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100% of it. Whether you believe in man made global warming or natural global warming, it is the sun that warms the planet. It is the sun's energy that gets "trapped" by the greenhouse effect. All of the warming on earth is caused by the sun.

2007-04-13 19:30:34 · answer #1 · answered by dsl67 4 · 2 0

It depends what time scale you're looking at and it's also a hard question to answer without going into laborious explanations scattered with what may be meaningless scientific jargon.

In the last 25 years humans are probably responsible for 99% of global warming, in the last 100 years 95%, in the last 250 years 90%, in the last 10,000 years 50%.

Solar variation over short periods of time is minute, the difference between minimum and maximum output during a full sun spot cycle is a little less than 0.1% (1.3 from 1366 W/m²/yr). A deviation over many years can add up but the deviation from year to year is much smaller than the cyclical variation range, more like 0.001%).

Heat from solar radiation attributable to solar variation has increased by approximately 0.3W/m²/yr since 1750, anthropogenic global warming has contributed a further 2.4 W/m²/yr. In percentage terms human have contributed 89%.

There's other things that should be taken into account which I've ignored in order to keep the answer short and because they won't radically alter the figures. A more accurate answer should account for the Feedback Cycle (anthropogenic and natural) and Milankovitch Cycles.

2007-04-13 20:12:29 · answer #2 · answered by Trevor 7 · 0 2

Here I'll give you all the information you need to decide if warming and cooling on Earth is due to changes in the Sun or changes in Carbon Dioxide levels on Earth.

A lot has been made the last week about how cold it has been.

So far it has been the coldest April in over 100 years. This compared to April 2006 which was the warmest April ever on record.

See:
http://www.agweb.com/get_article.aspx?pageid=135336&src=gennews

Carbon dioxide levels have not changed much.

So what else has changed?

Here are comparisons in solar activity comparing last April and this April:

April 2006 (the warmest April ever on record):

http://www.dxlc.com/solar/old_reports/2006/april/indices.html

April 2007 (so far the coldest in over 100 years)

http://www.dxlc.com/solar/indices.html

Notice a pattern???????

Pretty amazing isn't it.

2007-04-13 18:29:53 · answer #3 · answered by michdell 1 · 1 0

The answer to this is well known, because solar radiation is carefully measured by many people.

A little less than 10%.

Page 4 of this report:

http://www.ipcc.ch/SPM2feb07.pdf

Also seen on this graph:

http://en.wikipedia.org/wiki/Image:Climate_Change_Attribution.png

And available in many other places.

This is well known science. Skeptics imply climatologists are ignoring the sun, when actually it's always a part of climatologist's analysis. The skeptics who say "it's the sun" are ignoring solid peer reviewed data, that's measured independently by many people.

EDIT Figured out what's going on below. That site is for a shortwave radio club, and the "solar flux" is radio emission at one frequency. That is of course very different from the visible and infrared solar radiation which heats the Earth. That "data" is great for shortwave radio enthusiasts, but worthless for global warming.

Bottom line (from the not so liberal media)

"While evidence suggests fluctuations in solar activity can affect climate on Earth, and that it has done so in the past, the majority of climate scientists and astrophysicists agree that the sun is not to blame for the current and historically sudden uptick in global temperatures on Earth, which seems to be mostly a mess created by our own species."

http://www.foxnews.com/story/0,2933,258342,00.html

2007-04-13 18:28:36 · answer #4 · answered by Bob 7 · 0 2

There are a whole list of scientists who think so. You may want to look up these articles:

a. “Solar variability and the earth’s climate: introduction and overview” George Reid Space Science
Reviews 94 (2000) p.1-11
Provides a general overview of the sun’s impact on the earth’s climate through the Little
Ice Age as well as through geological times and the complexity in establishing the
solar/climate link.
b. “Low cloud properties influenced by cosmic rays” N D Marsh & H Svensmark Physical Review
Letters 85 (2000) p. 5004-5007
Documents how galactic cosmic rays can influence the earth’s low cloud cover and how
this in turn would impact the mean temperature.
c. “Global temperature forced by solar irradiation and greenhouse gases?” Wibjorn Karlen Ambio,
Vol. 30 (2001)p. 349-350
Argues that the present interglacial has been cooler by about 2°C than the previous ones
during the last 400,000 thousand years when the atmospheric concentration of CO2 was
100 ppmv less than at present.
d. “The sun’s role in climate variations” D Rind Science Vol. 296 (2002) p. 673-677
Provides a general overview of the sun’s impact on the earth’s climate through the Little
Ice Age, as well as through geological times, and the complexity in establishing the
solar/climate link.
e. “Solar influence on the spatial structure of the NAO during the winter 1900-1999” Kunihiko Kodera
Geophysical Research Letters, Vol. 30 (2003) 1175 doi:10.1029/2002GL016584
North Atlantic oscillation is shown to be strongly modulated by high & low solar activity as
identified through sunspot cycles.
f. “Can slow variations in solar luminosity provide missing link between the sun and the climate?”
Peter Fokul EOS, Vol. 84, No. 22 (2003)p.205&208
Presents additional evidence of recent changes in solar irradiance and make a case for
solar impact on the earth’s climate.
3
g. “Celestial driver of phanerozoic climate?” N Shaviv & J Veizer Geological Society of America 13
(2003) p.4-10
Documents, using a “sea-shell thermometer”, how the earth’s temperature over last 500
million years is decoupled with atmospheric CO2 levels, while showing strong correlation
with variations in the cosmic ray flux.
h. “Variable solar irradiance as a plausible agent for multidecadal variations in the Arctic-wide surface
air temperature record for the past 130 years” Willie W-H Soon Geophysical Research Letters Vol.
32 (2005) L16712
Demonstrates a strong link between total solar irradiance and Arctic-wide surface
temperature over a long period from 1875-2000.
i. “Solar forcing of the polar atmosphere” P A Mayewski et al Annals of Glaciology Vol. 41 (2005) p.
147-154
Analyzes high-resolution calibrated proxies for atmospheric circulation from several
Antarctic ice cores, which reveal decadal-scale association with solar variability over the
last 600 years.
j. “The influence of the 11-yr solar cycle on the interannual-centennial climate variability” Hengyi
Weng J of Atmosphere and solar-terrestrial physics Vol. 67 (2005) p. 793-805
Re-confirms the solar variability impact on earth’s climate by analyzing monthly sunspot
numbers in conjunction with global and regional sea surface temperatures.
k. “Living with a variable sun” Judith Lean Physics Today (2005) Vol 58, No. 6 p. 32-37 American Inst.
Of Physics USA
Presents additional evidence of recent changes in solar irradiance and makes a case for
solar impact on the earth’s climate.
l. “Phenomenological solar contribution to the 1900-2000 global surface warming” N Scafetta & B J
West Geophysical Research Letters Vol. 33 (2006) L05708
Constructs a phenomenological model to include solar forcing and demonstrates its
linkage to the earth’s temperature change over last 400 years.
m. “Phenomenological solar signature in 400 years of reconstructed northern hemisphere temperature
record” N Scafetta & B J West Geophysical Research Letters Vol. 33 (2006) L17718
Constructs a phenomenological model to include solar forcing and demonstrates its
linkage to the earth’s temperature change over last 400 years.
n. “Empirical evidence for a nonlinear effect of galactic cosmic rays on clouds” R G Harrison & D B
Stephenson Proceedings of the Royal Society A (UK): 10.1098/rspa.2005.1628 (2006)
Documents how galactic cosmic rays can influence the earth’s low cloud cover and how
this in turn would impact the mean temperature.

2007-04-13 20:30:17 · answer #5 · answered by eric c 5 · 1 0

Really global warming is caused mainly by human activites say scientists but that sun is causing global warming 5 percent
Hope this helped

2007-04-13 19:22:15 · answer #6 · answered by MiSZ.LiZ 2 · 0 2

http://www.fightglobalwarming.com/viewads.cfm?video=train

2007-04-13 23:27:13 · answer #7 · answered by hello 3 · 0 1

99.9%

2007-04-13 18:23:57 · answer #8 · answered by John S 6 · 0 0

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