There has been much media interest in recent times over the melting of the polar icecaps, both Arctic and Antarctic, and this has raised questions in many people’s minds as to what is really happening to our planet – so what is the effect of the melting polar ice on climate change?
Climate change is an extremely complex subject with many different factors to take into consideration. Alteration of one factor of the global climate affects another – sometimes in ways which we do not yet fully understand.
It is known, however, that the polar ice caps have an effect in a number of different ways on global climate. Firstly, there is the reflective quality that ice and snow have. This ability to reflect solar energy means that a proportion of the sun’s energy is reflected back into space instead of being absorbed by the surface of the Earth, the percentage of global solar energy reflected back by the ice and snow cover on the Earth being known as the albedo. On a very simplistic level, the more solar energy that is reflected back, the lower the mean surface temperature of the Earth as a whole (known as the Global Mean Surface Temperature or GMST).
So the ice and snow cover plays a part in maintaining the balance of the planet’s temperature. This means, therefore, that any reduction in ice and snow cover causes the Earth to reflect back less solar energy and this may lead, in conjunction with other aspects of the climate, to an increase in temperature globally. This increase in temperature then triggers further loss of snow and ice, which in turn causes another increase in temperature, creating a cycle of imbalance.
A less obvious consequence of the loss of the polar icecaps is the possible change to the deep ocean currents that are powered by temperature and salinity differences between one area of the ocean and another. Cold water is denser than warm water and sinks below it. This difference in density causes a natural current in the deep oceans between warmer water from the equatorial regions, which moves across the upper ocean towards the polar regions, and the colder, denser water that sinks below it flowing away from the poles towards the equator. This natural mechanism brings warmer water to higher latitudes, by way of the North Atlantic Drift for example, helping to maintain a temperate climate on land masses further away from the equator.
There is a danger that with the melting of the polar ice caps and the resulting warming of the waters at the poles, this natural pump will slow down or cease altogether. There is the added problem of polar melt diluting the ocean waters and lowering salinity, thereby reducing yet more the density of the water. This further inhibits the polar waters sinking below the warmer layers of water which are travelling away from the equator and towards the poles.
The slowing or stopping of the natural deep ocean currents could lead to cooling of the higher latitudes, both to the north and south of the equator, triggering significant climate change.
Another effect on the climate of the melting of the ice caps is the increase of water vapour in the atmosphere as a consequence of warmer temperatures. Although it is widely advertised that carbon dioxide is a major greenhouse gas, the media does not dwell on the fact that water vapour is a contender in the equation too. Any rise in the level of water vapour in the atmosphere, caused by an increase in the GMST, leads to further trapping of the Earth’s heat by the atmosphere, creating further imbalance.
In conclusion, the melting of the polar ice caps has a significant part to play in the changing climate of the Earth and is the subject of much current scientific research internationally.