“The more interesting and potentially controversial result is that our data indicate surface water temperatures during a part of the Medieval Warm Period that are similar to today’s…”
“Although there are significant uncertainties with our own reconstruction, our work raises the idea that perhaps even the Northern Hemisphere temperature reconstructions need to be looked at more closely.”
Woods Hole Oceanographic Institution: News Release : New Temperature Reconstruction from Indo-Pacific Warm Pool
The First Word in an Unfolding Story
Media Relations Office
93 Water Street MS #16
Woods Hole Oceanographic Institution
A new 2,000 year long reconstruction of sea surface temperatures (SST) from the Indo-Pacific warm pool (IPWP) suggests that temperatures in the region may have been as warm during the Medieval Warm Period as they are today.
The IPWP is the largest body of warm water in the world, and, as a result, it is the largest source of heat and moisture to the global atmosphere, and an important component of the planet’s climate. Climate models suggest that global mean temperatures are particularly sensitive to sea surface temperatures in the IPWP. Understanding the past history of the region is of great importance for placing current warming trends in a global context.
The study is published in the journal Nature.
In a joint project with the Indonesian Ministry of Science and Technology (BPPT), the study’s authors, Delia Oppo, a paleo–oceanographer with the Woods Hole Oceanographic Institution, and her colleagues Yair Rosenthal of Rutgers State University and Braddock K. Linsley of the University at Albany-State University of New York, collected sediment cores along the continental margin of the Indonesian Seas and used chemical analyses to estimate water past temperatures and date the sediment. The cruise included 13 US and 14 Indonesian scientists.
“This is the first record from the region that has really modern sediments and a record of the last two millennia, allowing us to place recent trends in a larger framework,” notes Oppo.
Global temperature records are predominantly reconstructed from tree rings and ice cores. Very little ocean data are used to generate temperature reconstructions, and very little data from the tropics. “As palaeoclimatologists, we work to generate information from multiple sources to improve confidence in the global temperature reconstructions, and our study contributes to scientists’ efforts towards that goal,” adds Oppo.
Temperature reconstructions suggest that the Northern Hemisphere may have been slightly cooler (by about 0.5 degrees Celsius) during the ‘Medieval Warm Period’ (~AD 800-1300) than during the late-20th century. However, these temperature reconstructions are based on, in large part, data compiled from high latitude or high altitude terrestrial proxy records, such as tree rings and ice cores, from the Northern Hemisphere (NH). Little pre-historical temperature data from tropical regions like the IPWP has been incorporated into these analyses, and the global extent of warm temperatures during this interval is unclear. As a result, conclusions regarding past global temperatures still have some uncertainties.
Oppo comments, “Although there are significant uncertainties with our own reconstruction, our work raises the idea that perhaps even the Northern Hemisphere temperature reconstructions need to be looked at more closely.”
Comparisons
The marine-based IPWP temperature reconstruction is in many ways similar to land temperature reconstructions from the Northern Hemisphere (NH). Major trends observed in NH temperature reconstructions, including the cooling during the Little Ice Age (~1500-1850 AD) and the marked warming during the late twentieth century, are also observed in the IPWP.
“The more interesting and potentially controversial result is that our data indicate surface water temperatures during a part of the Medieval Warm Period that are similar to today’s,” says Oppo. NH temperature reconstructions also suggest that temperatures warmed during this time period between A.D. 1000 and A.D. 1250, but they were not as warm as modern temperatures. Oppo emphasizes, “Our results for this time period are really in stark contrast to the Northern Hemisphere reconstructions.”
Reconstructing Historical Temperatures
Records of water temperature from instruments like thermometers are only available back to the 1850s. In order to reconstruct temperatures over the last 2,000 years, Oppo and her colleagues used a proxy for temperature collected from the skeletons of marine plankton in sediments in the Indo-Pacific Ocean. The ratio of magnesium to calcium in the hard outer shells of the planktonic foraminifera Globigerinoides ruber varies depending on the surface temperature of the water in which it grows. When the phytoplankton dies, it falls to the bottom of the ocean and accumulates in sediments, recording the sea surface temperature in which it lived.
“Marine sediments accumulate slowly in general — approximately 3 cm/yr — which makes it hard to overlap sediment record with instrumental record and compare that record to modern temperature records,” says Oppo. “That’s what is different about this study. The sediment accumulates fast enough in this region to give us enough material to sample and date to modern times.”
The team generated a composite 2000-year record by combining published data from a piston core in the area with the data they collected using a gravity corer and a multi-corer. Tubes on the bottom of the multi-corer collected the most recently deposited sediment, therefore enabling the comparison of sea surface temperature information recorded in the plankton shells to direct measurements from thermometers.
Oppo cautions that the reconstruction contains some uncertainties. Information from three different cores was compiled in order to reconstruct a 2,000-year-long record. In addition sediment data have an inherent uncertainty associated with accurately dating samples. The SST variations they have reconstructed are very small, near the limit of the Mg/Ca dating method. Even in light of these issues, the results from the reconstruction are of fundamental importance to the scientific community.
More Questions to Answer
The overall similarity in trend between the Northern Hemisphere and the IPWP reconstructions suggests that that Indonesian SST is well correlated to global SST and air temperature. On the other hand, the finding that IPWP SSTs seem to have been approximately the same as today in the past, at a time when average Northern Hemisphere temperature appear to have been cooler than today, suggests changes in the coupling between IPWP and Northern Hemisphere or global temperatures have occurred in the past, for reasons that are not yet understood. “This work points in the direction of questions that we have to ask,” Oppo says. “This is only the first word, not the last word.”
The US National Science Foundation and the WHOI Ocean and Climate Change Institute provided funding for this work.
The Woods Hole Oceanographic Institution is a private, independent organization in Falmouth, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment.
h/t to WUWT reader Glenn
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Coral off the coast of Oregon would be nice, but only in your dreams. That water is friggin cold even in its WARM phase! In contrast, my first dive into waters surrounding the South side of Jamaica was a startling experience! Crystal clear, as clear as Clear Lake in the Cascades but at completely opposite ends of the thermometer. Bathtub warm. And definitely NOT refreshing. But then no one in their right mind would frolic in Clear Lake either. Equally not refreshing, even on the hottest day of the year.
The other think I noticed was that the Oregon coast has murky waters filled with tiny food that entices whales close in. I have stood on the rocky coast near the end of a shelf and eyeballed a whale while the whale eyeballed me! The Jamaican waters just don’t have floating food. There is food but it is attached to the bottom. Instead of whales the size of a ranch house, I came nose to nose with fishbowl fish. They looked like butterflies only underwater. It was only later when I found out that in Jamaica, sewer water is dumped untreated right into its shoreline nearby. Yuck.
And by the way, anybody who lives near a coastline, any coastline, knows from birth that what the seas do, predicts what the weather will be out the back door just a couple days later.
Pamela Gray (19:06:21) :
And by the way, anybody who lives near a coastline, any coastline, knows from birth that what the seas do, predicts what the weather will be out the back door just a couple days later.
Yep, give me an old Port Orford Crabber or Charleston Troller’s prediction any day.
I lived on the coast 25 years sailed some, but I could never quite read the sea they way those old men did…
John Ryan (16:05:51) :
so even though we have been in a 10+ year solar cool ctcle ocean temps are as warm as they were back then Gee I wonder what is causing it to get so warm ??
————-
Wow, John! You make your point so cogently! I bet more than a few of us will be taking up arms against CARBON now. Is it recorded how those knights of yore subdued the dreaded Warmth? So much Ancient Wisdom has been lost in our pursuit of pleasure and prosperity!
“Oppo cautions that the reconstruction contains some uncertainties.”
When was the last time you heard Mann, Hansen, or Gore say anything like this?
Mike Abbott (11:06:20) :
I don’t understand all the excitement over this paper. Maybe I’m missing something. Aren’t the authors merely saying their SST reconstruction closely follows Mann’s except for a 250-year period from 1000 – 1250 AD? And even then I don’t see the “stark contrast” they refer to. I can envision Mann and his supporters claiming that this study actually reaffirms Mann (2008) because it follows it so closely overall despite using entirely different methodology
I’m with you on this. If anything, the Mann reconstructon shows a greater range between MWP and LIA. Between 0-1000 AD, SST seems to be more or less flat which makes it nigh on impossible to define the start of MWP.
Perhaps we’re both “missing something”.
I don’t think Prof Wei-Chyung Wang of SUNYA would be happy with Braddock K. Linsley’s co-authourship.
Sam the Skeptic (08:51:47) :
Sam, you are correct. Lamb’s book is a great read, simply a must for any student of climate and history.
Gene L (09:58:48) : “…did anyone else see the article and video, also on Science Daily this week (under “breaking news”), in which a physicist “discovered” that higher CO2 levels now are making plants grow faster?”
I’d like to follow up on that, Gene, but the only links I can find (to very similar stories) are Science Daily (1998) and INFOWARS.COM (2008). Nothing for this week.
Andrew (10:01:09) :
It makes perfect sense on the part of an oil company to let environmental issues raise energy prices: more revenue from existing oil fields. Higher energy prices means higher oil prices. Also, prices at the pump can be raised and the blame fixed on environmentalist and politicians.
Those guys at Exxon are dumb like foxes.
Douglas DC & Pamela:
Ditto for old farmers on predicting the weather.
Vincent (14:16:14) and crosspatch (15:19:46)
Something that strikes me about these studies based on phytoplankton is that extra CO2 would itself make these organisms more productive by stimulating photosynthesis.
The blurb above says the study is based on the observation that “The ratio of magnesium to calcium in the hard outer shells of the planktonic foraminifera Globigerinoides ruber varies depending on the surface temperature of the water in which it grows.”
Googling, one can find papers showing that higher temperatures correspond to higher productivity. But other papers also show higher CO2 contributes to productivity of these types of organisms and the exact mechanisms “are not well understood”.
One wonders if the authors of this study appropriately corrected for the direct “aerial fertilizer” effect of CO2 in the last century. If not, the last century is going to look artificially warm relative to the MWP when CO2 levels were lower.
John Ryan (16:05:51) :
The same processes that caused the Medieval Warming Period?
Roger Carr:
See if this link gets you such a story with a short video. My apologies: this is actually a “recycled” story from June 2007, and I did not catch the date until I looked at it again.
http://www.sciencedaily.com/videos/2007/0603-can_carbon_dioxide_be_a_good_thing.htm
Sorry I did not provide the link earlier… If it doesn’t work, search for the researcher by name: Scott Denning, Ph.D., a physicist from Colorado State University in Fort Collins, Colorado
Here’s the first paragraph:
Mr. Smith, I was reporting from a PBS show that stated those things. Indonesian royal records record the event, and the separation of the two islands, which as I wrote, was Sumatra and Java, NOT Java and Borneo. Borneo only came in as the ocean between Sumatra/Java and Borneo would have had even less circulation with the outside Pacific potentially allowing it to warm even more. The subject of the show was actually the 535 sudden dramatic cooling event (“The Wasteland” in the Arthurian cycles), the likelihood (not certainty) that it was a catastrophic eruption, and the search for the “smoking caldera”, with Krakatoa being thought the likely spot. If you had read what I had written this confusion could have been avoided.
Hey Steve, I believe you. As I noted in my second post, either I was going nuts, or I just didn’t read closely enough; which is not my nature. I certainly wouldn’t have pasted your post; if I had actually seen the Sumatra-Java part. My apologies; green flag, no foul sail on.
George.
And Mr Smith was my father.
crosspatch (15:08:56) : Yes, it was Java and Sumatra that became separated by the caldera forming eruption in 535. The impact of the eruption was global. You can read more here [URL] about the results of this eruption.
Stunning info crosspatch, thanks.
Ray (15:25:07) : “Global Warming BY Dummies”, by Elizabeth May
Yes, indeed, BY dummies and FOR dummies – the level of science is appalling. Now I’ve been encouraged to write a real “Climate Science for Dummies” telling it like it is, drawing on my online Primer and other research (click my name). Haven’t got there so far – I’d still rather see a skeptics’ Climate Science wiki – starting with a wiki-led powerpoint presentation we can perfect to take around and show folk.
Much as I love WUWT, I’m always nervous of the “preaching to the converted” energy rising too high; moreover, I long to see an accessible consolidation of the real climate science that has been developing – I mean real climate science, not the mockery of RealClimate science.
>> FerdinandAkin (10:00:57) :
You might as well just be reading a blog post from some electrical engineer. <<
I agree. Stay away from those other guys. We electrical engineers are the only ones who make cents (and dollars) from current (and voltage) thinking.
Jim
“Interesting also that the coral reefs there are thriving and beautiful (at temperatures above 33 degrees Celsius). This is worth remembering whenever you hear claims that global warming will destroy the world’s coral reefs. There is no ocean water in the world that is too warm for coral reefs ….”
So, if the coral organisms from Bougainville were transplanted to the reefs now in trouble, they’d recover (?). Why doesn’t somebody try it on a test patch or two?
“”” Roger Knights (16:03:43) :
“Interesting also that the coral reefs there are thriving and beautiful (at temperatures above 33 degrees Celsius). This is worth remembering whenever you hear claims that global warming will destroy the world’s coral reefs. There is no ocean water in the world that is too warm for coral reefs ….”
So, if the coral organisms from Bougainville were transplanted to the reefs now in trouble, they’d recover (?). Why doesn’t somebody try it on a test patch or two? “””
Nobody said that the same species can thrive anywhere; they choose their own niche; just like any other species. When corals spawn; the offspring can be carried to the 8 corners of the globe, and thrive anywhere they settle that suits them; so if Bouganville species liked Glacier Bay temperatures better, they would go there eventually.
George E Smith
You are quire right, coral species thrive in their appropriate location and those locations may cover a much wider spread of ocean than may be generally imagined.
These are the corals off the coast in Lyme Bay South Devon UK. My house overlooks this coast .
http://www.bbc.co.uk/devon/outdoors/nature/2003/lyme_coral.shtml
The sea temperature immediately around the coast is around 16C today, in a normal summer perhaps a degree or so warmer. Out in the Bay you can take a few degrees off that. In winter the temperature goes down to around 8C.
So corals appear to thrive over a wider temperature range than may be imagined.
tonyb