Glaciers Darken: Pollution's Impact On Ice

Glaciers are large masses of snow and ice that have accumulated over many years and are present year-round. They are highly effective at reflecting solar radiation back into space, helping to cool the planet. However, glaciers worldwide have been losing mass since at least the 1970s, and this loss has accelerated in recent years. One phenomenon contributing to this is the darkening of glaciers due to pollution. This pollution includes particles of fine dust, soot from fires, and black carbon resulting from incomplete combustion of fossil fuels. As glaciers turn darker, they absorb more solar heat, accelerating melting and contributing to rising sea levels. This dark snow has been observed from the Himalayas to the Arctic, with potential consequences for global food and water systems.

Glacier algae

The three main species of glacier algae are Ancylonema nordenskioldii, Chlamydomonas nivalis, and Raphidonema sempervirens. Glacier algae are found on glaciers and ice sheets across the world, including in Alaska, the Himalayas, and Greenland. Glacier algae are a type of snow algae, which thrive on snow fields, glaciers, and ice sheets. Snow and glacier algae are distinct from sea ice algae because they are pigmented and grow in freshwater habitats.

The abundance of glacier algae changes with the seasons and is highest during the summer months, which is the melting season for glaciers. Climate change is affecting both the start of the melting season and the length of this period, which will lead to an increase in the amount of algae growth. As the ice and snow begin to melt, the area the ice covers decreases, exposing more land. The land underneath the ice has a higher rate of solar absorption due to it being less reflective and darker.

The dark pigments within the structure of glacier algae increase sunlight absorption, which leads to an increase in the melting rate. Glacier algae blooms have been shown to appear on glaciers and ice sheets once the snow had begun to melt, which occurs when the air temperature is above the freezing point for a few days. The growth of glacier algae darkens local surface conditions, decreasing the albedo and thus increasing the melt rate on these surfaces. Glacier algae were calculated to be directly responsible for 9-13% of the surface melting in the Dark Zone of the Greenland Ice Sheet in 2016.

Dark snow

The darkening of snow and ice has significant implications for the planet's climate system. Snow and ice are highly reflective, bouncing solar radiation back into space and helping to cool the planet. However, as snow turns darker, its reflectivity decreases, causing it to absorb more solar heat and melt earlier and more intensely. This creates a positive feedback loop where the surface of the snow gets darker due to increased water content, further reducing reflectivity and accelerating melting.

The sources of the particles darkening the snow vary but are often a result of human activity. For example, industrial dust and soil from bare soil in Africa and the Middle East are being blown thousands of miles and settling on ice sheets. In addition, nearly invisible particles of "black carbon" from diesel engines in industrial centres in the US, Europe, and Southeast Asia are being swept across the globe and deposited on snow and ice.

The impact of dark snow is already being measured. Satellite measurements show that the surface of Greenland's ice sheet has considerably darkened during the melt season, which is now between six and eleven days longer per decade than it was 40 years ago. This longer melt season is contributing to the accelerated loss of ice in the Arctic, with potential consequences for sea-level rise.

The phenomenon of dark snow highlights the interconnectedness of the planet's systems and the far-reaching impacts of human activity. It serves as a potent symbol of the global problem with pollution and the urgent need to address it. As Ulyana Horodyskyj, an American geologist studying dust pollution in the Himalayas, stated, "Governments must act, and people must become more aware of what is happening. It needs to be looked at properly."

Industrial pollution

Glaciers are turning darker due to the deposition of industrial pollutants on their surfaces. This phenomenon, known as "dark snow," is accelerating the melting of glaciers worldwide, from the Himalayas to the Alps and the Arctic.

In addition to soot, dust from the surroundings, including bare soil and drought-affected regions, is also contributing to the darkening of glaciers. This dust is being blown onto glaciers by strong winds, further reducing the albedo effect and enhancing melting. The problem is particularly pronounced in regions like the Himalayas, where dust and soot accumulation have led to a significant decrease in the reflectivity of ice and snow.

The impact of industrial pollution on glacier melting has important implications for global sea level rise. As glaciers in Antarctica and Greenland melt, they contribute significantly to rising sea levels, increasing coastal erosion and elevating storm surges. The rapid melting of glaciers due to industrial pollution and other human activities underscores the urgent need for global action to mitigate climate change and its impacts.

Furthermore, the darkening of glaciers due to industrial pollution has far-reaching consequences beyond rising sea levels. As the glaciers retreat and snow cover disappears, larger areas of dark soil and ocean are exposed. This exposure further contributes to warming by absorbing more solar radiation, creating a positive feedback loop that accelerates warming and melting rates. The disruption of normal patterns of ocean circulation due to changing Atlantic Ocean currents has already been linked to the collapse of fisheries and more destructive storms and hurricanes worldwide.

Ice reflectivity

The reflectivity of ice is impacted by various factors, including pollution and the growth of glacier algae. Human-created and natural air pollutants, such as dust, soot, and black carbon, are darkening the ice and reducing its reflectivity. For example, dust from Africa and the Middle East, caused by worsening droughts and dust storms, has travelled thousands of miles and contributed to the darkening of snow and ice. This dust, along with soot from fires and ultra-fine particles of black carbon from the incomplete combustion of fossil fuels, absorbs heat and accelerates the melting of glaciers.

Glacier algae also contribute to the darkening of ice. As temperatures rise, glacier algae grow on melting ice surfaces, causing the ice to absorb more solar energy and melt faster. The growth of these algae further reduces the reflectivity of the ice and contributes to a faster melting process.

The reduction in ice reflectivity has significant consequences. As glaciers melt and disintegrate, more dark soil and ocean surfaces are exposed, absorbing more sunlight and causing further warming. This loss of ice also leads to expanded shipping and oil drilling in the region, worsening air and noise pollution, and increasing the risks of environmental disasters.

Scientists have observed a marked rise in the amount of solar energy absorbed by the planet, beyond what is expected from rising greenhouse gas levels alone. While falling pollution levels have contributed to clearer skies, the planet has become less reflective, indicating that other factors are at play. The complex interactions between pollution, cloud behaviour, and reflectivity continue to be studied by climate scientists to better understand their impact on global warming.

Climate change

Glaciers are large masses of snow and ice that have accumulated over many years and are present year-round. They are highly effective at reflecting solar radiation back into space, thereby cooling the planet. However, due to climate change, glaciers worldwide have been losing mass since at least the 1970s, with some records suggesting shrinkage as early as the 1950s. This loss of ice has led to an exposure of darker soil and ocean surfaces, which absorb more solar heat, further accelerating warming, disrupting climate patterns, and increasing flood and avalanche risks.

One phenomenon contributing to the accelerated melting of glaciers is "dark snow." From the Himalayas to the Arctic, glaciers are turning visibly darker as particles of fine dust, soot from fires, and "black carbon" from incomplete combustion of fossil fuels settle on the bright, fresh snow. This dark layer reduces the ice's ability to reflect sunlight, causing it to heat up and melt faster. American geologist Ulyana Horodyskyj observed this phenomenon on Mount Himlung on the Nepal-Tibet border, where the Khumbu glacier was turning dark as dust from bare soil and soot from fires accumulated.

Pollution, including soot from the Industrial Revolution, has also been implicated in the melting of Alpine glaciers. NASA scientists suggest that this pollution may have heated the ice, causing the glaciers to retreat even before temperatures started to rise. Additionally, as glaciers retreat and snow cover disappears, larger areas of bare soil are exposed, increasing the amount of dust in the atmosphere and creating a feedback loop that further accelerates melting.

The consequences of melting glaciers are significant. Glaciers are deeply intertwined with daily life, providing millions with water for drinking, agriculture, and hydroelectric power generation. The loss of glaciers leads to a disruption in these vital water systems, impacting both human civilization and natural ecosystems. Furthermore, as ice disappears, shipping and oil drilling activities expand, bringing with them increased air and noise pollution, as well as the risk of catastrophic oil spills and waste discharges.

To address the issue of darkening glaciers and the accelerating melting rates, urgent action is required from governments and increased awareness from the general public. By reducing air pollution, particularly soot and black carbon emissions, and mitigating the effects of climate change, we can help slow the disappearance of glaciers and the subsequent negative consequences on the environment and human societies.

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