As I mentioned in my post here about one of the satellite data sets (RSS) that showed a marked cooling globally in 2008, La Niña and PDO seem to be drivers of this change. Here is Joe D’Aleo’s take on it below. – Anthony
By Joseph D’Aleo, CCM ICECAP
Evidence is growing this La Niña will be a longer term event. Most similar important La Niñas are often multi year events (1949-1951,1954-1956, 1961-63, 1970-1972, 1973-1976, 1998-2001). Though the easternmost Pacific near South America has warmed at the surface as the seasonal weakening of the tropical easterlies led to weakened upwelling, it is still cold beneath. Below you can see the latest depth-section of ocean temperatures (top) and anomalies (bottom). Temperature are in degree Celsius. Note the large reservoir of subsurface anomalously cold water (up to 4 degrees C) in the eastern tropical Pacific at 50 to 100 meters.
Also see the latest CPC depicted ocean heat content in the tropical Pacific. This shows the heat content remains at near maximum deficit levels.
These suggest as the easterlies increase again, cooling will return to the east Pacific and La Niña will persist at least well into 2008. The Pacific Decadal Oscillation (PDO) has dropped strongly negative (latest value from NCEP is -1.54 STD). This decline may represent another Great Pacific Climate Shift as the PDO warm and cold phases tend last 25 to 30 years and the last change , to a warm Pacific, occurred in 1976. See more in this pdf here. If indeed the PDO shift is the real deal, we might expect more La Niñas and fewer weaker El Niños over the next few decades with a net tendency for cooling. Add to that a quieter sun and eventually a cooling Atlantic, and you have a recipe for global cooling.
However, this has its own drawbacks, La Ninas bring more drought and summer heat waves, landfalling hurricanes, large tornado outbreaks, spring floods, winter snows and cold outbreaks than their more famous counterpart, El Niño, which has dominated during the warm PDO era. A while back, Stan Changnon did an interesting analysis which I reported on recently here that suggests the era we have gone through since the late 1970s with dominant El Niños was unusually benign with more benefits than damages and will be looked on as the golden era, a modern climate optimum. Even if all this is correct, you might expect the media and enviro-alarmists ‘evidence’ we are affecting our climate to morph from warming and ice melt to the climate extremes characteristic of La Niñas.
See full pdf here.
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davidsmith1,
Ah, I have the mental picture now. The winds push the warmer water west into a tighter and tighter area, much of it forced subsurface. The decreased surface area has less ability to affect the atmospheric temperature.
Well, I told you I was simple!
Matt N. “You sure we’re not looking as a phase shift? The SOI index is really high….”
The graph in the link you provided comes from the Australian Bureau of Meteorology here: http://www.bom.gov.au/climate/enso/
SOI only reached that level for a short period of time, the monthly average is 14.4 in Dec 2007 and 14.1 for Jan 2008. If you look at monthly SOI averages for pre climate shift years you will notice monthly averages that are much higher and for longer periods of time, for instance it went up to 31.6 in Nov 1973. http://www.bom.gov.au/climate/current/soihtm1.shtml
So I do not think the SOI record supports the possibility that there has been another Pacific climate shift.
Kristen,
ENSOs are based on anomolies. The average temperature has been rising so a large variation today would cause a lower cold anomoly than it would in the past – assuming that the base period does not change over time.
Is it possible that the lower ENSO indexes actually represent as large a deviation from normal as in the past but it is masked by the choice of base periods?
It looks to me that La Nina is breaking up and the February early temps are increasing from the January temps.
The 30 day anomaly from the CDC (as of February 27th) shows colder than normal temps for the past 30 days but these are less extreme than those of January.
http://www.cdc.noaa.gov/map/images/rnl/sfctmpmer_30a.rnl.html
The 7 day anomaly shows the majority of areas are now above normal.
http://www.cdc.noaa.gov/map/images/rnl/sfctmpmer_07a.rnl.html
The El Nino / La Nina animation of the past two months appears to show some weakening of La Nina conditions over the past month or so.
http://coralreefwatch.noaa.gov/satellite/current/crblrg_sstanom_2m.html
So, it appears to me that the past 12 months of very significant cooling is now over.
Davidsmith1, I have come across a couple of references recently to increases in ocean up-welling. One was off the coast of Morocco. The increase was surprisingly large, 30% from memory over 3 or 4 years.
I am not aware of any explanation for this increase. Nor I am aware of any systematic attempt to measure up-welling on a global basis.
I understand these up-welling currents are part of the ocean heat transport from the tropics toward the poles. So more up-welling would mean more heat transfer poleward. What effect this has on climate is anyone’s guess.
It also leads to the paradox of warmer temps toward the poles causing the Earth to lose more heat.
Raven,
First, I have no faith in the surface temperature record (my volunteers did 26 stations for Anthony), but all surface temp records (GISS, HADCRUT, NOAA, NCDC) and both satellites show a lot of cooling in the past year, so I am not sure if average temperatures have been rising. I suppose if you average them out over decades it may be warming. As for the anomalies, I do not recall the base periods changing over time, but that may be a better question for Steve McIntyre since statistics are his specialty (and I have been so involved with school that I am rusty on the subject). However, all of the temperature records, both surface and sat, have been behaving exactly as I would expect given the La Nina that has developed during the past 12 months. One thing I have noticed though is that the temps this year are a little cooler than past La Nina’s of similar strength, that is probably from the lower solar activity.
John Willit, “The El Nino / La Nina animation of the past two months appears to show some weakening of La Nina conditions over the past month or so.” and “So, it appears to me that the past 12 months of very significant cooling is now over.”
It depends on the Nino region.
Nino 1+ 2 is mostly controlled by high-pressure systems in the south Pacific near South America; this is something one of my volunteers has been watching very closely. The high-pressure systems in this area have been weakening lately causing the Peru current to slow down (the Peru current brings cool water from the tip of South America, as well as cool upwelling water along the coast of South America, up to the equator). This appears to be seasonal, the farther into the southern hemisphere summer, the warmer the water down there, which causes high pressure systems to be less dominant. High-pressure systems in the southern hemisphere create surface winds that blow in a counter clockwise direction. The weaker the high-pressure system in that area, the weaker the surface winds that blow surface water north along the South American coast.
If you look at the Nino 4 region, that area is more affected by oceanic Kelvin waves. As the trade winds become stronger, they blow warm surface water to Indonesia. The warm surface water evaporates leaving saltier, denser (heavier) water near Indonesia, this water sinks, moves a little east, then rises causing a warm wave at the surface. Since there is no coriolis effect at the equator, this warm water can move east along the equator. This is a major part of the thermocline. If the trade winds above are weak and there is a strong Kelvin wave, you will get an El Nino. Lately the trade winds have been strong and they have prevented the Kelvin waves from moving much to the east, but at the moment there is a strong upwelling so you should expect the Nino 4 region to warm a little in the next few weeks.
In an earlier post I said that this La Nina will probably weaken a little then strengthen in about 6 months or so. This is because cool surface water is being blown from Baja California to the equator south of Hawaii. This seems to be contributing to the current La Nina. But the important point is that past La Nina’s did not last more than a year unless this condition existed.
If you guys want some really good stuff on ENSO I suggest the following links.
http://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/enso.shtml
There is a lot of good stuff there, especially if you go down to the “expert discussions” section there is a weekly PowerPoint presentation that is really good. There is also a link in the left hand frame on that page on the MJO, they also have a weekly PowerPoint presentation (and PDF) that will help you with MJO which affects ENSO if you have the time to learn it.
For tracking daily sea level pressure and surface winds I suggest this link by the Australian Bureau of Meteorology.
http://www.bom.gov.au/nmoc/MSLP.shtml
There is also a lot of other stuff there if you have the time.
Have fun! 🙂
Regarding global temperature and ENSO, I offer this plot
http://davidsmith1.files.wordpress.com/2008/01/0125081.jpg
This is a plot of satellite-derived lower troposphere temperature anomalies over the satellite era, with two modifications. One, I removed two periods of volcanic activity (El Chicon and Pinatubo). Two, I “de-ENSO’d” the plot by attempting to remove the effects of ENSO activity. (This is done by estimating the impact of changes in the ONI on global temperature then subtracting those.)
What the plot does is to allow an eyeball guess as to the direction of global temperature, ignoring the swings of ENSO and impacts of volcanoes. To me it shows that global temperature anomalies peaked around 2001 and have been on a flat-to-decling trend since.
It’ll be interesting to see how 2008 “scores” as the year progresses. To me, the January 2008 anomaly looks normal for a La Nina.
Philip_B, doesn’t that mean that the heat is going to Africa instead the poles?
Dave, neat plot. Can you put a trend line on it?
Also, another one I’d like to see is a plot of all the minimums, only the points where the raw global average chages from cooling to warming.
Aaron, no problem, the trended plot is here:
http://davidsmith1.files.wordpress.com/2008/03/0304081.jpg
To my eyes the global temperature anomaly was flat from 1979 to the early 90s, then rose about 0.2C over the next 5 to 10 years then became flat again.
Thanks.
1.1C per century seems like a downright sane number.
People are forever calling this cooling a localised La Nina in the pacific. Well that may be the focus but surely if Baghdad sees its first snow in all recorded history we are not looking at simply a localised La Nina. Look at this piccie … is this just a La Nina?
http://www.osdpd.noaa.gov/PSB/EPS/SST/data/anomnight.3.6.2008.gif
Check the Indian ocean surface cooling and see that it is in the tropics and mainly on the equator like the pacific cooling. Check also where the warmer surface is being pushed ….i.e to the higher latitudes and its leading edge is not unremarkably the warmest.
Does anyone get the picture of what’s happening?
REPLY: Good point, we’ll look further
As there has been a predominance of El Ninos over the last 30 years, (I have read 1 every 2 years instead of 1 every 7 years pre late 70`s) could this in itself raise global temperatures, if so by how much.
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