Science a GoGo's Home Page Forums General Discussion Climate Change Forum Climate change sceptics lose vital argument

The "hockey stick" graph, which shows a rapid rise in world temperatures over recent decades, has been both poster child for the dangers of human- induced global warming and prime target for climate change sceptics. They cite an anomaly in the graph - it does not record a dip in temperature between 1200 and 1850 - as reason to ditch the whole thing. Now new data may help explain why the graph does not record the "little ice age".

Ocean currents in the North Atlantic, dominated by the Gulf Stream, usually keep winter temperatures in western Europe mild by carrying warm water north from the tropics towards Europe and heating the westerly winds travelling from North America. Climate scientists have suspected that a weak Gulf Stream may have caused the little ice age, but until now there has been no direct evidence for this theory.

Jean Lynch-Stieglitz at the Georgia Institute of Technology in Atlanta and her colleagues calculated the strength of the Gulf Stream during the little ice age by looking at marine fossils in sediment cores taken from the Straits of Florida. Ocean circulation is driven by variations in water density caused by differences in temperature and salinity. These variations also affect the ratio of oxygen isotopes in marine fossil shells. By measuring these isotope ratios, the team calculated that the Gulf Stream was 10 per cent weaker during the little ice age (Nature, vol 444, p 601).

Moreover, the cooling that resulted was confined mainly to the northern hemisphere, says Lynch-Stieglitz - which indicates it was a regional effect. Michael Mann at Pennsylvania State University in University Park, who constructed the hockey stick graph, has always argued that if this were so, the little ice age would not show up on a global temperature record (New Scientist, 18 March, p 40).

"We're seeing a rearrangement of heat around the globe - so globally overall it's not colder," says Lynch-Stieglitz.

Last month, climate scientists played down the possibility of a mini ice age in the near future (New Scientist, 7 November, p 13). "We usually look for a much more dramatic weakening - an almost total shutdown of the circulation - when considering the impact on future climate," says Meric Srokosz at the National Oceanography Centre in Southampton, UK. By contrast, the 10 per cent weakening found by the Georgia team is surprisingly small, says Lynch-Stieglitz. She says that climate scientists have to incorporate this finding into their models to better understand how such a small change brought about the little ice age.

Source:
http://www.newscientist.com/article/mg19225804.300-climate-change-sceptics-lose-vital-argument.html

DA wrote:

"Moreover, the cooling that resulted was confined mainly to the northern hemisphere, says Lynch-Stieglitz - which indicates it was a regional effect."

Small point. When Captain Cook first reached NZ about 1760 the glaciers on the South Island west coast pretty much reached the coast. They now terminate well inland. The mini ice age must have occurred in the southern hemisphere too.

Glaciers in the Andes are shrinking,the Ruwenzori Massif is virtually gone, and the snowpack on Mt. Kilimanjaro is shrivelling like an ice cube on a hot griddle. The Kili glaciers survived a 300 year drought in Africa that occurred 4,000 years ago; they won't make it this time. Crisis? What Crisis?

I just came up with an idea to ferret out the difference between those posturing that global warming does not exist and those who truly believe it.

I suggest we pass laws, in all countries, that state that "should global warming be proven" those corporations contributing to it must pay each inhabitant of their home country 1000 Euros.

If they truly believe it isn't happening they will allow the law to be enacted in as it will have no affect. Those that put up money to squash it ... are knowingly lying about the consequences of their actions.

The shareholders would take their money of of any such company as global warming came closer to being proven. By the time of proof the company would simply declare bankruptcy. No payout.

Oh I know they'd never pay. I'd just like to watch them squirm in their obvious hypocrisy: Opposing a law that would make them liable for something they claim doesn't exist.

Terry, re: "The mini ice age must have occurred in the southern hemisphere too." I would think that the glaciers of 1760 had been there all along and not suddenly reappeared as evidence of a mini ice age.

....been there all along -until recently, as Wolfman's glaciers: "Glaciers in the Andes are shrinking,the Ruwenzori Massif is virtually gone, and the snowpack on Mt. Kilimanjaro is shrivelling like an ice cube on a hot griddle. The Kili glaciers survived a 300 year drought in Africa that occurred 4,000 years ago...."

Watcha think??
~samwik

re: the 10% (accuracy?) drop in the Gulf Stream -from above....

From the amount of water in the subtropical gyre and the flow southwards at depth, they calculate that the quantity of warm water flowing north had fallen by around 30%.
When Bryden added previously unanalysed data ? collected in the same region by the US government?s National Oceanic and Atmospheric Administration ? he found a similar pattern. This suggests that his 2004 measurements are not a one-off, and that most of the slow-down happened between 1992 and 1998.
The changes are too big to be explained by chance, co-author Stuart Cunningham told New Scientist from a research ship off the Canary Islands, where he is collecting more data. "We think the findings are robust."

http://www.newscientist.com/article.ns?id=dn8398

-from an article in Nature?
http://www.nature.com/news/2005/051128/full/051128-9.html

30% !!!
So why aren't we seeing an ice age in Europe already? Maybe there is a lag of a few years, so let's see if the euro-glaciation starts soon.

Hey, I was wondering where Al Gore got the giant ice cubes his cartoon characters used to cool the oceans. Now I know....

~samwik

I am new to this forum and I am not a scientist. I simply have questions about human induced global warming and would like to get a response to a skeptic's argument that warming oceans are the main cause of carbon dioxide increases, not human behavior . If you care to take the time, read this link and hammer it as you wish. I just would like to hear a counter argument to this article. Thank you. I apologize if I am wasting your time. Please let me know if that is the case. I am simply attempting to get informed on the subject.

http://nov55.com/gbwm.html

Glad to tackle it.

Lets start with the basic premise that nothing violates the laws of physics, chemistry, and mathematics.

Given that premise ... lets look at what you wrote ... "that warming oceans are the main cause of carbon dioxide increases."

Why is the ocean getting warmer? It is getting warmer because of something quantifiable in physics and chemistry. It is getting warmer because of either:

1. The atmosphere is getting warmer and transferring heat to it.
2. It is absorbing more radiation from the sun
3. The ocean floors are getting warmer and transferring heat to the water.

We can forget number 2 because the radiation trapped from the sun has been accurately measured and accounted for.

We can forget number 3 because the ocean surface is warming faster than the depths.

That leaves number 1 as the only viable choice: Though #2 does enter into it in as much as polar melting decreases reflection and exposes more water to absorb solar radiation.

So tackle number 1 the same way. What are the possible causes of #1? If as is claimed in the statement you wrote ... that ocean warming preceeds CO2 release ... then the premise is backwards.