Where glaciers melt, new ecosystems emerge

Ash from a nearby fire clung to the strands of my hair as I raced through a smoke-darkened sky in British Columbia’s Selkirk Range. It was late July 2021. The previous weeks had brought thunderstorms and millennial heat to this Canadian province, sparking hundreds of fires.

But at 8,000 feet, I was cold, my hands wet with meltwater from the Avalanche Glacier that covers the eastern flank of Mount Avalanche. I was there as a researcher with the Mountain Legacy Project, taking landscape photographs that we would later compare to glass plate negatives from the early 19th century. The original photographs were used to draw maps when the boundaries of the region were still being established. My team would contrast the images to map the boundaries of receding glaciers and new ecosystems springing up in their wake.

British Columbia’s interior mountains – the Selkirk, Purcell, Monashee and Cariboo ranges – are experiencing some of the fastest melting of any place on Earth. Some models predict a BC landscape with no glaciers at all as early as the 2080s. I had come to the Selkirks expecting to be overwhelmed with leaden grief. But with every inch of glacier retreat, new habitat emerges for cold-climate species that will be driven out of surrounding valleys as they warm. Instead of grief, I felt uplifted by the new life I saw growing everywhere.

Below the jagged edge of the Avalanche glacier, I stood on a red rock where 10 years ago there was ice. Around me were avalanche lilies, leatherleaf saxifrages, broadleaf arnica, and Indian paintbrushes in full bloom. These flowers are among the first visible species to appear in the early stages of primary succession, the process by which organisms begin to inhabit a newly exposed patch of land. The flexible thorns of young pine trees have grown from cracks in the granite. Even the barren slabs were mosaicked with technicolor lichens.


Scientists call places like this glacial forefields. When glaciers melt, they leave behind a mess of talus and till, rocks and sediments scattered chaotically over a slabbed bedrock scarred by the entrainment of ice. Bacteria on the surface of the glacier settle on the ground as the ice melts. Water collects in low places, then moss develops. Lichens have spread. Together, these organisms convert minerals into carbon-rich soil. Some research has shown that lichens can convert bedrock to soil in as little as three years.

And in this soil, plants begin to grow. First come the little things with fine roots, like the lilies and saxifrages I’ve seen in the Selkirk Range. But as I trudged up the infield of the Avalanche Glacier, I also had to part alders with my hands, digging tunnels through two-decade-old thickets. Alders are a primary “engineer species” in the interior mountains of British Columbia, arriving in some places only five or ten years after the ice disappeared. With their strong woody roots, they stabilize the soil. In a decade or two, these alders will likely give way to a diverse canopy of poplar, hemlock, and fir.

For more than a century, ecologists have understood primary succession to be a mostly linear process. The dirt gives way to bacterial, algal and fungal networks, then the pioneer plants arrive. Decades pass before a landscape settles into its final composition, perhaps a forest or a meadow. But in post-glacial environments, these time-tested theories falter. When mapping the melting of a glacier, one does not find an outline map of the successive stages that reflect the passage of time. Ecological development takes place in fits and starts. It is a complex mosaic.

Fascination with this mosaic in no way diminishes the loss of glaciers. A friend of mine called the glaciers the charismatic megafauna of the landscape. We are naturally obsessed with their disappearance. “We don’t know which one to fear more,” Craig Santos Perez wrote in his poem “Thirteen Ways to Look at a Glacier (After Wallace Stevens)”: “The terror of change / Or the terror of uncertainty / The glacier calving / Or just after.”

For millennia, glaciers have been the architects of the planet’s topography. They carve mountains; they absorb greenhouse gases from the atmosphere; they provide drinking water to one in six people. Even today, about 10% of the total land surface of our planet is covered by glaciers.

Much of this ice will melt in this century, leaving millions of acres available for new ecosystems. In the province of British Columbia alone, up to 9,300 square miles of land is expected to emerge from glacial recession by the end of the century, according to a 2015 article in the journal nature geoscience. Such newly exposed land will quickly transform. On Avalanche Glacier, we found complex new plant communities where our analyzes showed there had been ice a decade earlier.


Of course, there is no guarantee that all land exposed by retreating glaciers will turn into lush grasslands or sheltering woodland. In many places around the world, glacial forefields will remain unstable scree fields. No amount of new growth can mitigate the net impact of the climate crisis and deglaciation. There will be substantial impacts for downstream communities. Deglaciation leads to poor slope stability and glacial flooding. Seasonal flow will be changed. The way sediment moves through proglacial rivers and lakes will change, putting already threatened fish like salmon and sturgeon at even greater risk. Millions of people will be affected.

The ecosystem services provided by glacial forefields will not make up for the mess we have created. Still, the study of glacial forefields offers reason for hope. They remind us that the earth is adapt. The earth is home to a dynamic planetary system; the mechanisms of its lands and waters will rebalance in complex and vital ways.

Categorizing this geography as a site of loss, I realized that while standing beneath this cracked, groaning glacier, I would be missing the point. I remembered other lines from Perez’s poem. He wrote: “When the terminus of the glacier broke / It marked the beginning / Of one of the many waves.” There is a huge loss; there is enormous potential, which germinates in the fertile unknown of what comes next.