Models the prime cause of global warming – Sun may or may not be involved in climate change

from: Phil Jones
subject: FW: Your graph regarding global temperature anomaly
to: heino.schmid

The warming from 1915 to about 1940 is generally believed to be due to a slight increase in solar output and a reduction in volcanism. The recent warming from 1975 is due to the build-up of greenhouse gases, as they begin to dominate over sulphate aerosol releases. The slight cooling from 1940 to 1975 is thought to be due to industrial development (using lots of dirty coal) increasing aerosol emissions.

From: Phil Jones
To: Ian Strangeways
Sent: 01 December 2008 13:01
…

1. Were the changes of temperature before about 1940 due mostly to natural causes? You say in one of your notes on my chapter 9 that they might in part be anthropogenic, and that I should not be categorical. I assume that the answer is 'we don't know for sure'

Yes, if anthropogenic explains much of the trend since the 1970s, then it should also explain a small part of the changes before 1940.

2. Were these natural causes mostly or entirely changes in the SOI, the PDO and the other oscillations?

No the natural factors are the Sun and volcanoes. How these factors influence the SOI, PDO and other oscillations is a factor also. The SOI, PDO and others are natural modes of variability - that the atmosphere likes. Solar changes and volcanoes may push the atmosphere towards one of these modes. Anthropogenic forcing is likely to manifest itself as changes in atmospheric modes.

3 I assume that volcanoes affect just individual years (e.g. 1991).

Volcanoes probably affect the year after and the year after that. So for Pinatubo, you'd expect to see the effects in 1992 and 1993 (for a 1991 eruption).

4. I assume that post 1975 some of the changes are still due to the SOI and PDO (especially in view of the big jumps in their indexes at that time).

Possibly, but blaming the changes on an Oscillation doesn't help that much as we've no idea why the oscillation change. See the earlier argument in Q2.

4. [sic] Is proof of CO2 involvement post 1975 derived entirely from models or is there evidence in the actual instrumental data?

Mostly from models - a la Ch 9 of the IPCC Report.

Say what? The models are mostly the evidence?

At 14:43 01/12/2008, you wrote:
Phil

Thanks, that all looks fine.

But just one surprising thing:-

You say the sun (and volcanoes) cause the changes (of the temperature anomalies), possibly by affecting the oscillations. But I was under the impression that the sun was supposed to have no influence whatsoever (in the short term anyway). Now you are saying it is a major factor. In what way does the sun act to cause the changes. It's not through its variations in the solar constant because that is very stable. So how?

Hopefully this really is the last question

Ian

And here comes the answer:

date: Mon Dec 1 15:13:50 2008
from: Phil Jones

subject: RE: Fall of temperatures around 1945
to: "Ian Strangeways"

Ian,

The Earth's atmosphere system is chaotic. Volcanoes alter circulation oscillations by cooling the surface and warming the stratosphere. The Sun does similar things through variations in cloud around the world.

The Sun's output needn't change hardly at all.

The various oscillations are know to change and have done since they were discovered. This could be internal dynamics of the climate system, but it is also likely that the major forcing factors are involved as well.

If the Sun suddenly increased its output - say by 5%, we all wouldn't get warmer. The atmospheric circulation patterns would change to attempt to still move the heat from the equator to the poles. Most regions would get warmer but some cooler.

Cheers

Phil

Does Phil Jones postulate a strong negative climate feedback through clouds? Apart from the hole "the sun influences the climate, but then again it doesn't do much change" logical inconsistency?

Contrast with:

From: Caspar Ammann
To: Michael E. Mann

The more we are able to explain why the first half of the 20th century warmed up naturally,the more confidence we get on the detection of the anthropogenic signal afterwards.

And:

The industrial revolution (at the turn of the century - 1890-1910) is often taken to be the beginning of humans influencing global warming.