In northern latitudes, the ground swells with color as tundra mosses, grasses, and flowers transform into a crimson carpet, soon to be covered in snow. But climate change is dulling this burst of radiance.

In southern latitudes, autumn is best sensed by looking up. Against crisp skies, red, orange, and yellow leaves cling gingerly to tree branches until a gust of wind sends them floating down to earth. In northern latitudes, however, it’s best to look down to detect fall’s arrival. The ground swells with color as mosses, grasses, and flowers transform the tundra into a crimson carpet, soon to be covered in snow. Freshwater rivers and ocean waves grind to a halt as water prepares to hibernate until the sun decides to show itself again.

Or at least, that’s what used to happen. In recent years, as is all too known, sea ice has thawed and glaciers have retreated. But the seasons are changing, too: summer is lasting longer and fall is coming later. This temporal shift bears a range of negative effects, from postponed animal migrations to increasing numbers of invasive species and pathogens, which benefit from a delayed autumn. Worryingly, as birds linger longer waiting to head south, they feed on these already-successful invasive plants, spreading their seeds more and more.

Warming temperatures don’t push everything later, however. In Alaska, berries are ripening earlier at a time that now coincides with salmon runs. This overlap makes it difficult for hunters, gatherers, and fishers, who only have so much time in the day to harvest.

Despite these ill effects, scientists haven’t examined the consequences of a later autumn as much as they have an earlier spring. One group of researchers attributes this disproportionate attention to “human enchantment with the sudden burst of spring flowers and wildlife following winter.”

The fall tundra cascading into a fjord near Narsarsuaq, Greenland.

I find myself enthralled by fall, however. Perhaps it’s because I never experienced it growing up in San Francisco, where there is only one season: fog. The stampede of color produced by the breakdown of chlorophyll is a phenomenon I only came to appreciate once I was too old to be jumping in piles of leaves. Not that there were any around, though: one of the most memorable displays of the changing of colors I’ve encountered was in the treeless tundra of southern Greenland.

During that trip in September 2017, I went hiking in Flower Valley outside of the airport town of Narsarsuaq. The sight of electric blue icebergs and pearly white glaciers against a red-hot Earth was simply sanguine. The valley, fittingly, is located along the fjord that Erik the Red sailed up and settled in the summer of 985 AD.

Flower Valley outside Narsarsuaq, Greenland. September 2017.

Yet now, climate change is muddying the spectacular contrast of fiery foliage and ice. The few studies that exist breaking down a warming planet’s impacts on “autumn senescence” – the scientific term for the changing of the leaves – focus on forests in places like New England, where “leaf peeping” is a $3 billion industry. One study associates climate change with “color change” in the form of duller leaves. Another study analyzing forests in France forecasts that by 2100, leaves will turn color an average 13 days later compared to the early 21st century.

Even less research considers climate change’s effects on fall colors in the Arctic. Autumn is not a big period for Arctic tourism. People prefer to travel north to see the chartreuse, magenta, and violet glow of the shimmering aurora in winter rather than the blushing tundra. As such, any loss of fall color would have fewer financial effects than in a place like New England, meaning there is little economic impetus for such a study. Many academics also have to teach in fall, making Arctic fieldwork in September and October logistically challenging.

With climate change, we are not only losing ice: the riotous rainbow of colors presented by a peacocking Arctic across all its seasons seems to be contracting, too. Every passing autumn may therefore portend a “vegetative farewell,” as one writer terms it, in more ways than one.

Farewell, fall: An autumn twig sinks into an icy fjord in Greenland.
Categories: Climate Change

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