Missing(?) heat isn’t missing after all

curryja

14 years ago

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:

Those measurements are at the heart of a puzzle climate scientists have been trying hard to crack: why, as greenhouse gas emissions rose and satellite data showed an increasing amount of energy trapped in the planet’s atmosphere, the amount of heat absorbed by the world’s oceans — a major heat sink — wasn’t rising as quickly.One answer to the puzzle came from climate scientists Kevin Trenberth and John Fasullo of the National Center for Atmospheric Research, who coined the term “missing heat” — and later suggested it may be stored in the deep ocean, where there are few measurements to track the energy’s path.But new research, published yesterday in the journal Nature Geoscience, argues that what Trenberth and Fasullo dubbed “missing heat” isn’t missing, after all — that the amount of radiation trapped in Earth’s atmosphere, as measured by satellite sensors, is consistent with measurements of heat absorbed by the ocean.Any discrepancy falls within the margin of error on those measurements, say the study’s authors, led by NASA climate scientist Norman Loeb.“Given that there’s a lot of uncertainty in the ocean measurements, given that there was this transition from XBT to Argo right around the time that satellite data and ocean data deviated, it raises a lot questions in my mind about whether you can say there is missing energy,” Loeb said.His analysis examining the amount of solar radiation entering and leaving the atmosphere estimates the heat content of the upper ocean using three different data sets.

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?

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