It’s my pleasure to welcome another guest writer to Hot Topic â€” Peter Barrett, professor of geology at Victoria University, deputy director of the Climate Change Research Institute and former director of VUW’s Antarctic Research Centre. He is also convener of the ANDRILL science advisory panel. Last week, the Dominion Post carried this challenging article from Peter, and as it is not available at the DP web site, he has kindly agreed to allow it to appear as a guest column here. I hope it won’t be the last.
The world economy appears to be heading into the worst recession in 60 years. The nominal wealth of global markets has almost halved in the last couple of months and the United States Government alone is shoring up its banking system with $US7.6 trillion. Commentators expect conditions will be difficult in the next few years and say we need to get the fundamentals right.
Severe downturns have happened before and our society has recovered. Each time, confidence and perception of wealth has grown to exceed tangible assets and credible wealth by a big margin, and the illusion could not be sustained. Each time we had to go back to the fundamentals.
At same time the global ecosystem has suffered from economic growth and rising population. The United Nationâ€™s Millennium Ecosystem Assessment of 2005 found that more than 60 percent of the Earthâ€™s ecosystem services were degraded by overuse and pollution. The importance of ecosystem services to our economic and social well being is now understood as fundamental, though progress is slow.
On top of this, changes in Earthâ€™s climate are now compounding both economic and ecosystem crises. Estimates based on our current knowledge of the climate system show Earth is now absorbing more heat from the Sun than it is emitting back into space. Direct observations of ocean warming to depths of 3 km account for about 60% of the excess – the rest is warming the surface. This increasing warmth is the fundamental driver behind climate change. The graph shows annual average global temperature based on measurements from thousands of recording stations around the world over the last 150 years. The increase is only about 0.8ÂºC, though this figure hides the fact that continents are warming substantially faster than oceans.
Sceptics say Earth has been cooling since 1998, but this claim rests on the single high value for that year. The scatter of annual measurements (circles in graph) shows how annual measurements fluctuate due to changes in cloud cover, wind patterns, ocean upwelling and currents that move heat around the planet in complex patterns. Climate change is only meaningfully identified from averages over decades. This shows that Earth recently has been warming persistently.
Greenhouse gases have been the subject of scientific research for more than a century. We know that they warm the planet and, without them, the Earthâ€™s average temperature would be a freezing -18Â°C. Evidence for rising greenhouse gases leading to further warming has been reviewed many times over two decades. It is also obvious from melting glaciers and rising sea levels.
The most comprehensive is the 2007 Assessment of the Intergovernmental Panel on Climate Change (IPCC). This concluded that our climate is changing largely as a consequence of rising greenhouse gases released by human activities. Both the observed temperature rise and the patterns it shows are those expected from known physics. Some still insist the sun is behind the observed warming, but that this cannot explain the lack of change in the past three decades, when temperature has risen most.
The basic conclusions of the IPCC have now been endorsed by all the major national science academies. We have yet to agree on solutions, but two simple principles stand out – shifting away from fossil fuels and returning CO2 from the atmosphere to Earth as fast as possible.
This also makes sense from a geological perspective. The coal, oil and gas that fueled industrial growth accumulated over hundreds of millions of years at times when Earth had much higher temperatures and 4 to 8 times pre-industrial CO2 levels. We are returning this carbon to the atmosphere in centuries.
If we do not stop carbon emissions rising in the next few years, the consequences will be with us for many generations. Carbon dioxide, unlike methane, remains in the atmosphere for hundreds of years to heat the earth. Most governments are now heeding such messages.
As President-elect Obama said last month: â€œDelay is no longer an option. Denial is no longer an acceptable response. The stakes are too high. The consequences, too serious â€œ Governments and communities should now be focussing on getting the fundamentals right for not only the economy but also climate change. Markets recover in a few years â€“ climate takes millennia.