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Peter Harris provided us with a challenging debate here on this blog where the similarity between the current situation and the 400 kya glacial transition was discussed. I sought more information from Jan Hollan – but some background here first.

So if the present time was really analogous to 400,000 years ago (kya) transition, the advice to the IPCC that no ice age was due for many 10,000s of years would be incorrect and a major concern to humanity.

Augustin et al in Nature 429, 623-628 (10 June 2004) | doi:10.1038/nature02599 discuss 8 glacial cycles from Antarctic ice cores. The transition from glacial to interglacial conditions about 430,000 years ago (Termination V) resembles the transition into the present interglacial period in terms of the magnitude of change in temperatures and greenhouse gases, but there are significant differences in the patterns of change. The interglacial stage following Termination V was exceptionally long—28,000 years compared to, for example, the 12,000 years recorded so far in the present interglacial period. Given the similarities between this earlier warm period and today, our results may imply that without human intervention, a climate similar to the present one would extend well into the future.

Jan Hollan reported here that the first ever pronounced fall of summer insolation happens some 130 thousands years from now, but it is not at all so deep as those ones that started the last two Ice Ages. So, we can say there is no conceivable cause for another glaciation for at least those 130,000 years. Quite probably, another glaciation cannot come sooner that 620 thousand years from now.

Berger and Loutre argue in their Science paper that with or without human perturbations, the current warm climate may last another 50,000 years. The reason is a minimum in the eccentricity of Earth’s orbit around the Sun.

There are three interacting aspects of the Earth’s orbit that need to be accounted for in making the Milankovitch radiation calculations – discussed here. The mechanisms are orbit eccentricity (roundness to elliptical); obliquity (axial tilt) and precession (wobble around the axis).

The calculations of solar radiation at 65 degree North from Milankovitch mechanisms are based on a derivative of Laskar et al.

Jan Hollan now provided an additional graph from 500,000 years ago to 200,000 years from present.

Made for a rather low 1366.3 W/m2 solar constant again. -400 ka summer insolation minimum was some 10 W/m2 lower than that one we have almost reached already. No pronounced decline of solar orbital summer forcing at 65° N is ahead of us next 50,000 years. Jan Hollan suggests we should not extrapolate past trends (like decline in summer insolation, or the shape of the past glaciation cycles). We should look at reliably computed past, current and future forcings instead (see Laskar et al for the mathematics involved). Hollan states that it is evident we have almost reached the near-future insolation minimum already. Before the atmosphere returns to normal (thousands of years), we will be on the increasing part of the insolation curve again.

Which all means – no Milankovitch based ice age predicted for 50,000 years and more likely 130,000 or 620,000 years hence according to Jan Hollan.

From Marc Morano:

The Cryosphere Today

UPDATE: Monday, October 1, 2007 – Record SH sea ice maximum and NH sea ice minimum

Just when you thought this season’s cryosphere couldn’t be more strange …. The Southern Hemisphere sea ice area narrowly surpassed the previous historic maximum of 16.03 million sq. km to 16.17 million sq. km. The observed sea ice record in the Southern Hemisphere (1979-present) is not as long as the Northern Hemisphere. Prior to the satellite era, direct observations of the SH sea ice edge were sporadic.

The NH sea ice area reached an historic minimum on September 16, 2007 (2.92 million sq. km), representing a 27% drop in sea ice coverage compared to the previous (2005) record NH ice minimum.

We have updated our high resolution animation of this year’s sea ice retreat (01/01/2007 – 09/23/2007). WARNING – This quicktime animation is very large at 200Mb, but it illustrates nicely the temporal evolution of this year’s sea ice. Animation: 2007 sea ice minimum animation

Follow this link for some background information on historic sea ice minima.

Also note that Antarctic is NOT following climate models.

A February 2007 study reveals Antarctica is not following predicted global warming models. Excerpt: “A new report on climate over the world’s southernmost continent shows that temperatures during the late 20th century did not climb as had been predicted by many global climate models.” The research was led by David Bromwich, professor of professor of atmospheric sciences in the Department of Geography, and researcher with the Byrd Polar Research Center at Ohio State University. [See: Antarctic temperatures disagree with climate model predictions]

Reply to Lockwood and Fröhlich – The persistent role of the Sun in climate forcing

Svensmark, H. and Friis-Christensen, E.
Danish National Space Center, Copenhagen, Denmark

In a recent paper (ref. [1]) Mike Lockwood and Claus
Frohlich have argued that recent trends in solar climate
forcing have been in the wrong direction to account for
“the observed rapid rise in global mean temperatures”.
These authors accept that “there is considerable evidence
for solar in°uence on Earth’s pre-industrial climate and
the Sun may well have been a factor in post-industrial
climate change in the first half of the last century.” But
they argue that this historical link between the Sun and
climate came to an end about 20 years ago. Here we
rebut their argument comprehensively.

pdf here.

By Lockwood and Frohlich’s own data, solar magnetic
activity is still high compared with 100 years ago. As
to when the recent easing of activity began, counts of
cosmic-ray muons at low altitudes were historically low
when the muon record-keeping ended in the early 1990s
(ref. [7]). That implies an increase in relevant solar mag-
netic activity continuing till that time. A scarcity of
muons can be linked to elevated global temperatures by a
reduction in low cloud cover (ref. [8]) and low cloudiness
was indeed at a minimum around 1992-93. By other so-
lar indicators, like those cited by Lockwood and Frohlich,
the minimum muon counts may well be a little higher in
the current solar cycles. That would explain the pause in
global warming evident in our Table as well as in Lock-
wood and Frohlich’s own Fig. 1e.

That would explain the pause in global warming ev-
ident especially in the ocean (Fig. 1) and the tropo-
sphere (Fig. 3). The continuing rapid increase in carbon
dioxide concentrations during the past 10-15 years has
apparently been unable to overrule the flattening of the
temperature trend as a result of the Sun settling at a
high, but no longer increasing, level of magnetic activity.
Contrary to the argument of Lockwood and Frohlich, the
Sun still appears to be the main forcing agent in global
climate change.

SPINNING THE CLIMATE

Excerpt: However, the authors of Chapter 1 “The Climate System: An Overview” signed their own death warrant when they wrote: “ The fact that the global mean temperature has increased since the late 19th century and that other trends have been observed does not necessarily mean that an anthropogenic effect on the climate has been identified. Climate has always varied on all time-scales, so the observed change may be natural” This true statement has led to the replacement in “Climate Change 2007” of this introductory Chapter with a completely different Chapter entitled “Historical Overview of Climate Change Science” which is a highly selective history boosting the activities of the IPCC…..

One of its features is to conceal the very existence of measurements of atmospheric carbon dioxide concentration before 1958 which show a variability which would interfere with the IPCC calculations of “radiative forcing” The Chapters in “Climate Change 2007” are only slightly rearranged and they all push the same message, enforced by an increase in gloomy “opinions” derived from the “spin” process described herein. < > It is all (the UN IPCC process) a magnificent example of what public relations can achieve, but the consequences for most of us, and for the scientific community before it is eventually exposed for the deception that it is do not bear contemplation.

George Taylor, Oregon State Climatologist, responds to the Willamette Week article written by Paul Koberstein:

HOT OR NOT: Oregon’s official weatherman has good news about global warming-it doesn’t exist.

Extract:

George Taylor shouldn’t scare anybody. He has been a vegetarian since the 1970s. He commutes to work by bicycle. He’s an ex-hippie and an ex-surfer. He recycles. He likes trees and salmon.
He’s also, according to his critics, one of the most dangerous men in Oregon.

Nestled comfortably in a state that boasts of its environmental cred the way California touts its sunshine, Taylor is one of the leading circuit riders for the church of Global Warming Ain’t Happening.

From his third-floor office in the Strand Agriculture building at Oregon State University, Taylor, 58, a state employee who runs an agency with a half-million-dollar annual budget, is often at work discrediting the well-established scientific facts about global warming.

His views have been read on the floor of the U.S. Senate and, most recently, influenced global-warming bills in Salem. In the past, he also has tried to undermine global-warming legislation in Canada.

“Look, it’s not that complicated,” says Taylor, who, as head of the Oregon Climate Service at OSU, is known as the state climatologist. “It’s not clear that we are seeing unprecedented warming, and it’s definitely untrue that any warming trend can be assigned to human activities. Natural variations in climate are much more significant than any human activities…………………..”

Video of Taylor’s response is here.

A transcript is here.

Excerpt: I get most of my information from peer-reviewed journals, including Journal of Climate, Journal of Geophysical Research, and Climate Research. The articles I write (including, for example, the Arctic article) are based on journal articles and contain full bibliographies. Admittedly, I seldom give“both sides” of the argument, because the “other side” (the one that suggests that human activities exert a dominant role in the climate system) is well-represented in journals and the media. My goal is to be a voice saying “wait, maybe there’s another side to this. Take a look at THIS data and see what you think. Then let’s talk about it.” Unfortunately, this issue has become such a divisive and angry one that ad hominem attacks have replaced dialogue..

When I write about global climate issues, I do so on my own time from home. I’m cautious about having my opinion construed as representing the State of Oregon or Oregon State University, and I try to separate my analyses of global climate from my day to day work as the State Climatologist.