From Penn State , another Mann paper with proxy sets, and a divergence problem. At least they are talking about the MWP, or as they call it, the Medieval Climate Anomaly which had been erased in previous papers Mann had been involved with. The attempt to link paleo data to the PDO is interesting too. Mann was not lead author, and hopefully none of the flawed PCA math he’s used to mess up other papers made it into this one. I’m hopeful, as the SI contains some equations/code.
The gist of the paper is this: they wanted to determine patterns of drought in the Pacific Northwest, so the authors used proxy data obtained both from tree rings and from oxygen isotopes related to lake sediments.
According to lead author Byron Steinman.“The data matched up on a short-term, decadal scale, however, on a longer-term, century scale, the records diverged. The tree-ring data suggests dry conditions during the Medieval Climate Anomaly summers while the isotope data suggest wetter-than-expected winters.”
New methods help scientists shed light on ancient climates
Tree ring and oxygen isotope data from the U.S. Pacific Northwest do not provide the same information on past precipitation, but rather than causing a problem, the differing results are a good thing, according to a team of geologists.
The researchers are trying to understand the larger spatial patterns and timing of drought in the arid and semiarid areas of the American West.
“We generally understand that the Medieval Climate Anomaly, a warm period in much of the northern hemisphere that occurred about 950 to 1250 was a dry period in the American West,” said Byron A. Steinman, postdoctoral researcher in meteorology, Penn State. “But there is complexity to the patterns of drought and it may not have been dry in winter in the Pacific Northwest.”
East of the Cascade Mountains, the Pacific Northwest is dry and hot in the summer and wet in the winter now.
Estimates of past precipitation are made from proxies like tree rings, which can record amounts of precipitation and temperature. But tree rings are better at recording what happens during the spring and summer, when the tree is growing, than in the winter when the tree is not.
Steinman, who worked with Mark B. Abbott, professor of geology and planetary science, University of Pittsburgh, his Ph.D. advisor, looked at oxygen isotopes found in 1,500 years of sediment at the bottom of lakes. The isotopic composition of these sediments can reflect the amount of water that enters the lake, especially during the wet season.
The analyzed lake sediments contain calcium carbonate in the form of calcite. The oxygen isotope ratios in this mineral relate directly to the isotope ratio of water in the lake. The researchers looked at sediment from two small lakes in Washington state. Castor Lake is on a plateau and water inflow is only from precipitation and groundwater. This lake has no outflow, so most water loss is through evaporation. Lime Lake, on the other hand, loses the majority of water through a permanent outflow stream, although all water enters in the same manner as for Castor Lake. By comparing the two lakes, the researchers could determine the water balance between evaporation and precipitation.
The researchers looked at two stable isotopes of oxygen — oxygen 16 and oxygen 18 — in the sediments. Oxygen 16 is lighter than oxygen 18, so during evaporation and lake draw down, more oxygen 16 evaporates out and the calcite in the sediments contain more oxygen 18. If the lakes are full of water, then there will be more oxygen 16 in the calcite. The layers of sediment that are laid down each year can be dated either by using carbon 14 dating of organic material or by locating layers of tephra — volcanic ash, that signifies known — dated volcanic eruptions. In this way, the researchers could pinpoint when drought occurred.
“The tree ring data and isotope data match up on a short term, decadal scale,” said Steinman. “On a longer term, century scale, the records diverge.”
While the decadal ups and down remain the same for both proxies, when viewed on a 100-year or longer scale, the proxies show differences. The tree ring data suggest dry conditions during the Medieval Climate Anomaly summers, while the isotope data suggests wetter than expected winters.
Comparing the lake sediment records to existing records of the Pacific Decadal Oscillation, a warming or cooling of the coastal waters off the Pacific Northwest, the researchers report in the current online issue of the Proceedings of the National Academy of Sciences “a strong centennial timescale relationship over the past 1,500 years between winter precipitation amounts in eastern Washington and Pacific Decadal Oscillation temperature anomalies.”
The PDO is linked to the El Nino Southern Oscillation, a tropical phenomenon that influences global weather patterns. During and before the Medieval Climate Anomaly, the North Pacific Ocean was warmer and Washington had greater precipitation than during the Little Ice Age, which occurred from about 1450 to 1850, when there was less precipitation.
Steinman used a previously published and validated model based on established lake physics and modern recorded precipitation and temperature to determine the amounts of rainfall indicated by the isotopic record
“The best thing we could do now is to produce additional quantitative precipitation records, this time with different lake systems,” said Steinman.
Other researchers on this project were Michael E. Mann, professor of meteorology and geosciences and director of the Penn State Earth System Science Center; Nathan D. Stansell, former Ph.D. student at the University of Pittsburgh, now a research fellow, Byrd Polar Research Center, Ohio State University and Bruce Finney, professor of biological sciences, Idaho State University.
The National Science Foundation funded this research.
=============================================================
Paper: 1500 year quantitative reconstruction of winter precipitation in the Pacific Northwest, by Byron A. Steinman, Mark B. Abbott, Michael E. Mann, Nathan D. Stansell, and Bruce P. Finney, PNAS, 2012.
Abstract
Multiple paleoclimate proxies are required for robust assessment of past hydroclimatic conditions. Currently, estimates of drought variability over the past several thousand years are based largely on tree-ring records. We produced a 1,500-y record of winter precipitation in the Pacific Northwest using a physical model-based analysis of lake sediment oxygen isotope data. Our results indicate that during the Medieval Climate Anomaly (MCA) (900–1300 AD) the Pacific Northwest experienced exceptional wetness in winter and that during the Little Ice Age (LIA) (1450–1850 AD) conditions were drier, contrasting with hydroclimatic anomalies in the desert Southwest and consistent with climate dynamics related to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). These findings are somewhat discordant with drought records from tree rings, suggesting that differences in seasonal sensitivity between the two proxies allow a more compete understanding of the climate system and likely explain disparities in inferred climate trends over centennial timescales.
-
Data deposition: Precipitation reconstruction data are available for download at the NCDC/NOAA Paleoclimate data archive website (www.ncdc.noaa.gov/paleo).
-
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1201083109/-/DCSupplemental.
david brown says:
July 5, 2012 at 5:27 pm
Johanus, the heat wave has been in the media but the reasons for it are ignored. and America is a bigger polluter than China ”per head of population”.
The phrase you wanted was “per capita.” The US may produce more CO2 per capita than China — and CO2 is not pollution, despite what you may believe — but 16 of the 20 most-polluted cities in the world are in China…
http://www.asiaone.com/Health/News/Story/A1Story20071102-33814.html
…40% of it’s rivers are too polluted to drink safely, with half of those in Category V (too toxic to touch), and
http://www.wantchinatimes.com/news-subclass-cnt.aspx?id=20120217000048&cid=1105&MainCatID=11
…up to 40% of its farmland is unsafe for growing crops due to cadmium, arsenic, and mercury contamination,
http://bbs.chinadaily.com.cn/thread-753470-1-1.html
Word around this part of Asia is “Don’t eat anything grown in China” — so your concern about the US producing more CO2 per capita than China is seriously misplaced.
duster ,the mwp was not warmer than today. every study confirms this . it is hardly based on”blind assertions ”. it is also irrelevant as MWP was a natural event . today we are discussing AGW. global temp at the time was cooler than today anyway . again you mention countries like greenland or england, countries in the ”northern hemisphere” ? where is your evidence for the southern hemisphere being effected ? please include sources . there are reasons for climate change it does not happen by magic, it is forced to change. what caused the MWP what was the solar output at the time? today the sun is in minimum and the planet increases in warming. so what is causing it ?. all previous warm periods had a logical explanation eg increased solar activity, a change in the earths orbit etc. present warming does not. the rise of c02 is unprecedented in speed. it can take 5000 years or more for c02 levels to raise 100 ppm when natural, not 150 years as is the case now . the speed of the rise is ”unprecedented” the fires are unprecedented in ”recorded history ”. which is no more than a few hundred years.
duster, mwp was caused by increased solar activity and decreased volcanic activity. todays warming is far different. the national academy of science studies show the warm period was not global. some parts of the world [ some south pacific regions were cooler ]
Prior temperature reconstructions tend to focus on the global average (or sometimes hemispheric average). To answer the question of the Medieval Warm Period, more than 1000 tree-ring, ice core, coral, sediment and other assorted proxy records spanning both hemispheres were used to construct a global map of temperature change over the past 1500 years (Mann 2009). The Medieval Warm Period saw warm conditions over a large part of the North Atlantic, Southern Greenland, the Eurasian Arctic, and parts of North America. In these regions, temperature appears to be warmer than the 1961–1990 baseline. In some areas, temperatures were even as warm as today. However, certain regions such as central Eurasia, northwestern North America, and the tropical Pacific are substantially cooler compared to the 1961 to 1990 average.
The evidence is unequivocal and irrefutable: The Medieval Warming Period was an extended period (hundreds of years) of extreme warmth and was global in nature. The empirical evidence and peer reviewed research supporting the unprecedented MWP is massive and diverse.
http://www.c3headlines.com/temperature-charts-historical-proxies.html
@David Brown
>there is no evidence to suggest that the MWP was warmer than today.
Then how do you explain this?
http://www2.sunysuffolk.edu/mandias/lia/vikings_during_mwp.html
This falsifies the CAGW argument, because it is the alarmists who have no conviincing evidence for their hypotheses.
Their best arugment (that increased CO2 is causing ‘runaway destruction’) is that current temps and CO2 are now both at “unprecedented” high levels. So one of them must be causing the other. “What else could it be?”
The MWP shatters this argument. It appears that Greenland was “recently” much warmer than it is now, and it didn’t destroy the Earth.
john day, MWP is irrelevant. that was a natural warming and despite what you say there is no peer reviewed published work that indicates it was warmer than today .and if it was it still proves nothing, as the reasons for it are different. eg increased solar activity, decreased volcanic activity, those two things are not factors for present warming. the sun is in minimum and volcanic activity is not decreasing. there is as i have mentioned before no evidence that MWP was global. some parts of the planet were actually cooler then.[ tropical pacific ] natural c02 was also absorbed by the sinks as it was part of the carbon cycle. manmade c02 is not absorbed by the sinks thats why it is accumulating at such a rapid rate. sunny suffolk only proves that a ”northern hemisphere ” country had increased warming. and that is not a ”global” observation
john day. that site you used as a source [ sunny suffolk] is actually pro AGW. you should have read all of it. c3 editor.MWP was warm enough to grow grapes and generally have a pleasant life that is not ”unprecedented warming ”. unprecedented warming would have meant drought and no grapes. grapes thrive in a certain temp range. you also cannot mention one southern hemisphere country where temp increased. all your evidence is for the northern hemisphere only. a study by the national academy of science, covering 2000 years of climate confirmed that some areas were cooler during MWP. that means the warming was not global
bill tuttle, in regards to c02 being a pollution. some countries classify it as such. it depends how you define pollution. if c02 is causing climate change and that change is damaging the environment [ and things like flood damage the environment ] then it could be classified as pollution. per capita, per head of population it makes no difference? america is still a massive polluter. [ using the dictionary definition of a pollutant ]. what you say about chinese rivers etc is true. but we not discussing heavy metals or arsenic. we are discussing c02
bill tuttle, per capita per head mean the same thing. using that as a guage, america is a bigger emitter of c02
david brown says: america is a bigger emitter of co2
Using that same logic, then Luxembourg and Monaco are the biggest producers of wealth (“GDP”) in the world:
http://en.wikipedia.org/wiki/List_of_countries_by_GDP_%28nominal%29_per_capita
At least you agree with us that the strongest argument for CAGW is based mainly on “unprecedented-ness”. Where’s the ‘convincing proof’ that CO2 is causing catastrophes?
per head of population america is a bigger emitter of c02 than china johanus. america is a massive emitter of c02 even if you ignore china altogether. your analogy is a poor one as monaco and luxembourg have tiny economies regardless. no. the strongest argument for agw is the fact that there is no other explanation for present warming.. if c02 is responsible for climate change, and climate change is damaging the environment, that means using the dictionary definition of the word pollution, then c02 is a pollutant. the present heat wave in america is a catastrophe. flooding in australia was a catastrophe. how many more examples do you need?
@David brown
> … how many more examples do you need?
I happen to believe that all frogs come from rain drops. I have very convincing proof of this.
Every time it rains I start to hear frogs croaking in my yard. When the rain stops the frogs’ croaking stops soon afterward. I even found a frog in my rain spout once (unprecedented!).
The more it rains the stronger becomes my belief in froggy-hydro-genesis.
What else could it be? How many more examples do you need?
Do you know what “confirmation bias” is? (Yes, both sides, CAGW and Skeptic, practice it).
😐
david brown says……
______________________________
David Brown ignores the evidence which show the Holocene is not only doing just fine but is gradually cooling down not warming. The Holocene has a more even temperature than any of the past four interglacials. Also the last graph of CO2 and temperature show an increase in CO2 has not effected temperature in the Holocene.
Greenland GISP Ice Core – Last 10,000 years
Antarctic Vostok Ice Core – Last 10,000 years
five interglacial temperature and CO2 data from Vostok Ice Core
David also ignore this paper showing higher temperatures in the Holocene.
Temperature and precipitation history of the Arctic
“..Solar energy reached a summer maximum (9% higher than at present) ca 11 ka ago and has been decreasing since then, primarily in response to the precession of the equinoxes. The extra energy elevated early Holocene summer temperatures throughout the Arctic 1-3° C above 20th century averages, enough to completely melt many small glaciers throughout the Arctic, although the Greenland Ice Sheet was only slightly smaller than at present… As summer solar energy decreased in the second half of the Holocene, glaciers reestablished or advanced, sea ice expanded, and the flow of warm Atlantic water into the Arctic Ocean diminished. Late Holocene cooling reached its nadir during the Little Ice Age (about 1250-1850 AD), when sun-blocking volcanic eruptions and perhaps other causes added to the orbital cooling, allowing most Arctic glaciers to reach their maximum Holocene extent…”
David you want to go all hyper on something look at the time intervals of those last four interglacials and compare it to the Holocene. Based on the end of the Younger Dryas, the Holocene this year is 11,715 years old. We are at the long end of the precession cycle at 23,000 years and we are due to head into glaciation not “Global Warming”
Lesson from the past: present insolation minimum holds potential for glacial inception (2007)
And from this link (which I suggest you read.)
This suggest we are in the “Danger Zone” for the next 4,000 years and anything that decreases the solar insolation at the earth’s surface could very well tip us into the onset of glaciation which could occur within less than two decades.
The biggest problem with these papers and the CAGW theory, is they assumes no changes in the energy from the sun received by the earth yet we know the sun is a variable star. Several scientists such as Alexander Ruzmaikin, Joan Feynman, Yuk Yung, John Eddy, Alexandre Joukoff, physicist Richard Willson, and Henrik Svensmark to name just a few are working on the problem of how the sun varies and what effect it has on climate. And then there is Dr. Nir J. Shaviv’s article The Milky Way Galaxy’s Spiral Arms and Ice-Age Epochs and the Cosmic Ray Connection That is just the outside variables and does not include , clouds, albedo, volcanoes and what ever else such as Bond Events. Bond Events are climate fluctuations occurring every ≈1,470 ± 500 years throughout the Holocene. Bond events may be the interglacial relatives of the glacial Dansgaard–Oeschger events. We are do for a Bond Event now. link
david brown says:
July 6, 2012 at 6:10 am
bill tuttle, in regards to c02 being a pollution. some countries classify it as such.
Some countries also classify ketchup — a condiment — as a vegetable. In neither instance is there any scientific reason for doing so.
it depends how you define pollution. if c02 is causing climate change and that change is damaging the environment [ and things like flood damage the environment ] then it could be classified as pollution.
Provide the proof that CO2 is responsible for climate change and natural disasters. So far, you have only made unsupported statements without providing any proof.
per capita, per head of population it makes no difference? america is still a massive polluter. [ using the dictionary definition of a pollutant ].
The dictionary defines pollution as “the contamination of air, water, or soil by substances that are harmful to living organisms.” Using that definition, China is the biggest polluter (per capita) on Earth — it has poisoned 40% of its farmland and 40% of its rivers with arsenic, cadmium, and mercury. We have problems with pollution in the US, but none of our rivers are Category V — which means the water is too toxic to even touch.
what you say about chinese rivers etc is true. but we not discussing heavy metals or arsenic. we are discussing c02
We are discussion pollution. You keep insisting that CO2 is a pollutant, “using the dictionary definition of a pollutant.” I quoted the dictionary definition (above), and in order to continue to claim CO2 is a pollutant, you have to produce some proof that it is harmful to living organisms.
david brown says:
July 6, 2012 at 9:13 am
no. the strongest argument for agw is the fact that there is no other explanation for present warming..
You need to do some research on how much the climate has fluctuated in the past and the multitude of reasons for the changes — Gail’s links (July 6, 2012 at 10:54 am) are an excellent start. The strongest arguments *against* AGW are that
1. we have been in a cooling phase for over a decade while CO2 has continued to rise and
2. none of the so-called “fingerprints” of AGW have been found — no tropospheric hot spot, no dramatic increase in the altitude of the tropopause.
I’ve lived long enough to see multiple instances of floods, droughts, wildfire seasons, blizzards, tornadoes, hurricanes, and other disasters that warmists claim are “unprecedented,” and most of them are only claiming that because they haven’t lived long enough to have seen them before…
Nick Stokes says:
July 5, 2012 at 4:05 am
“the Medieval Climate Anomaly which had been erased in previous papers Mann had been involved with. “
Hardly erased. Mann’s 2008 PNAS paper says, for example:”
Nick what about the stick? Yeah by 2008, he had to back-pedal. Are you not alerted by the change from MWP with the word warming to the MCA which “hides the incline”. Yes he’s had to accept the existence of the MWP, but he’s darn well not going to grace it with a warm name. and note he makes reference to it becoming cooler but doesn’t give any idea how severe the LIA was – one third of all Finns died, New York harbour, the Thames and the Bosphorous froze over .,,,,And, with the significant error bars on the proxies, how can he say that MWP was perhaps warmer than up to 1990 but fell short of the next decade! Give me a break if you have not sold your soul to the devil. After climategate, which changed the world, and then the egregious whitewashes and then some of the penitent, like P. Jones who acknowledged that it hasn’t warmed in a statistically significant sense since 1995. Please tell me Nick that you’re certainty of CAGW 15-20 years ago has been softened by some doubts or at least modifications in your thinking. Afterall, you weren’t aware of the cooking, cherry picking, the blackballing, the coercion, the blacklisting and forced resignations of editors and other shenanigans until climategate broke (you don’t also believe they were hacked, too, I hope). Anyway why would all this chicanery be necessary if what was going on was good robust science. History is not going to be kind to the ‘consensus’.
bill turtle, we have not been in a warming phase for the last decade. the last decade has been the warmest on record according to the world met. increased flooding, heatwaves and drought are not associated with cooling. there is also no missing hotspot. the hotspot is a sign of ”any” warming it is not specific to agw anyway. the real indicator of warming is a cooling stratosphere. that is an indication that less heat is escaping the troposphere. you mention floods, droughts, fires etc have always happened? that is true. but increased heat is usually caused by an increase in solar activity . there has been a solar minimum for 40 years. so the heat related things you mention have not been caused by increased solar activity. so what is causing them? nick stokes. saying scientific findings have been ”erazed ” is just a conspiracy theory. you must prove allegations. mann’s hockey stick has been confirmed by multiple proxy studies. conspiracy theory is not science
pollution is something that damages the environment. c02 damages the environment by changing climte
bill tuttle. the last decade has been the hottest on record according to the world met. heat waves, flooding and drought are not signs of cooling. the hotspot is also not missing. the hotspot is a sign of ”any” warming it is not specific to agw anyway. a cooling stratosphere is an indicator of a warming stratosphere. it means less heat is escaping. and guess what.? it is cooling. previous floods, heat waves etc are usually associated with increased solar activity. we have been in a solar minimum for 40 years. so there is no natural explanation for present warming
gail combs, all the periods you mention were before industrialization and have no relevance to the discussion. we are discussing agw not naturally occurring warming. we are heading into another ice age in around 9,000 years. scientists are well aware of the warming cycles after any major ice age. and they consider they do not apply to the present situation. you are skeptical of scientific data and methodology and yet you or your sources use the same methodology to produce your data. the difference is your conclusions are not endorsed by any major scientific group. from nasa to the world met, to the royal society to every academy of science on earth.. that does not necessarily mean you are wrong. but there is a very high possibility that you are
david brown says:
July 6, 2012 at 5:56 pm
bill tuttle. the last decade has been the hottest on record according to the world met. heat waves, flooding and drought are not signs of cooling.
You are what Eric Hoffer termed a “True Believer” — your mind is made up, and no facts will change it. If this were the hottest decade on record and heat waves, flooding, and drought were only signs of warming, then why did they happen in the past, when it was supposedly cooler? Or are you saying that the temperature has been warming continuously for three-plus billion years?
the hotspot is also not missing. the hotspot is a sign of ”any” warming it is not specific to agw anyway.
Where is it? The AGW crowd would love to find it, and they can’t — because it’s *not there*.
a cooling stratosphere is an indicator of a warming stratosphere. it means less heat is escaping. and guess what.? it is cooling.
That is a physical impossibility. If less heat is escaping the stratosphere, it must therefore be remaining in the stratosphere, which means the stratosphere will *not* be cooling.
previous floods, heat waves etc are usually associated with increased solar activity. we have been in a solar minimum for 40 years. so there is no natural explanation for present warming
Previous floods, heat waves, etc. are usually associated with weather patterns, and the sun is only one of at least a dozen factors influencing the weather — and *all* of them are natural.
david brown says:
July 6, 2012 at 5:50 pm
pollution is something that damages the environment. c02 damages the environment by changing climte
1. Prove that CO2 changes the climate, and don’t just say “World Met says it does,” because there is no proof that it does, and don’t say, “It can’t be anything else,” because there is no proof of that, either.
2. If climate change does not damage the environment — the environment adapts to the climate. You have the odd notion that the environment is supposed to be static, and it isn’t.
david brown says:
July 6, 2012 at 5:56 pm
we have been in a solar minimum for 40 years. so there is no natural explanation for present warming
If you knew what a solar minimum was, you’d realize how funny that statement is.
Go here and learn something:
http://science.nasa.gov/science-news/science-at-nasa/2009/01apr_deepsolarminimum/
Warmer than usual summers, with lots of sunshine, and wetter than usual winters.
Sounds like a pretty good deal for growing things and humans! Bring back the global MWP, please.