Climate Controlling Ocean Thermostat Discovered

  • Date: 29/12/10

The influence of the Sun on Earth’s climate over time scales of centuries and millennia is all but ignored by current climate change dogma, with many climate scientists dismissing solar variation as too feeble to have much of an impact. Though it was recently discovered that variation at ultraviolet wavelengths is considerably greater than at lower frequencies, the change in total solar irradiance over recent 11-year sunspot cycles amounts to <0.1%. New research on longer time scales finds the change in total irradiance sufficient to affect the dynamics of the El Niño–Southern Oscillation (ENSO). Detailed model studies of the Little Ice Age (~1400 to 1850 AD) conclude that the Sun controls an “ocean dynamical thermostat” that affects climate variability over large regions of the globe. It was also found that fully coupled general circulation models (GCMs), the kind used by the IPCC to make predictions of future global warming, lack a robust thermostat response. This means that the sensitivity of the climate system to solar forcing is underestimated by current GCMs—the climate models are proven wrong again.

A report in the December 3, 2010, issue of Science has reinforced what many scientists have suspected all along: variation in the Sun’s output causes significant change in Earth’s climate. Writing in “Dynamical Response of the Tropical Pacific Ocean to Solar Forcing During the Early Holocene,” Thomas M. Marchitto, Raimund Muscheler, Joseph D. Ortiz, Jose D. Carriquiry and Alexander van Geen present a high-resolution magnesium/calcium proxy record of Holocene sea surface temperature (SST) from off the west coast of Baja California Sur, Mexico. Their work is in agreement with the theoretical “ocean dynamical thermostat” response of ENSO to radiative forcing. Here is their description of the work:

The influence of solar variability on Earth’s climate over centennial to millennial time scales is the subject of considerable debate. The change in total solar irradiance over recent 11-year sunspot cycles amounts to <0.1%, but greater changes at ultraviolet wavelengths may have substantial impacts on stratospheric ozone concentrations, thereby altering both stratospheric and tropospheric circulation patterns. Estimates of the secular increase in total irradiance since the late 17th century Maunder sunspot minimum range from ~0.05 to 0.5%. Values in the middle of this range are sufficient to force the intermediate-complexity Zebiak-Cane model of El Niño–Southern Oscillation (ENSO) dynamics into a more El Niño–like state during the Little Ice Age (A.D. ~1400 to 1850), a response dubbed the “ocean dynamical thermostat” because negative (or positive) radiative forcing results in dynamical ocean warming (or cooling, respectively) of the eastern tropical Pacific (ETP). This model prediction is supported by paleoclimatic proxy reconstructions over the past millennium. In contrast, fully coupled general circulation models (GCMs) lack a robust thermostat response because of an opposing tendency for the atmospheric circulation itself to strengthen under reduced radiative forcing.

A number of things stand out here. First, irradiance changes that have been dismissed by some in the CO2 fan club were shown to be sufficient to drive changes in the ENSO. Much like the atmospheric solar heat amplifier found previously, seemingly minor changes in solar output can cause big changes here on Earth. Because the Pacific region is so large, any thing that affects the ENSO also affects climate world wide.

Second, the response is the reverse of what you might think. An increase in total irradiance causes the waters of the eastern tropical Pacific to cool. Conversely, a reduction in solar output causes the circulation patterns to change in such a way that the sea surface temperatures (SST) rise. This is an example of negative feedback, where the response to a signal is in opposition to the expected change engendered by that signal. Negative feedback loops have been compared to thermostatically controlled temperature in a house.

When the internal temperature of the house drops drops below the temperature at which the thermostat is set, the thermostat turns on the furnace. As the temperature within the house rises, the thermostat again senses this change and turns off the furnace when the internal temperature reaches the pre-set point. There are many such control loops found in nature—the regulation of body temperature for example. Here the result is to maintain stability to the planet’s temperature in the face of variation in solar forcing, hence the designation “ocean dynamic thermostat.”

Naturally, temperature and solar radiation history is based on proxy data, primarily from sediment cores. Specifically, Marchittoet al. measured the SST proxy Mg/Ca in the planktonic foraminifer Globigerina bulloides. In addition to G bulloides, data from other planktonic organisms, representing other locations, were included and are shown in the figure below.


SST reconstructions based on Mg/Ca in surface-dwelling planktonic foraminifera.

Note that the temperature reconstructions contain signals from other forcings besides the Sun. The data had to be corrected to compensate for orbital-scale changes—variation in irradiance patterns caused by Earth’s shifting orbital parameters. To estimate the level of solar activity, the researchers used the cosmogenic nuclide proxies 14C and 10Be, isotopes formed by cosmic ray collisions with atoms in the atmosphere.

“An active Sun generates a higher total irradiance and a stronger interplanetary magnetic field that helps to shield Earth from the galactic cosmic rays that produce 14C and 10Be in the atmosphere,” state the authors, though they note that significant uncertainties in such estimations exist: “atmospheric levels of 14C may be affected by changes in Earth’s carbon cycle, 10Be fluxes from ice sheets may be influenced by local climate, and the production rates of both nuclides are modulated by long-term variations in Earth’s magnetic field.”

Why does all this matter? La Niña has historically been associated with stronger summer monsoons over Asia, as both are linked to strong easterlies over the tropical Pacific. Solar forcing of La Niña and persistent, decadal-scale droughts over the southwestern United States indicates a connection between solar-activity maxima and dry conditions. “Taken together with our SST record, these observations are consistent with solar-induced dynamical cooling of the ETP and provide predictions for millennial-scale fluctuations in the hydrologic balance over the western United States during the early Holocene,” the authors state.


The three phases of the ENSO.

But it is not just Asia and North America that are affected by the ENSO. Keep in mind that the Pacific Ocean covers a major portion of the globe. The massive amounts of moisture being pumped into the atmosphere in the tropical Pacific are a major part of world climate. Changes in the ENSO can influence temperatures and precipitation worldwide. In atmospheric science speak the ENSO and climate oscillation around the the world are teleconnected.

Teleconnection in atmospheric science refers to climate anomalies being related to each other at large distances, typically thousands of kilometers. Identifying teleconnections is fundamental in understanding climate variability, otherwise climate oscillations can seem random and unpredictable. Marchitto et al. claim that solar variation is directly linked to teleconnections among regions of the Pacific. The correlation between irradiance and climate change is shown in the figure below.


Teleconnected climatic and solar proxy records spanning the early Holocene.

The third and final point is that the paper’s authors specifically comment on the inability of current GCM computer models to capture this climatic response. The upshot is that the response of Earth’s climate system to changes in solar radiation has been under estimated. Here is how the author’s concluded the paper:

GCMs fail to reproduce the La Niña–like nature of the MWP because the ocean thermostat mechanism is either absent or dampened by atmospheric effects in such models. If our observations are supported by future SST reconstructions from the equatorial Pacific, then it is possible that the sensitivity of the climate system to solar forcing is underestimated by current GCMs. The nature of the climate response appears to be one of shifting atmosphere-ocean circulation patterns, with the tendency for global radiative surface warming being countered by the ocean dynamical thermostat.

This new work indicates that even small variations in the Sun’s output can have significant affect here on Earth. This is unsurprising, since the energy that drives Earth’s climate comes from the Sun. Monsoon floods and decades long droughts are both part of the natural variation driven by our neighborhood star, but every climate fluctuation that causes human discomfort is blamed on anthropogenic global warming. Floods in Pakistan, blizzards in Paris and New York, typhoons in the Philippines are all blamed on human CO2 emissions. What utter rubbish—it’s the Sun, you bloody fools!

Scientists are constantly making new discoveries, uncovering new evidence that reveals complexities in the climate system that were not even suspected a few years ago. Yet the cheering section for predicted global warming disaster continue to insist that the consensus view (ie. their view) of climate science is correct. This is yet another example of how incomplete climate science is and how inaccurate the computer climate models used by the IPCC and other climate change catastrophists are. In the face of new revelations, the old CO2-centric view of climate change is laughable and computer model predictions based on that view absurd.

Be safe, enjoy the interglacial and stay skeptical.

The Resilient Earth, 28 December 2010

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