From “The Hockey Schtick“, some inconvenient truth that breaks Mann’s already broken hockey stick into even smaller pieces. A new paper finds significant cooling of Atlantic Ocean over past millennium, making the MWP warmer in terms of sea surface temperature than today. Since land temperatures (including forest lands of Sheep Mountain and Yamal) respond significantly to ocean temperatures (the ocean is the big kahuna of global heat sinks) it is a pretty safe bet that those favored trees (including YAD 061) experienced warmer temperatures during the MWP than today. The eastern tropical North Atlantic reconstruction of SSTs was based on foraminiferal (marine plankton shells) Mg/Ca ratios that resolves multidecadal variability over the past 1700 years. see below:
The paper, published December 29th, 2011 in the journal Paleoceanography finds that Atlantic Ocean surface temperatures have significantly cooled over the past millennium, since the Medieval Warming Period from about 950-1200 AD.
- Monsoon season SST is reconstructed for the past 3 millennia
- Over the past 1700 years, several intervals show multidecadal SST variability
- Late medieval cooling amounts to approximately 0.5 degree Celsius
PALEOCEANOGRAPHY, VOL. 26, PA4224, 11 PP., 2011
doi:10.1029/2011PA002130
Henning Kuhnert et al
Multidecadal variations in Atlantic sea surface temperatures (SST) influence the climate of the Northern Hemisphere. However, prior to the instrumental time period, information on multidecadal climate variability becomes limited, and there is a particular scarcity of sufficiently resolved SST reconstructions. Here we present an eastern tropical North Atlantic reconstruction of SSTs based on foraminiferal Mg/Ca ratios that resolves multidecadal variability over the past 1700 years.
Spectral power in the multidecadal band (50 to 70 years period) is significant over several time intervals suggesting that the Atlantic Multidecadal Oscillation (AMO) has been influencing local SST. Since our data exhibit high scatter the absence of multidecadal variability in the remaining record does not exclude the possibility that SST variations on this time scale might have been present without being detected in our data. Cooling by ∼0.5°C takes place between about AD 1250 and AD 1500; while this corresponds to the inception of the Little Ice Age (LIA), the end of the LIA is not reflected in our record and SST remains relatively low.
This transition to cooler SSTs parallels the previously reconstructed shift in the North Atlantic Oscillation toward a low pre-20th century mean state and possibly reflects common solar forcing.
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WGI Chapter 5 zero draft summary says the opposite – that today is warmer than the past.
http://www.gallopingcamel.info/WGI.htm
Please enlighten them.
Izen posts…
@- Latitude says:
“You just said the climate is sensitive to something besides CO2.”
I didn’t, but the climate reacts to the energy balance, a radiative forcing, positive for an addition of CO2 or an increase in solar irradience, negative for SOx injected into the stratosphere by volcanic eruptions, or a reduction in solar insolation.
How much the surface temperature (in degrees C) changes in response to a radiative forcing (in W/m2) depends on the value of the climate sensitivity.
This is all very basic…”
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Really Izen so you claim climate senstivity is the same for all W/m2 forcing. There is no difference if the forcing is CO2 induced, or TSI induced. This is basic all right, but basically wrong. Now for some really basic radiative balance theory. At its most basic only two things can effect the energy content of any system in a radiative balance. Either a change in the input, or a change in the “residence time” of some aspect of those energies within the system.”
It therefore possibly follows that any effect which increases the residence time of LW energy in the atmosphere, (green house gases) but reduces the input of SW energy entering the oceans, (atmospheric heating causing more cloud cover oand or water vapor) causes a net reduction in the earth’s energy balance, proportioned to the energy change involved, relative to the residence time of the radiations involved. The critical fact is that the energy is CUMLITIVE for everyday of “residence” and some of this energy may increase DAILY for as many days, months, years or decades that a change in TSI or cloud cover continues. Hence my paraphrase of an old maxim, ” A SW photon in the ocean is worth two LWIR photons in the atmosphere,” Of course it could be 30 to one for all anyone knows.
Izen, every year the TSI changes by about 100 W/m2. And when the earth is recieving that increase of 100 W/m2, the atmosphere is about 4 degrees cooler.