by Judith Curry
Earth’s “missing heat” might not be missing after all.
That’s the conclusion of a new study that examines how accurately satellites and floating ocean instruments track the flow of energy from the sun to Earth and back again.
Observed changes in top-of-the-atmosphere radiation and upper-ocean heating consistent within uncertainty. Nature Geoscience (2012)doi:10.1038/ngeo1375
Norman G. Loeb, John M. Lyman, Gregory C. Johnson, Richard P. Allan, David R. Doelling, Takmeng Wong, Brian J. Soden & Graeme L. Stephens, 2012:
Abstract: Global climate change results from a small yet persistent imbalance between the amount of sunlight absorbed by Earth and the thermal radiation emitted back to space1. An apparent inconsistency has been diagnosed between interannual variations in the net radiation imbalance inferred from satellite measurements and upper-ocean heating rate from in situ measurements, and this inconsistency has been interpreted as ‘missing energy’ in the system2. Here we present a revised analysis of net radiation at the top of the atmosphere from satellite data, and we estimate ocean heat content, based on three independent sources. We find that the difference between the heat balance at the top of the atmosphere and upper-ocean heat content change is not statistically significant when accounting for observational uncertainties in ocean measurements3, given transitions in instrumentation and sampling. Furthermore, variability in Earth’s energy imbalance relating to El Niño-Southern Oscillation is found to be consistent within observational uncertainties among the satellite measurements, a reanalysis model simulation and one of the ocean heat content records. We combine satellite data with ocean measurements to depths of 1,800 m, and show that between January 2001 and December 2010, Earth has been steadily accumulating energy at a rate of 0.50±0.43 Wm−2 (uncertainties at the 90% confidence level). We conclude that energy storage is continuing to increase in the sub-surface ocean.
Roger Pielke Sr. points to a Climate Wire article on the paper, which is the source of the quote at the beginning of this post. Some excerpts:
Loeb’s conclusion? That, if you consider the margin of error on the satellite and ocean measurements, the two data sources are in agreement — and there may not be any “missing energy.”
“It’s not to say that it’s not happening,” Loeb said. “It’s just that you can’t easily make that conclusion from the data.”
In a follow up post, Pielke Sr. makes the following comment:
This question about whether or not the IPCC model predictions (as represented by the GISS models) are still consistent even with the large Loeb et al estimate should have been a major part of their article. The Loeb et al 2012 even cited the Hansen paper but did not take the next step and complete model and observational comparisons. That the IPCC models are close to being refuted with respect to the magnitude of global warming even with the large Loeb et al values is an unspoken result of their findings. They missed a major implication from their results.
Update: Kevin Trenberth responds at Quark Soup. Concluding paragraph:
So while their conclusions may be valid: yes there is no evidence of a discrepancy, given their uncertainties, and yes there is no “statistically significant” decline in OHC rates of change, but the uncertainties are so large that neither dataset is useful to know what is really going on, and that is the key point. The discrepancies among OHC data sets remain huge. We MUST do better. So the key point in their title is “within uncertainty”. It should add: “but the uncertainty is too large.”
JC comment: The Loeb paper is notable for its comprehensive integration of satellite observations and in situ measurements to address this issue. Unfortunately, the data set is not very long, and there are substantial uncertainties in ocean heat content measurements. But these uncertainties seem to have been accounted for carefully in this paper.
Interesting to Kevin Trenberth take on the uncertainty mantle, after reversing the null hypothesis and all that.
For reference, this topic was discussed previously at Climate Etc. in Where’s the ‘missing’ heat?