Glaciers. Conjures up visions of gigantic structures lifeless and
immovable. But actually they are teeming with life. Microbial organisms of an
amazing variety thrive and grow in glaciers. This is the story one of these.
Cyanobacteria or blue-green algae are single-celled organisms. They are visible when they
grow in colonies and are found in Himalayan, Alaskan and Arctic glaciers.
They rank among the oldest of fossils found on earth and have played a
major role in the evolution and ecological changes on our planet. Heard of chloroplast
with which plants make their food? This is actually a cyanobacterium living in
But now these little heroes are being
labelled as villain number one. Why? Because they have been found guilty of contributing
to that dreaded phenomenon global warming. Here is how they do it.
Albedo in algae triggering global warming?
You must have read about rising global temperatures and of climate change, that have
created panic amongst the scientists across the world. According to them, carbon
particles, a dusty by-product of incomplete combustion of fossil fuels has been
responsible for 25 per cent rise in global temperatures since 1880. The dark soot found on
glaciers is nothing but the "dark coloured" bacteria that we are talking about.
The cyanobacteria grow on the ice by trapping organic materials like
carbon dioxide, and a dark-coloured algal mat is formed. This drills holes into the
glacier, by melting it. Glaciers are normally not nutrient-rich. But these holes provide
an aquatic habitat for the algae and bacteria living on them.
Glaciers reflect sunlight back into the atmosphere and remain immune to
the heat. The algal mat covering the Himalayan and Alaskan glaciers reduces surface albedo
that is, the capacity of the glacier to reflect radiation or sunlight. Result? The
snow melts at a much faster rate
and the glacier dissolves slowly but steadily.