Air samples show build-up of CO2

THE world's oldest library of airsamples has recorded the biggest increases in atmospheric carbon dioxide since sampling began in 1978.
CSIRO air librarian Paul Fraser said the levels of the primary greenhouse gas have been growing at an increasing rate each year since 1978 and may reach an annual increase of two parts per million by the end of this year.
Global CO2 levels have increased from 340ppm to 380ppm in the past 30 years due to combustion of fossil fuels.
Mainstream climate scientists argue the world needs to stabilise levels to around 450ppm by 2050 to avoid the catastrophic impacts of climate change.
Dr Fraser said while the library had revealed CO2 emissions had grown by 70 per cent a year since the 1970s, methane emissions had stabilised in the past seven years.
To find this data, the CSIRO captures a 40km-long sheet of clean air from the Southern Ocean as it blows through Cape Grim on the rugged northwest coast of Tasmania.
Dr Fraser said the recording instrumentation was so sensitive that samples could be contaminated by the gases released by ships beyond the horizon.
"We sometimes collect tanks and find that they are a bit strange and the assumption is that something has got into the airstream that we weren't aware of," Dr Fraser said.
"You could have a drop in the wind and the local vegetation could impact on it, or maybe cows - so we like to keep the wind speed nice and high and the wind direction off the ocean."
Wind is sampled each season and stored in pressurised cylinders at the CSIRO Marine and Atmospheric research centre near Melbourne, where it is analysed for both greenhouse and ozone-depleting gases.
While long-term trends are relatively stable, Dr Fraser said there was some natural variation as a result of El Nino and La Nina weather patterns and natural events such as the eruption of Mount Pinatubo in 1991 and the Indonesian bushfires in 1998.