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Can we prevent global cooling

 
 
Reply Sat 8 Jan, 2011 01:08 pm
Given the strong pattern of global warming and cooling we see in long term ice core records (included below) it seems inevitable that the Earth is about to return to it's more common (at least in recent times) ice age conditions.

Given the likely strength of the natural forces involved in producing this cycle, is it even possible for the actions of humans to have any hope of altering the natural cycle?

http://rst.gsfc.nasa.gov/Sect16/carbon_dioxide.jpg

Hare are some opinions from Woods Hole Oceanographic Institute

Excerpt:
"Are We on the Brink of a 'New Little Ice Age?'

By Terrence Joyce, Senior Scientist, Physical Oceanography and
Lloyd Keigwin, Senior Scientist, Geology & Geophysics

When most of us think about Ice Ages, we imagine a slow transition into a colder climate on long time scales. Indeed, studies of the past million years indicate a repeatable cycle of Earth’s climate going from warm periods (“interglacial”, as we are experiencing now) to glacial conditions.

The period of these shifts are related to changes in the tilt of Earth’s rotational axis (41,000 years), changes in the orientation of Earth’s elliptical orbit around the sun, called the “precession of the equinoxes” (23,000 years), and to changes in the shape (more round or less round) of the elliptical orbit (100,000 years). The theory that orbital shifts caused the waxing and waning of ice ages was first pointed out by James Croll in the 19th Century and developed more fully by Milutin Milankovitch in 1938.

Undefined Ice age conditions generally occur when all of the above conspire to create a minimum of summer sunlight on the arctic regions of the earth, although the Ice Age cycle is global in nature and occurs in phase in both hemispheres. It profoundly affects distribution of ice over lands and ocean, atmospheric temperatures and circulation, and ocean temperatures and circulation at the surface and at great depth.

Since the end of the present interglacial and the slow march to the next Ice Age may be several millennia away, why should we care? In fact, won’t the build-up of carbon dioxide (CO²) and other greenhouse gasses possibly ameliorate future changes?... "
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engineer
 
  0  
Reply Sat 8 Jan, 2011 01:51 pm
@rosborne979,
This graph shows an excellent correlation between the CO2 level and global temperature. It looks like something has driven the CO2 concentration through the roof, so the question is whether the CO2 correlation reflects causation. If it does, then yes, we've managed to break the global cycle through human action.
Setanta
 
  2  
Reply Sat 8 Jan, 2011 01:55 pm
I seriously doubt that human production of carbon dioxide is on a scale to make a profound change in global climate. What is more troubling is the slaughter of huge swathes of forest, which greatly reduces a significant natural mechanism to reduce CO2. We also know little enough about the effect of the oceans.

I do recall, though, that in the late 1960s and early 1970s, before "global warming" became academically trendy, the story being forwarded in acadmic circles which dealt with climate was that we are approaching a new ice age.
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roger
 
  1  
Reply Sat 8 Jan, 2011 02:01 pm
@rosborne979,
Probably not. Anything we spend trying to alter climate could probably be spent on coping with the change, if we ever get a clear sense of what is happening.
0 Replies
 
rosborne979
 
  1  
Reply Sat 8 Jan, 2011 02:46 pm
@engineer,
engineer wrote:
This graph shows an excellent correlation between the CO2 level and global temperature. It looks like something has driven the CO2 concentration through the roof, so the question is whether the CO2 correlation reflects causation.

The graph doesn't clearly show whether CO2 is a leading indicator of atmospheric warming or a trailing indicator.
engineer wrote:
If it does, then yes, we've managed to break the global cycle through human action.

In either case, a spike in CO2 doesn't necessarily prove that previous cycles have been stopped, it only indicates that one part of the pattern has been changed. But we don't know to what degree that change will affect things.
0 Replies
 
rosborne979
 
  1  
Reply Fri 2 Oct, 2015 08:39 am
This looks to me like the beginning of the shut-down of the thermohaline ocean system: http://www.weather.com/news/climate/news/north-atlantic-cold-blob
The article wrote:
But the massive ice melt occurring in the Arctic has introduced a lot of cold, fresh water into the mix, and it's not behaving the same as cold salt water. It's preventing the sinking that usually happens with cold water, as fresh water is less dense than salt water, and that could be weakening the circulation.

"The fact that a record-hot planet Earth coincides with a record-cold northern Atlantic is quite stunning," Stefan Rahmstorf, one of the authors of the study published in Nature Climate Change, told the Washington Post. "There is strong evidence — not just from our study — that this is a consequence of the long-term decline of the Gulf Stream System, i.e. the Atlantic ocean’s overturning circulation AMOC (Atlantic Meridional Overturning Circulation), in response to global warming."

Rahmstorf also told the Washington Post he doesn't expect the blob to remain at record cold levels indefinitely, though the circulation should continue to decline. Everything is connected, and climate scientists believe that connection will drive temperatures, and sea levels, higher and higher.

http://dsx.weather.com//util/image/w/download.jpg?v=ap&w=980&h=551&api=7db9fe61-7414-47b5-9871-e17d87b8b6a0
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