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In last week’s we celebrated Russia’s ratification of the Kyoto Protocol.  We continue this theme with a number of articles on climate change; firstly asking what is the evidence behind the phenomenon of climate change.

Scientists agree that the global climate is slowly changing; in most areas temperatures are rising, thus there has been mention of global warming.  But on realizing there has been decrease of temperatures in some other areas, scientists now have a preference of referring to climate change rather than global warming.  The bone of contention has been on whether this change is anthropogenic, i.e. caused by man, or is part of a natural cycle and that the earth will revert to its normal climatic conditions.

It is worth mentioning that there are two things we are sure of as far as climate change is concerned.  One is that there is an increase in the concentration of "greenhouse gases" (known as greenhouse gases (GHGs), because they trap heat like glass on a greenhouse in the atmosphere), and two is that these gases are capable of trapping heat that would otherwise escape to space.  Logic demands that we accept therefore that there will be an increase in the heat that is trapped within our atmosphere and thus the globe is bound to warm up.

So why is this happening?  To maintain a steady temperature, the earth must shed energy into space at the same rate at which it absorbs energy from the sun.  Gases in the earth’s atmosphere help regulate the amount of energy and heat that enter into and escape from the earth’s atmosphere.  Most of the emitted infra-red (energy from the earth) is absorbed in the atmosphere by water vapour, carbon dioxide and other naturally occurring GHGs.  This process prevents energy from passing into space. 

The process of energy being trapped by these greenhouse gases is a fortunate happening for us otherwise the earth would be a cold, lifeless place.  Without the blanket of GHGs the earth would be 30oC colder than it is today. 

What is regrettable is that human activity is thickening this blanket and thus disturbs the way climate maintains this balance between incoming and ongoing energy.  The burning of coal, oil and natural gas results in the release of CO2.  Deforestation also helps in the increase of CO2 in the atmosphere, as trees act as sinks for CO2 and methane.  Cattle especially in concentrated farms also emit methane, N2O and other gases.

If the current trends prevail we should expect a global warming of 1.4 - 5.8oC over the next 100 years.  It is hard to predict how we will be affected, but we expect changes in wind and rainfall patterns.  Sea levels are expected to rise threatening islands and low lying coastal areas.  We will deal more with the effects of climate change in next week’s column.