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Most reversals are estimated to take between 1,000 and 10,000 years. The latest one, the Brunhes–Matuyama reversal, occurred 780,000 years ago. Brief disruptions that do not result in reversal are called geomagnetic excursions.
[...]an excursion does not permanently change the large scale orientation of the field, but rather represents a dramatic, typically short-lived decrease in field intensity[...]
[...]There is evidence that glaciations (ice-ages) are an effect of geomagnetic excursions.
Originally posted by mc_squared
reply to post by jdub297
Polar Ice is melting faster than expected
Glaciers are melting faster than expected
Sea level rise may exceed worst expectations
Migrations are happening MUCH faster than before
This past year, … between last summer and this one, global sea level actually fell by about a quarter of an inch, or half a centimeter.
A WARNING that climate change will melt most of the Himalayan glaciers by 2035 is likely to be retracted after a series of scientific blunders by the United Nations body that issued it.
The scientists behind the warning have admitted that it was based on a news story in the New Scientist, a popular science journal, published eight years before the IPCC's 2007 report. It has also emerged that the New Scientist report was itself based on a short telephone interview with Syed Hasnain. Hasnain has since admitted that the claim was "speculation" and was not supported by any formal research.
In a new research, scientists in India and China have determined that glaciers in the Himalayas and the Tibetan plateau … are melting faster because of the effects of clouds of soot from diesel fumes and wood fires (NOT CO2).
I note all denialist talking points mention 'belief' and 'faith' in AGW as if it were 'faith based'.
Yes, there are millions of studies that have been done on AGW since the 1970's by scientists worldwide.
[AGW] is currently a theory that approximately 98% of the worlds scientists have signed on to.
All of them come to the same inescapable conclusion.
One of those sets of data and modeling studies published in 1998 by the IPCC caused me to move myself and family to a part of the US less likely to suffer disastrous weather effects
What about federally-funded AGW prophet Mark Serreze, of the US National Snow and Ice Data Center, who predicted the complete loss of polar ice in 2008?
One of the last comments to my “100 years of warming” post suggested that the GISP2 “present” followed a common paleoclimate convention and was actually 1950. This would make 95 years BP 1855 — a full 155 years ago, long before any other global temperature record shows any modern warming. In order to make absolutely sure of my dates, I emailed Richard Alley, and he confirmed that the GISP2 “present” is 1950, and that the most recent temperature in the GISP2 series is therefore 1855.
Once again you are completely distorting the info you provide and blowing it entirely out of proportion, therefore misleading the ATS readership. So there are two options here:
1. Either you are careless and have an inexcuseably poor comprehension of the subject matter being discussed (considering how much you constantly seek to eviscerate it).
2. You are knowingly and willfully distorting the information you present to support an agenda, and simply hoping no one will actually check ....
So which one is it?
Please explain yourself. It's been made clear there is a mod closely watching our behaviour in this thread, so I am holding you accountable for yours.
Originally posted by mc_squared
Wow. Grasp at straws much?
Oceanic Influences on Recent Continental Warming
GILBERT P. COMPO
PRASHANT D. SARDESHMUKH
Climate Diagnostics Center,
Cooperative Institute for Research in Environmental Sciences,
University of Colorado, and
Physical Sciences Division, Earth System Research Laboratory,
National Oceanic and Atmospheric Administration
325 Broadway R/PSD1
Boulder CO 80305-3328
Compo, G.P., and P.D. Sardeshmukh, 2008: Oceanic influences on recent continental warming. Climate
Dynamics, doi: 10.1007/s00382-008-0448-9.
This article is published by Springer-Verlag. This author-created version is distributed courtesy of Springer-Verlag.
The original publication is available from www.springerlink.com at
Evidence is presented that the recent worldwide land warming has occurred largely in response to a worldwide warming of the oceans rather than as a direct response to increasing greenhouse gases (GHGs) over land.
Atmospheric model simulations of the last half-century with prescribed observed ocean temperature changes, but without prescribed GHG changes, account for most of the land warming. The oceanic influence has occurred through hydrodynamic-radiative teleconnections, primarily by moistening and warming the air over land and increasing the downward longwave radiation at the surface. The oceans may themselves have warmed from a combination of natural and anthropogenic influences.
Thousand of new volcanoes revealed beneath the waves
10:04 09 July 2007 by Catherine Brahic
For similar stories, visit the Mysteries of the Deep Sea Topic Guide
The true extent to which the ocean bed is dotted with volcanoes has been revealed by researchers who have counted 201,055 underwater cones. This is over 10 times more than have been found before.
The team estimates that in total there could be about 3 million submarine volcanoes, 39,000 of which rise more than 1000 metres over the sea bed.
"The distribution of underwater volcanoes tells us something about what is happening in the centre of the Earth," says John Hillier of the University of Cambridge in the UK. That is because they give information about the flows of hot rock in the mantle beneath. "But the problem is that we cannot see through the water to count them," he says.
Satellites can detect volcanoes that are more than 1500 m high because the mass of the submerged mountains causes gravity to pull the water in around them. This creates domes on the ocean's surface that can be several metres high and can be detected from space.
Originally posted by mc_squared
He stated that the North Pole itself might be ice-free, not the entire Arctic Ocean. There is a HUGE difference. It says right below that 2008's melting sea ice "could match" 2007's record.
Late Holocene Environmental and Hydrologic Conditions in Northwestern Florida Derived from Seasonally Resolved Profiles of δ18O and Sr/Ca of Fossil Bivalves.
Elliot, M.; de Menocal, P. B.; Linsley, B. K.; Howe, S. S.; Guilderson, T.; Quitmyer, I. R.
AA(Edinburgh University, Dept. Geology and Geophysics, West Mains Road, Edinburgh, EH9 3JW United Kingdom ; email@example.com), AB(Lamont Doherty Earth Observatory, Route 9W, Palisades, NY 10964 ; firstname.lastname@example.org), AC(University at Albany, 1400 Washington Ave, Albany, NY 12222 ; email@example.com), AD(Laurence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550 ; firstname.lastname@example.org), AE(Laurence Livermore National Laboratory, 7000 East Ave, Livermore, CA 94550 ; ), AF(Florida Museum of Natural History, Dickinson Hall, Gainesville, FL 32611 ; )
American Geophysical Union, Fall Meeting 2002, abstract #PP72A-0429
3344 Paleoclimatology, 4215 Climate and interannual variability (3309), 4227 Diurnal, seasonal, and annual cycles, 4870 Stable isotopes, 4875 Trace elements
We reconstruct environmental conditions of coastal Northwestern Florida from combined measurements of δ18O and Sr/Ca of fossil marine bivalves deposited in an archeological site during the late Holocene period. We first investigated the environmental controls of seasonally resolved records of δ18O and Sr/Ca of modern Mercenaria mercenaria and Mercenaria campesiensis collected live from five coastal sites along the east coast of North America. Seasonal profiles were obtained by sub-sampling the incremental growth layers of aragonite and were compared with in situ historical records of temperature and salinity. We show that these bivalves precipitate their shell in isotopic equilibrium with the water in which they grew and that the δ18O records are not affected by variations in growth rate. Winter growth appears to be interrupted or strongly reduced below water temperatures ranging from 7 to 18° C, depending on latitude. The annual average δ18O decreases with latitude, reflecting both the parallel trend of freshwater δ18O with latitude over the North American continent and the reduced winter growth rate. The Sr/Ca records of the 5 modern bivalves also exhibit seasonal variations can be correlated to water temperature. However, contrary to corals, the Sr/Ca ratio is considerably lower than the average sea water Sr/Ca composition and is positively correlated to the water temperature. We dated and measured the δ18O and Sr/Ca of 30 fossil M. campesiensis from an archeological site close to Cedar Key, in the Gulf of Mexico. Accelerator Mass Spectrometry 14C dates obtained for each shell show ages which cluster between 1100 to 1400 and 2300 to 2600 14C years BP corresponding approximately to two historical warm periods known as the Medieval Warm Period (~ 1300-900AD) and the Roman Warm Period (~ 250AD-200BC). The average annual and summer Sr/Ca of 4 fossil shells are higher than that of modern bivalves from the same location suggesting that annual coastal water temperatures were 3 to 4° C warmer than today. The bulk δ18O values show a marked trend towards more positive values. 24 fossil shells have bulk δ18O values 0.2\permil to 0.7\permil more positive than modern bivalves from the same location. These results suggest that the coastal waters off northwest Florida were warmer and less saline compared to today and attest of considerable differences of the regional climate and hydrological balance during the Medieval Warm Period and Roman Warm Period.
Copyright © 2007 Elsevier Ltd and INQUA All rights reserved.
Extreme Nile floods and famines in Medieval Egypt (AD 930–1500) and their climatic implications
References and further reading may be available for this article. To view references and further reading you must purchase this article.
Fekri A. Hassana,
aInstitute of Archaeology, University College London, 31-34 Gordon Square, WC1H 0PY, London, UK
Available online 7 June 2007.
Nile gauge records of variations in Nile floods from the 9th century to the 15th century AD reveal pronounced episodes of low Nile and high Nile flood discharge. Historical data reveal that this period was also characterized by the worst known famines on record. Exploratory comparisons of variations in Nile flood discharge with high-resolution data on sea surface temperature of the North Atlantic climate from three case studies suggest that rainfall at the source of the Nile was influenced by the North Atlantic Oscillation. However, there are apparently flip-flop reversals from periods when variations in Nile flood discharge are positively related to North Atlantic warming to periods where the opposite takes place. The key transitions occur atAD 900, 1010, 1070, 1180, 1350 and 1400. The putative flip-flop junctures, which require further confirmation, appear to be quite rapid and some seem to have had dramatic effects on Nile flood discharge, especially if they recurred at short intervals, characteristic of the period from the 9th to the 14th century, coincident with the so-called Medieval Warm Period. The transition from one state to the other was characterized by incidents of low, high or a succession of both low and high extreme floods. The cluster of extreme floods was detrimental causing famines and economic disasters that are unmatched over the last 2000 years.
Originally posted by mc_squared
2. You are knowingly and willfully distorting the information you present to support an agenda, and simply hoping no one will actually check your sources.
Hormes, A., Beer, J. and Schlüchter, C., 2006. A geochronological approach to understanding the role of solar activity on Holocene glacier length variability in the Swiss Alps. Geogr. Ann., 88 A (4): 281–294.
Abstract — We present a radiocarbon data set of 71 samples of wood and peat material that melted out or sheared out from underneath eight present day mid-latitude glaciers in the Central Swiss Alps. Results indicated that in the past several glaciers have been repeatedly less extensive than they were in the 1990s. The periods when glaciers had a smaller volume and shorter length persisted between 320 and 2500 years. This data set provides greater insight into glacier variability than previously possible, especially for the early and middle Holocene. The radiocarbon-dated periods defined with less extensive glaciers coincide with periods of reduced radioproduction, pointing to a connection between solar activity and glacier melting processes. Measured long-term series of glacier length variations show significant correlation with the total solar irradiance. Incoming solar irradiance and changing albedo can account for a direct forcing of the glacier mass balances. Long-term investigations of atmospheric processes that are in interaction with changing solar activity are needed in order to understand the feedback mechanisms with glacier mass balances.
On-line Publication Documentation System for Stockholm University
Full DescriptionUpdate record
Publication type: Article in journal (Reviewed scientific)
Author: Grudd, H (Department of Physical Geography and Quaternary Geology)
Title: Torneträsk tree-ring width and density ad 500–2004: a test of climatic sensitivity and a new 1500-year reconstruction of north Fennoscandian summers
In: Climate Dynamics
Publisher: Springer, Berlin / Heidelberg
Department: Department of Physical Geography and Quaternary Geology
Language: English [en]
Subject: Physical geography, Climatology
Abstract: This paper presents updated tree-ring width (TRW) and maximum density (MXD) from Torneträsk in northern Sweden, now covering the period ad 500–2004. By including data from relatively young trees for the most recent period, a previously noted decline in recent MXD is eliminated. Non-climatological growth trends in the data are removed using Regional Curve Standardization (RCS), thus producing TRW and MXD chronologies with preserved low-frequency variability. The chronologies are calibrated using local and regional instrumental climate records. A bootstrapped response function analysis using regional climate data shows that tree growth is forced by April–August temperatures and that the regression weights for MXD are much stronger than for TRW. The robustness of the reconstruction equation is verified by independent temperature data and shows that 63–64% of the instrumental inter-annual variation is captured by the tree-ring data. This is a significant improvement compared to previously published reconstructions based on tree-ring data from Torneträsk. A divergence phenomenon around ad 1800, expressed as an increase in TRW that is not paralleled by temperature and MXD, is most likely an effect of major changes in the density of the pine population at this northern tree-line site. The bias introduced by this TRW phenomenon is assessed by producing a summer temperature reconstruction based on MXD exclusively. The new data show generally higher temperature estimates than previous reconstructions based on Torneträsk tree-ring data. The late-twentieth century, however, is not exceptionally warm in the new record: On decadal-to-centennial timescales, periods around ad 750, 1000, 1400, and 1750 were equally warm, or warmer. The 200-year long warm period centered on ad 1000 was significantly warmer than the late-twentieth century (p < 0.05) and is supported by other local and regional paleoclimate data. The new tree-ring evidence from Torneträsk suggests that this “Medieval Warm Period” in northern Fennoscandia was much warmer than previously recognized.