Pretty much everybody one talks to these days believes that climate change is a man made phenomenon.  However, there are those who believe that global warming is part of a natural process that has been around since the beginning of the Earth’s four or so billion year history.  They point out that the warmest periods in the last 10,000 years happened well before the industrial revolution and man’s production of large amounts of carbon dioxide. 

In medieval times temperatures in Europe were significantly higher than today.  The “Medieval Warm Period” or “Medieval Climate Optimum” as it is known was a time of unusually warm climate in the North Atlantic region, lasting from about the tenth century to the fourteenth century.  This was followed by “The Little Ice Age”, a cooler period which lasted from around the sixteenth to the mid nineteenth century.  The Little Ice Age brought bitterly cold winters to many parts of the world, but is most thoroughly documented in Europe and North America.  In the mid-17th century, glaciers in the Swiss Alps advanced, gradually engulfing farms and crushing entire villages. The River Thames and the canals and rivers of the Netherlands often froze over during the winter, and people skated and even held frost fairs on the ice. The first Thames freeze was in 1607; the last in 1814, although changes to the bridges and the addition of an embankment affected the river flow and depth, hence the possibility of freezes.  In more recent history, the temperature rose prior to 1940 but unexpectedly dropped in the post-war economic boom, when carbon dioxide emissions rose dramatically.

In the greenhouse model of global warming, heat from the sun's rays is trapped by greenhouse gases in the atmosphere.  If it weren't for these gases, Earth would be too cold for life.  Too much, however, and temperatures continue to rise with catastrophic consequences.  Advocates also argue that carbon dioxide isn't the only greenhouse gas and that human emissions could tip up a finely balanced system.

Those who think global warming is a natural phenomenon point to the fact these dramatic swings in temperature coincide with both solar and volcanic activity.  During the period 1645–1715, right in the middle of the Little Ice Age, solar activity as seen in sunspots was extremely low, with some years having no sunspots at all.  Throughout the Little Ice Age, the world also experienced heightened volcanic activity.  When a volcano erupts, its ash reaches high into the atmosphere and can spread to cover the whole earth. This ash cloud blocks out some of the incoming solar radiation, leading to worldwide cooling that can last up to two years after an eruption.  Also emitted by eruptions is sulfur in the form of SO2 gas.  When this gas reaches the stratosphere, it turns into sulfuric acid particles, which reflect the sun's rays, further reducing the amount of radiation reaching the earth's surface.  The 1815 eruption of Tambora in Indonesia blanketed the atmosphere with ash; the following year, 1816, came to be known as the “Year without a summer”, when frost and snow were reported in June and July in both Northern Europe and North America.

There are huge amounts of scientific and anecdotal evidence to support both viewpoints and everyone would agree that we cannot afford to gamble with the future of our planet.  But I for one can’t help but feel there is another agenda when listening to the likes of London’s deputy Mayor Nicky Gavron at the recent CIBSE National Conference 2007, using the words “taxation” and “big stick” when outlining the GLA’s Climate Change Action Plan.

There is no doubt that this position will generate lots of work for our industry (the bandwagon is already well and truly on the move) but surely the way forward is legislation to encourage innovation, not prescriptive measures and taxation.

The Kyoto agreement and more recently the Bangkok “Climate Change Road Map” have little appeal to the developing nations.  To quote a respected Kenyan development expert “I don’t see how a solar panel is going to power a steel industry or a railway network. There is somebody keen to kill the African dream, and the African dream is to develop. We are being told don't touch your resources, don't touch your oil, don't touch your coal; that is suicide.”