Earth's Energy Imbalance and Its Implications

The video below is from the GISS Wednesday Lunch Seminar Series.

The talk is about the Earth's Energy Imbalance and it contains a great deal of interesting ideas, given by James Hansen.

The section that particularly grabbed my attention started at the 27 minute mark where Hansen discusses the rapidity with which the planet approaches equilibrium energy balance with increasing carbon dioxide in the atmosphere.

This has been an item of discussion in Australia's debate on reducing carbon emissions recently. Here is a link to a discussion of the confusion (deliberate or otherwise) in the political debate on this issue.

I had thought that energy balance would be achieved after a few decades, but Hansed indicates that maybe only 60% of the energy imbalance has been redressed in that time period.

The whole talk and question session takes over an hour so I have also proveded a copy of the abstract of the talk after the video.

Abstract:

Improving observations of ocean temperature confirm that Earth is absorbing

more energy from the sun than it is radiating to space as heat, even during the

recent solar minimum. This energy imbalance provides fundamental verification

of the dominant role of the human-made greenhouse effect in driving global

climate change. Observed surface temperature change and ocean heat gain

constrain the net climate forcing and ocean mixing rates. We conclude that

most climate models mix heat too efficiently into the deep ocean and as a

result underestimate the negative forcing by human-made aerosols. Aerosol

climate forcing today is inferred to be -1.6 +/- 0.3 Wm2 implying substantial

aerosol indirect climate forcing via cloud changes. Continued failure to

quantify the specific origins of this large forcing is untenable, as knowledge

of changing aerosol effects is needed to understand future climate change.

A recent decrease in ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era can readily be accounted for by thermal expansion of the ocean and ice melt, but the ascendency of ice melt leads us to anticipate a near-term acceleration in the rate of sea level rise.