December 7, 2016
Dr Peter Barrett published his first article on the potentially “unstoppable and catastrophic” effects of climate change on Antarctica in the NZ Listener in 21 February, 1981. This came after almost two decades of research on the ancient coal-bearing strata of the Transantarctic Mountains, and a decade drilling for Antarctica’s past climate history coring strata off the Victoria Land coast.
Peter explained how further drilling has shown that Antarctica’s ice sheet first formed around 34 million years, as atmospheric CO2 levels declined from 800+ parts per million in the “Greenhouse World”, cooling global temperatures. A further decline below 400 ppm 2-3 million years ago led to further cooling and the Ice Ages, with ice sheets in the Northern Hemisphere as well as Antarctica.
Antarctica has been over the South Pole for around 130 million years, and for most of that time, pretty much ice-free and subtropical around the margins, he says. Cooling over the last 50 million years occurred mainly because of mountain building and weathering that soaked up CO2, and through swamps and forests, which also take CO2 out of the atmosphere.
But, says Peter, human activities now emit CO2 into the atmosphere a million times faster than it is sequestered. Each doubling of atmospheric CO2 levels leads to an increase of around 3°C, or possibly more with feedbacks.
CO2 from fossil fuel use causes about 80% of the current temperature rise, and is the most influential greenhouse gas because it persists for thousands of years. Methane, which comes from natural gas seeps and ruminant animals, is more powerful, but levels are much lower and it decays in 10 years.
We now know there is 57 metres of potential sea level rise tied up in the Antarctic ice sheet. Warming ocean currents are bathing the margins and melting the ice since the 1990s at an increasing rate.
The good news, Peter says, is that we can choose not to let this continue by reducing our own carbon footprint and voting for leaders who support carbon reduction policies. We can also talk to friends and climate sceptics about taking this seriously, as he does most Wednesday evenings in the pub. At a national level there are many opportunities for reducing carbon emissions with renewable energy, technology and disinvestment in fossil fuels, and this is already happening world-wide.
The key goal is to reach zero carbon emissions by 2050. This is a fundamental message of a film he helped produce in 2013, available on www.thiniceclimate.org. It’s also a current campaign for 2017 by young Kiwis – see www.generationzero.org/zero_carbon_act.