News & Events

A new method of comparing climate forcing agents

Monday, January 13, 2014, 12:00PM - 1:00PM

Speaker

Ben Kravitz

Pacific Northwest National Laboratory

Location:

ARC room 620

Determining the climate response to radiative forcing agents is a key area of climate research.  However, due to the complicated nature of calculating radiative forcing, as well as the state dependence of climate feedbacks, determining the climate sensitivity to changes in forcing agents is difficult.  I illustrate a new method of comparing climate forcing agents by introducing an explicit feedback into climate models.  This method allows rapid characterization of the response of climate models to varying amounts of offsetting forcings (e.g., an increase in CO2 offset by a reduction in solar irradiance).  A doubling of the CO2 concentration is radiatively "worth" approximately a 2.2% change in solar irradiance in multiple models; this result is highly linear.  Comparisons between solar irradiance and methane are similarly robust across models.  Comparisons between CO2 and methane are more difficult due to a low signal, but a 10% increase in the preindustrial CO2 concentration could radiatively offset a removal of all methane from the atmosphere.  With a suitable benchmark, this new method could be used to characterize modeled climate response to a multitude of different forcings.