tag:blogger.com,1999:blog-2220966763638300672.post3325925097776824823..comments2023-07-29T05:11:23.558-04:00Comments on Climate Observations: Regarding Missing Comments At The Minnesota Public Radio Climate Change BlogBob Tisdalehttp://www.blogger.com/profile/15462377647970214137noreply@blogger.comBlogger6125tag:blogger.com,1999:blog-2220966763638300672.post-15776608787368975092009-10-31T16:53:06.162-04:002009-10-31T16:53:06.162-04:00John: Sorry for the delay. You asked, “When Knig...John: Sorry for the delay. You asked, “When Knight et al say that the models take into account internal variability and thus these type of decades can be anticipated and are included in the models, do you have any idea what type of internal variability they are talking about?”<br /><br />ENSO and the Atlantic Multidecadal Oscillation. <br /><br />The AMO has a 50- to 80-year cycle so they can anticipate it within a few decades. ENSO also has an underlying multidecadal cycle, but I don’t recall it being discussed in papers about how GCMs address ENSO. Most of those papers assume that NINO3.4 SST anomalies and the frequency of El Nino events will increase this century, even though the NINO3.4 SST anomaly trend line is flat in the 20th Century (and now declining). <br /><br />In your next comment you asked, “I notice from the Svaalgard reconstruction that we are at a minimum now. This doesn't change any arguments about ENSO influences, etc, but if we were at a maximum instead of a minimum, would we see current temperatures about .1c higher (which would push SST to ‘record’ highs), perhaps lending strength to the AGW view that this decade is merely a ‘respite’ from warming? That the solar minimum is masking increased forcing from co2?”<br /><br />First, the record highs existed in only one SST dataset, the NCDC’s ERSST.v3b. The NCDC’s OI.v2 and the Hadley Centre’s HADSST2 and HADISST did not reach records this year in terms of SST or SST anomalies. Second, the estimates of the impact of the solar cycle vary, as does the time lags associated with it. Estimates of the impact of the “average” solar cycle as it goes from minimum to maximum on global temperature vary from ~0.07 to 0.15 deg C. And the estimates of the time lags depend on what medium is being measured. The lag in the change in temperature over land to a change in the solar cycle is usually measured in terms of a few months, but over the ocean, due to thermal inertia, the lag varies per study from a few years to a few decades. If the solar cycle stays an extended time at minimum, global temperatures would “remain” at a lower temperature (after all of the lags); temperatures would not continue to drop, and drop, and drop more the longer the sun stays at minimum. <br /><br />You asked, “A .1c varation in a decade is half of what they'd expect from co2 forcing, right? A .1c varation in a decade is half of what they'd expect from co2 forcing, right?”<br /><br />Right, assuming the projected rise over a century is 2 deg C and that climate models have a basis in reality, which they do not from all that I’ve seen, but the IPCC as you know provides wide variations in those projections.<br /><br />You asked, “But wouldn't they take these solar variations into account for the models for the 2000-2010 period?” <br /><br />But a solar cycle varies in length from 9 to 13 years, so over a decade it would pretty much be the mean; that is, half the time we’re on the up slope and on the other half we’re on the down slope.<br /><br />You asked, “Or I am off because, if it's a steady anomaly, the variation down from past would have cancelled out the variation up now, making overall anomalies unimpacted?”<br /><br />I’m not sure in what context you’re using “steady anomaly”, but over a decade, the upward part of the cycle cancels out the downward part.<br /><br />Regards.Bob Tisdalehttps://www.blogger.com/profile/15462377647970214137noreply@blogger.comtag:blogger.com,1999:blog-2220966763638300672.post-8998032897652599402009-10-30T12:21:19.722-04:002009-10-30T12:21:19.722-04:00Thanks Bob.
If at any point my numerous questions...Thanks Bob.<br /><br />If at any point my numerous questions become bothersome, please let me know! I will gladly stop them.Johnnoreply@blogger.comtag:blogger.com,1999:blog-2220966763638300672.post-77543104148160400822009-10-30T12:14:14.122-04:002009-10-30T12:14:14.122-04:00John: I'll try to answer your recent questions...John: I'll try to answer your recent questions, those that I can, this afternoon or tomorrow. I'm busy off line today.<br /><br />RegardsBob Tisdalehttps://www.blogger.com/profile/15462377647970214137noreply@blogger.comtag:blogger.com,1999:blog-2220966763638300672.post-6733419050760994482009-10-30T11:47:56.544-04:002009-10-30T11:47:56.544-04:00Or I am off because, if it's a steady anomaly,...Or I am off because, if it's a steady anomaly, the variation down from past would have cancelled out the variation up now, making overall anomalies unimpacted?Johnnoreply@blogger.comtag:blogger.com,1999:blog-2220966763638300672.post-13976082764884368032009-10-30T11:40:50.014-04:002009-10-30T11:40:50.014-04:00One other question -
I notice from the Svaalgard ...One other question -<br /><br />I notice from the Svaalgard reconstruction that we are at a minimum now. This doesn't change any arguments about ENSO influences, etc, but if we were at a maximum instead of a minimum, would we see current temperatures about .1c higher (which would push SST to "record" highs), perhaps lending strength to the AGW view that this decade is merely a "respite" from warming? That the solar minimum is masking increased forcing from co2? <br /><br />A .1c varation in a decade is half of what they'd expect from co2 forcing, right?<br /><br />But wouldn't they take these solar variations into account for the models for the 2000-2010 period? I don't remember anyone saying "oh, the slight variation in solar cycle is what is creating the flat temperatures."<br /><br />Thanks again, as always. I appreciate being able to use you as a sounding board - your knowledge obviously vastly outweighs mine.Johnnoreply@blogger.comtag:blogger.com,1999:blog-2220966763638300672.post-51185026706885449332009-10-29T18:18:06.120-04:002009-10-29T18:18:06.120-04:00Hi Bob -
When Knight et al say that the models ta...Hi Bob -<br /><br />When Knight et al say that the models take into account internal variability and thus these type of decades can be anticipated and are included in the models, do you have any idea what type of internal variability they are talking about?<br /><br />He separates out ENSO ... what else could he be referring to?<br /><br />I've heard it many times that the models anticipate stable or even decreasing decades, but I've never understood how they do it, absent a negative external forcing like aerosols or whatever. <br /><br />Am I misconstruing something? Can you offer any insights?Johnnoreply@blogger.com