Jochem Marotzke, director of the Max Planck Institute for Meteorology in Hamburg, Germany, will present the 2015 Henry W. Kendall Memorial Lecture on Wed., April 15, at 5 p.m. in the Wong Auditorium (Room E51-115).
Marotzke’s talk is titled “Recent Global Temperature Trends: What do they tell us about anthropogenic climate change?” He will discuss the implications of the recently-observed slowdown in global warming, often referred to as a warming “hiatus.”
Observations suggest a hiatus in global surface-temperature rise since 1998, whereas most climate model simulations suggest continued warming. The gap between observations and simulations raises a number of questions: What causes this difference? Do climate models respond too sensitively to the increase in greenhouse-gas concentrations such as that of carbon dioxide, and thus overestimate climate change systematically? Or has the discrepancy arisen by chance? And what is the relevance of this discrepancy for the assessment of long-term anthropogenic climate change?
Marotzke’s lecture will first illustrate the physically fundamental manifestation of anthropogenic climate change — increasing ocean heat content in relation to rising greenhouse-gas concentrations. This increase in heat content has gone on unabated for at least the past 40 years.
He will then show that differences between different model simulations — and hence, also differences between simulations and observations — are dominated by chance events when temperature changes over periods as short as 15 years are considered. By contrast, it matters little whether models respond more or less sensitively to increasing greenhouse-gas concentrations, if changes over only 15 years are considered.
The difference between simulated and observed global surface-temperature changes during the hiatus period thus tells us very little about model capability or lack thereof; and as an indicator of anthropogenic climate change the surface-warming hiatus is largely irrelevant, Marotzke will conclude.
The Henry W. Kendall Memorial Lecture Series introduces the MIT community to leading researchers in the field of global-change science. The Kendall Lecture is free and open to the public, and a reception will follow in the Green Building Lounge (Room 54-923). Those wanting more information may contact Jen Fentress with questions at 617-252-2127 or jfen@mit.edu.
The Kendall Memorial Lecture is sponsored by the MIT Department of Earth, Atmospheric and Planetary Sciences and the Center for Global Change Science.
