Do you think the current global warming is or is not part of a natural cycle?

This will be a "weight of the evidence" approach. These things are somewhat unrelated but they all point to the same answer. I'll use easily read references, and add some of the the underlying scientific papers under Source.

In past natural warmings CO2 lagged temperature by hundreds of years. Warming started for other reasons and CO2 was released from warming ocean waters. This time CO2 is going up simultaneously with temperature, because it's mostly the cause. Details here:

http://www.realclimate.org/index.php/archives/2007...

The lower atmosphere is warming, while the upper is cooling. The obvious explanation is that something is trapping heat down low.

http://www.realclimate.org/index.php/archives/2006...

The obvious natural cause would be increased solar radiation. But solar radiation has actually been decreasing just a bit for years.

http://news.bbc.co.uk/1/hi/uk/6290228.stm

It's possible to model the last hundred years decently only if you include man made greenhouse gases, and then they must be the most important thing for the last 30 years. Purely natural equations just don't work.

http://www.globalwarmingart.com/wiki/Image:Climate...

LARRY - Solar "activity" is sunspots, which don't affect solar _radiation_ much, and which move in 11 year cycles, which doesn't correlate well with the past 30 years of warming. Lockwood and Frohlich address this issue, as do these:

http://environment.newscientist.com/channel/earth/...

http://www.realclimate.org/index.php/archives/2006...

Also see:

Variations in solar luminosity and their effect on the Earth's climate, P. Foukal, C. Fröhlich, H. Spruit and T. M. L. Wigley, Nature 443, 161-166 (14 September 2006), doi:10.1038/nature05072

Scientists advancing this theory have manipulated the data in very strange ways:

Pattern of Strange Errors Plagues Solar Activity and Terrestrial Climate Data, Damon and Laut, Eos,Vol. 85, No. 39, 28 September 2004

The rate of warming in the last 50 years was double the rate observed over the last 100 years.

In fact from ice core samples at the poles, the top scientist has been able to see that the amount of damage done to the environment in the last 50 years is greater than the last 2000 years. I believed that the changes were natural and had been going on forever until I saw this on the history channel.

The West Antarctic Ice Sheet contains enough ice to raise sea level by 5-6 meters (17-20 feet). Possible instabilities in the ice sheet could allow it to slide into the oceans after a sustained warming, or if other factors raised sea level (IPCC, 2007). There is a small chance the collapse of this ice sheet could occur within a few centuries, but the response of the ice sheet to future climate change is uncertain and a subject of debate (IPCC 2007, NRC 2002).

The Greenland ice sheet contains enough ice to raise sea level about 7 meters (23 feet). Although it is already contributing to sea level rise (from melting), it does not contain the same instabilities as Antarctica that could result in a rapid collapse. Most model projections suggest a gradual melting over millennia related to sustained climate warming (IPCC, 2007). http://www.epa.gov/climatechange/science/futureslc...

'Scientific evidence' is not required. All you have to do is read a definition.

Global Warming and Global Cooling are natural cycles. Anthropogenic Global Warming is human induced. End of argument.

But then you already know this. It is beneath you to troll for answers to support an entrenched belief. It lowers you to the level of the AGW deniers who do exactly the same thing.

Yes, I do believe it is mostly a natural cycle. I do not dispute that man has caused a small part of it though. You have often pointed out that solar activity has been declining and it has, but solar activity has been higher in the past 7 decades than it was in the last 8000 years and the last solar cycle was still extremely active. It takes several decades for the heat energy reserves in the ocean to dissipate. Earth's temperature has not recently, been higher than it was 1998. There is very good correlation between solar activity and low cloud cover. Low clouds have a much stronger influence on surface temperatures than CO2. This is evident when we are sun bathing and a gray cloud comes by and the shade cools us. It has the same cooling effect on the surface of the planet. Less energy reaches the surface because it is reflected back toward space. When solar activity is high, there are fewer clouds to reflect incoming solar radiation. When solar activity is low, more clouds develop and less solar radiation reaches the surface of the planet.

Bob, that's right, total solar irradiance does not change that much with solar activity, but the radiation that is received at the surface of the planet varies more significantly with solar activity by cloud modulation. Many scientists agree with this explanation and the geological record shows that global temperatures correlate exceptionally well with solar activity over the past 500 million years regardless of CO2. In fact, The CO2 levels in past climates have been 10 to 15 times higher than they are now through out two different ice ages.

The answer is that there is no way to know. We have always had natural cycles. There has never been a time when the climate was static. The burden of proof lies with those making extraordinary claims and examples of consensus is not proof. If you think a bunch of Native Americans can dance around the fire and make it rain, how am I supposed to prove you wrong. It is up to you to prove it. I am content to believe that natural cycles are being followed. The cooling of the 1970s proves that CO2 is not the significant driver in spite of the pathetic explanation of reduced sulfur.

The most accepted way climatologist's determine past climate conditions is a technique called oxygen isotopic stratigraphy.

Other techniques include the study of:

plate tectonic concepts

Paleowinds

Regression-Transgression

Land Plants

Paleosols

Phosphorites

Glacial Deposits

Redbeds

Plant Morphological Features

Carbonate-Noncarbonate Lithofacies

Coal

Evaporites

Sorry.. I don't have an opinion. Too complicated.

I don't care if I get a best answer or not. Global Warming is much ado about nothing. My biggest irritaion about the subject is the amount of money spent on something we can't change (atleast not in this lifetime) instead of using those funds for something like the national debt. I may sound stupid to ya'll, but I don't care. Global warming is stupid.

This is like watching a game of tennis. Global warming is caused by man! No it's not! Yes it is! etc etc etc.

One thing is for sure though; those of you completely rejecting the idea of AGW are taking a hell of a risk based on shoddy, shoddy evidence and will live to regret it. Sea level rise, risng temperatures and extremes in weather patterns will affect us all. Even if you don't believe in AGW you should, for your kid's sake take some measures to reduce emissions "just in case".

I admit I've studied this a lot at college and am convinced by the data. Forget my bias and please try and understand the message I'm trying to convey. This isn't about ideology, right versus left or any of that bullshit. This is almost certainly real and we need to act now.

Those of you who genuinely haven't studied the science and are basing your opinions on political or ideological allegiances please wake up. Study the facts and then make an INFORMED argument.

I have read a few times that the extreme to which the warming has occured has been more acute recently than it should be.

Jim Z-Evidence has been sighted and shown. If you refuse to believe studies that are accesible to you that provide evidence of man made GW, you're a denier, not a skeptic.

It's clear that the Earth has natural cycles of warmth and cold.

Why would anyone think that durring this time the climate should be static?