I was alerted to a news release concern ocean heat content by the British Met Office [h/t Joe D’Aleo] titled
It reads [highlight added]
4 August 2011 – Two research papers shed new light on why the upper layers of the world’s oceans have seen a recent pause in warming despite continued increases in greenhouse gases.
The independent studies from the Royal Netherlands Meteorological Institute (KNMI) and the Met Office show how natural climate variability can temporarily mask longer-term trends in upper ocean heat content and sea surface temperature.
The upper 700 metres of the global ocean has seen a rise in temperature since reliable records began in the late 1960s. However, there has been a pause in this warming during the period from 2003 to 2010. The papers published this week offer explanations for this.
Climate model simulations from KNMI show that such pauses in upper ocean warming occur regularly as part of the climate system’s natural variability.
This is because of two factors. Firstly variations in the El Niño – Southern Oscillation, known as ENSO (a climate cycle which affects sea surface temperatures in the Pacific Ocean), cause more of the heat stored in the upper ocean to be released into space.
Secondly, heat can be temporarily moved to the deeper ocean below 700m due to changes in the Atlantic Meridional Overturning Circulation – the oceanic conveyor belt that transports vast amounts of heat in the North Atlantic Ocean.
Both these explanations are supported by recent observations of ENSO and upper ocean temperatures in the North Atlantic.
A different set of model simulations from the Met Office supports the idea of heat moving to the deeper ocean explaining the recent pause in upper ocean warming.
The same research also suggests that with deeper ocean observations it would be possible to account for movement of heat within the ocean and do a better job of monitoring future climate change.
Both papers can be read online in GRL:
GRL website (KNMI paper)(Katsman, C.A. and G.J. van Oldenborgh)
GRL website (Met Office paper) (Palmer, M. D., D. J. McNeall, and N. J. Dunstone)
First, if “…more of the heat stored in the upper ocean to be released into space”, this represent Joules that will never contribute to global warming. To compensate for this loss of heat, if global warming is to fit the IPCC model predictions, there must be well above average heating in the coming years to “catch up”. This large loss of heat also further supports the findings in
Spencer, R.W.; Braswell, W.D. On the Misdiagnosis of Surface Temperature Feedbacks from Variations in Earth’s Radiant Energy Balance. Remote Sens. 2011, 3, 1603-1613.
that the IPCC models are inaccurately representing this aspect of the climate system (see also my post). Spencer and Braswell wrote
“….the satellite-based metrics for the period 2000–2010 depart substantially in the direction of lower climate sensitivity from those similarly computed from coupled climate models…”
The British Met Office also wrote “Secondly, heat can be temporarily moved to the deeper ocean below 700m…”. They fail, however, to present what time period is meant by “temporary”. Indeed, heat transfer to deeper in the ocean will disperse horizontally and likely would only slower reemerge, if ever, (decades or centuries?) back into the upper levels of the ocean.
The news article is also making the typical error of assuming that the “recent pause in warming [occurs] despite continued increases in greenhouse gases.” This assumption concludes (erroneously) that the added greenhouse gases dominate the climate system over the last ten years. However, as documented by Spencer and Braswell, and others, natural climate variations are larger than modeled by the IPCC multi-decadal predictions. Also, there is a much wider diversity of human climate forcings (e.g. see NRC 2005) which in terms of the Earth’s radiative imbalance are variously positive and negative, as well as having diverse spatial signatures. The climate system is a much more complex system that portrayed in the British Met press release.
The coming years will be quite informative about the conclusions in the Katsman and van Oldenborgh, and the Palmer et al articles. I have recently posted on both of them;
Their studies provide important new research insight. The interpretation of their findings, as given in the Met Office Press release, however, does not accurately report on the diversity of perspectives on the reasons for the lack of warming.
This issue will be eventually be resolved using the Litmus Test that I first proposed in 2007; see
Summarizing and editing from that post
1. We need an unambiguous litmus test to diagnose global warming which can be accepted by all credible climate scientists (e.g. see Pielke, 2003).
2. Ocean heat content changes fits this requirement (e.g. see Knox and Douglas, 2010)
3. The global average surface temperature trend, in contrast, has serious uncertainty and bias issues and is not the appropriate metric to use to assess global warming (e.g. see Pielke et al, 2007).
4. The focus on the human emissions of carbon dioxide from fossil fuels is to promote energy policy changes, which is implicit in the Met Office press release. Their narrow view does not permit the much-needed development of an appropriate comprehensive climate policy (e.g. see Kabat et al 2004).
4. There is a major risk, of course, in making CO2 the only villain in climate change, and in making definitive forecasts of what the climate will do in the coming decades such as indicted by the Met Office Press release in their use of the phrase “pause in upper ocean warming“. The risk is that if the IPCC forecasts do not occur as projected, then the credibility of the climate science community will be lost for a long time. This would be tragic as we need an effective climate policy to deal with the threats that climate variability and change pose to society.
The Met Office [and Katsman and van Oldenborgh and Palmer et al] should make their forecasts today of what the heating rate is expected to be over the next few years, as well as what level of a lack of heating would force them to reject the IPCC models as being skillful multi-decadal global average radiative heating predictive tools.