is little remaining doubt that human activities since the mid 19th
century have played a significant role in climate change by overloading
the atmosphere with carbon dioxide, hence retaining solar heat that
would otherwise radiate away.
300 parts per
million ( p.p.m.) is a healthy level of CO2 in the atmosphere, and
measurements from ice cores show a CO2 level of 280 p.p.m. before
the industrial revolution. In 2005 atmospheric levels of CO2 were
379 p.p.m., higher than at any time in the past 650,000 years. 11
of the 12 warmest years on record were in the last decade ( 1995
– 2006 ) and so the trend continues into the 21st century.
The global carbon dioxide in 2006 neared 32 billion tons, equivalent
to 15% of the millions of years worth of carbon locked up in the