The Chemistry of Snow - by Christoper Boxe

This graphic illustrates the path of ozone-damaging molecules at Earth’s poles. Image credit: NASA-JPL

Remember the warning to beware of yellow snow? Well, what’s true in your backyard is true on a much larger scale too. (For those from warmer climates, yellow-tinted snow is a sign that a dog or other animal has recently “paid a visit.”)

Snow at Earth’s north and south poles can also be tainted. Certain molecules — ones that can eventually damage our protective ozone layer in the stratosphere, affect the air down in the troposphere where we live, and possibly contribute to climate change — are being deposited into the snow.

Just how is this happening? Start with the fact that air at lower latitudes circulates toward the poles. This air carries ozone-damaging molecules picked up in industrial, highly populated areas. Once over the poles, some of these molecules are deposited onto the snowpack, where they migrate to thin liquid films in snow. Once sunlight hits the snow, the light energy breaks down these molecules, which are then released back into the atmosphere, giving the area over the poles a double hit of ozone-damaging molecules.

Scientists are finding that snow has unique properties that make these chemical reactions happen much faster than we used to believe. We don’t fully understand why this is happening, but we know that the mixture of sun (an energy source) and snow bring about the release of these ozone-damaging molecules into the atmosphere much faster than in areas without snow.

Many of the polluting molecules that remain in the snow eventually get incorporated in the polar food chain. When the snow melts into the sea, the molecules may be ingested by sea creatures. Not all of them are unhealthy, but some of them are.

Why care about reactions going on in distant, frozen expanses at Earth’s poles? Those regions are a beacon of climate change, where we see chemical processes that may play a large role in the planet’s future.

    6 Responses to “The Chemistry of Snow - by Christoper Boxe”

  1. Jerome Says:
    August 25th, 2008 at 9:32 am

    Melting polar ice-caps has gotten a lot of press lately, but tainted polar ice caps are a potential more dangerous threat! Hopefully someone more influential than I am is reading this post.

  2. johnny Says:
    September 2nd, 2008 at 11:06 am

    It is undersood that the chemical makeup of planet earth is under attack. everybody must ride a bike at least once a week to help save the planet! how bout we plant some carbon eating, floating bacteria/plants across a wide swath of the ocean to help clean up the air!

  3. Kathy Says:
    September 6th, 2008 at 7:53 am

    I believe we as a species are too insignificant to effect this planet greatly. I wonder who caused the global warming 10,000 yrs ago? How about a million yrs ago? Better yet 10,000,000 yrs ago!!

  4. brian Says:
    September 17th, 2008 at 6:09 am

    There is no doubt that global warming cycles have been a naturally accuring event thru-out the years. However to say that we, (humans) as an influence to that effect are insignificant is incorrect. Thats a fact. If there is debate it would be whether our influence is powerful enough at this point in time to accelerate the intensity of the global warming cycle in a relatively short period of time to a point at which our planet will not recover. This I believe to be True. Time to wake up and treat the health of our world with the respect it commands. After all…, Where we gonna go!

    Boxe says:

    As stated by commenter 4, the scientific debate and question is the degree to which
    humans are contributing to global warming compared to all contributions of natural
    forcing (i.e., both external and internal natural variability on Earth) - that is the
    debate and question to quantify. In other words, although past warming cycles were due to natural causes, the current warming cycle, which, to some degree, is linked to natural causes, is also linked to human-induced forcing (i.e., greenhouse gas emissions, such as CO2). Below, is detailed information from one of NOAA’s web-links:

    It is a user-friendly link that goes over the past warming cycles on Earth and (to the best of our knowledge) what has likely contributed to those warming cycles.

  5. johnny Says:
    October 16th, 2008 at 9:29 pm

    This theory of the winds dissipating as a effect of global warming, or currents will be reduced with which carries the moisture from one point on earth to another point, is an indication of what is to come. This should show a change in the future, or disguise the situation of the globe.

  6. Reader Says:
    January 27th, 2009 at 11:24 am

    Great! Thank you!
    I always wanted to write in my site something like that. Can I take part of your post to my site?
    Of course, I will add backlink?

    Regards, Timur Alhimenkov

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