• Question: what effect is the melting of the pola ice caps effecting the whole ecosystems of the seas and oceans?

    Asked by bubblesfish to Clare, Dave, Glo, Ozge, Sean on 15 Jun 2011.
    • Photo: Ozge Ozkaya

      Ozge Ozkaya answered on 14 Jun 2011:

      The melting of the polar ice cap caused my global warming will have several effects on the oceans such as acidification, oxygen depletion and rise in the sea level. The oceans take up the CO2 from the armosphere but too much CO2 causes acidification, and this in turn makes structures made of calcium carbonate like the exoskeleton of sea urchins crabs etc + corals vulnerable to dissolution. Oxygen depletion will also have adverse effects on marine life. It is quite difficult to summarise all the effects in a short paragraph but let me give you an example using krill which is the organism I work on. The ice cap acts as a nursery for krill and if the size of the ice cap is reduced there simply wouldnt be enough space for the krill to grow. Krill feed on phytoplanctons (algae) which bloom in spring. Global warming can cause the algal blood to happen too early, i.e. before the krill are developmetally ready to feed on them and if they miss the algal bloom they will not be able to make it to adulthood, this also will decrease krill numbers. Then all the other animals that rely on krill such as whales penguins fish squid etc etc will be affected. 🙁

    • Photo: Dave Sproson

      Dave Sproson answered on 14 Jun 2011:

      Hey Bubblesfish,

      This is a hard one to answer for many reasons. We’re pretty sure that the ice-caps are starting to melt due to man-made global warming, but this is in its early stages so it’s very difficult to predict how fast and how far these will melt. Although the melting is in its early stages, it’s likely to keep melting for a long time, even if we suddenly stopped emitting CO2, as the climate has a form of ‘inertia’ (meaning that it likes to keep moving in the same direction). It’s also important to distinguish between the forms of ice: Ice-sheets (which are on land in Greenland and Antarctica), ice-shelves (which is ice that formed on the land, but now mostly floats on the ocean, attached to land at one end) and sea-ice (which is simply where the sea has frozen). Each of these melting has a slightly different effect.

      Ice sheets melting cause the ocean to become more fresh (or less salty, if you like) which may have a direct impact on organisms, or may affect them by altering ocean currents on which they rely. The melting of ice sheets may also be the major cause of sea-level rise (extreme estimates put this at about 1 metre rise by the end of the century), which could be a major problem for some coral reefs which only like to live in a narrow depth range.

      Ice shelves melting won’t affect sea-level much, but will have a similar freshening effect as the ice sheets.

      Sea-ice melting doesn’t contribute much to either freshening (as it makes the ocean saltier to begin with when it freezes) or sea-level rise (as it was formed from sea water to start with) but when it melts it does make the planet appear ‘darker’ and so encourages it to warm up even faster which makes the ice sheets melt faster and so on (this is known as the albedo-feedback process). We also need to think about the poor polar bears which rely on the sea-ice in order to be able to hunt!

      I’d disagree slightly with Ogze in that I think that ocean acidification (while a very real problem) is a different one to ice-cap melting.

    • Photo: Clare Woulds

      Clare Woulds answered on 14 Jun 2011:

      On the subject of climate change probelms in general the other big one to mention, which is only just starting to be recognised, is the likely spread of low oxygen water. If you add fresh water to the surface of the water it floats. This means that the water does not get mixed so much by waves as the water at the surface stays at the surface. Less mixing means less oxygen from the atmosphere getting down to greater depths. If you warm the surface of the ocean the same thing happens (warm water floats). In addition, the warmer water is, the less easy it is for oxygen to dissolve in it. For all these reasons global warming is likely to lead to bigger areas of the seafloor where there isn’t much oxygen. this can change the chemistry of the sediments, cauing metals and nutrients to be released which may pollute the water. Also, of course, animals in the sea require oxygen to breathe, so reduction in oxygen concentrations may change the types of animals that are present.

    • Photo: Gloeta Massie

      Gloeta Massie answered on 15 Jun 2011:

      Bubblefish – a great and important question that I’m definitely not qualified to answer. However, I WILL, hopefully, be qualified to say what impact ocean acidification (which is a different, and from my perspective, far scarier result of climate change) has on cephies in three years. Email me then and I’ll let you know what I’ve found out! Until then – I defer to my colleagues.

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