What do you men by “we”? The United States or the world? Please cite your source.

Teach said: Why have we had warm periods in the past with no cars?

There have been many reasons we have had warm periods in the past…changes in the Earth’s orbit around the Sun, major tectonic activity, etc., but the fact that natural factors caused climate changes in the past does not mean that the current climate change is primarily natural. Just because forest fires have long been caused naturally by lightning strikes does not mean that fires cannot also be caused by a careless camper.

The difference between your argument and mine is that I actually have some numbers to back it up. Please look at Figure TS.5 (Global Mean Radiative Forcings) on page 32 of the IPCC Fourth Assessment Report:

http://ipcc-wg1.ucar.edu/wg1/Report/AR4WG1_Pub_TS.pdf

Do you have something similar to support your claim?

The other is that higher water levels may push more water into the magma chambers, creating more gasses, which can cause volcano’s to become more active. This can also effect fault zones which are not under water.

As far as your disbelief in the majority of temp increase being natural, other then a silly non scientific report from the UN, what proof do you have that it is other then mostly natural? Why did we have so many really hot years back in the late 20’s through late 30’s? We did not have huge amounts of cars and air travel back then, did we? Why have we had warm periods in the past with no cars?

But how can rising sea levels cause volcanoes to erupt? The answer lies in the enormous mass of the water pouring into the ocean basins from the retreating ice sheets. The addition of over a hundred metres depth of water to the continental margins and marine island chains, where over 60% of the world’s active volcanoes reside, seems to be sufficient to load and bend the underlying crust.
This in turn squeezes out any magma that happens to be hanging around waiting for an excuse to erupt. It may well be that a much smaller rise can trigger an eruption if a volcano is critically poised and ready to blow.
Eruptions of Pavlof volcano in Alaska, for example, tend to occur during the winter months when, for meteorological reasons, the regional sea level is barely 30cm (12in) higher than during the summer. If other volcanic systems are similarly sensitive then we could be faced with an escalating burst of volcanic activity as anthropogenic climate change drives sea levels ever upwards. (from the article Teach cites above)

Is this wrong? Please explain.

Actually I think that number is a little higher. The IPCC’s Fourth Assessment Report states 0.74 degree Celsius per the last 100 years. I believe your figure comes from the Third Assessment Report.

jt said: That 0.1 degree difference that you slough off is an error of 16.666%.

Actually the error for the hottest year on record was 0.03, not 0.1 and the error you site is comparing two different numbers. The error with NASA’s numbers has to do with temperatures in the United States only. The second number you were comparing it to has to do with global temperature averages.

As stated at the site I recommended it said…

The net effect of the change was to reduce mean US anomalies by about 0.15 ºC for the years 2000-2006. There were some very minor knock on effects in earlier years due to the GISTEMP adjustments for rural vs. urban trends. In the global or hemispheric mean, the differences were imperceptible (since the US is only a small fraction of the global area).

jt said: As for sea level changes due to volcanism etc,…

I thought it was the other way around – i.e. McGuire is saying that the added pressure from sea level changes may cause an increase in volcanic activity. Is this possible?

Sorry for the long response. I’m still interested in seeing any reports you might have that would indicate the temp changes are primarily natural.

The discussion is very informative and there is a paucity of ad-hominem attacks, for once. it’s a healthy debate. Besides, I live in the Great White North – the western part of it. Our temperature for August 14 was 6 C this morning, or 42.8 F. We have already had frost up north this week, summer is over. Frankly, I would welcome a warmer climate up here for a longer period of time, so why fight it?

I’m not a geologist so I can’t speak to what Bill McGuire is claiming about the effects of climate change on the Earth’s surface (see my statement above). But since you are a geologist can you tell me if there is any correlation at all between rising sea levels and volcanic activity?

Also, regarding my last question in the statement above – since Teach doesn’t seem interested in providing different numbers to back up his claim, do you know of a different report (as extensive as the IPCC’s) that would indicate the temp changes are primarily natural?

http://www.climateaudit.org is currently down and has been for a few days via a DNS attack – as soon as this researcher released his data on NASA temperature re-configurations (oops NASA had a Y2K bug and didn’t (wink) know it) his site went down. This same researcher, Steve McIntyre, debunked Mann’s “hockey stick” graph.

AGW climate change is a HOAX! The biggest FRAUD ever perpetrated. As for AGW having anything to do with “Plate Tectonics”, that statement is pure, unadulterated bull! I am a professional Geologist with 30 years experience – that premise is completely un-scientific, don’t even go there, because you do not know what you are talking about.