\u201cIt felt really scary \u2026 like being in the middle of a burning city during a night raid.\u201d Dr Arwyn Edwards is not describing urban warfare but a recent hot and foggy day on a Svalbard glacier, where record-breaking summer heat turned his workplace into a cascade of meltwater and falling rocks.<\/p>\n
Edwards is a leading researcher in glacier ecology \u2013 the study of life forms that live on, within and around glaciers and ice sheets. Over two decades of polar research, he has always felt \u201crelaxed and at home\u201d on ice. But the accelerating climate breakdown is beginning to erode that sense of security.<\/p>\n
While mean global temperatures have not yet breached the 1.5C Paris target, the Arctic blew past that landmark long ago. Svalbard is heating seven times faster<\/a> than the world average.<\/p>\n Dr Arwyn Edwards examines a sample of microbe-rich \u2018cryoconite\u2019 from glacier ice on Svalbard. Photograph: Ben Martynoga<\/p>\n Time is running out to understand these fragile ecosystems and the trillions of dollars in climate costs they could unleash.<\/p>\n Edwards describes the cold-adapted microbes he studies as \u201cthe watchkeepers and arch-agitators of Arctic demise\u201d. Recent research implicates snow and ice-dwelling microbes in positive feedback loops that can accelerate melting. With more than 70% of the planet\u2019s freshwater stored in ice and snow<\/a> \u2013 and billions of lives sustained by glacier-fed rivers \u2013 this has profound implications everywhere.<\/p>\n Yet not all polar microbes amplify global heating. Emerging evidence suggests that certain populations are \u2013 for now \u2013 applying a brake to methane emissions.<\/p>\n Frozen rainforests<\/p>\n Until recent decades, most scientists assumed Arctic<\/a> ice and snow were largely devoid of life. On Longyearbreen, a Svalbard glacier close to the world\u2019s most northerly town, Edwards digs through the remnants of last winter\u2019s snow pack, to explain how that assumption missed the mark.<\/p>\n Edwards notes that all fresh snowfall contains microbes<\/a> and, remarkably, microbes themselves can trigger snowflake formation. Each cubic centimetre of snow on the glacier contains hundreds to thousands of living cells, he says, and typically four times as many viruses \u2013 a microbial habitat as complex as topsoil. \u201cThe organisms that can survive here are very, very evolutionarily advanced,\u201d Edwards says.<\/p>\n During summer, snow surfaces can host red-pigmented algae that swim up and down through surface layers, seeking sunlight for photosynthesis without getting burned. Intense blooms create the phenomena known as \u2018watermelon snow\u2019 or \u201cblood snow<\/a>\u201d, first described by Aristotle.<\/p>\n Microbe-rich \u2018cryoconite granules\u2019, also called \u2018rainforests of the ice\u2019, embedded in glacier ice. Photograph: Ben Martynoga<\/p>\n Beneath the snow, Edwards\u2019 shovel hits solid glacier ice \u2013 another rich habitat where microbes flourish despite intensely low temperatures, minimal nutrients, and extreme oscillations between perpetual winter darkness and the endless days of Arctic summer. \u201cIf I look at a glacier surface, I don\u2019t see ice. I see \u2026 a three dimensional bioreactor,\u201d Edwards says.<\/p>\n Embedded in the ice are dark, soil-like fragments. Despite their unremarkable appearance, these \u201ccryoconite granules\u201d have been called the \u201cfrozen rainforests\u201d of the ice. Each granule is a self-sustaining ecosystem in minature, containing diverse bacteria, fungi, viruses, protists and even tiny animals like tardigrades and worms.<\/p>\n These microbial communities can exert influence on a global scale but Edwards is frustrated that many glaciologists treat them as mere \u201cimpurities\u201d. \u201cOceanographers would not treat fish in the sea as impurities,\u201d he says.<\/p>\n Microbes that live in surface ice and snow produce dark-coloured pigments to harness sunlight and shield themselves from damaging UV light. They also trap dark-coloured dust and debris. Together, these factors darken snow and ice, causing it to absorb more heat and melt faster \u2013 a process known as \u201cbiological darkening\u201d.<\/p>\n Microbes also respond to global changes, such as increased nutrients from air pollution<\/a>, wildfire smoke or wind-blown dust<\/a> from receding glaciers and expanding drylands. \u201cThe snowpack chemistry is now different to preindustrial era snow,\u201d Edwards says. Rising temperatures and longer melt seasons caused by global heating further accelerate the growth of ice-darkening microbes.<\/p>\n Together, these factors have the potential to trigger an amplifying positive feedback loop: ice-darkening microbes nudge up temperatures and accelerate melt, exposing more nutrient-rich debris that encourage the growth of yet more microbes, which darken the surface further still.<\/p>\n Edwards steps over a melt channel beneath a Svalbard glacier. Photograph: Ben Martynoga<\/p>\n Each summer, a biologically darkened zone, visible from space, covering at least 100,000 sq km, appears on the south-western part of the Greenland ice sheet. According to a 2020 study<\/a>, microbes there are responsible for 4.4 to 6.0\u2009gigatons of runoff, representing up to 13% of total melt, from an ice mass that holds enough water to raise global sea levels by more than 7 metres. These effects are acknowledged in IPCC reports<\/a> but not yet incorporated into climate projection models.<\/p>\n Across the European Alps, Himalayas, central Asia and beyond, at least 2 billion people depend on glacial meltwater for drinking water, agriculture and hydropower. Yet even if the world meets Paris targets, half these glaciers will not survive<\/a> this century.<\/p>\n skip past newsletter promotion<\/a><\/p>\n The planet’s most important stories. Get all the week’s environment news – the good, the bad and the essential<\/p>\n Privacy Notice: <\/strong>Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy<\/a>. We use Google reCaptcha to protect our website and the Google Privacy Policy<\/a> and Terms of Service<\/a> apply.<\/p>\n after newsletter promotion<\/p>\n Methane eaters<\/p>\n Beyond surface darkening lies a second threat: methane. In many parts of the Arctic, glaciers and permafrost cap vast underground stores of this potent greenhouse gas, preventing its release. Recent studies have also revealed that microbes thriving in the cold, dark, high-pressure world underneath glaciers<\/a> can produce large volumes of fresh methane. Thawing permafrost and receding glaciers can trigger previously unanticipated<\/a> methane emissions from deep underground.<\/p>\n Across the fjord from Longyearbyen, Prof Andy Hodson, of the University Centre in Svalbard, demonstrates this at a collection of \u201cpingos\u201d \u2013 mounds formed when pressurised groundwater surges upward through frozen ground. The water that emerges is saturated with methane. Hodson likens the effect to glaciers and ice \u201cfracking the landscape and pushing this gas out. We\u2019ve got methane pissing out the ground from wherever fluids can migrate from beneath the permafrost.\u201d<\/p>\n On cue, a sudden belch of methane disturbs the surface of a pingo pool. \u201cI\u2019m not going to say there\u2019s a 50 petagram methane bomb about to go off,\u201d Hodson says. But with recent estimates suggesting emissions from Arctic feedback loops could add $25-70tn<\/a> to climate costs, the stakes couldn\u2019t be higher.<\/p>\n Prof Andy Hodson stands on a natural methane seep known as a \u2018pingo\u2019. Photograph: Ben Martynoga<\/p>\n One reason Hodson remains relatively calm about this particular site is because he and colleagues discovered recently<\/a> that specific microbial communities living in the pingo can out-compete methane-producing microbes and actively consume methane. \u201cThis is where the methanotrophs [\u2018methane eaters\u2019] are really saving the day,\u201d Hodson says. Methanotrophs will certainly not curtail emissions everywhere but without them, much more methane would escape.<\/p>\n \u2018A terminally ill glacier\u2019<\/p>\n Standing on the surface of Foxfonna, a central Svalbard glacier, Edwards describes how the ice surface here is 4 metres lower than it was last summer, with the glacier much diminished since his first visit in 2011. \u201cThis is a terminally ill glacier,\u201d says Edwards, \u201cThis is palliative, and yet nobody cares.\u201d<\/p>\n