[Global] Climate change is speeding up dramatically because of red snow, according to new research.
Algae living on Arctic glaciers are turning the surface crimson reducing their ability to reflect sunlight.
And it is creating a vicious circle – particularly on the Greenland and Antarctic ice sheets – as the extra meltwater fuels the growth of more microbes.
The phenomenon has not been factored into climate models and ignoring it risks ‘underestimating rates of warming and consequent sea level rise,’ said biologist Professor Roman Dial from Alaska Pacific University.
Red snow as ‘dark as red port’ was first discovered 200 years ago in the fabled North-West Passage – a treacherous ice-bound sea route linking the North Atlantic to the Pacific via the Arctic Circle.
But it’s effect on global warming through the acceleration of thaw is only now coming to light.
Experiments on an Alaskan ice field showed red snow increased melting by almost a fifth.
It is caused by a cold-loving, fresh-water algae known as Chlamydomonas nivalis that contains a scarlet pigment.
Also known as ‘watermelon snow’ it’s common during summertime along coastal polar regions – as well as high alpine areas.
But the snow-dwelling microbes could substantially speed up glacier melt by making the surface darker and decreasing its reflectivity.
This in turn encourages the growth of more algae, according to the study published in Nature Geoscience.
Professor Dial said although fresh white snow reflects most sunlight impurities such as black carbon and dust can darken the surface.
This dirty snow increases glacial melting as the snow warms more easily.
The specialised algae living on glaciers have a similar effect as they change the snow to red – making it darker than unaffected landscape.
Professor Dial, of Alaska Pacific University in Anchorage, said: ‘This study highlights the substantial impact of red-snow communities on glacier melt at high elevations and latitudes.
‘Experimental results presented here, together with previous correlative observations, laboratory experiments and theoretical calculations provide a compelling case for the magnitude of the glacier microbiome’s effect on hydrology and climate.’
In the study Professor Dial and colleagues added nutrients and water to different areas of snow on an Alaskan glacier.
Compared to a control area left undisturbed there was about 50 per cent more algae when water was added – and almost four times as much when the fertiliser called nitrogen-phosphorous-potassium was included.
Using data from satellites to estimate snowmelt across an area of 1,180 square miles (1,900 sq km) they showed red-snow algae increased melting by about 17 per cent.
‘The red-snow area extended over about 700 sq km (435 sq miles) and in this area we determined microbial communities were responsible for 17 per cent of the total snow melt there’, said Professor Dial.
He said as the areas of algae-covered red snow generate more meltwater this could lead to a feedback of more microbial growth and glacial melting.
Due to their red pigmentation the algal blooms change their ‘albedo’ – the amount of light reflected off the surface of an object.
Just as black concrete is much hotter than pale glaciers covered in red absorb more light and melt at a faster rate.
This sets off a chain reaction of additional melting as the meltwater creates a habitat for algae to colonise and low-albedo rocks and dirty ice underneath glaciers are exposed.
‘A lack of liquid water limits life on glaciers worldwide but specialised microbes still colonise these environments’, said Professor Dial.
‘These microbes reduce surface albedo which in turn could lead to warming and enhanced glacier melt.
‘Our results support hypotheses snow-dwelling microbes increase glacier melt directly in a bio-geophysical feedback by lowering albedo and indirectly by exposing low-albedo glacier ice.’
Two things keep the Arctic ice sheets stable – one is the temperature and the other the albedo or reflectivity of the ice.
‘Given an upward-elevation shift with warming, algae will increase most rapidly across flat, snow covered topography, such as Greenlandic and Antarctic ice sheets, regions with critical albedo effects on global climate’, said Professor Dial.
‘Worldwide ash from biomass burning and dust from agricultural regions are increasingly deposited on these high-latitude ice sheets.
‘This airborne nutrient input – together with growing meltwater availability – will certainly increase the glacier microbiome’s impact on polar albedo.
‘Climate and melt models that ignore the ecology of microbial radiative forcing risk underestimating rates of warming and consequent sea level rise.’
Red snow was first reported by Captain John Ross’s 1818 expedition through the Northwest Passage.
He said there were patches or streaks across snowfields some of which was ‘so dark a red as to resemble red port wine.’
Photo: Algae living on Arctic glaciers (pictured) are turning the surface crimson – reducing their ability to reflect sunlight. Also known as ‘watermelon snow’ it’s common during summer time along coastal polar regions – as well as high alpine areas
View original article at: ‘Red snow’ created by microbes is supercharging climate change by causing glaciers to melt faster