by Judith Curry
Jim Hansen has just posted his latest draft paper, entitled “Earth’s Energy Imbalance and Implications.” This is quite a meaty paper, and will be of particular interest to those of you wondering “where’s the missing heat?”
Earth’s Energy Imbalance and Implications
James Hansen, Makiko Sato, Pushker Karecha, Karina von Schuckmann
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 W/m2, 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.
The paper is lengthy, 47 pages of single space typing, with 22 figures. The comprehensiveness of the paper is evidenced by the section headings:
1. Climate forcings
2. Climate sensitivity and feedbacks
2.1 Fast feedback climate sensitivity
2.2 Charney climate sensitivity and aerosols
2.3 Slow climate feedbacks
2.4 Climate sensitivity including slow feedbacks
3. Climate response function
4. Green’s function
5. Alternative response functions
6. Generality of slow response
7. Implication of excessive ocean mixing
8. Ambiguity between aerosols and ocean mixing
9. Observed planetary energy imbalance
9.1 Non-ocean terms in planetary imbalance
9.2 Ocean terms in planetary imbalance
9.3 Summary of contributions to planetary imbalance
10. Modeled versus observed energy imbalance
11. Is there closure with observed sea level change
12. Why did planetary energy budget decline the past decade?
12.1 Greenhouse gas climate forcing
12.2 Solar irradiance forcing
12.3 Stratospheric aerosol forcing
12.4 Simulated surface temperature and energy imbalance
13. Discussion
13.1 Human-made climate forcing versus solar variability
13.2 Climate response function
13.3 Aerosol climate forcing
13.4 Implications for climate stabilization
13.5 Implications for sea level
13.5 Implications for observations
JC comments: I haven’t had time to digest all of this, but if there is a more comprehensive analysis of the Earth’s energy budget, I don’t know what it is.
Moderation note: this is a technical thread, comments will be moderated for relevance.