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 .
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.)
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]
The Al Gore View of Global Warming basically states that the world is doomed, unless (snarky remarks deleted.) The ward does seem to have warmed by maybe .6C or so over the last 120 some odd years. The Gore crowd claims this is unprecedented, rational people point out that the historical record says that it isn’t.
As I mentioned in the previous post, 1500 year cycles, there were a number of times during the last ice ages where temps rose 7-8C in a matter of decades. Before SUVs were invented or any fossil fuel was being burned.
I found this in a WUWT comment:
“The Greenland (Arctic) and Vostok (Antarctic) ice cores are particularly informative, offering fine temporal resolution and continuity. This has revealed surprising oscillations of climate on a millennial scale within the main 100-kyr cycle. The Greenland Ice Core Project (GRIP) identifies some 24 interstadials through the last ice age with average temperature rising rapidly by ~7 C over just decades. Further ice and sediment cores from around the world are demonstrating the global scale of these major climatic events.”
From: Hewitt, G. 2000. The genetic legacy of the Quarternary ice ages. NATURE, Vol. 405, 22 June 2000 (www.nature.com)
Here’s a 2004 paper from the same author (and it’s a Royal Society paper)
Our climate has been cooling for ca. 60Myr, with the Antarctic ice sheet forming ca. 35 Ma and the Arctic icecap growing from ca. 3 Ma. The Quaternary Period has been dominated by Ice Ages, which involve repeated global cooling and increasing advances of these ice sheets. These oscillations are paced by regular eccentricities in the Earth’s orbit around the sun every 100, 41 and 21 kyr. The large ice sheets, surrounding permafrost, lower global temperature and reduced water availability caused great changes in the distribution of species, which can be seen in the fossil record (Bennett 1997; Williams et al. 1998). Recent work with cores from ice sheets and sea beds confirms the effects of millennial-scale change in climate nested within the main 100 kyr cycle. These involved changes of as much as 7–15 °C over a few decades, which then lasted for hundreds of years, and there is fossil evidence that these, including the Younger Dryas ca. 11 ka, caused shifts in species distributions.
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).
Shades of 1975. Once upon a time the DOOM! story of choice was the coming ice age. Actually, at least a couple of times. Now it’s back, at least in one story.
Filling the atmosphere with greenhouse gases associated with global warming could push the planet into a new ice age, scientists have warned.
Researchers at the University of Birmingham found that 630 million years ago the earth had a warm atmosphere full of carbon dioxide but was completely covered with ice, the Daily Telegraph reported.
The scientists studied limestone rocks and found evidence that large amounts of greenhouse gas coincided with a prolonged period of freezing temperatures.
So maybe some scientists are looking for grants to study cooling and made some scary statements to the T of I to enhance their chances of receiving said grants. Maybe they said something pretty tame and the T of I ran with it. Maybe they made it all up, which is what the alarmist accuse skeptics of doing about the 1975 reports. (No reputable scientists were involved in the making of these reports…)
Now, the writers are right about CO2 being far higher in the distant past and they are right about the occasional ice age happening, despite the CO2 levels. However, way back when, it was mostly much warmer than now (by as much as 10C) and mostly very very green.
So, if anything, the story shows that CO2 has nothing to do with tipping points dropping us into an ice age. It also points to CO2 not being a primary driver of climate.
And then the most recent series of ice ages started and the Earth cooled…
Except for a few short interglacials, when it warmed again, and we are in one of those interglacials.
The late Ordovician period (about 450 million years ago) was an ice age with CO2 levels 10-12 times higher than today’s levels.
This page shows a history of the Earth over the last 600 million years. Even with the uncertainty of measurement, it’s still fascinating. Among other things, it notes that the Earth has been cooling over the last 30 million years. It also offers a geological hypothesis for ice ages.
I’ll just drop them in as I come across them. Most recent are at the top of the list.
In 1971, the world’s top climate scientists Schneider, Hansen and Rasool predicted that burning fossil fuels would trigger an ice age. They also determined that CO2 was nothing to worry about. Here.
The End Holocene – a discussion of abrupt climate change leading to an ice age. Includes clips from the 70s of scientists warning Nixon of exactly that. Also see Glacial Inception and the prior articles linked to from these two posts.
PopTech added a comment noting that the list of cooling alarmism is his. Here’s his page: 1970s Global Cooling Alarmism. (It’s also linked to, below.) The comment below, from Newsbusters, is also his.
Update 2/7: Some wags claim that the 70s ice age scare has been discredited. Unfortunately for their argument and their meme of “Doom!”, they’re wrong. As usual.
Deniers from the hockey team tell us that the 1970s ice age scare never happened, or that scientists were not behind it. They are as well informed as holocaust deniers. Below is overwhelming evidence that the 1970s were colder than earlier in the century.
update 12/17: ClimateDepot has a writeup on the subject:
Despite many claims to the contrary, the 1970’s global cooling fears were widespread among many scientists and in the media. Despite the fact that there was no UN IPCC organization created to promote global cooling in the 1970s and despite the fact that there was nowhere near the tens of billions of dollars in funding spent today to promote man-made global warming, fears of a coming ice age, showed up in peer-reviewed literature, at scientific conferences, voiced by prominent scientists and throughout the media.
Newsweek Magazine even used the climate “tipping point” argument in 1975. Newsweek wrote April 28, 1975 article: “The longer the planners delay, the more difficult will they find it to cope with climatic change once the results become grim reality.”
But on October 24, 2006, Newsweek admitted it erred in predicting a coming ice age in the 1970’s.
The following selection of links is from Newsbusters, and was posted in the comments section: (5/27/13 – this list was posted on Newsbusters by PopTech.)
Read the whole Newsbusters article here: 100 Years of Headlines About Catastrophic Climate Change (The video above is an updated version of the one on the Newsbusters page, provided by one of their commenters, and is much easier to watch.)
Lies? Truths?
The alarmists say that the warnings of cooling in the 70s are a skeptic lie. Yeah, well, somebody was feeding those stories to the media. Maybe it was a noisy Al Gore type or maybe the media made it all up, much like they do today. Maybe it’s the alarmists who are lying, given the hysteria that their side is pushing.
Either way, the media is relevant, since that’s where most people get their info. The media IS the voice of science for most people. Perhaps the alarmists should be concerned about modern reporting on climate?
NASA (no scientists there, right?) predicted the coming ice age back in ’71. The model for the prediction seems to have been written by… one James Hansen.
Love this quote, “One might almost conclude that, in the world of climatology, theories are made to order.” From this article describing a ’74 CIA report on the threat of global cooling.
In a few years will the media be telling us, again, of the approaching ice age? Will the fear-mongering crowd (Al Gore crowd) be telling us that “scientists were not warming of Global Warming in the 90s and early 2000s?”
The World in Winter (Alpha Books) – A post apocalyptic world where an ice-age has rendered much of the northern world uninhabitable. Out of print, but available used.
Fallen Angels – Reeling under a new ice age, the lunatic fringe of the environmental movement controls the US government. Abandoned by Earth, the space colonies replenish their air by scoop-ships diving into the atmosphere – but Alex and Gordon’s ship was hit by a missile, and they are now wanted dead or alive.
Links:
– A post apocalyptic world where an ice-age has rendered much of the northern world uninhabitable. Out of print, but available used.
– Reeling under a new ice age, the lunatic fringe of the environmental movement controls the US government. Abandoned by Earth, the space colonies replenish their air by scoop-ships diving into the atmosphere – but Alex and Gordon’s ship was hit by a missile, and they are now wanted dead or alive.
Another View on Climate 