Global warming realâ€™ say new studies according to the Financial Times, February 18, 2005. Tim Barnett of Scripps Institute of Oceanography crowed:
â€œThe debate over whether there is a global warming signal is over now at least for rational people.â€
The article records the team’s triumph:
A leading US team of climate researchers on Friday released â€œthe most compelling evidence yetâ€ that human activities are responsible for global warming. They said their analysis should â€œwipe outâ€ claims by sceptics that recent warming is due to non-human factors such as natural fluctuations in climate or variations in solar or volcanic activity.
In a related article reported from the reliable UK Met Office.
The world’s best efforts at combating climate change are likely to offer no more than a 50-50 chance of keeping temperature rises below the threshold of disaster, according to research from the UK Met Office.
The chilling forecast from the supercomputer climate model of the Met Office’s Hadley Centre for Climate Prediction and Research will provide a sobering wake-up call for governments around the world
Fast forward to 2008, and Nir J. Shaviv, Dr. Shaviv, 37, an associate professor at the Racah Institute of Physics of the Hebrew University of Jerusalem, claims the theory that solar and cosmic rays, not human activity, are the driving forces behind climate change is gaining traction. He recently published a paper on ocean heat flux called “Using the oceans as a calorimeter to quantify the solar radiative forcing“.
My main criticism of this paper is that it provides no background on studies of heat transport into oceans, hence this preamble. I wanted to find out what the various numeric values of heat flux into the ocean are, to attempt to reconcile the various views.
The paragraphs from Climate Change 2001: Working Group I: The Scientific Basis are worth reading; they seem to indicate how uncertain the ocean flux is, and flag the problems caused by clouds:
Improved resolution and understanding of the important facets of coupling in both atmosphere and ocean components of global climate models have also been proven to reduce flux imbalance problems arising in the coupling of the oceanic and the atmospheric components. However, it must still be noted that uncertainties associated with clouds still cause problems in the computation of surface fluxes.
Among the prominent web accessible works that record estimates of the fluxes are these:
Anthropogenic Warming of the Oceans: Observations and Model Results by David W. Pierce and Tim P. Barnett et al..
Analysis of PCMâ€™s heat budget indicates the warming is driven by an increase in net surface heat flux that reaches 0.7 watts m2 by the 1990s; the downward longwave flux increases by 3.7 watts m2, which is not fully compensated by an increase in the upward longwave flux of 2.2 watts m2. Latent and net solar heat flux each decrease by about 0.6 watts m2.
In another by Southern Ocean warming due to human influence by John C. Fyfe was equally impressed by a “remarkable agreement”.
I show that the latest series of climate models reproduce the observed mid-depth Southern Ocean warming since the 1950s if they include time-varying changes in anthropogenic greenhouse gases, sulphate aerosols and volcanic aerosols in the Earthâ€™s atmosphere. The remarkable agreement between observations and state-of-the art climate models suggests significant human influence on Southern Ocean temperatures.
Nir Shaviv provides an alternative view:
Another interesting point to note is that the solar cycle induced variations in low-altitude cloud cover [Marsh and Svensmark, 2000b], presumably from CRF modulation over the oceans (where CCNs are most likely to be a bottleneck), give rise to a radiative imbalance which can be estimated [Marsh and Svensmark, 2000a; Shaviv, 2005] to be of order 1.1 Â± 0.3 W/m2 over the past two cycles. Together, with the TSI variations, we find that the ratio between the cloud + TSI variations compared with the change in the solar constant is: 1:3 Â± 0:4 W/m2. After comparing with equation (21), we can conclude that the heat flux going into the oceans is consistent with the apparent variations in the low-altitude clouds.
Clearly there is rough quantitative agreement between Barnett and Shaviv about the heat entering the oceans, but there is disagreement on the source. Nir’s evidence shows the influx is consistent with a net increase in solar forcing of 1:3 Â± 0:4 W/m2. Tim Barnett’s proof of AGW, is that without CO2, climate models cannot reproduce the warming seen in the oceans. But this is assuming the latent and net solar heat flux has decreased by about 0.6 W/m2. Presumably, this assumption is crucial to his findings and if solar were increased to +1W/m2, would not indicate CO2 as the cause.
Nir Shaviv is already known for his contribution to the field of astrophysics, where he demonstrated that the Eddington luminosity is not a strict limit. He would seem to regard the proof of Prof Barnett, the rationalist, as a case of ‘mistaken identity’, where CO2 stands falsely accused. There is also an element of ‘proof by calling the other guy an idiot‘.
The real numeric disagreement between the camps appears to be over the extent of solar forcing: surely a measurable, resolvable dispute. Shaviv claims to have proved this enhanced forcing, a finding that seems to me to be worth a Noble Prize nomination:
We find that the total radiative forcing associated with solar cycles variations is about 5 to 7 times larger than just those associated with the TSI (Total Solar Irradiance) variations, thus implying the necessary existence of an amplification mechanism, …
Shaviv said in a recent interview:
“People will see that the apocalyptic forecasts are not coming true. Today there is no fingerprint attesting that carbon dioxide emission causes a rise in temperature.”
The statements from the project leader at Scripts Institute of Oceanography that the debate is over for ‘rational’ people, and their results should â€œwipe outâ€ claims by sceptics, are already beginning to sound like famous last words.