Science Forums 2

[modest]

Originally Posted by modest

It seems to me the onus is on you in this regard. If the video struck a chord with you then by all means... critique it.

It now strikes me that you did, in fact, comment on the video—so, the above is not entirely fair.

Originally Posted by Biochemist

In this video, the argument is that warming is better correlated with solar activity over the long term (300 to 1000 years)

There is no record of solar irradiance over such time periods. However, even if we approximate solar irradiance using sunspots, the AGW camp is not claiming that solar irradiance is not a significant actor on global temperature. I'm sure AGW allows for both solar irradiance and atmospheric CO2 to impact the climate.

Originally Posted by Biochemist

and that the increase in temperature over the last 100 years is more likely from solar activity than from CO2 increases.

While solar activity certainly affects climate, to say an increase in temperature over the last 100 years is primarily due to solar activity strains credulity at the least. Consider Occam's razor. There is something (CO2) that is expected to increase global temperatures when present in the atmosphere due to a well-tested law of physics. People add to the level of CO2 in the atmosphere then measure an increase in temperature. Exactly what we expect to happen, in fact, happened.

We don’t need elaborate coincidences in the way of unmeasured solar irradiance to explain the obvious. Moreover, we’ve been measuring the sun’s output since 1979. The data is as follows:


-source

The sun's output certainly doesn't seem to be increasing over the past 30 years since we began measuring it. Global surface temperatures have increased markedly over that time. This evidence directly supports AGW over the statement that "increase in temperature over the last 100 years is more likely from solar activity than from CO2 increases".

Originally Posted by Biochemist

It also argues that CO2 increases are generally a result of warming, not a cause (since warm oceans undeniably store less CO2 than cold ones).

Increasing CO2 doesn't have to be either a cause or a result of warming. It easily can be both. In the case of human released carbon dioxide from burning fossil fuels we can be pretty certain—that is *not* caused by increase in temperature or solar irradiance.

Originally Posted by Biochemist

The recent drop of global temperatures (2008) back to about the 100 year mean supports this position.

Quickly putting this data into excel tells me that global temperatures haven't been equal to the current 100 year average since 1975 and we're currently well above that average now. To imply that our measurements of solar irradiance have correlated with global temperatures over the past 30 years is simply not true.

~modest