Tuesday, September 9, 2014

New paper finds climate of tropical Atlantic is not driven by greenhouse gas forcing

A recent paper published in Climate Dynamics finds the sea surface temperatures of the tropical Atlantic cooled by 1°C or more from 1964-1975 during the 70's ice age scare, followed by warming that is not explained by greenhouse gas forcing. According to the authors, 
Examining data sets of surface heat flux during the last few decades for the same region, we find that the SST [sea surface temperature] warming was not a consequence of atmospheric heat flux forcing. Conversely, we suggest that long-term SST warming drives changes in atmosphere parameters at the sea surface, most notably an increase in latent heat flux, and that an acceleration of the hydrological cycle induces a strengthening of the trade winds and an acceleration of the Hadley circulation. These trends are also accompanied by rising sea levels and upper ocean heat content over similar multi-decadal time scales in the tropical Atlantic.
"Not a consequence of atmospheric heat flux forcing" is code for "not due to forcing from greenhouse gases." Rather, the paper finds changes in the [natural] "Atlantic meridional overtuning circulation [AMOC] and the subtropical cells are required to explain the observations."

As Dr. Bill Gray and other skeptics have pointed out, the climate heat transfer sequence is: Sun heats the oceans, the Sun [plus possibly lunar tidal forcing] drive ocean oscillations, and ocean oscillations then drive the climate. Longwave IR from greenhouse gases cannot penetrate or heat the oceans, and warming of the atmosphere cannot heat the oceans because heat rises and the oceans have 1000 times greater heat capacity than the atmosphere.

Recent climatic trends in the tropical Atlantic
Jacques Servain, Guy Caniaux, Yves K. Kouadio, Michael J. McPhaden, Moacyr Araujo

A homogeneous monthly data set of sea surface temperature (SST) and pseudo wind stress based on in situ observations is used to investigate the climatic trends over the tropical Atlantic during the last five decades (1964–2012). After a decrease of SST [sea surface temperatures] by about 1 °C during 1964–1975, most apparent in the northern tropical region, the entire tropical basin warmed up. That warming was the most substantial (>1 °C) in the eastern tropical ocean and in the longitudinal band of the intertropical convergence zone. Surprisingly, the trade wind system also strengthened over the period 1964–2012. Complementary information extracted from other observational data sources confirms the simultaneity of SST warming and the strengthening of the surface winds. Examining data sets of surface heat flux during the last few decades for the same region, we find that the SST [sea surface temperature] warming was not a consequence of atmospheric heat flux forcing. Conversely, we suggest that long-term SST warming drives changes in atmosphere parameters at the sea surface, most notably an increase in latent heat flux, and that an acceleration of the hydrological cycle induces a strengthening of the trade winds and an acceleration of the Hadley circulation. These trends are also accompanied by rising sea levels and upper ocean heat content over similar multi-decadal time scales in the tropical Atlantic. Though more work is needed to fully understand these long term trends, especially what happens from the mid-1970’s, it is likely that changes in ocean circulation involving some combination of the [natural] Atlantic meridional overtuning circulation [AMOC] and the subtropical cells are required to explain the observations.

1 comment:

  1. The results of this paper are consistent with instrument measurements of solar variability reported by Kopp and Lean (2011).

    "Measured TSI variability levels can exceed 0.3% over solar rotation time scales of 27 days and are typically ∼0.1% over the 11‐year solar cycle..." (note to Figure 5).

    Greg Kopp and Judith L. Lean, A new, lower value of total solar irradiance: Evidence and climate significance, 2011

    URL:

    http://chicagowilderness.org/members/downloads/Strategic/February%2011_CCTF_solar_irradiance.pdf

    The figure 0.3% for TSI variability is roughly double the estimate of surface energy imbalance of 0.6 ±0.4 Wm–2 (0.17%) inferred from the rise in OHC (Ocean Heat Content) by Hansen et al. (2011).

    Hansen et al. Earth’s energy imbalance and implications, Atmos. Chem. Phys., 11, 13421-13449, 2011.

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