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My Own View of Global Warming

Archive for the ‘Cycles’ Category

Abrupt Climate Change Over the Last 15,000 Years.

Posted by greg2213 on June 2, 2013

Alarmists love to call the modern warming “unprecedented.” This is pretty hysterical given that number of much larger and more abrupt changes over the years. The .5 to .8C over the last 150 years just doesn’t compare.

And all of those other changes (warming and cooling) were without benefit of significant CO2 changes. Thi sis another nail in the coffin of the “CO2 is the primary cause of CC” argument.

On, WUWT, the conclusion: 

(1) The ice core isotope data were hugely significant because they showed that the Younger Dryas, as well as the other late Pleistocene warming and cooling events, could not possibly be caused by human emissions of CO2 because they occurred thousands of years before such emissions had any effect on atmospheric CO2.

(2) The magnitude and intensity of multiple climatic fluctuations has been up to 20 times larger than warming during the past century.

(3) Single events, i.e., volcanic activity or cosmic impacts, cannot have caused the abrupt Dansgaard/Oerscher warming and cooling events because of the multiplicity of warm/cold events over periods of thousands of years.

(4) The absence of a time lag between the N and S Hemisphere glacial fluctuations precludes an oceanic cause and is not consistent with the North Atlantic Deep Ocean Water hypothesis for the cause of the Younger Dryas.

(5) The abruptness of the climate changes and their multiplicity could not have been caused by slow, Croll-Milankovitch orbital forcing, which occurs over many tens of thousands of years. Since fluctuations to and from full glacial climates occurred over short periods of time, clearly a cause other than the Croll-Milankovitch theory is capable of causing the Ice Ages .

The whole article is here.

The modern warming compared to prior warmings:

(see the full article for details.)

a-nice-graph Links:

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Posted in Cycles, Temerature Records | Tagged: , , , , | 1 Comment »

Evidence for Warmer Interglacials from Ice Cores

Posted by greg2213 on January 12, 2013

Ok, let’s pretend this paper is onto something (yes, I noticed the 2009 date.)

6K warmer than this interglacial. Let’s pretend that Climate Sensitity is 3K (it’s a lot lower.) That’s two doublings of CO2, meaning that CO2 levels were roughly 15-1600 ppm back then.

So either the was a massive human civilzation back then pouring out gigatons of CO2, several times, since there were several interglacials, or a whole bunch of volcanoes poured an insane amount of CO2 into the air without adding the aerosols to cool things (and do it on a cyclical basis,) or…

The CO2 theory is bunk and CO2 is trivially important to global temps. Or this paper is bunk and we move on.

The abstract:

Stable isotope ratios of oxygen and hydrogen in the Antarctic ice core record have revolutionized our understanding of Pleistocene climate variations and have allowed reconstructions of Antarctic temperature over the past 800,000 years (800 kyr; refs 1, 2).

The relationship between the D/H ratio of mean annual precipitation and mean annual surface air temperature is said to be uniform ±10% over East Antarctica3 and constant with time ±20% (refs 3–5). In the absence of strong independent temperature proxy evidence allowing us to calibrate individual ice cores, prior general circulation model (GCM) studies have supported the assumption of constant uniform conversion for climates cooler than that of the present day3, 5.

Here we analyse the three available 340 kyr East Antarctic ice core records alongside input from GCM modelling. We show that for warmer interglacial periods the relationship between temperature and the isotopic signature varies among ice core sites, and that therefore the conversions must be nonlinear for at least some sites. Model results indicate that the isotopic composition of East Antarctic ice is less sensitive to temperature changes during warmer climates.

We conclude that previous temperature estimates from interglacial climates are likely to be too low. The available evidence is consistent with a peak Antarctic interglacial temperature that was at least 6 K higher than that of the present day —approximately double the widely quoted 3 ± 1.5 K (refs 5, 6).

The whole paper is behind a paywall, as usual, but the abstract is here.

More

Posted in Cycles, Ice | Tagged: , | Leave a Comment »

Bond Events, Dansgaard-Oeschger events, Climate Cycles, and stuff

Posted by greg2213 on January 7, 2011

Pretty much everyone agrees that the warming we’ve seen over the last 130 year or so is on the order of .7C. The argument is over what caused it and where it’s going.

So then what would one make of increases, and declines, that are ten times (or more) greater and that happen in 1/10th the time (or less?) (Also see 1500 year cycles.)

WUWT have a nifty post covering some of these events and there’s more good stuff in the comments.

Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. For example, roughly half the north Atlantic warming since the last ice age was achieved in only a decade, and it was accompanied by significant climatic changes across most of the globe. Similar events, including local warmings as large as 16°C, occurred repeatedly during the slide into and climb out of the last ice age. Human civilizations arose after those extreme, global ice-age climate jumps.”

“The new paradigm of an abruptly changing climatic system has been well established by research over the last decade, but this new thinking is little known and scarcely appreciated in the wider community of natural and social scientists and policy-makers.” (“Abrupt Climate Change – Inevitable Surprises”, Committee on Abrupt Climate Change, National Research Council of the National Academy of Sciences, 2002, ISBN: 0-309-51284-0, 244 pages, Richard B. Alley, chair.)

The rest: On “Trap-Speed”, ACC and the SNR

Vostok Ice Core, Antarctic: (click to enlarge)

Vostok Ice Core Warming Periods

 

At the recent end of the climate cycle there is the Younger Dryas event. The Earth was emerging from the last ice age, things were warming up, and the it rapidly dropped into full=blown ice age conditions for another 1200 years.

Apparently the recovery was pretty rapid, too.

What caused it? No one knows. Some have an impact hypothesis, and there’s an idea that giant glacial lakes flooded the Northern Atlantic with fresh water, cutting off all circulation, leading to the cooling. The problem is that the lake outflow seems to have been blocked by ice. From the comments:

This one has been out there for some time and keeps being repeated, but Thomas V Lowell showed that the St Lawrence River was blocked by ice during the Younger-Dryas. [Revised Deglacial Chronology of the Laurentide Ice Sheet and Implications for Catastrophic Meltwater Discharge as Triggers for Abrupt Climate Change,” Eos Trans AGU 86 (52) Fall Meet. Supple., Abstract (2005): F1234″ — This from “Sudden Cold” by climatologist Rodney Chilton (2009)]

A second study that involved a simulation of meltwater originating from the Laurentide Ice Sheet did not produce any appreciable meltwater during the entire 15,000 to 8,000 BP interval. [T.C. Moore (2000)]

The northern route at least appears to have suffered the same fate as the St. Lawrence in also being blocked by ice until well after the Younger-Dryas ended. [Thomas V. Lowell, ibid]

Fun stuff.

 

Posted in Cycles | Tagged: , , , | 1 Comment »

1500 Year warming Cooling Cycles

Posted by greg2213 on April 18, 2010

While reading some stuff on volcanoes and climate change, specifically Toba, I came across this Wiki article on Dansgaard-Oeschger events. D-O events are warming periods that appear in the Greenland ice cores. Temps warmed by as much as 8C over periods of around 40 years, then dropped again over the next couple hundred years.In the current interglacial these are referred to as Bond events.

These cycles don’t appear in the Antarctic ice cores, or if they do then they’re very subtle. This makes sense if the D-O events are caused by northern oceanic changes.

The little ice age of ~400 to 200 years ago has been interpreted by some as the cold part of a D-O cycle, putting us in a period of warming climate (Bond et al.. 1999).

Posted in Cycles | Tagged: , , , | 1 Comment »