Posted on 04/22/2008 11:32:05 AM PDT by cogitator
PASADENA, Calif. -- Boosted by the influence of a larger climate event in the Pacific, one of the strongest La Ninas in many years is slowly weakening but continues to blanket the Pacific Ocean near the equator, as shown by new sea-level height data collected by the U.S.-French Jason oceanographic satellite.
This La Nina, which has persisted for the past year, is indicated by the blue area in the center of the image along the equator. Blue indicates lower than normal sea level (cold water). The data were gathered in early April.
The image also shows that this La Nina is occurring within the context of a larger climate event, the early stages of a cool phase of the basin-wide Pacific Decadal Oscillation. The Pacific Decadal Oscillation is a long-term fluctuation of the Pacific Ocean that waxes and wanes between cool and warm phases approximately every five to 20 years. In the cool phase, higher than normal sea-surface heights caused by warm water form a horseshoe pattern that connects the north, west and southern Pacific, with cool water in the middle. During most of the 1980s and 1990s, the Pacific was locked in the oscillation's warm phase, during which these warm and cool regions are reversed. For an explanation of the Pacific Decadal Oscillation and its present state, see: http://jisao.washington.edu/pdo/ and http://www.esr.org/pdo_index.html .
A La Nina is essentially the opposite of an El Nino. During El Nino, trade winds weaken and warm water occupies the entire tropical Pacific Ocean. Heavy rains tied to the warm water move into the central Pacific Ocean and cause drought in Indonesia and Australia while altering the path of the atmospheric jet stream over North and South America. During La Nina, trade winds are stronger than normal. Cold water that usually sits along the coast of South America is pushed to the middle of the equatorial Pacific. A La Nina changes global weather patterns and is associated with less moisture in the air, and less rain along the coasts of North and South America.
"This multi-year Pacific Decadal Oscillation 'cool' trend can intensify La Nina or diminish El Nino impacts around the Pacific basin," said Bill Patzert, an oceanographer and climatologist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The persistence of this large-scale pattern tells us there is much more than an isolated La Nina occurring in the Pacific Ocean."
Sea surface temperature satellite data from the National Oceanic and Atmospheric Administration also clearly show a cool Pacific Decadal Oscillation pattern, as seen at: http://www.cdc.noaa.gov/map/images/sst/sst.anom.gif .
The shift in the Pacific Decadal Oscillation, with its widespread Pacific Ocean temperature changes, will have significant implications for global climate. It can affect Pacific and Atlantic hurricane activity, droughts and flooding around the Pacific basin, marine ecosystems and global land temperature patterns.
"The comings and goings of El Nino, La Nina and the Pacific Decadal Oscillation are part of a longer, ongoing change in global climate," said Josh Willis, a JPL oceanographer and climate scientist. Sea level rise and global warming due to increases in greenhouse gases can be strongly affected by large natural climate phenomenon such as the Pacific Decadal Oscillation and the El Nino-Southern Oscillation. "In fact," said Willis, "these natural climate phenomena can sometimes hide global warming caused by human activities. Or they can have the opposite effect of accentuating it."
Jason's follow-on mission, the Ocean Surface Topography Mission/Jason-2, is scheduled for launch this June and will extend to two decades the continuous data record of sea surface heights begun by Topex/Poseidon in 1992. JPL manages the U.S. portion of the Jason mission for NASA's Science Mission Directorate, Washington, D.C.
For more information on NASA's ocean surface topography missions, see: http://sealevel.jpl.nasa.gov/ ; or to view the latest Jason data, visit: http://sealevel.jpl.nasa.gov/science/jason1-quick-look/ .
so much for the 2008 Atlantic hurricane season
If you give a fudge factor a technical name, is it still a fudge factor?
If you don’t understand the primary influence on a system, do you really understand the system?
Aaaah yes, the obligatory CYA.
I find it telling that the last time the pacific was in its “cool phase” corresponded almost exactly to the time when scientists worldwide were warning of a new ice age, and winters were especially strong. Then, all through the 80s and into the 90s, temps warmed, just in time for scientists worldwide to yammer about a coming “global warming” heatwave.
Now we’ve just had a particularly strong winter, which still lingers in the north, and the pacific is cooling again. Global temps have stayed static or even declined over the past several years.
From 2001....We wonder why the Arctic Sea ice waxes and wanes? Must be global warming>? Nah, more likely the shifting currents of the Pacific Ocean. But you say, the sea ice is at record low. Nah, has pretty much returned to ‘normal’ extent. But, but, it was lowest on record last summer, it will be totally gone in 20-30 years. Nah, the ‘records’ only go back to 1978, when the first sat to take daily pictures of Arcitc was sent up. Today, April 22, 2008, we have much more sea ice in Arctic than April 22, 2007.
Like fall and winter of 2000, this year’s (2001) TOPEX/Poseidon satellite data shows that the Pacific Ocean continues to be dominated by the strong Pacific Decadal Oscillation, which is larger than the El Niño/La Niña pattern. The data, taken during a ten-day collection cycle ending Oct. 29, 2001, show that the near-equatorial ocean has been very quiet in the past year, and sea levels and sea surface temperatures are near normal. Above-normal sea surface heights and warmer ocean temperatures, indicated by the red and white areas, still blanket the far western tropical Pacific and much of the north mid-Pacific.
The cool phase of the PDO could potentially exert a cooling influence on the climate. But the difference between now and the 1970s is twofold; higher atmospheric CO2 concentrations and lower SO2 aerosol pollution (though the Chinese are doing their best to counteract that). It’ll be interesting to see what happens next.
Sea ice records go a lot further back than 1978.
Given the relatively cool Northern Hemisphere winter, there has been a good freeze of the Arctic Ocean, but it's mostly first-year ice. I'll be curious to see how much the Arctic sea ice melts this summer.
Not sat data...the other data was gathered by ships and coastal observations and thus is like comparing apples to oranges.
I’m just Hoping we have summer. I want Change.
Come on, cogitator... you know damned well that those are reconstructions.
Plus, I note you’re cherry picking... How come you didn’t post that same site’s more recent, detailed record... the one showing the remarkable rebound in sea ice?
Then there’s that little matter of the Antarctic sea ice shattering the old records...
I am aware that the data is not satellite data; but going back to the 1950s at least, ice extent was estimated by aerial survey. Going back further than that, ship and coastal surveys provide the data. How would you argue that such observations are so flawed that they do not provide a reasonably accurate indication of sea ice extent?
I offer the following references for your examination. If you have problems with the methodologies, explain what they are.
Global Warming and Northern Hemisphere Sea Ice Extent
The key reference is 13, by Chapman and Walsh. Here's their Web site:
Arctic Climate Research at the University of Illinois
The data is online and Dr. Chapman invites anyone with questions about it to contact him by email. Why don't you email him and discuss how the data quality of the observational archive compares with the more recent satellite data?
Here is the documentation page for the sea ice data. I recommend reading the "Expert User Guidance" section:
Walsh and Chapman Northern Hemisphere Sea Ice Data Set
dangus, there are a couple of nice papers out there reporting that increased Antarctic sea ice is a consequence of global warming. I've posted the links to them before and I'm a tad lazy today. Google works to find them.
Try an example: The warmest year in recent history was 1934. 1931, 1938 and 1939 were in the top ten. However this cannot be discerned in the ground-based ice extent observations shown in your chart. 1953, the seventh warmest year...had the greatest sea ice extent, according to your chart!
Either the chart is flawed, or its association with average temperatures is flawed.
Only in the United States. I assume that the rest of your dates are for the U.S., and not the global values?
Anyway, sea ice is influenced by more factors than temperature, though temperature is important. And the values look pretty constant, so it would be hard to discern an overriding temperature influence, I would think.
Who’s Nina Linger?
Looks like we are still coming out of the Little Ice Age.
Ok, 1945 was a particularily warm year by global standards.
And 1957 was an espscially cool year.
Yet your graph shows no change.
And by your own admission, sea ice is not a good indicator of average atmospheric temperature.
The key factor is the number of melting days.
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