OT - Hansen acknowledges solar forcing

On Mon, 19 Jan 2009 13:17:57 +0000, Raveninghorde wrote:

Interesting. But there was a lot more there to quote. For example, the actual context. Don't be so selective.

: Summary: the Southern Oscillation and increasing GHGs continue to be, : respectively, the dominant factors affecting interannual and decadal : temperature change. Solar irradiance has a non-negligible effect on : global temperature [see, e.g., Reference 7, which empirically : estimates a somewhat larger solar cycle effect than that estimated by : others who have teased a solar effect out of data with different : methods]. Given our expectation of the next El Nino beginning in 2009 : or 2010, it still seems likely that a new global temperature record : will be set within the next 1-2 years, despite the moderate negative : effect of the reduced solar irradiance.

and, more particularly the earlier discussion that bears on the subject:

: 2) Solar irradiance: the solar irradiance remains low (Figure 4), at : the lowest level in the period since satellite measurements began in : the late 1970s, and the time since the prior solar minimum is already : 12 years, two years longer than the prior two cycles. This has led : some people to speculate that we may be entering a ?Maunder Minimum? : situation, a period of reduced irradiance that could last for : decades. Most solar physicists expect the irradiance to begin to pick : up in the next several months ? there are indications, from the : polarity of the few recent sunspots, that the new cycle is beginning. : However, let?s assume that the solar irradiance does not recover: in : that case, the negative forcing, relative to the mean solar : irradiance is equivalent to seven years of CO2 increase at current : growth rates. So do not look for a new ?Little Ice Age? in any case! : Assuming that the solar irradiance begins to recover this year, as : expected, there is still some effect on the likelihood of a near-term : global temperature record due to the unusually prolonged solar : minimum. Because of the large thermal inertia of the ocean, the : surface temperature response to the 10-12 year solar cycle lags the : irradiance variation by 1-2 years. Thus, relative to the mean, i.e, : the hypothetical case in which the sun had a constant average : irradiance, actual solar irradiance will continue to provide a : negative anomaly for the next 2-3 years.

The solar cycle is indeed unusual. But the difference between the peak forcing (during high sun spot periods) and valley forcing (no sunspots to speak of) is 0.2W/m^2 (peak to peak) and the current "dip" below the bottoms of earlier valley points is about 1/10th of that difference or about 0.02W/m^2.

Jon

I wasn't too selective. I highlighted the point that Hansen has started back tracking on solar forcing which is significant. For the curious I gave the link to the full document which you took advantage of.

The original research is referenced from the Hansen doc, nothing was hidden to those with an interest.

That selection was as narrow as a selection can get, really. Better would have been to at least cite the paragraph to provide a frame for understanding it. At a minimum.

Indeed.

Jon

Roughly a page or two earlier in that article, Hansen says that solar output decreasing to "Maunder Minimum" level is about equal to effect of 7 years' worth of change in CO2 at recent rates.

He is still expecting global temperature to hit a new record with the next El Nino, likely around 2009 or 2010. (That may fail to set a new record acording to HadCRUT - which shows a stronger spike from the 1998 El Nino than the two other "main-major" global surface temperature trend determinations. NASA's GISS [where Hansen is] also shows IIRC about .004 degree C per decade more warming than the other two by incluing polar regions that have both less coverage by weather stations and more recent-decades-warming).

Myself, I am expecting the cyclic downturn in solar output and the also-likely currently-largely-in-phase global temperature effect of the "Multidecadal Oscillation" to cause global temperature to accomplish little rise from average of 2001-2007 to the 2020's or around 2030 or so. Hansen reports in above link that the 2001-2007 stretch had global temperature anomaly was .54 C. Since NASA's GISS uses the 1951-1980 as "baseline" while HadCRUT and IPCC use 1961-1990 (about .1 degree C warmer than 1951-1980) as "baseline" and NCDC uses for global temoperature trends 1901-2000 (much closer to 1961-1990 than to 1951-1980), I would like to call the 2001-2007 anomaly (as determined by Hansen) +.44 C.

I am expecting global surface-level temperature anomaly as of 2020's to around 2030 to be hardly warmer - in the range of .5 to .6 degree C above

1961-1990 average. Watch out for what happens from then to 2065-2070 when solar output and the "Multidecadal Oscillation" are likely to favor upturn in global temperature - I fear 3-3.5 decades averaging .2-.25 degree C per decade warming in that stretch, putting global surface-level temperature at 2070 around 1.05 to 1.25, possibly 1.3 degrees C above 1961-1990 average as of 2065-2070 or so.

- Don Klipstein ( snipped-for-privacy@misty.com)

John

John S. Theon is not a scientist's bootlace - search for him on scholar.google.com and his publication record is no more impressive than mine (his most cited paper also attracted nine citations).

James Hansen does rather better.

John S.Theon does seem to envy Hansen's success, and that may be what prompted him to join Senator Inhofe's collection of denialists, or it could just be that he needed money. Either way, his opinion isn't all that persuasive, and only people as ignorant as your or Ravinghorde would be silly enough to take his vapourings seriously.

-- Bill Sloman, Nijmegen