Tag Archives: ocean warming

Another fingerprint

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When my kids were younger, they asked me why the ocean was blue. I would answer that the ocean mirrors the blue sky. However, I would not think much more about it, even though it is well-known that the oceans represent the most important source for atmospheric moisture. They also play an important role for many types of internal variations, such as the El Nino Southern Oscillation. Now a new study by Durack et al. (2012) has been published in Science that presents the relationship between the oceans and the atmosphere.

 

When it rains over the ocean, the salty ocean water gets diluted by fresh water from the clouds, whereas in regions with high evaporation and little rainfall, the evaporation takes away the water and leaves the salt behind in the ocean. If there is a systematic increase in rainfall over some regions and enhanced evaporation in others, then this ought to leave a fingerprint in form of reduced and increased salinity in the respective regions. This is exactly what Durack et al. (2012) have found.

This finding is consistent with earlier model-based suggestions that dry regions will become drier and wet regions will become wetter in response to warming (Giorgi et al., 2011). The Durack et al. (2012) study was based on surface salinity measurements from the ARGO floats combined with sparser historical data over a period of 50 years (Durack et al., 2010). They studied the changes in the spatial structure in terms of linear regression against time over the 50-year period. The change in salinity was consistent with the notion of a strengthening of the hydrological cycle by ~8%/°C.

They also compared their results with global climate model simulations (which involve coupled atmosphere-ocean models) as well as ocean model simulations (forced by atmospheric data). Ocean models use the laws of physics to describe how the ocean currents flow, the water masses mix, and how these processes affect temperature and salinity. The most important inputs to the ocean models are wind forcing, evaporation and rainfall.

The model results give a similar picture as the observations, albeit with an under-estimation of the hydrological cycle speed-up. By looking at projections for the future, the Durack et al. (2012) analysis points to a “substantial (16 to 24%) intensification of the global water cycle [that] will occur in a future 2°C to 3°C warmer world”.

The mean surface salinity of the world oceans. Source: http://serc.carleton.edu/eslabs/corals/4c.html

There is a sinister twist to these inferences. A warmer world is predicted to result in both increased rainfall intensity (mean precipitation estimated for the wet days only) as well as increased length of dry spells (Giorgi et al., 2011). Moreover, in a recent paper, I have together with two colleagues shown that the more extreme rainfall amounts closely follow the rainfall intensity (Benestad et al. (2012). From these results, it seems that we can expect more extremes in both floods and droughts.

Finally, the analysis by Durack et al. (2012) provides another fingerprint of a global warming. However, this finding aspect is not entirely new: the last IPCC report already concluded there is an enhancement of the hydrological cycle, based on observed ocean salinity changes. The method and the conclusion are therefore not new, but the new Argo data confirm earlier findings and strengthen previous observations: the global warming and changes to the hydrological cycle are closely entangled.

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The Unsettled Science of Ocean Warming and Acidification

The world’s climate alarmists would have us believe that they know all they need to know about earth’s climate system and its biological ramifications to justify an unbelievably expensive and radical restructuring of the way the industrialized world both obtains and utilizes energy. But is this really so?

In an eye-opening “perspective” article published a couple of years ago in the 9 December 2009 issue of the Proceedings of the National Academy of Sciences of the United States of America, three researchers from the Marine Biogeochemistry Section of the Leibniz Institute of Marine Sciences in Kiel, Germany, describe their assessment of various possible responses of the global ocean’s seawater carbonate system, plus its physical and biological carbon pumps, to ocean warming and associated changes in vertical mixing and overturning circulation, as well as the closely-allied phenomena of ocean acidification and carbonation.

All of these phenomena, many of which are nonlinear and extremely complicated, are interlinked; and Riebesell and his colleagues thus conclude, from their objective review of the pertinent scientific literature, that the magnitude and even the sign of the global ocean’s carbon cycle feedback to climate change are, in their words, “yet unknown.”

They note, for example, that “our understanding of biological responses to ocean change is still in its infancy.” With respect to ocean acidification, in particular, they write that the impact it will have on marine life “is still uncertain,” and that the phenomenon itself is but “one side of the story,” the other side being what they call “ocean carbonation,” which, as they describe it, “will likely be beneficial to some groups of photosynthetic organisms.” Thus, they write that “our present understanding of biologically driven feedback mechanisms is still rudimentary,” and that with respect to many of their magnitudes, “our understanding is too immature to even make a guess.” What is more, they imply that even what we do think we know could well be wrong, because, as they elucidate, “our present knowledge of pH/CO2 sensitivities of marine organisms is based almost entirely on short-term perturbation experiments, neglecting the possibility of evolutionary adaptation.”

So who are you going to trust? Genuflexing gurus? … who kneel at the altar of the earth goddess Gaia? … who just know that CO2 is bad for the planet? Pontificating preachers? … who claim to have obtained a similar testimony during some environmental epiphany? Celebrated scientists? … for whom the all-powerful climate model is their Holy Grail? Or, will you give heed to much more down-to-earth researchers … who value real-world data and who appreciate the almost unbelievable complexity of the world of nature? … who are not afraid to declare their lack of understanding of all that we know to be of importance to the phenomena of climatic, oceanic and biological change, as well as the likelihood that there is much of importance relative to these matters that we still do not understand?

We do not know to whom you look for guidance in these important matters; but we look to those scientists who are not afraid to acknowledge the limitations of what they think they know, and who will not be goaded into implying they know enough to justify something as drastic as what the world’s climate alarmists are trying to force upon all of humanity, especially when the science of the subject is so clearly unsettled.

Sherwood, Keith and Craig Idso

Reference
Riebesell, U., Kortzinger, A. and Oschlies, A. 2009. Sensitivities of marine carbon fluxes to ocean change. Proceedings of the National Academy of Sciences of the United States of America 106: 20,602-20,609.


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