BU Economics Professor Pierre Perron and global warming

By: Courtney Sullivan
November 10, 2013

In the last couple of hours, BU Economics Professor Pierre Perron has generated a few more cites, this time in different outlets than usual — National Geographic, Mother Jones, Climate News Network, and the BBC to name a few. His paper, Statistically derived contributions of diverse human influences to twentieth-century temperature changes, coauthored with Francisco Estrada and Benjamin Martinez-Lopez was published earlier today in Nature Geoscience. The abstract of the paper will give you some idea why it has attracted so much attention so quickly:

The warming of the climate system is unequivocal as evidenced by an increase in global temperatures by 0.8 °C over the past century. However, the attribution of the observed warming to human activities remains less clear, particularly because of the apparent slow-down in warming since the late 1990s. Here we analyse radiative forcing and temperature time series with state-of-the-art statistical methods to address this question without climate model simulations. We show that long-term trends in total radiative forcing and temperatures have largely been determined by atmospheric greenhouse gas concentrations, and modulated by other radiative factors. We identify a pronounced increase in the growth rates of both temperatures and radiative forcing around 1960, which marks the onset of sustained global warming. Our analyses also reveal a contribution of human interventions to two periods when global warming slowed down. Our statistical analysis suggests that the reduction in the emissions of ozone-depleting substances under the Montreal Protocol, as well as a reduction in methane emissions, contributed to the lower rate of warming since the 1990s. Furthermore, we identify a contribution from the two world wars and the Great Depression to the documented cooling in the mid-twentieth century, through lower carbon dioxide emissions. We conclude that reductions in greenhouse gas emissions are effective in slowing the rate of warming in the short term.

In short, time series econometrics shows that human activity in the form of reducing greenhouse gas emissions affects global temperatures. You can find the full article at http://www.nature.com/ngeo/journal/v6/n12/full/ngeo1999.html?WT.ec_id=NGEO-201312.

In addition to BU Today’s story, Montreal Protocol Has Slowed Global Warming, various news outlets have also covered the study and its implications.

http://www.nature.com/news/ozone-hole-treaty-slowed-global-warming-1.14134

http://www.bbc.co.uk/news/science-environment-24874060

http://www.theaustralian.com.au/higher-education/cfc-ban-slowed-global-warming/story-e6frgcjx-1226756101628

http://carbonbrief.org/blog/2013/11/did-the-montreal-protocol-cause-the-surface-warming-slowdown/

http://www.climatenewsnetwork.net/tag/montreal-protocol/

http://www.sciencemediacentre.co.nz/2013/11/11/did-saving-the-ozone-layer-pause-warming/

http://phys.org/news/2013-11-ozone-pact-cool-planet.html

http://www.climatecentral.org/news/ozone-treaty-accidentally-slowed-global-warming-study-16726

http://www.globalpost.com/dispatch/news/afp/131110/ozone-pact-helped-cool-the-planet

http://www.motherjones.com/blue-marble/2013/11/cutting-emissions-really-does-slow-global-warming-study-finds

http://news.sciencemag.org/climate/2013/11/scienceshot-ban-ozone-destroyers-slowed-global-warming