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Climate Change: Nothing New

It seems that everyone is now alive to the issue of global warming (all except the governments of Brazil and the USA), and the blame sits squarely on us for pumping too much carbon dioxide into the atmosphere. For some, to argue any differently amounts to environmental heresy, but is this the full picture?

There is little doubt that over the last 150 years global temperatures have risen:

Climatechange1

Source: Antarctica.org

What stands out is the pace of change. The rate of temperature rise is increasing. At the same time CO2 emissions have increased exponentially as the human race has burned increasing amounts of fossil fuels; see below:

Climatechange2

Source: Global Climate News

So, climate change is human induced. The correct term is anthropomorphic change.

But is this the case? Is it the whole story?

In fact, climate change is not a recent phenomenon. Cycles of warming and cooling appear to be the norm. Have a look at this set of stats:

Climatechange3

Source: Guy Midgley (National Biodiversity Institute South Africa)

Over the past 500,000 years, there have been warmer and cooler periods which coincide with increased levels of methane and CO2 in the atmosphere which was not anthropomorphic. Research also shows that the rate of change from warmer to cooler periods was relatively rapid.

Other factors are at play. A review of the Milankovitch cycles tells us that the amount of solar radiation reaching the earth is variable and this has a major impact on global temperatures, particularly in the northern hemisphere.

We live in the Holocene Period, which some believe to be an interglacial period. During this period temperatures have been relatively stable by comparison.

Climagechange4

Source: Central Greenland Ice Core Records

So, what do we make of this record? Even in the last 8,000 years global temperatures have been higher than they are today. It suggests that climate change is not simply the result of human activity. It also suggests, to me at least, that our knowledge of how the global climate works is still limited.

Does it mean that we should take the view adopted by Trump amongst others that we don’t have to reduce carbon emissions because they are not causing climate change?

No, it doesn’t.

  • Increased emissions of greenhouse gases are probably the cause of the latest temperature rise.
  • Increased emissions of CO2 will exacerbate any changes that are occurring naturally.
  • They are a major contributing factor in the acceleration in the rate of change of temperature.
  • In any case we should not be pumping pollutants into the atmosphere on the scale that we do not only for the sake of our health but also the broader health of the global environment.

Drastically reducing greenhouse gas emissions should slow down the rate of global warming. Whether it would stop it altogether, however, depends on what other factors are at play.

By Phil Brighty

Former Geography Teacher

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