- 29 Feb 2020
- 2 min read
Why in News
The phenomenon of “red snow” or “watermelon” has been observed over the last few weeks around Ukraine’s Vernadsky Research Base, off the coast of Antarctica’s northernmost peninsula.
- The snow is red because of a red-pigmented, microscopic algae called Chlamydomonas nivalis chlamydomonas, which thrives in freezing water as the ice melts.
- This phenomenon has been known since ancient times but now it raises concerns about climate change.
- Aristotle is believed to be one of the first to give a written account of red snow, over 2,000 years ago. He attributed the redness of the snow to the colour of worms and grub (larva of an insect), which are found in long-lying snow.
- According to modern-day scientists, it is an algae species, Chlamydomonas nivalis chlamydomonas which exists in the snow in the polar and glacial regions and carries a red pigment to keep itself warm.
- Algae contain chlorophyll (green pigment) as well as a red carotene layer in their cells which mixes with the green colour to cause snow to look like “raspberry jam”.
- This layer is also said to protect the algae from ultraviolet radiation.
- These algae change the snow’s albedo (the amount of light or radiation the snow surface is able to reflect back).
- The intensity of the redness increases with the dense presence of the algae. The darker tinge leads to more absorption of heat by the snow. Subsequently, the ice melts faster.
- The melting is good for the microbes that need the liquid water to survive and thrive but it is bad for already melting glaciers.