Monday, May 19, 2014

New paper falsely claims 87% of thermosteric sea level rise since 1970 is anthropogenic

A new paper published in Geophysical Research Letters uses climate models to claim most of the sea level rise due to thermal expansion since 1970 is of anthropogenic origin. However, the paper relies upon false premises that do not justify the conclusions.  Climate models falsely assume infrared radiative forcing from greenhouse gases can heat the oceans, but IR cannot significantly heat the oceans due to a penetration depth of only a few microns, which causes evaporative skin surface cooling, not warming [in addition to other physical reasons]. 

Even RealClimate indirectly admits IR from greenhouse gases cannot significantly heat the oceans. This false premise of IR heating of the oceans in the climate models falsifies the conclusion of this paper that "87% of the observed trend in the upper 700 m since 1970 is induced by human activity."

In addition, the climate model forcing assumptions have been falsified at confidence levels of 95-98%+, thereby also falsifying the conclusions of this paper. Climate models are also unable to simulate natural ocean oscillations such as ENSO and the AMO, which have large effects on thermosteric sea level changes [from thermal expansion], thus the models cannot be used to separate natural variability from anthropogenic causes. 


Sea levels have been rising for 20,000 years since the last ice age, and there is no evidence of acceleration over the past 204 years. Therefore, there is no evidence of a human contribution to sea level rise. In addition, recent data indicates a 31% deceleration of sea level rise since 2002 despite an unrelenting rise in CO2


Quantifying anthropogenic and natural contributions to thermosteric sea level rise

Marta Marcos and Angel Amores

Changes in thermosteric sea level at decadal and longer time scales respond to anthropogenic forcing and natural variability of the climate system. Disentangling these contributions is essential to quantify the impact of human activity in the past and to anticipate thermosteric sea level rise under global warming. Climate models, fed with radiative forcing, display a large spread of outputs with limited correspondence with the observationally based estimates of thermosteric sea level during the last decades of the twentieth century. Here we extract the common signal of climate models from Coupled Model Intercomparison Project Phase 5 using a signal-to-noise maximizing empirical orthogonal function technique for the period 1950–2005. Our results match the observed trends, improving the widely used approach of multimodel ensemble averaging. We then compute the fraction of the observed thermosteric sea level rise of anthropogenic origin and conclude that 87% of the observed trend in the upper 700 m since 1970 is induced by human activity.

9 comments:

  1. Not air-water heat exchange? You just need a high volume of warm air to transfer significant amounts of heat to the water.

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  2. Very true - try warming a bucket of water with a hair dryer - it will not warm the water, it will just cause compensatory evaporative cooling of the surface.

    Secondly, the oceans have ~1000 times more heat capacity than the atmosphere, thus the atmosphere would have increase its heat content by ~1000 times before it would be capable of warming the oceans.

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  3. Warming a bucket of water with a hair dryer is easy, I use the bucket as the heat transfer medium: air heats the bucket, the bucket heats the water. I don't think blowing hot air across the surface of the water will cool the water, I rather think it will heat the water. You should get quite a bit of evaporation, but the net effect should be some heat transfer to water. It should work as a function of the heat capacities, area and temperature differential. If water can transfer heat to the air, thereby freezing the surface, it has to also go the other way.

    We aren't talking about efficiency. The point made above is that IR doesn't heat water all that well, so how do you warm the water?

    You can transfer enough heat with hot air to ignite and burn wood.

    As far as 87% of sea level rise being from heating the surface water, not at all very likely for the reasons given.

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  4. What happens to the energy of the IR that is absorbed in the top few microns?

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    1. However the effect of downwelling infrared is always to use up all the infrared in increasing the temperature of the ocean surface molecules whilst leaving nothing in reserve to provide the extra energy required (the latent heat of evaporation) when the change of state occurs from water to vapour. That extra energy requirement is taken from the medium (water or air) in which it is most readily available. If the water is warmer then most will come from the water. If the air is warmer then most will come from the air. However over the Earth as a whole the water is nearly always warmer than the air (due to solar input) so inevitably the average global energy flow is from oceans to air via that latent heat of evaporation in the air and the energy needed is taken from the water. This leads to a thin (1mm deep) layer of cooler water over the oceans worldwide and below the evaporative region that is some 0.3C cooler than the ocean bulk below."

      http://hockeyschtick.blogspot.com/2010/08/why-greenhouse-gases-wont-heat-oceans.html

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  5. Why don't you try to publish these facts you mention in a scientific journal instead in a blog?

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    1. 1. Most of the facts are already published in journal articles - follow my links
      2. Papers that bring together facts from different papers to support skeptical positions in climate science are rejected - see Bengtsson's paper. Not true in most other fields of science, fortunately.

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    2. How do you explain that water is warmer in summer than in winter?

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    3. Increased insolation from the Sun. The solar spectrum can penetrate the oceans up to 100 meters to heat the bulk of the oceans. LWIR from greenhouse gases can only penetrate a few millionths of a meter to cause evaporative cooling of the ocean skin surface.

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