Which is the more significant cause of global climate change:?

Question

1 - Natural Variation of the Sun

2 - Man-made influences

Defend your answer with data and analysis.

Sorry Simon...no data...no analysis...no points.

Sorry Mr. Taco. The NRDC site does not include data nor analysis. It asks you to accept things on faith. Your ecobridge site describes carbon dioxide, and attempts to declare it the main cause, but does not even consider natural variation of the sun.

The Pew site, after drilling down a bit, goes to a study which includes the now infamous "hockey stick" graph, which predicts "catastrophic" golbal warming. Unfortunately, the hockey stick predictions ignore these critical questions:

1 - Why, when even *RANDOM* data are used for past temperatures, do global climate models predict future warming?

2 - How are the estimates of golbal temperature validated for years prior to 1700?

So, Mr. Taco, I did look it up myself. maybe you should read the full question and not let yourself be drawn into conclusions without reviewing the data and analysis yourself.

And, Mr. Taco, are you sure you want to bet your life savings that there is no evidence of natural variation of the sun contributing to current global climate change? Are you really sure? I don't think either of your suggestions stands up by itself. How much is your life savings, anyway?

At least campbelp2002 is wise enough to acknowledge that which he does not know.

disgracedfish has made a valid point with respect to solar irradiance. However, note on the site you reference that the irradiance estimates are based upon "Quantitative modelling of total and spectral irradiance variations and of the surface magnetic flux."

Unfortunately, the site provides no description of efforts at verification, validation, or accreditation of these models. It gives a chart, but does not describe how the data in that chart were estimated. Note that I said estimated and not measured, since the data came from, by the site's own admission, a computer model or models.

How is that model, and the data input into the model, validated?

Jamie Jamie Jamie...do you realize that you have made an error? Ask your teacher whether statistical correlation proves causality.

Your "Power Point" speech...did it have any data at all that showed the percent of global climate change casued by man and by the sun?

No, it did not. You just lambasted the US because they have a larger output of CO2 than their percent of the worlds population. What does that prove?

Answer 1

With regards to solar contribution:

1. "We estimate that the sun contributed as much as 45–50% of the 1900–2000 global warming, and 25–35% of the 1980–2000 global warming. These results, while confirming that anthropogenic-added climate forcing might have progressively played a dominant role in climate change during the last century, also suggest that the solar impact on climate change during the same period is significantly stronger than what some theoretical models have predicted."

2. "The main cause of climate change during the last millennia is the corresponding cyclic variation of the 80- and 200-year component of irradiance correlated with activity. That is why, the contemporary is not anomalous but is ordinary secular global warming."

3. "While the impact of direct solar radiative forcing relative to amplification of TSI by
indirect mechanisms is still a subject of debate, the detection/attribution assessments of climate models “suggest that the solar influence on climate is greater than would be anticipated from radiative forcing estimates. This implies that either the radiative forcing is underestimated or there are some processes inadequately represented in those models” (Gray et al., 2005)."

So here we have three different papers, all of which lend credence to solar variations. The first suggests that a significant percentage of warming is due to the sun, while suggesting man has some role. The second points out the cyclic relationship of solar output and temperature, while telling us that the warming we are seeing now is not anomalous. The third tells us that the models currently being used underestimate solar forcings.

For those that doubt that the sun has any influence, this must be a bit of a shock.

I am still of the opinion that we just do not know the cause at this point. There are many climate forcing variables that need to be accounted for. The models do not account for the most important one (clouds), nor do the directly account for CO2, but rather, they use an "energy equivalence" factor.

Poor models make a poor basis for policy decisions.

Answer 2

You mean which is more significant to the current change, or just climate change in general?
If you mean the current change, then the answer is 2.

Natural variation of the sun most certainly did contribute, as solar irradiance increased from 1910 to about 1940: http://www.mps.mpg.de/en/projekte/sun-climate/

So a part of the warming during that period was probably due to solar forcing (I've heard it estimated at about 50% solar, 50% anthropogenic greenhouse gases).

However, as you can see from the graph I linked to, there has been no increase in solar irradiance since then, so none of the warming after 1940 can be explained with variation in solar output.

I think a good estimate of the total amount the sun has contributed to global warming over the last century is about 30%. (slightly more than half of the warming occurred before 1940, so if the estimate that 50% of that warming was due to the sun is correct, then a little more than a quarter of the total warming this century is due to the sun).

That means the majority (70%) of the warming is likely due to anthropogenic influences.

::Edit::

If you want sources to the work on solar irradiance reconstructions, you can find them here: http://www.mps.mpg.de/homes/natalie/PAPERS/asr2004.pdf

Unfortunately, satellite measurements of solar irradiance didn't begin until 1978, so I'm afraid model based reconstructions leading up to that time are the best I can offer.

After 1978, we have direct measurements of both solar irradiance and temperature. You can compare them side by side if you like:

Solar irradiance: http://www.logicalscience.com/skeptic_arguments/images/comp06_d41_61_0702.png

Temperature: http://www.logicalscience.com/skeptic_arguments/images/1975-5avg.gif

Answer 3

Up until now, it has not been man. There has been natural warming in the past that far exceeds the projected maximum end result of the present warming. For example, in the age of dinosaurs there was no polar ice cap at all and sea level was several hundred feet higher than today.

However, there is no proof that past warming was caused by variations in the Sun. There is no proof that it wasn't either. We just don't know. We still don't know what causes ice ages and the warming that always occurs between them.

But we do know that humans are causing CO2 to increase at an unprecedented rate, and it is starting to take an alarming trend. See the source.

Answer 4

I bet you my life savings that you can't find any evidence whatsoever that the first option has any bearing on this whatsoever. Even the few (very few) scientists that don't believe that man has made that much of an impact on it don't think it is the sun that causes global climate change.

In any case, it is really scary that this is such a hot topic when the overwhelming majority of scientists are in agreement on the subject. Here's some data and analysis for you. Look it up yourself:

Answer 5

I believe its man-made influences. Im in high school and I did a power point speech on global warming. The United States only makes up 4% of the worlds population, but we make up over 25% of the worlds CO2 and toxic gasses.

Answer 6

The Earth has increased in temperature at a far greater rate (remember to look up what 'rate' means!) over the last 100 years (when industrial output REALLY got going) than EVER before.

Answer 7

the sun

The sun is causing our warming along with interplay between the sea currents. For proof look at the fact that mars is also warming.
http://web.dmi.dk/solar-terrestrial/space_weather/
http://www.geocraft.com/WVFossils/Reference_Docs/The_Geologic_Record_and_Climate_Change.pdf
http://www.livescience.com/environment/070312_solarsys_warming.html
http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html
http://biocab.org/Global_Warming.html
http://www.nasa.gov/vision/universe/solarsystem/mgs-092005.html
http://www.nasa.gov/vision/universe/solarsystem/mgs-092005.html
http://www.eurekalert.org/pub_releases/2000-03/UoCS-Nrol-1903100.php
http://www.aip.org/enews/physnews/2003/split/642-2.html
http://www.space.com/scienceastronomy/060926_solar_activity.html
http://www.globalwarming.org/article.php?uid=900
http://www.sciencedaily.com/releases/2004/08/040803093903.htm
http://www.msnbc.msn.com/id/18397549/
http://science.nasa.gov/headlines/y2003/17jan_solcon.htm