouged out by an advancing glacier. When the glacier retreats, rising seas enter these trenches, eventually forming finger-shaped, steep-sided inlets, commonly more than 1,000 feet deep.

Fjords, therefore, can be thought of as arms of the sea that are stretching out; and most of these lovely limbs have been crafted by glaciers.

While they comprise a mere 0.1 percent of the surface area of the ocean, fjords punch far above their weight in their ability to pull carbon from the atmosphere and store it in the mud; in fact, they sequester an outsized 11 to 12 percent of the carbon stored in the ocean. In other words, they sock away 18 million tons of carbon during interglacial periods (like the one we’re in now), even though they take up the equivalent space of a speck of zest on an orange.

And scientists learned of this small-but-mighty role that fjords play in our world only recently.


Long, deep fjords reach far into both the east and west coasts of Greenland in complex systems, offering magnificent scenery. In Tasillaq Fjord, large chunks of ice break off from glaciers and slide into the water as icebergs.

Finding fjords

Alaska, Greenland, New Zealand and Norway are just a few of the places that are renowned for their beautiful fjords.

For example, Kenai Fjords in south-central Alaska is a 607,000-acre national park on the Kenai Peninsula. The park’s dramatic landscapes include jaw-dropping mountains with great glaciers flowing down between them to the sea, as well as mile-deep fjords that provide a habitat for thousands of nesting seabirds and small marine mammals, such as harbor seals, sea lions and sea otters.

The Ilulissat Icefjord on the west coast of Greenland is located 155 miles north of the Arctic Circle. The fjord, listed as a UNESCO World Heritage site, runs 25 miles from the Greenland ice sheet to Disko Bay, making it one of the few places where ice from the Greenland ice cap—in the form of the Sermeq Kujalleq glacier—enters the sea. The area around the head of the fjord is an amazing spot, where icebergs from one of the world’s most active and fastest moving glaciers (130 feet per day) create fantastic scenery.

Doubtful Sound, New Zealand, was so named because in 1770, Captain James Cook decided if he and his crew ventured into the fjord, it would be “doubtful” whether they would be able to sail back out against the westerly wind. ©gmoorenator, flickr

In New Zealand, Milford Sound—also known by its Maori name, Piopiotahi—lies at the most northern and accessible end of Fiordland National Park (an area that has held UNESCO World Heritage status since 1986) on the South Island. This mighty fjord formed by ancient glacial movement is one of the nation’s most treasured natural landmarks. It offers some of the world’s most staggering coastal scenery with its dramatic peaks and dark-blue waters. The area’s frequent downpours only enhance the fjord’s charm, sending numerous waterfalls cascading down the cliffs. The pristine environment also provides a perfect habitat for birdlife and a haven for dolphins, endangered penguins and fur seals.

Norway, known as “the land of fjords,” has an abundance of these natural wonders. Sognefjord, for instance, is the largest fjord in the country and the third longest in the world. It stretches for 127 miles inland until it reaches the small village of Skjolden. At one point, this impressive fjord descends 4,291 feet below the sea. And Geirangerfjord, a UNESCO World Heritage site, is surrounded by snowcapped mountains 5,250 feet high, with thundering waterfalls dropping almost perpendicular into the waters that go 820 feet deep. That makes Geirangerfjorden as deep as the Grand Canyon.

It’s no wonder that Norwegians consider fjords their very symbol.


Fjords symbolize Norway: the country has more than a 1,000 of them. These beautiful landscapes evoke images of the nation’s past: a time when people lived as farmers in impossibly steep and rocky surroundings. In some places, they still do.

Figuring out fjords

In 2015, an ocean geochemist and professor at the University of Florida, Thomas Bianchi, and one of his graduate students pioneered research, published in the journal Nature Geosciences, that first opened the world’s eyes to the powerful role that fjords play in global carbon storage.

But for years after Bianchi’s groundbreaking study, a vexing question became an itch that marine scientists couldn’t scratch: are fjords the carbon storage gift that keeps on giving, or is their ability to store carbon-rich sediments deep in their bellies temporary? And further, what will happen to that locked-away warehouse of carbon during the next glacial period when it is again exposed to oxygen as the ice returns and the waters recede?

Answering those questions would require an understanding of how reactive the carbon in fjord sediments is compared to the carbon buried in other ocean reservoirs, such as at the bottom of the middle of the ocean, far away from the coasts. A unique instrument, called the Ramped Pyrox C-14 System—otherwise affectionately known as “the dirt burner”—was indispensable in solving the mystery.

Knight Inlet in British Columbia, Canada, is part of the wildlife-filled Great Bear Rain Forest and is the longest fjord along the British Columbia Coast. ©Frank Martens, flickr

A paper published in November 2022 in Science Advances unearths a new understanding of the role of fjords in the global carbon cycle. The bottom line is that they act as both carbon sink and source.

The authors of the paper collected sediment samples from 25 fjords around the world, placed them in the dirt burner, gradually increased the temperature, recorded when and how fast the organic matter broke down and then turned that into a “reaction energy” equivalent. In short, the fjord sediments were highly reactive.

What that reactivity means is that the rock-star ability of fjords to store carbon is transitory, not permanent. Fjords are carbon sinks during interglacial periods and become carbon sources during glacial periods.


Small but mighty, fjords—such as this one in Iceland—are planetary “thermostats.” Their role in the global carbon cycle is both sink and source, proving once again that size doesn’t matter.

So, akin to the thermostat in your home, fjords help regulate temperature. They counterbalance the cooling of the planet in glacial periods by adding roughly 50 parts per million of carbon dioxide back to the atmosphere.

Fancying fjords

In British Columbia, Canada, a network of fjords is situated immediately northwest of Vancouver. In this labyrinth, lush, forested peaks protrude right from the sea and form staggering terrain in Howe Sound, the southernmost and most accessible fjord in North America. Howe Sound was designated as a UNESCO Biosphere Reserve in 2021.

In Iceland, Bulandstindur, or Pyramid Mountain, in the East Fjords region, is believed to have supernatural healing powers. Reached via the famous Ring Road, Bulandstindur is loved by locals and travelers as a place to experience unspoiled nature and fresh air and to hike on mystical land.


In certain fjords in Patagonia, glaciers still hang from the mountainsides, ghosts of a Pleistocene past.

Heading into the Southern Hemisphere, southernmost Patagonia is a wilderness of twisting fjords and towering glaciers, where the frosty Andes finally slope into the sea. In this remote area, ice has scoured its way between the mountains, creating the isolated islands and hidden bays that make up the unique fjord landscape of Chile. Snowcapped mountains and steep valleys contrast with verdant coastlines that are rich in wildlife. Andean condors, sea lions and several bird species that can only be found here reside in relative tranquility.

For a long time, fjords were overlooked by climate scientists and the rest of us merely because of their size relative to the vast ocean basin. But while fjords take up just a small amount of space, they play a significant role in modulating temperature swings from glacial to interglacial periods. Human-caused warming of the planet interrupts the heartbeat of natural glacial–interglacial cycles, making our understanding of fjords and other hot spots of carbon storage critical.

And besides, they are awfully pretty to look at.

Here’s to finding your true places and natural habitats,