Myth of "Consensus Science" Explodes, APS reverses stance

[TimBikes]

Originally Posted by MegansPrius

Well, you appear alone in your opinion.

Are you suggesting PDO does not have a significant influence on climate? NOAA says otherwise:

"The PDO is strongly correlated to the NPI/ALPI through air-sea interactions in the North Pacific. The effects of abnormal atmospheric conditions over the North Pacific affect both the currents and temperature of the ocean, which in turn, may feedback on the atmosphere. The ultimate result of variations in these modes is tangible effects on wintertime conditions in the Bering Sea, Alaska and western Canada. A notable shift in these modes occurred in the late 1970s, bringing about a rapid change from relatively cold winters in western North America in the early 1970s to relatively warm, benign winters in the late 1970s and 1980s. There is evidence, based on sea surface temperature, that the PDO changed to a negative or neutral phase in the late 1990s, bringing colder coastal waters once again to the U.S. North Pacific coast."

And then of course there is AMO:

"The NAO has been recognized for decades and has been considered "the dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe and much into Northern Asia. The NAO is a large scale see-saw in atmospheric mass between the subtropical high and the polar low. The corresponding index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting several years." The positive phase of the NAO is associated with more frequent and intense storms in the North Atlantic Ocean, warmer and wetter winters in Europe, and cooler, drier winters in Greenland and northern Canada."

Josh Willis of JPL says:
“These natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it.”

So indeed, I think I am correct to conclude that the warming of the late 20th C may have been influenced by PDO.

[dragonfly]

Originally Posted by TimBikes

My bet is on PDO, which does a much better job of tracking to temperature change than does CO2:

PDO does appear to track the 20-30 year oscillations within the global temperature graph, however, the overall trend throughout the past century is still in the upwards direction. That means that the "cooling off" period you refer to will be followed by an even warmer "heating up" than we just went through. Your explanation does not account for the overall heating trend.

[TimBikes]

Originally Posted by dragonfly

PDO does appear to track the 20-30 year oscillations within the global temperature graph, however, the overall trend throughout the past century is still in the upwards direction. That means that the "cooling off" period you refer to will be followed by an even warmer "heating up" than we just went through. Your explanation does not account for the overall heating trend.

What accounts for the warming trend pre-1945?

[MegansPrius]

Originally Posted by TimBikes

Are you suggesting PDO does not have a significant influence on climate? NOAA says otherwise:

"The PDO is strongly correlated to the NPI/ALPI through air-sea interactions in the North Pacific. The effects of abnormal atmospheric conditions over the North Pacific affect both the currents and temperature of the ocean, which in turn, may feedback on the atmosphere. The ultimate result of variations in these modes is tangible effects on wintertime conditions in the Bering Sea, Alaska and western Canada. A notable shift in these modes occurred in the late 1970s, bringing about a rapid change from relatively cold winters in western North America in the early 1970s to relatively warm, benign winters in the late 1970s and 1980s. There is evidence, based on sea surface temperature, that the PDO changed to a negative or neutral phase in the late 1990s, bringing colder coastal waters once again to the U.S. North Pacific coast."

And then of course there is AMO:

"The NAO has been recognized for decades and has been considered "the dominant mode of winter climate variability in the North Atlantic region ranging from central North America to Europe and much into Northern Asia. The NAO is a large scale see-saw in atmospheric mass between the subtropical high and the polar low. The corresponding index varies from year to year, but also exhibits a tendency to remain in one phase for intervals lasting several years." The positive phase of the NAO is associated with more frequent and intense storms in the North Atlantic Ocean, warmer and wetter winters in Europe, and cooler, drier winters in Greenland and northern Canada."

Josh Willis of JPL says:
“These natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it.”

So indeed, I think I am correct to conclude that the warming of the late 20th C may have been influenced by PDO.

If you're going to revise your position to "may have been influenced" from "PDO was likely responsible for much of the warming of the late 20th Century" then I don't have a problem with it.

[dragonfly]

Originally Posted by TimBikes

What accounts for the warming trend pre-1945?

Maybe I don't understand the point of your question. The background warming trend pre-1945 is not steep like it is after. What we see by looking at the graph as a whole is a combination of natural and anthropogenic effects, with the natural effects working on shorter time scales and causing the large oscillations. The increasingly steep warming as we get closer to today reveals that the anthropogenic impact is overtaking the natural variations. There of course exist natural effects that work on longer time scales, but those don't explain the sharp temperature increase we're seeing over the past century. You offered PDO as an explanation for most of the increase, but that won't cut it since it is only a 20-30 year phenomenon.

[TimBikes]

Originally Posted by MegansPrius

If you're going to revise your position to "may have been influenced" from "PDO was likely responsible for much of the warming of the late 20th Century" then I don't have a problem with it.

Scott - this is getting a bit non-quantitative, but I'll respond.

If as Willis says, the effect of PDO is significant enough to "hide" global warming, then in relative terms, it would be larger. After all, you can't fit 10 lbs of $h!t in a 5 lb bag, now can you?

Anyway - better run for now Scott - I've burned way too much time on this thread already. You made your points, I made mine. As usual we disagree. Ciao.

[TimBikes]

Originally Posted by dragonfly

... There of course exist natural effects that work on longer time scales, but those don't explain the sharp temperature increase we're seeing over the past century. You offered PDO as an explanation for most of the increase, but that won't cut it since it is only a 20-30 year phenomenon.

I'll respond to this last comment - then I really gotta run.

The late 20th C temp increase spanned from about 1975 - 2000. That is a "20-30" year timescale. So you bet - I think PDO is probably a big factor in the temp increase since the most recent PDO warm phase spanned that exact same time period. Does it account for "all" of the warming? Not likely. Does CO2? Not likely. Are there factors beyond PDO and CO2? Most assuredly. Could CO2 drive any of this warming? Most probably. Is CO2 the primary driver of late 20th C warming? You can see why I have my doubts, particularly since - as Willis notes - PDO's magnitude is apparently large enough to hide global warming on the downside. So logic would suggest it is capable of overwhelming CO2 on the upside.

[dragonfly]

Originally Posted by TimBikes

I'll respond to this last comment - then I really gotta run.

The late 20th C temp increase spanned from about 1975 - 2000. That is a "20-30" year timescale. So you bet - I think PDO is probably a big factor in the temp increase since the most recent PDO warm phase spanned that exact same time period. Does it account for "all" of the warming? Not likely. Does CO2? Not likely. Are there factors beyond PDO and CO2? Most assuredly. Could CO2 drive any of this warming? Most probably. Is CO2 the primary driver of late 20th C warming? You can see why I have my doubts.

Why limit your analysis to the "late 20th C"? I'm talking about the whole last century. The question is what is accounting for the increasing background trend over the last century. The answer fundamentally cannot be PDO.

[MegansPrius]

Originally Posted by dragonfly

Why limit your analysis to the "late 20th C"? I'm talking about the whole last century. The question is what is accounting for the increasing background trend over the last century. The answer fundamentally cannot be PDO.

And the people who actualy study the PDO, including Steven Hare, who named it, make no such claims as to PDO causing Global Warming. Saying PDO can mask climate change IS NOT the same as saying it causes it.
Pacific decadal oscillation - Wikipedia, the free encyclopedia
http://www.iphc.washington.edu/Staff...pers/ei/ei.pdf
http://www.springerlink.com/content/...7/fulltext.pdf

To the contrary, Mr. Hare is co-author of a report on how AGW will affect coastal systems:
Coastal and Marine Ecosystems & Global Climate Change
Since life began on earth, changes in the global climate have affected the distribution of organisms as well as their interactions. However, human-induced increases in atmospheric concentrations of greenhouse gases are expected to cause much more rapid changes in the earth’s climate than have been experienced for millennia. If this happens, such high rates of change will probably result in local if not total extinction of some species, the alteration of species distributions in ways that may lead to major changes in their interactions with other species, and modifications in the flow of energy and cycling of materials within ecosystems.

[icarus]

Kudos to Scott (MeagansPrius) for bringing informed, cited information. Tim has also done a much better job of arguing his case. At least if I have the motivation, I could follow up on what has been said,,,not like many of the nut case deniers who spew forth.

Keep up the good work Scott!

Icarus