It is sobering to realise that over the past 100 years, humans have burned approximately 1,800 billion barrels of oil, 377 billion tonnes of coal, 150,000 billion m3 of gas1 and cut down 46 per cent of all trees on earth2.
by Jacqueline Balston, Director of Sustainability and David Jenkins, CEO IPWEA Australasia
As a result, 1.5 trillion tonnes of CO2 have been released into the atmosphere since 17513 and levels are now higher than at any other time in the past 800,000 years - and rising rapidly. Added to the CO2 are the emissions of other greenhouse gasses including methane and nitrous oxide.
Most of us are now well aware of the effect that these increased levels of greenhouse gasses have in the atmosphere. As they trap solar heat close to the surface the result is an increase to average and extreme temperatures, cyclone intensity, humidity and rainfall (especially in the tropical regions). In the drier mid-latitudes the frequency and severity of drought and bushfire are increased. And in the oceans, CO2 forms carbonic acid and reduces the pH of the water, the warmer water expands, land-based ice caps and glaciers melt, and the sea level rises. Evidence for all these changes is now well documented and the impacts on infrastructure are increasing.