News

Global warming “missing energy” row erupts

11.01.2011
11.01.2011 09:21 Age: 3 yrs
Category: Oceans
By: Leon Clifford

An angry discussion has erupted over recent research which appears to suggest that the build-up of heat in the oceans that is predicted to be associated with global warming is not happening.

The research based on an analysis of ocean buoy temperature measurements suggests that the oceans cooled between 2003 and 2008, that this cooling does not support the idea that the oceans are stockpiling heat and that it does not support the idea that the Earth is in positive radiative balance – that is, acting as a net absorber of heat and therefore warming.

Physicists Robert Knox and David Douglass of the University of Rochester, New York, bluntly state in their paper that their research “does not support the existence of either a large positive radiative imbalance or a “missing energy.””

Rubbish

Climate scientist Kevin Trenberth of the US National Center for Atmospheric Research (NCAR) , who made famous the phrase “missing energy”, has reportedly dismissed the paper as “rubbish”, according to the websites of climate scientists Roger Pielke Sr of the University of Colorado and Judy Curry of the Georgia Institute of Technology. Pielke Sr described the research as “a solid scientific study” on his website.

The Knox and Douglass paper, “Recent energy balance of Earth”, was published in November by the International Journal of Geosciences.

The idea that the oceans are stockpiling heat is a key tenet of global warming as the oceans store between 80 and 90 per cent of the heat in the climate system. Furthermore, research co-authored by NCAR's Trenberth and colleague John Fasullo in 2010 based on satellite data and computer models suggested that the Earth was absorbing more energy than it was radiating back into space – a necessary requirement for global warming – and that this energy has been accumulating in the oceans since 2005.

Missing energy

The trouble is that this energy was not showing up in any measurements which led to Trenberth's well publicised “travesty” comment in an email published as a result of the “Climategate” leaks which stated: “The fact is that we can’t account for the lack of warming at the moment and it is a travesty that we can’t”.

Knox and Douglass analysed Argo float temperature data for the period from 2003 to 2008 to estimate changes in ocean heat content (OHC). They state that “Our four estimates of the recent OHC trend for 2003–2008 adequately consider interannual variability and we find that the trend is negative”. That is that the ocean heat content has been falling and not increasing.

It is clear from their paper that Knox and Douglass believe that there is no missing energy and that the problem of missing energy is an artifact caused by a “serious overestimate” by Trenberth and Fasullo of the radiation imbalance at the top of the Earth's atmosphere. Essentially, they are saying that there is no positive radiation imbalance and therefore no need to assume that a store of energy is being built up in the oceans - with the clear implication, although not explicitly stated in their paper, that the Earth may not be warming.

Nature Robust warming paper

In May 2010 Nature published a paper that appeared to confirm that the upper layer of the world’s ocean has warmed since 1993, indicating a strong climate change signal. The paper “Robust Warming of the Global Upper Ocean” by Lyman et al analysed nine different estimates of heat content in the upper ocean from 1993 to 2008 ranging from the surface to a depth of around 700m. The measurements included data from Argo, an array of autonomous free-floating ocean floats, as well as from earlier devices called expendable bathythermographs or XBTs that were dropped from ships to obtain temperature data. This analysis yielded “a statistically significant linear warming trend for 1993–2008,” according to the Nature paper.

However, while the linear warming trend spanned the period from 1993 to 2008 it is an average and the authors of the Nature paper reported that the individual upper ocean heat content anomaly curves “all flatten out after around 2003”. The team reported that the causes of this flattening are “unclear” but referred to the fact that sea surface temperatures had been constant since 2000 and also suggested that increased sea levels since then may be due more to melting continental ice rather than thermal expansion.

Sources

Roger Pielke Sr's website here.

Judy Curry's website here.

Citations

“Recent energy balance of Earth”, by Robert Knox and David Douglass was published in November by the International Journal of Geosciences click here.

"Robust warming of the global upper ocean", by John M. Lyman et al, published on 20 May 2010 in Nature click here .

“Tracking Earth’s energy”, by Kevin Trenberth and John Fasullo, Science, Vol. 328, 2010, pp. 316–317 click here.


Share this story on Twitter!