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Blockbuster: Earths Energy Balance measured – models are wrong

Posted By Joanne Nova On October 31, 2012 @ 10:26 pm In Global Warming | Comments Disabled

For all the data we can scrape out of rocks, shells and cylinders of ice, what we really need to know, in detail on a planetary scale, is how much energy comes in and how much goes out. That can only be measured (even roughly) with satellites.

This paper rattles the whole table of key numbers, with empirical results. It puts core numbers into a new perspective, numbers like the 3.7Watts per square meter that a doubling of CO2 is supposed to add to the surface budget.

The models are hunting for imbalances and build-ups in planetary energy. But according to the observations, the longwave (infra-red) energy coming onto the earth’s surface, the infamous back radiation, is 10 – 17 W/m2 higher than in the famous Trenberth diagram from 1997. So the models are trying to explain tiny residual imbalances, but the uncertainties and unknowns are larger than the target. The argument that “only the forcing from CO2 can fill the gap in the models” is not just argument from ignorance rhetorically, but factually too.

Another major implications is that water is churning up and falling out of the sky faster than the experts thought. The Earth’s evaporative cooler is lifting more water, taking more heat, and dumping that heat in the atmosphere. At the top of the atmosphere heat is radiating off the planet to offset the radiation coming in. On the water planet, it really is all about water.

(Click to enlarge) Figure B1 | The global annual mean energy budget of Earth for the approximate period 2000–2010. All fluxes are in Wm–2. Solar fluxes are in yellow and infrared fluxes in pink. The four flux quantities in purple-shaded boxes represent the principal components of the atmospheric energy balance.

 

The main observational data comes from the  ARGO ocean buoys, and the ERBE and later CERES satellites.

  An update on Earth’s energy balance in light of the latest global observations

[Nature Geoscience]

Climate change is governed by changes to the global energy balance. At the top of the atmosphere, this balance is monitored globally by satellite sensors that provide measurements of energy flowing to and from Earth. By contrast, observations at the surface are limited mostly to land areas. As a result, the global balance of energy fluxes within the atmosphere or at Earth’s surface cannot be derived directly from measured fluxes, and is therefore uncertain. This lack of precise knowledge of surface energy fluxes profoundly affects our ability to understand how Earth’s climate responds to increasing concentrations of greenhouse gases. In light of compilations of up-to-date surface and satellite data, the surface energy balance needs to be revised. Specifically, the longwave radiation received at the surface is estimated to be significantly larger, by between 10 and 17 Wm–2, than earlier model-based estimates. Moreover, the latest satellite observations of global precipitation indicate that more precipitation is generated than previously thought. This additional precipitation is sustained by more energy leaving the surface by evaporation — that is, in the form of latent heat flux — and thereby offsets much of the increase in longwave flux to the surface.

The effect of CO2 forcing “is lost in the noise of uncertainty”.

Hat tip to Doug Hoffman for the phrase is his, from well-written review. Furthermore:

“What this means is that all current climate models are based on bad assumptions. And because the raw output of those models do not reproduce the actual state of the environment, climate modelers have applied “adjustments” to get the numbers to work out. The result is that climate models are both fundamentally wrong and have been wrongly adjusted”

The authors describe just how lost:

“For the decade considered [2000-2010], the average imbalance is 0.6 = 340.2 − 239.7 − 99.9 Wm2 when these TOA fluxes are constrained to the best estimate ocean heat content (OHC) observations since 2005 (refs 13,14). This small imbalance is over two orders of magnitude smaller than the individual components that define it and smaller than the error of each individual flux. The combined uncertainty on the net TOA flux determined from CERES is ±4 Wm2(95% confidence) due largely to instrument calibration errors12,15. Thus the sum of current satellite-derived fluxes cannot determine the net TOA radiation imbalance with the accuracy needed to track such small imbalances associated with forced climate change11.”

 

Look at the errors on the budget (the imbalances listed on the right hand side). TOA means top of the atmosphere. CMIP5 means the climate models. Once again, the models are not predicting the measurements, especially at the surface. As explained in the paper, comparisons with models are not insightful here because the models are tuned (trained) on these numbers — in other words, the models are constructed so as to give these numbers, the numbers are not predictions or calculations of the models (as in the infamous “we put the physics in and then the answer pops out” statement).

Earths Energy Balance watts per meter. Stephens Diagram 2012.

Figure 1 | Surface energy balance. Observed and climate model deduced energy fluxes (all in Wm2) in and out of the TOA (a) and at the surface (b). The observed fluxes (containing error estimates) are taken from Fig. B1 and the climate model fluxes are from simulations archived under the World Climate Research Programme’s Coupled Model Intercomparison Project phase 5 (CMIP5) twentieth-century experiments. The fluxes from a 16-model ensemble are summarized in terms of the range in model values (maximum and minimum fluxes) with the ensemble mean fluxes given in parenthesis. ‘SW in’ and ‘SW out’ refer to the incoming and outgoing (reflected) solar fluxes at the TOA and ‘LW out’ is the outgoing longwave radiation. Similarly ‘SW down’ and ‘SW up’ refer to downward and upward (reflected) solar fluxes at the surface, and ‘LW up’ and ‘LW down’ refer to the upward emitted flux of longwave radiation from the surface and the downward longwave flux emitted from the atmosphere to the surface, respectively. SH and LH refer to latent and sensible heat fluxes.

 

It makes sense that a professor of hydrological processes at JPL would lead a team to push forward the bounds of our knowledge of planetary radiation. Graeme Stephens is a physicist and meteorologist who studied at Melbourne Uni, then worked at CSIRO, before going to JPL.

How much don’t we know about rain and snow?

Though latent heat and evaporation are so important to our energy balance, the uncertainties on the water cycle are large. How much rain falls on the oceans? We only know to within 10 or 20%.

“New global precipitation information from the CloudSat radar suggests that precipitation has been underestimated by approximately 10% over tropical ocean regions49 and by even larger fractions over mid-latitude oceans51–53. (2) The total contribution from snowfall to the global precipitation is also not precisely known and has been excluded from previous global latent heat flux estimates. Based on new estimates of global snowfall54, we estimate the contribution to the total global latent heating is approximately 4 Wm–2 (Supplementary Information). For these reasons, the value of latent heat flux stated in Fig. B1 has been increased by 4 Wm–2 over the Global Precipitation Climatology Project49 estimate of 76 Wm–2 and then increased by 10% (8 Wm–2). The uncertainty on annual oceanic mean precipitation lies between approximately ±10% and ±20% (refs 51,56). The quoted uncertainty on the evaporation (±10 Wm–2) derives from our very sketchy understanding of the uncertainty in global precipitation.”

 For comparison, the IPCC 2007 Energy Budget Diagram (originally from Keihl and Trenberth, 1997)

UPDATE: John Hultquist in comments points out the original diagram comes from ** ‘Modern Physical Geography’, 2nd. Ed. (1978 & 1983) by Strahler & Strahler: Figure 4.11, p. 65. This uses numbers taken from a W. D. Sellers ‘Physical Climatology’ book of 1965 (Univ. of Chicago), Tables 6 & 9.

IPCC Energy Budget

..

And here is Trenberth, Fasullo and Keihl’s energy budget from 2009:

H/t to Michael Asten.

REFERENCE

Graeme L. Stephens, Juilin Li, Martin Wild, Carol Anne Clayson, Norman Loeb, Seiji Kato, Tristan L’Ecuyer, Paul W. Stackhouse Jr, Matthew Lebsock & Timothy Andrews An update on Earth’s energy balance in light of the latest global observations, Nature Geoscience, 5, 691–696  (2012)

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