Marine Scientist Finds 'Little Ice Age' Had Dramatic Effect on Gulf

Feb 22, 2010 By Vickie Chachere
Marine Scientist Finds 'Little Ice Age' Had Dramatic Effect on Gulf

(PhysOrg.com) -- More than 350 years ago, the temperatures in northern Europe dropped dramatically in an event known as the “Little Ice Age.” Now - deep below the waters of the Gulf of Mexico and buried in the sand, silt and mud - a USF marine geologist has discovered new evidence showing just how this long-ago climate change also affected the low latitude of subtropical areas.

Using deep-sea sediment samples pulled from below the gulf floor, researcher Julie Richey has been able to reconstruct what happened to temperatures on the gulf’s surface. Her discovery: the Gulf of Mexico cooled 2 to 3-degrees during the Little Ice Age, a much more dramatic effect that suggests the region may be more sensitive to climate change than scientists expected.

“The more we learn about past climate change, the more we understand about what is occurring now,” said Richey, a presidential doctoral fellow at the College of Marine Science.

Richey’s research was able to examine 1,500 to 2,000 years of climate change by examining the of microscopic fossils in the , was published in a recent edition of .

Richey’s research has focused on the Atlantic Warm Pool, which develops west of Central America in the spring and expands east through the fall. She has also conducted similar studies using sediment cores from Lake Tulane near Sebring in an effort to examine 2,000 years of climate change in Florida.

The core samples in her most recent study were pulled in 2006 from a section of the Gulf of Mexico floor (samples were gathered from basins due south and southwest of Louisiana) where sediments from the have collected for eons. Because the majority of climate records covering the past millennium are derived from higher latitude land environments, Richey said very little is known about how past episodes of climate change affected the tropics and sub-tropics. The Gulf of Mexico is unique because of its high volume of sediment carrying telltale minerals and organic matter from the U.S. Midwest and northern regions that now give scientists clues about how climate has changed.

Richey’s study was able to generate three 600-year long records of sea surface temperature from three locations in the northern Gulf of Mexico. Sea surface temperature was calculated by examining the calcium carbonate in the fossilized remains of a tiny creature that normally lives at the ocean surface, but whose shells sink to the gulf floor as they die. The magnesium/calcium ratios in calcium carbonate change in proportion to the water temperature in which the calcium carbonate forms, giving scientist a picture of what temperatures were like through the ages.

Richey’s research project found that in all three Gulf of Mexico basins recorded a ~2ºC cooling during the Little Ice Age, which is much larger than the 0.6ºC global average estimated from broad-scale climate reconstructions. The findings imply that natural climate variability in the Atlantic Warm Pool is quite dynamic, and may be especially vulnerable to future climate change, Richey said.

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david_42
3.9 / 5 (7) Feb 23, 2010
This also shows that the cooling was not restricted to Europe or even the high northern latitudes.
dachpyarvile
3 / 5 (5) Feb 23, 2010
An excellent point, david_42. Mikey Mann may not like this news very well. :)
JayK
3.1 / 5 (7) Feb 23, 2010
@david_42: It does? Please explain, when the article clearly spells out that the Gulf of Mexico data is interesting because it is built off of sediments carried down from northern climes?

The Gulf of Mexico is unique because of its high volume of sediment carrying telltale minerals and organic matter from the U.S. Midwest and northern regions that now give scientists clues about how climate has changed.
freethinking
1.8 / 5 (10) Feb 23, 2010
JayK, AGW caused the little ice age. The people of Atlantis were buring fuel to heat their spaceships causing the earth to warm up, then when the sea level rised and they sunk to the bottom of the ocean the CO2 level dropped again and caused the little ice age. Then the rest of the people of the world started to burn stuff to warm themselves causing a rise in the CO2 levels again.
JayK
2.3 / 5 (6) Feb 23, 2010
freethinking, don't you need to go pray the gay away or something?
freethinking
1.4 / 5 (9) Feb 23, 2010
Boy AGW fanatics have no sense of humor. Why is that? We'll if Al Gore was my prophet and I always listen to his voice, I would be grumpy as well.

PinkElephant
4.5 / 5 (8) Feb 24, 2010
This also shows that the cooling was not restricted to Europe or even the high northern latitudes.
Well, considering the Gulf Stream is what keeps Europe warm, then it stands to reason that a cooling off in the Gulf of Mexico is what drove a knock-on cooling of Europe.
dachpyarvile
3.3 / 5 (3) Feb 24, 2010
@david_42: It does? Please explain, when the article clearly spells out that the Gulf of Mexico data is interesting because it is built off of sediments carried down from northern climes?

The Gulf of Mexico is unique because of its high volume of sediment carrying telltale minerals and organic matter from the U.S. Midwest and northern regions that now give scientists clues about how climate has changed.


Misreading yet again, MikeyK et al.?

"Northern regions" != "high northern latitudes" in the article and david_42 is not mistaken or contradictory to the article above. The US midwest and northern regions are in regions of North America which have connection with the Mississipi River, which, in turn, dumps sediments into the Gulf of Mexico.

"High northern latitudes," on the other hand, refers to the Arctic.

PE,

Now, what triggered the substantive cooling of the Gulf of Mexico?
PinkElephant
3.8 / 5 (4) Feb 24, 2010
Now, what triggered the substantive cooling of the Gulf of Mexico?
I doubt anyone knows for sure. There are some suggestions:

http://en.wikiped...e#Causes
Loodt
2.3 / 5 (3) Feb 24, 2010
So, the sun went to sleep and didn't shine as hard and bright on the tropics as well!

But we know weather is not Climate!
dachpyarvile
2 / 5 (2) Feb 25, 2010
PE, I am inclined to agree that no one knows for a certainty. Thanks for the link.

Now, notice this image of solar activity:
http://upload.wik...bels.png

Take a close look at the far left side of the graph. I'll be damned if that doesn't look a lot like the end of the infamous 'hockey-stick' graph at the heart of contraversy. Doesn't it?

Now, considering hypotheses regarding lag-time between warming oceans and global warming, I wonder whether this might possibly point to at least some connection. What do you think?
PinkElephant
4.5 / 5 (2) Feb 25, 2010
That's not an image of solar activity; that's a record of Carbon-14, which isn't taken up by photosynthetic organisms as readily as Carbon-12. Dips and peaks in C14, might indicate respective absorption and outgassing of "heavy" CO2 by the ocean and/or landmass buffers (or, in case of outgassing, also by volcanic activity.) It can also be related to sunspots or cosmic rays, which presumably can transmute some C12 into C14. It's not clear from your graph whether it represents global averages, or just a single location. Nor is it clear whether it's talking about relative measured concentration, or some sort of periodic (e.g. yearly, or decadal) change.

With respect to the sun itself, though, take a look at this image of solar activity:

http://en.wikiped...data.png

Note that solar irradiance hasn't substantially changed since *at least* 1975.
PinkElephant
4.5 / 5 (2) Feb 25, 2010
Eh, my memory's failing. So of course, I had to look up C14 and refresh. It's not C12 that is transmuted into C14, it's N14. And C14 rapidly decays back into N14 (which is the basis for carbon dating); so of course, you won't see C14 from volcanic activity, rather you'd see an abundance of C12. To an extent, I was confusing C13 with C14... What can I say; I'm neither a nuclear scientist nor a chemist.

Anyway, despite all the confusion on my part, the main point remains: your graph isn't indicative of solar irradiance. At best, it's indicative of cosmic ray flux (which may be in turn related to solar magnetic field strength, earth magnetic field strength, or variable cosmic ray sources), but even that is open to interpretation.

Also, see here: http://en.wikiped...spot.svg
Note that the 14C record since 1950 has been distorted by nuclear testing.
dachpyarvile
2 / 5 (3) Feb 25, 2010
PE,

Reconstructed solar activity is exactly what the chart represents and that is what was extrapolated from the C14 data. When solar activity increases cosmic radiation reaching the upper atmosphere decreases.

But, what you failed to notice is that there is a considerable time lag between the charts. Nuclear testing since 1950 and solar irradiance from 1975 are completely irrelevant. Take a closer look at the chart for solar activity reconstructed from the C14 data. Notice the lag that precedes both periods noted in your objections?

You can disagree (and misinterpret charted data, too, if you like) but that is alright. I just thought it was an interesting coincidence that the shapes in the graphs are remarkably similar, even if one lags behind the other. But, we know that there are lag times between cause and effect in certain elements of the environment.
PinkElephant
4.5 / 5 (2) Feb 25, 2010
Actually, from this again (pay attention to the caption):

http://en.wikiped...spot.svg

It is evident that the time lag between cosmic ray flux changes and sunspot activity, is 60 years (!!!) I really can't imagine why it would be such a large lag. Cosmic rays travel at nearly light-speed, magnetic field changes travel at light-speed, and solar wind travels A LOT faster than the Voyager spacecraft, which are projected to reach heliopause a mere 40 years after launch. Unless somebody can propose a plausible mechanism, perhaps this correlation is merely coincidental. Consider the magnitude of change, as well: we're talking about total natural variation range of less than 40 parts per quadrillion (C14 constitutes about one-trillionths of the carbon in the atmosphere to begin with.)

Plus, the period from 1950-2000, to which you referred as a "hockey-stick" analogue, is muddled by noise from atmospheric nuclear blasts.
PinkElephant
4.5 / 5 (2) Feb 25, 2010
Also, it's still not clear to me whether these charts represent changes in C14 fraction, or changes in absolute quantities within the air column. If the latter, then the same outgassing/resorption dynamics that play out between the atmosphere and warming/cooling oceans, would also drive (or at least muddle) the C14 signal. If the former, then it is indeed a cosmic ray correlate; but recent studies have shown there's no statistically significant correlation between cosmic ray flux and cloud cover (the frequently alleged mechanism by which cosmic rays might affect climate), and by themselves cosmic rays don't carry enough energy to measurably affect atmospheric or surface temperatures.

Solar cycles do subtly modulate irradiance, but from peak to trough of a strong cycle, the change (1 Wm^-2, on top of the 1365.5 Wm^-2 'floor') is just a fraction of the radiative forcing attributed to even pre-industrial CO2 concentrations.
dachpyarvile
1.7 / 5 (3) Feb 25, 2010
...Plus, the period from 1950-2000, to which you referred as a "hockey-stick" analogue, is muddled by noise from atmospheric nuclear blasts.


No, look at the graph again, PE. Look at the scale and the timeline. You are not seeing it and you will need to look at it very carefully if you want to understand the meaning behind the chart. Look at the ending year for the END of the hockey-stick in the solar activity graph. It is prior to the 50-year mark. Be careful also to look at the range of years for the graph. You eventually may see that 1950-2000 is not included in the line.

And, I am saying nothing about cosmic rays altering temperatures in climate. Nothing at all. You are doing that MikeyK/JayK thing again. Read carefully.

C14 is created by bombardment of the upper atmosphere by cosmic radiation. Increases of solar radiation result in reductions of cosmic radiation to earth. This has been observed. It is how much cosmic radiation influences climate that is questioned.
PinkElephant
5 / 5 (3) Feb 25, 2010
Hah, well ONE of the two graphs has its x axis shifted by 60 years in the wrong direction. I'm betting it's yours. THIS graph shows that the precipitous rise at the end of the curve occurred between 1950-2000:

http://en.wikiped...spot.svg

Since this one is officially captioned, and linked from an actual Wikipedia article -- as opposed to residing under an "upload" destination -- I'll trust it before I trust the one you linked.

The caption on the graph above explicitly mentions the -60 year shift, which seemingly lines up the C14 curve with the sunspot curve (which reaches all the way to 2000.) The x-axis of the C14 curve is plotted at the top of the graph. The rather incredible 60-year offset, though, makes me very dubious as to whether this alignment is at all reflective of any real mechanism, or merely an artifact of overzealous pattern matching...
dachpyarvile
1.7 / 5 (3) Feb 26, 2010
It is NOT my graph, PE. It is the very same one on the page to which you linked us above. I just went after the original file on the original site in the original location because the original file has a better image resolution. But, it still was a graph found in YOUR link you provided before the one you now are providing.

By the way, are you sure you want to go down the road of denying that there are aspects of environment science that demonstrate lag times? Perhaps you might want to do so, after all, if the data holds that there could be as much as an 80-year lag on global CO2 measurable on Antarctica.

The chart to which you have linked on the current page is interesting but its C12 data have been smoothed quite a bit and your chart may well have been the one shifted for pattern matching in order to remove the lag-time. Think about it... :)
dachpyarvile
2 / 5 (2) Feb 26, 2010
PE,

YOU provided this link above:

http://en.wikiped...e#Causes

Go to that page and look to the right. Click the image and click the image on the following page and you will see that until someone removes or edits that one out, it is the graph to which I linked. I just linked the original image's location rather than displaying a web page. But I didn't alter the image or location.

Note the more than 50-year lag carefully. I would give a little more trust to this graph than to a composite graph that may have been adjusted.

Aside from this, I am not relying on anything to which you have linked, really. It comes from Wikipedia. While people try to be accurate, there are times when people play around with the information and edit out things they do not like. It is human nature to be petty and vindictive like that. It is akin to what happens when people from the IPCC and elsewhere try to get funding pulled from other scientists with whom they disagree. :)
dachpyarvile
2 / 5 (2) Feb 26, 2010
There is something else that needs to be considered. Did you stop to think that perhaps, just perhaps, corrections were made for two things:

1. half-life calculations?

2. Nuclear testing?
PinkElephant
4 / 5 (2) Feb 26, 2010
I've looked into the sources of these graphs a bit deeper. For your graph, the source is this paper:

http://pubs.usgs....5-00.pdf

For mine, concatenate the two pieces below (the forum mangles the full url):

"http://www.radioc.../"
"IntCal04 files/intcal04.14c"

which cites a 2004 paper.

At this point, I can't tell why the results appear so different, without diving into the sources in detail (for which I don't have the time.)

For example, aside from the different shapes of the two curves, note that the 2000 paper (from USGS) claims a 20-60 year LEAD by C14 over the sunspot cycle. Whereas the data from the 2004 paper reflects a 60 year LAG.

It seems to me that different sampling methods and analysis procedures are yielding quite different results in this case. Perhaps not surprising, considering how tiny the C14 concentration is in the first place, and then how tiny the ostensible variations of it are, and hard to tease out when overlaid with noise.
mary_hinge
5 / 5 (3) Feb 28, 2010
Maybe the C14 is created by astrological processes, well the septics count this is a cause of global warming....http://legis.stat...009P.htm
Note especially "(2) That there are a variety of climatological, meteorological, astrological, thermological, cosmological, and ecological dynamics that can effect world weather phenomena and that the significance and interrelativity of these factors is largely speculative;"
This is what they want to teach our kids, next step Intelligent Design and creationism... The dark age is about to return...
dachpyarvile
Mar 09, 2010
This comment has been removed by a moderator.
dachpyarvile
1 / 5 (2) Mar 11, 2010
PE,

First of all, it is NOT my graph! It was one of yours because you first posted the link to the page containing it. I just used it.

That said, go with the USGS study. It may be dated to 2000 but it accurately gives the data for solar minima and maxima and the converse delta-14C minima and maxima for the period. It does take from 20-60 years for the result of the 14C to become manifest as it works its way into the earth system from the upper atmosphere.

From the article itself:
Note that the sunspot minima lead the Δ14C maxima by 20–60 years, which is the time it takes for the effect of solar activity on 14C production to cycle through the atmosphere-ocean system.


Solar maxima, in point of fact, do seem to correspond with delta-14C minima, and vice versa. There also are correponding decreases and increases in global temperature but the amount still is being hotly debated.

It still is a curious thing to see the "hockey stick" in the delta-14C data, nonetheless.
dachpyarvile
1 / 5 (2) Mar 14, 2010
This is interesting. Yet another hockey-stick in the solar proxy data, this time in the delta-10Be proxy data.

http://upload.wik...xies.png

As Spock would say: "Fascinating."