Carlin Economics and Science

On August 2, 2011 Professor Murry Salby, Chair of Climate Science at Macquarie University in Australia with visiting professorships at Paris, Stockholm, Jerusalem, and Kyoto, made a presentation entitled Global Emission of Carbon Dioxide: The Contribution from Natural Sources showing that changes in atmospheric CO₂ levels appear to be primarily related to natural temperature changes, not human CO₂ emissions. A summary by Jo Nova can be found here. As she puts it, “It’s not just that man-made emissions don’t control the climate, they don’t even control global CO₂ levels.” Salby analyzed the annual variations in atmospheric CO₂ levels as measured at Mauna Loa with temperatures and found a strong correlation. The largest increases year-to-year occurred when the world warmed fastest due to El Nino conditions. The smallest increases correlated with volcanoes which pump dust up into the atmosphere and keep the world cooler for a while. In other words, temperature controls CO₂ levels on a yearly time-scale, and according to Salby, man-made emissions have little effect. These findings appear to further support the conclusions reached in Section 2.2 of my recent paper summarizing climate change science and economics and the idea that natural global temperature changes such as those due to ENSO and volcanoes are the main drivers of global atmospheric CO₂ levels, not human emissions.