Saturday, June 12, 2010

Are the oceans cooling?

A recent discussion among myself and two friends brought up the contention made by a couple of Climatological web sites that the oceans have been cooling recently. The web sites in question are:
here and here.
Another source of ocean temperature data is here.

Plotting the data from the third source (the NOAA data for 180W - 100W, which covers most of the tropical Pacific Ocean) doesn't give much insight into cooling. A linear regression gives a very slight cooling, but that's probably just an artifact of where the regression starts and ends:

One fact that jumps right out is that the ocean temperature fluctuates quite a bit, and this can translate into greater atmospheric temperature fluctuations near the surface because of the higher specific heat of water.

The decline in ocean temperature my friend and the two web sites were referring to is the decline from late 2009 to the present (latest data May 2010):

This represents nearly a 3 degree (C) decline, but it's not all that much compared to earlier fluctuations (see the first figure). A Google Scholar search turned up a number of papers on ocean temperature, mostly showing warming, but all with considerable up and down fluctuations.

Still, it's of interest to assess the causes of ocean temperature fluctuations. It doesn't seem the oceans should be affected as much by the greenhouse effect as the atmosphere, since greenhouse gases trap rising heat. It would seem the ocean temperature would be more directly affected by the Total Solar Irradiance (TSI) and by cloud cover, which in turn is driven (among other things) by cosmic rays. Sunspots affect the TSI, and sunspots are currently in decline, as shown in the following figure:
When sunspots are low, less energy is released by the sun, contributing to less warming due to TSI. Furthermore, the magnetic field of the sun is at its lowest, letting more cosmic rays impinge on the atmosphere. This in turn causes more air to be ionized, which provides nuclei for clouds to condense around, increasing cloud cover and increasing the reflectance of solar radiation back into space. This of course cools the atmosphere. Also, some recent research by Qing-Bin Lu of the University of Waterloo, links the decline of CFC gases (chlorofluorocarbons once used as refrigerants and according to Professor Lu, "well known greenhouse gases") under the influence of cosmic rays to the recent cooling of the atmosphere.

My conclusions:

  1. The study of earths temperature cannot be complete with the main emphasis on CO2
  2. Although the oceans temperature fluctuates considerably, the higher heat capacity of water argues strongly for including the influence of the oceans on earth's temperature
  3. Factors like sunspots and cosmic rays must be taken into account.

  1. Cosmic-ray-driven electron-induced reactions
    of halogenated molecules adsorbed on ice surfaces:
    Implications for atmospheric ozone depletion
    and global climate change
    Physics Reports, Volume 487, Issue 5,
    February 2010, Pages 141-167,
    ISSN 0370-1573, DOI: 10.1016/j.physrep.2009.12.002.
  2. Galactic Cosmic Rays - Clouds Effect and Bifurcation
    Model of the Earth Global Climate. Part 1. Theory
    Authors: Vitaliy D. Rusov, Alexandr V. Glushkov,
    Vladimir N. Vaschenko, Oksana T. Mykhalus,
    Yuriy A. Bondartchuk, Vladimir P. Smolyar,
    Elena P. Linnik,
    Strachimir Cht. Mavrodiev, Boyko I. Vachev
    The Journal of Atmospheric and Solar-Terrestrial
    Physics Vol. 72 (2010) p. 398-408
    arXiv:0803.2765v3 []
  3. Galactic Cosmic Rays - Clouds Effect and Bifurcation
    Model of the Earth Global Climate. Part 2.
    Comparison of Theory with Experiment
    Authors: Vitaliy D. Rusov, Vladimir N. Vaschenko,
    Elena P. Linnika, Oksana T. Myhalus,
    Yuriy A. Bondartchuk,
    Vladimir P. Smolyar, Sergey I. Kosenko,
    Strachimir Cht. Mavrodiev,
    Boyko I. Vachev
    Journal of Atmospheric and Solar-Terrestrial
    Physics Vol. 72 (2010) p. 380-497
    arXiv:0803.2766v3 []
  4. Testing the proposed link between cosmic rays
    and cloud cover
    Authors: T. Sloan, A.W. Wolfendale
    arXiv:0803.2298v1 []

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