Re: Solar Activity Reaches 1,000 Year Peak

On 10/04/07 18:38, in article Pine.BSI.
4.64.0704100613070.1669@xxxxxxxxxxxxxxxxx, "Alvin E. Toda"
<aet@xxxxxxxx> wrote:

Some may claim, like in the scifi books Dragon Riders
of Pern by Anne MaCaffrey, unexplain astronomical
events occuring at long time intervals. For example,
maybe every 100,000 or 200,000 years (it varies) that
the solar constant could change, or maybe a rogue
passing planet could disrupt the planetary tilt and
rotate the poles into the equator? No one has an
explanation (data) for such speculative events.

The irony with the term "solar constant" is that it changes throughout
the year!

The earth is not in a solar orbit, but the distance from the sun
varies from 147 million kms on January 3rd and to 152 million on July
3rd.

The measured solar "constant" varies from 1435 W/m2 on Jan. 3
(Perhelion) to about 1345 on July 3rd. Due to precession, in 11500
years that will be reversed,
summer will become winter and winter summer,
the sun will be closest to the earth in summer.
Winters will become colder because of this.

Anyway data like http://en.wikipedia.org/wiki/Image:Solar-cycle-data.png
does not show this because the data has been normalized to 149,598,000
kilometers, the average distance from the
earth to the sun.

Next, the earth is in a cold-ice age mode right now and this has
persisted for the last few million years, Roughly 30 million years ago
there was no ice cap at the south pole and glaciers were beginning to
develop there. Average surface ocean temperatures dropped from around
20°C 55 million years to suddenly cooled to below 10°C more about 30
million years ago and have remained low.

Formation of the Antarctica ice *** occurred
10 million years ago and the ice sheets in the Northern Hemisphere are
Pliocene events, less
that 5 million years ago. A goodly portion of these
changes are not due to variations in the sun's output,
which is supposedly constant increasing at the rate
of 10% per billion years. Plate tectonics, the movements,
the reconfiguration of the continents and forced redistribution
of the currents are the controlling factors in climate over the long
run.

Of the nearly constant factors during the last 50 million years, the
sun's output is probably the only one. The temperature has yo-yoed,
the CO2 content in the air has flipped and flopped as plate tectonics
feed at times carbonate rocks into the magma (subduction) and releases
CO2 via volcanic action back into the atmosphere. Sudden such
increases in CO2 in the past have caused sudden warming, Relatively
"rapid" removal of CO2 has caused cooling, the evolution of
temperatures went from 20° C in early Carboniferous Period (hot) 20°
C with cooling during the Middle Carboniferous reduced average global
temperatures to about 12° C.

At that time all the continents were fused together in a single mass.
(http://www.scotese.com/gzelclim.htm). The climate in the
Carboniferous went from hot to cold and remained that way throughout
the Permian until CO2 concentrations started up.

The atmospheric concentrations of carbon dioxide (CO2) in the Early
Carboniferous Period were approximately 1500 ppm), but by the Middle
Carboniferous had declined to about 350 ppm.

A review of the last 450 million years is given below

****

Greenhouse Gas Effect Consistent Over 420 Million Years
Terra Daily ^ | 03/29/2007 | Staff Writers

Posted on 03/29/2007 9:30:26 AM PDT

New calculations show that sensitivity of Earth's climate to changes
in the greenhouse gas carbon dioxide (CO2) has been consistent for the
last 420 million years, according to an article in Nature by
geologists at Yale and Wesleyan Universities.

A popular predictor of future climate sensitivity is the change in
global temperature produced by each doubling of CO2 in the atmosphere.
This study confirms that in the Earth's past 420 million years, each
doubling of atmospheric CO2 translates to an average global
temperature increase of about 3 Celsius, or 5 Fahrenheit.

According to the authors, since there has continuously been life on
the planet over this time span, there must be an ongoing balance
between CO2 entering and leaving the atmosphere from the rocks and
waters at Earth's surface. Their simulations examined a wide span of
possible relationships between atmospheric CO2 and temperature and the
likelihood they could have occurred based on proxy data from
geological samples.

Most estimates of climate sensitivity have been based on computer
simulations of climate or records of climate change over the past few
decades to thousands of years, when carbon dioxide concentrations and
global temperatures were similar to or lower than today. Such
estimates could underestimate the magnitude of large climate-change
events.

To keep Earth's carbon cycle in balance, atmospheric CO2 has varied
over geologic time. Carbon-cycle models balance chemical reactions
that involve carbon, such as photosynthesis and the formation of
limestone, on a global scale. To better predict future trends in
global warming, these researchers compared estimates from long-term
modeling of Earth's carbon cycle with the recent proxy measurements of
CO2.

This study used 500 data points in the geological records as "proxy
data" and evaluated them in the context of the CO2 cycling models of
co-author Robert Berner, professor emeritus of geology and geophysics
at Yale who pioneered models of the balance of CO2 in the Earth and
Earth's atmosphere.

"Proxy data are indirect measurements of CO2 - they are a measure of
the effects of CO2," explained co-author Jeffrey Park, professor of
geology and geophysics at Yale who created the computer simulations
for the project. "While we cannot actually measure the CO2 that was in
the atmosphere millions of years ago, we can measure the geologic
record of its presence. For example, measurement of carbon isotopes in
ancient ocean-plankton material reflects atmospheric CO2
concentrations."

Led by Dana L. Royer, assistant professor of Earth and Environmental
Sciences at Wesleyan University, who did his graduate work in geology
at Yale, the collaboration simulated 10,000 variations in the carbon-
cycle processes such as the sensitivity of plant growth to extra CO2
in the atmosphere. They evaluated these variations for a range of
atmospheric warming conditions, using the agreement with the geologic
data to determine the most likely warming scenarios. The model-
estimated atmospheric CO2 variations were tested against data from
ancient rocks.

Other proxy measurements of soil, rock and fossils provided estimates
of CO2 over the past 420 million years. Calculation of the climate
sensitivity in this way did not require independent estimates of
temperature. It incorporated information from times when the Earth was
substantially warmer and colder than today, and reflects the
sensitivity of the carbon-cycle balance over millions of years.

"Our results are consistent with estimates from shorter-term records,
and indicate that climate sensitivity was almost certainly greater
than 1.5, but less than 5.5 degrees Celsius over this period," said
Park. "At those extremes of CO2 sensitivity, [1.5C or 5.5C] the carbon-
cycle would have been in a 'perfect storm' condition."
et> wrote:


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