Measuring the Arctic Ice and sea levels

If someone tries to tell you that the seas are getting cooler and not warmer and therefore global warming is a myth then here is some food for thought. During the last five or six years satellite observations of sea ice in the Arctic Ocean show that the sea ice is shrinking and it is getting thinner. NASA has analysed data that it has collected from its satellites and thinks that the sea ice has thinned on average by about seven inches a year and the area covered by all year round sea ice has reduced in the past six years by 45%.

These are big numbers. Observations also show that seasonal sea Arctic ice, which once averaged nine feet in thickness is now on average about six feet in thickness. For those of you who think metric, these figures are around two metres and three metres. The lessening of Arctic ice has had an effect upon sea levels. The seas are at different levels – there is no single sea level. Using average sea level can be misleading because a very high level in one part of the ocean can increase the average quite significantly.

You can understand this better if you imagine that there were nine hundred ninety nine people in a room and Bill gates walks in; his wealth will increase the average wealth of the people in the room in a way that distorts things beyond recognition. So, when considering sea levels it is better to consider the mean sea level, not the average sea level.

Until fairly recently sea level measurements were made by long tide gauge records which were then corrected for things like sedimentation (which increases land levels). These measurements have shown an increase in mean sea levels of somewhere between one and three millimetres each year. Ten years would bring maybe an increase of three centimetres – just over an inch. Nowadays scientists use Global Positioning Satellite readings from 227 stations to measure sea levels. GPS tells us that the yearly sea level rise is happening at 1.61 millimetres a year. We can cope with this for a few years but if we take a longer term view, there is the heightened possibility that as the Arctic ice melts and as the oceans expand as they warm sea.

Loss of arctic ice and increases in mean sea level show that the climate is warming. If you choose to believe or disbelieve that the warming is induced by human activity will not make any difference to the warming of the planet. The theory of global warming by human greenhouse gas emissions is the best theory we have at the moment.

What is clear beyond doubt is that our sea defences should be strengthened, otherwise we shall continue to suffer the consequences of flooding.

2 Responses

  1. Well stated.

    Climate change has been extensively researched and the overwhelming majority
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    unprecedented and is very likely caused by humans. Although there is little
    serious debate between climate experts, many in the general public still
    think that these scientists are unsure about climate change and the role
    that humans have played in modern day global warming. The Website above
    summarizes some of the key research that has led scientists to their
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    The only plausible explanation is that today’s warming is primarily due to
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    • Thank you.

      You are right about the overwhelming consensus, but it still remains unproven in absolute terms, but so many things are unproven. In these matetrs we cannot deal in absolute truth – that path leads to madness. we must deal in probabilities, just as we do in every other aspect of our ordinary everyday lives.

      I think that it is the rate of climate change that is man made; there has always been climate change, but neevr at this rate.

      The issues do not just relate to changing climate. there is air pollution, ground pollution, water pollution (all caused by fossil fuel energy use) and the finite availabilty of fossil fuel. These are aslo good reasons for changing our ways.


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