Ocean heat content increases update - realclimate.org

Ocean heat content increases update

June 1, 2010 - realclimate.org

There is a new paper in Nature this week on recent trends in ocean heat content from a large group of oceanographers led by John Lyman at PMEL. Their target is the uncertainty surrounding the various efforts to create a homogenised ocean heat content data set that deals appropriately with the various instrument changes and coverage biases that have plagued previous attempts.

We have discussed this issue a number of times because of its importance in diagnosing the long term radiative imbalance of the atmosphere. Basically, if there has been more energy coming in at the top than is leaving, then it has to have been going somewhere – and that somewhere is mainly the ocean. (Other reservoirs for this energy, like the land surface or melting ice, are much smaller, and can be neglected for the most part).

The main problem has been that over time the network of XBT probes and CTD casts has been replaced by the Argo float network which has a much greater coverage and more homogeneous instrumentation. However, connecting up the old and new networks, and dealing with specific biases in the XBT probes is difficult. An XBT (eXpendable Bathy-Thermograph) is a probe that is thrown off the ship and whose temperature readings as a function of time are transferred to a profile in depth from knowledge of how fast the probe falls. Unfortunately, this function is a complicated one that depends on the temperature of the water, the depth, the manufacturer of the probe etc. Various groups – working with the same basic data – have shown that there were biases in the XBT associated with incorrect calibrations and have attempted to make better corrections.

The latest paper is a consensus effort from many of the people involved in the previous work and shows how robust the recent decades warming of the ocean has been. Indeed, the ‘best estimate’ for the changes in the top 700m seems to be a greater warming than seen in the NODC data and more than even the models were suggesting:

One thing that is interesting to note is that the interannual variability – particularly in the transition period between the two observing systems (1995-2005 say) is very dependent on exactly how you do the corrections, while the longer term trend is robust. This ties in directly with comments by Kevin Trenberth in this recent paper and in an accompanying commentary to the Lyman paper that while the energy budget changes over the long term are explainable, the changes over short time frames are still very difficult to quantify.

As usual, this is unlikely to be the very last word on the subject, but this is more evidence that the planet is basically behaving as the scientists think it is. And that isn’t necessarily good news.



Industrial biotechnology has the potential to save the planet up to 2.5 billion tons of CO2 emissions per year and support building a sustainable future, a WWF report found.

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Industrial biotechnology has the potential to save the planet up to 2.5 billion tons of CO2 emissions per year and support building a sustainable future, a WWF report found.

As the world is debating how to cut dangerous emissions and come together in an international agreement treaty which will help protect the planet from potentially devastating effects of climate change, innovative ideas how to reduce our CO2 are very valuable.

A recent report published by WWF Denmark identifies the potential to be between 1 billion and 2.5 billion tons CO2 per year by 2030, more than Germany’s total reported emissions in 1990.

Industrial biotechnology could help create a true 21st century green economy, the report states.

Industrial biotechnology applications are already widely used in everyday life. They help reduce the amount of time needed to bake fresh bread, increase the yield in wine, cheese and vegetable oil production and save heat in laundry washing.

“Low carbon biotech solutions are a good example of hidden or invisible climate solutions that are all around us already today but are easy to overlook for policymakers, investors and companies.” says John Kornerup Bang, Head of Globalization Program at WWF Denmark and coauthor of the report.

A newer example on how biotechnology solutions could help reduce carbon emissions is the harvesting of biogas from waste digesters and wastewater streams.

The report emphasizes the potential of taking that existing technology even one step further and creating fully closed loop systems.

Biorefineries are able to transform any biobased waste material into a valuable feedstock for the production of other biobased materials. The possible emission reductions for such processes are estimated to be as high as 633 million tons of CO2.

The report indentifies four fundamental dimensions of industrial biotechnology: Improved efficiency, the substitution of fossil fuels, the substitution of oil-based materials and the creation of a closed loop system with the potential to eliminate waste.

But as with most technologies, the potential to achieve sustainability objectives does not automatically translate into such goals be­ing realized.

“Politicians need to set the path toward a green economy. This will not be easy, and we must look for new solutions, which can help us reduce emissions very quickly. It is clear that there is no alternative to explore these inno­vative pathways,” John Kornerup Bang said.

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