Ice Core Samples and Global Weather

[Dantheman62]

Here's some interesting and informative articles on the study of ice core samples and the information they provide towards the cycles of global weather.

Here's a great article called Global Warming: A Chilling Perspective

British scientist Jane Francis, who maintains:

" What we are seeing really is just another interglacial phase within our big icehouse climate." Dismissing political calls for a global effort to reverse climate change, she said, " It's really farcical because the climate has been changing constantly... What we should do is be more aware of the fact that it is changing and that we should be ready to adapt to the change."
http://www.geocraft.com/WVFossils/ice_ages.html



Here's another one...

HIMALAYAN ICE REVEALS CLIMATE WARMING, CATASTROPHIC DROUGHT

COLUMBUS, Ohio - Ice cores drilled through a glacier more than four miles up in the Himalayan Mountains have yielded a highly detailed record of the last 1,000 years of earth's climate in the high Tibetan Plateau. Based on an analysis of the ice, both the last decade and the last 50 years were the warmest in 1,000 years.
The core also showed a clear record of at least eight major droughts caused by a failure of the South Asian Monsoon, the worst of these a catastrophic seven-year-long dry spell that cost the lives of more than 600,000 people.
http://researchnews.osu.edu/archive/monsoon.htm



And another one...

The Greenland Ice Sheet Project Two drilled to a depth of 10,000 feet (3,050 m) representing over 110,000 years of environmental record. Scientists working at the Russian Antarctic base at Vostok have recently completed drilling and obtained the longest record of climate and atmospheric history: 420,000 years!
http://www.mos.org/soti/icecore/warming.html


Total human contributions to greenhouse gases account for only about 0.28% of the "greenhouse effect" (Figure 2). Anthropogenic (man-made) carbon dioxide (CO2) comprises about 0.117% of this total, and man-made sources of other gases ( methane, nitrous oxide (NOX), other misc. gases) contributes another 0.163% .
Approximately 99.72% of the "greenhouse effect" is due to natural causes -- mostly water vapor and traces of other gases, which we can do nothing at all about. Eliminating human activity altogether would have little impact on climate change.

[Dantheman62]

Found some more stuff....

If global warming is caused by CO2 in the atmosphere then does CO2 also cause increased sun activity too?
Put another way, rising Earth temperatures and increasing CO2 may be "effects" and our own sun the "cause".

FUNFACTS about CARBON DIOXIDE
Of the 186 billion tons of CO2 that enter earth's atmosphere each year from all sources, only 6 billion tons are from human activity. Approximately 90 billion tons come from biologic activity in earth's oceans and another 90 billion tons from such sources as volcanoes and decaying land plants.

At 368 parts per million CO2 is a minor constituent of earth's atmosphere-- less than 4/100ths of 1% of all gases present. Compared to former geologic times, earth's current atmosphere is CO2- impoverished.

CO2 is odorless, colorless, and tasteless. Plants absorb CO2 and emit oxygen as a waste product. Humans and animals breathe oxygen and emit CO2 as a waste product. Carbon dioxide is a nutrient, not a pollutant, and all life-- plants and animals alike-- benefit from more of it. All life on earth is carbon-based and CO2 is an essential ingredient. When plant-growers want to stimulate plant growth, they introduce more carbon dioxide.

CO2 that goes into the atmosphere does not stay there but is continually recycled by terrestrial plant life and earth's oceans-- the great retirement home for most terrestrial carbon dioxide.

If we are in a global warming crisis today, even the most aggressive and costly proposals for limiting industrial carbon dioxide emissions would have a negligible effect on global climate!

[Jack]

Hey dan

You might find this interesting ;



In the early part of this century the famous Beresovka mammoth carcass was discovered in Siberia. Nearly intact, the animal was found buried in silty gravel sitting in the upright position. The mammoth had a broken foreleg, evidently caused by a fall from a nearby cliff 10,000 years ago. The remains of its stomach were intact and there were grasses and buttercups lodged between its teeth. The flesh was still edible, but reportedly not tasty.

No one has ever satisfactorily explained how the Beresovka mammoth and other animals found frozen in the subarctic could have been frozen before being consumed by predators of the time. Some have proposed a sudden change in climate, but this hardly seems a likely explanation. The scientist who uncovered the Beresovka mammoth conjectured that the animal fell into a snow-filled ravine that protected the body until it was perhaps covered by gravel during a summer flood.


Theory # 1

Huge herds of mammoths used t roam the tundra feeding off the grasses, reeds, and other plants that still cover the land in summer. Every now and then one of them would get trapped in ice or would fall to its death down a crevasse in a glacier, there the carcass would freeze and be preserved almost unchanged forever.

Problems with Theory #1

To begin with the carcasses were found in the wrong places. Vast areas of the Arctic are covered with ice, but most of the tundra is composed of soil, sand, river silt, and loam bound by frozen water. The frozen mammoths were discovered not in the ice but in the silt layers.

Furthermore, during the relevant period, there were no glaciers in Siberia except in the upper reaches of the mountains where the mammoths did not graze.

Theory #2

The mammoths had fallen into rivers and had been carried downstream to the estuaries, where they were buried in the silt.

Problems with Theory # 2

The mammoths were being found in the tundra between the river valleys and not all could have drowned because many were found standing upright.

Further Research

To get to the bottom of the mystery scientists consulted experts in the deep freeze butchery industry. However instead of clearing things up they made them much more troublesome. Basically they said it was not possible to deep freeze a creature the size of a mammoth in the relative moderate temps of the arctic.

Basically if meat is frozen slowly at freezing temp crystals form in the cells of the flesh bursting the cells and dehydrating the meat. The butchers concluded no such process could have produced the deep frozen mammoth meat.

To satisfactorily freeze a side of beef takes 30 minutes at -40 degrees Fahrenheit. To deep freeze a huge living warm blooded mammoth, insulated in thick fur, they estimated that temperatures below -150 degrees would be required. Temperatures so low have never been recorded in nature, not even in the artic.

This has simply made all normal theories for the Beresovka mammoth that much more obsolete.

To add to the mystery consider the climate needed for buttercups to grow. Buttercups enjoy temperate conditions with alternation sun and rain Click here for Buttercup Climate info

These are the unalterable facts a mammoth grazing buttercup in a temperate climate all of the sudden is frozen stiff by unimaginable cold. The question is how it happened, to this day a feasible explanation has not been put forward.

Reference:

Strange Stories, Amazing Facts, Readers Digest. 1980



When taking into consideration all of the evidence so far presented it is obvious that (a. - These mammoths were flash frozen in a matter of minutes at a temperature of -150 degrees or less. This would require a catastrophic event of phenominal proportions which has not been witnessed by humankind in recent history. (b. - The baby mammoth which was found preserved in siberia had buttercups stuck in its teeth as well as buttercups and other undigested vegetation in its stomach. This indicates that the mammoth was at one moment eating in a warm temperate climate as it is only possible for buttercups to grow in this environment and in an instant was exposed to temperatures of -150 degrees. The only logical conclusion is a rapid changing of climate in the polar regions.

This phenominal find has not been expanded upon very much by 'scientists' and is hardly a topic of discussion in the public domain.

Wolly mammoths did not live in cold climates, they thrived in warm temperate climates alongside saber tooth tigers, horses, foxes etc. How is it possible that so many are found frozen in the polar regions? It would be logical to assume that the regions in the north pole were once temperate in climate and in a moment were transported to the exreme north and south poles. The most simple and logical answer is usualy the best.

[Dantheman62]

Well hmmm that's a tough one Jack!, first off I don't agree that mammoths roamed in more temperate climates, I mean why did they have all that fur or hair? Now as far as instant freeze, well I've given it alot of thought ( about 5 minutes LOL! ) Maybe the sun was blocked instantly by something and winds increased to about 2 or 3 hundred miles per hour which would make the wind chill way below zero.

Or the earth was knocked away from the sun temporarily so as to make the temperature drop instantly and if the winds increased also then again the wind chill would be way,way below zero causing instant freeze. How does that sound? And that's my two thousand and twelve cents worth, LOL!

[Jack]

Originally Posted by Dantheman62

Well hmmm that's a tough one Jack!, first off I don't agree that mammoths roamed in more temperate climates, I mean why did they have all that fur or hair?

They did have a lot of hair, well spotted BUT their hair was greasless which is an extremely rare occurance in polar climate creatures. Most animals that live in cold climates have grease glands on their skin which cause their hair to be greasy in order to insulate from the cold. The 'woolly' or, hairy mamoths lacked these glands. There are many animals who have hair without grease glands most of which live in temperate climates.


I'll finish this later :P work must be done , what with this climate change and all we could be living in frozen tundra tomorrow!

[iainl140285]

An instant freeze to that degree ... kinda reminds me of that film, The Day After Tomorrow. Freezing temperatures were sucked down from the upper atmosphere by way of tornadoes/vortexes down to the planets surface freezing everthing/everybody in an instant.

http://www.youtube.com/watch?v=iG4mwwzT8T4&NR=1

Maybe thats an example of the typical Hollywood movie, entertainment mixed in with some concealed truths ...


Peace
Iain

[burgundia]

Why haven't they found deep-frozen people or other animals, only mammoths.

[Dantheman62]

I think they've found other animals too but there wasn't to many humans around probably at that time or place, hmmm good point though! I like iainl140285's Day After Tomorrow theory best so far.

[dagon]

I expect something to that affect. think about it. if the poles shift. or the rotation slows down and speeds up. gravitational pull from the alignment, galactic center. weakening fields of the earth. heck the poles have been moving for 10+ years already. ever so slightly. true north is not true. and these affects on earthquakes and volcanoes. it all make sense to me. were ina lot of trouble. I don't see anything that is contradicting this study. looks sound to me. carved in stone all over the planet. I dont understand why this isnt main streem news. I guess we dont want marshal law. I'm a bit taken back with the thought. once one accepts this as likely. life just seems to take on another meaning. the funny part of the whole thing is I welcome it. the planet needs it. if its to be. and I find myself walking threw the market just watching all the people who don't even have a clue. and wondering if they had a choice in knowing or not. most would want to stay in the matrix. think about it. just try to bring it up in a conversation. not happening. LOL!!! even with all the tv specials on doomsday here in the states. on the history channel all week it was dooms day. prophets, ancients, biblical. the whole thing.



I want to hear from the naysayers on this. think were drinking kool aid? and if your on board. why isn't this ground crew thing taking off. lets start meeting!!! to do what Im not sure yet. but at least we could put minds together. for a fighting chance. to many on the fence. waiting for a sign. LOL!!

[Dantheman62]

Vostok Station


Nationality: Russia

Location: Vostok - an outpost if there ever was one - is located near the South Geomagnetic Pole, at the center of the East Antarctic ice sheet, where the flux in the earth's electromagnetic field is manifested.

Vostok Station

History: It was built in 1957 (IGY) and named for one of Bellinghausen's two ships, Vostok (East). The station was resupplied by semi-annual tractor-train expeditions that took a month to travel the 868 miles (1400k) from the coast.
Information:
The coldest recorded temperature on Earth, -128.6°F (-89.2°C) was measured here on July 21, 1983.
Latitude/Longitude: 78°27'51"S 106°51'57"E
Altitude: 11,484 ft (3,500 m) above sea level
Average Annual Temperature: -67°F (-55°C)
Science:
Although this is a Russian research station, scientists from all over the world conduct research here. One of the primary projects at this site, a coordinated Russian, French and American effort, is drilling an ice core through the 3,700 m thick ice sheet. This ice core contains climate records for almost half a million years before present.


Big Bang in Antarctica - Killer Crater Found Under Ice
COLUMBUS, Ohio -- Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs -- an impact that they believe caused the biggest mass extinction in Earth's history.
The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years -- the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.


Discovery Of Antarctic Subglacial Rivers May Challenge Excavation Plans
Plans to drill deep beneath the frozen wastes of the Antarctic, to investigate subglacial lakes where ancient life is thought to exist, may have to be reviewed following a discovery by a British team led by UCL (University College London) scientists at the Natural Environment Research Council (NERC)Centre for Polar Observation and Modelling (CPOM).


Two more lakes near Vostok
Scientists have discovered two more subglacial lakes, raising renewed speculation of the existance of living ecosystems below the ice.


Team probes buried Antarctic lake
On the frozen Antarctic continent, subglacial lakes are a hot spot of scientific interest, but the information they contain remains untapped.
“The ice sheet in Antarctica can be as much as 5 kilometers thick, and at the bottom point, it can be quite warm, as warm as the melting point of ice,” said Sridhar Anandakrishnan, who led a science team to the South Pole this season to learn more about one lake that rests about 16 kilometers away from the U.S. Antarctic Program station.


LINK FOR ALL THE ABOVE ARTICLES... http://www.antarcticconnection.com/a...02/index.shtml

[Dantheman62]

Lake Vostok lies in the heart of the Antarctic continent hidden beneath 4 kilometers of ice (see map). As big as Lake Ontario in North America, Lake Vostok is one of the world's biggest freshwater lakes. Lake Vostok has been covered by the vast Antarctic ice sheet for up to 25 million years. The lake was named for the Russian research station that sits above its southern tip - a place where in 1983 the temperature fell below -129°F (-89°C), the coldest ever recorded temperature on Earth. More than 145 lakes have been identified beneath the thick Antarctic ice sheet. Most of these lakes, covered between 3-4 kilometers of ice, are several kilometers long (see map). One of these lakes, Lake Vostok (left), is an order of magnitude larger than all other known lakes (slide show).

http://www.ldeo.columbia.edu/~mstuding/vostok.html

[Dantheman62]

Another great article on Lake Vostok...

http://www.wired.com/wired/archive/8.04/vostok_pr.html

[Wormhole]

Thought I'd move my post info over for you Dan.

Notes on Microparticle Concentration and Electrical Conductivity of a 700 m Ice Core from Mizuho Station, Antactic:

Published in "Annals of Glaciology 1988" - " depth of microparticle concentration, electrical conductivity and Oxygen 18 at circa 1600 BC indicates a spike in readings for all of these elements. The evidence shows that this disturbance covered this designated period, but with a huge spike at c. 1600 BC. Similar evidence from the same source article exists at 5200 BC. This period shows a less severe but similar period. The oxygen 18 profile is close to normal, but there is a viable volcanic dirt band. ...it appears to correspond to the ash band from the Byrd station core"

"Nature", November 1980 article - Hammer, Clausen and Dansgaard date a disturbance from the Camp Century core to 5470 BC +/- 120 years. "This compares to the proposed Hekla eruption which was radiocarbon dated to 5450 BC +/- 190 years. There is a appreciably high acidity signal at therse sections of the core which indicates a high level of volcanic activity" once again right at the 3600 year cycle mark.

M. Legrand and R. Delmas of the Laboratory of Glaciology - "Soluble Impurities in Four Antarctic Ice Cores over the last 30,000 years" article 1988 Annals of Glaciology - "Oxygen 18 variations and the ionic components NH = NH (sub4) and Ca (sup 2) tha H and Cl and NO (sub 3) and SO (sub 4). The time scale for each ionic component level as well as the Oxygen 18 levels stretches back 30,000 years. Spikes at 5200 BC, 8800 BC, 12,400 BC, 16,000 BC, 19,600 BC... indicate times of great geological stress."

Now interestingly enough, southern ice cores do not register the same as the northern ones do. The northern ice cores begin to register slowly with the first true spike at around 1644 BC.

It would seem that once again the Northern hemisphere is on the data base... Ice age indications due to global event? Hmmmm...

Also... The strongest spike recorded lands around 8800 BC. which includes salt water and more intense molecular solidity, as does the 12,400 BC event.


Now I was recently contacted by a person who has concurrent findings in Greece, these are core samples in fresh water lakes. Also on the findings: Events every 3600 and 1600 years.

Peace of Mind,
Worm.

[Dantheman62]

Thanks Wormhole, I'm becoming fascinated with what's going on in Antarctica. I can't wait until they drill down to Lake Vostok, if they do! They say it'll be within 5 years!, JPL is working on little sterile cryobots to go in once they drill the rest of the way. Anything else you can add to this would be great!

[Dantheman62]

Interpreting Ice Core Data


Information from ice cores helps scientists understand how earth's climate has varied over time. The Greenland Ice Sheet Project 2 (GISP2) drilled an ice core from the summit of the Greenland ice sheet all the way down to bedrock. A total of 10,116 feet (3,053 m) of ice was retrieved, taking four years to complete! This ice core records the past 110,000 years of earth's climate history and provides one of the most detailed records for the northern hemisphere.
The ice core was sampled for 42 different measurements that tell us something about the earth's temperature, solar radiation, sea level, and the chemicals in the atmosphere over time. We have taken some of the data for the past 40,000 years and presented them in graphs for you to interpret just as the scientists did.

[Dantheman62]

The radar antenna sits inside the tire tube and is pushed across the surface of the snow by a Tucker.


Preparing to drill an ice core.

Studying Ice Cores


Ice cores drilled from the ice sheet provide a sample of all the layers of snow accumulated over thousands of years, the oldest at the bottom. Choosing a site to drill from can be just as important as the core that is recovered. Many factors are considered including the shape of the underlying bedrock and the height of the ice sheet. Radar antennae are use to survey the ice sheet. They provide very accurate calculations of the depth and surface contours of the ice as well as pinpoint the location of dangerous crevasses. Once a site is selected, a drill is set up and the coring begins. Mechanical drills can penetrate up to 3 feet (1 m) at a time before being withdrawn for the core to be recovered. To reach the 200 year depth, the team will have to drill 160-230 feet (50-70 m) which will typically take about a day. There are plans to drill cores as deep as 650 feet (200 m) to get longer records. Those cores will take three to four days to drill.
Ice cores are usually about 3 inches (10 cm) in diameter. As they are brought to the surface a scientist will examine the core and attempt to place that section of core in time. Alternating bands of light and dark snow can been seen when light is shone through the ice core from behind. The light layers represent summer snow and the dark layers are winter snow. By keeping track of the individual layers they can be counted in much the same way as tree rings. More sophisticated techniques for dating ice cores are done later back in the labora tory by analyzing the concentration of oxygen atoms in the ice.
Climatic parameters such as air temperature, precipitation rate, and solar radiation can be interpreted from ice cores. By studying this record, scientists can identify the natural cycles in global warming and cooling.

[Antaletriangle]

Yeah,i think it's quite feasible that interstitial fluid pressure could remelt ice at these levels not only making the movement more fluid but creating the water to be found here.The supercooling that fauna and flora were subject to could actually originate from a large,temporary hole in the atmosphere where there'd suddenly be space temperatures @ the surface of the earth...this could well be caused by a fragmented comet impact over thousands of square miles,detonating the atmosphere in areas which could allow these sudden temperature drops?

[Dantheman62]

Towards the end of 2009, ESA's ice mission CryoSat-2 will launch. With diminishing ice cover a reality, CryoSat-2 has been designed to measure the exact rate of change in the thickness of ice floating in the oceans and ice sheets on land. This will help explain the connection between the loss of polar ice, the rise in sea levels and climate change.



CryoSat measuring 'freeboard' sea-ice

[Dantheman62]

Just another interesting bit of info. This is on Lake Baikal in Russia....

At 1,637 meters (5,370 ft), Lake Baikal is the deepest lake in the world, and the largest freshwater lake in the world by volume.

Lake Baikal was formed in an ancient rift valley and therefore, is long and crescent-shaped with a surface area (31,494 km2/12,160 sq mi), less than that of Lake Superior or Lake Victoria. Baikal is home to more than 1,700 species of plants and animals, two thirds of which can be found nowhere else in the world and was declared a UNESCO World Heritage Site in 1996.At more than 25 million years old, it is the oldest lake in the world.
A Russian mini-submarine attempting to set a record for the deepest freshwater dive on July 29, 2008, was originally reported as being successful, but a correction later emerged that reported the MIR I failed to do so, reaching a depth of only 1,580 meters.

Lake Baikal has more water than all of North America's Great Lakes combined — 23,600 cubic kilometers (5,700 cu mi), about one fifth of the total surface fresh water on the earth. However, in surface area, it is exceeded by the much shallower Great Lakes, Superior, Huron and Michigan, in North America, as well as by the relatively shallow Lake Victoria in East Africa.Known as the "Galápagos of Russia", its age and isolation have produced some of the world's richest and most unusual freshwater fauna, which is of exceptional value to evolutionary science.


Lake Baikal is in a rift valley, created by the Baikal Rift Zone, where the crust of the earth is pulling apart.

The bottom of the lake is 1,371 meters (4,500 ft) below sea level, but below this lies some 7 kilometers (4.3 mi) of sediment, placing the rift floor some 8–9 kilometers (more than 5 miles) below the surface: the deepest continental rift on Earth. In geological terms, the rift is young and active—it widens about two centimeters per year. The fault zone is also seismically active; there are hot springs in the area and notable earthquakes every few years. It drains into the Angara tributary of the Yenisei.


Its age is estimated at 25–30 million years, making it one of the most ancient lakes in geological history. It is unique among large, high-latitude lakes, in that its sediments have not been scoured by overriding continental ice sheets. U.S. and Russian studies of core sediment in the 1990s provide a detailed record of climatic variation over the past 250,000 years. Longer and deeper sediment cores are expected in the near future. Lake Baikal is furthermore the only confined fresh water lake in which direct and indirect evidence of gas hydrates exists.

Lake Baikal






http://en.wikipedia.org/wiki/Lake_Baikal



31,494 square kilometers= surface area
23,600 cubic kilometers= volume
636 kilometers= length
79 kilometers= width
1,637 meters=depth
20 million years
(in present state: 2-3 million years)= age

[Dantheman62]

New Tibetan ice cores missing A-bomb blast.

Ice cores drilled last year from the summit of a Himalayan ice field lack the distinctive radioactive signals that mark virtually every other ice core retrieved worldwide.

That missing radioactivity, originating as fallout from atmospheric nuclear tests during the 1950s and 1960s, routinely provides researchers with a benchmark against which they can gauge how much new ice has accumulated on a glacier or ice field.


In 2006, a joint U.S.-Chinese team drilled four cores from the summit of Naimona'nyi, a large glacier 6,050 meters (19,849 feet) high on the Tibetan Plateau.

The researchers routinely analyze ice cores for a host of indicators - particulates, dust, oxygen isotopes, etc. -- that can paint a picture of past climate in that region.

Scientists believe that the missing signal means that this Tibetan ice field has been shrinking at least since the A-bomb test half a century ago. If true, this could foreshadow a future when the stockpiles of freshwater will dwindle and vanish, seriously affecting the lives of more than 500 million people on the Indian subcontinent.

"There's about 12,000 cubic kilometers (2,879 cubic miles) of fresh water stored in the glaciers throughout the Himalayas - more freshwater than in Lake Superior," explained Lonnie Thompson, distinguished university professor of earth sciences at Ohio State University and a researcher with the Byrd Polar Research Center on campus.

"Those glaciers release meltwater each year and feed the rivers that support nearly a half-billion people in that region. The loss of these ice fields might eventually create critical water shortages for people who depend on glacier-fed streams."

Thompson and his colleagues worry that this massive loss of meltwater would drastically impact major Indian rivers like the Ganges, Indus and Brahmaputra that provide water for one-sixth of the world's population.


"In ice cores drilled in 2000 from Kilimanjaro's northern ice field (5890 meters high), the radioactive fallout from the 1950s atomic test was found only 1.8 meters below the surface.

"By 2006 the surface of that ice field had lost more than 2.5 meters of solid ice (and hence recorded time) - including ice containing that signal. Had we drilled those cores in 2006 rather than 2000, the radioactive horizon would be absent - like it is now on Naimona'nyi in the Himalayas," he said.

In 2002 Thompson predicted that the ice fields capping Kilimanjaro would disappear between 2015 and 2020.

"If what is happening on Naimona'nyi is characteristic of the other Himalayan glaciers, glacial meltwater will eventually dwindle with substantial consequences for a tremendous number of people," he said.

Scientists estimate that there are some 15,000 glaciers nested within the Himalayan mountain chain forming the main repository for fresh water in that part of the world. The total area of glaciers in the Tibetan Plateau is expected to shrink by 80 percent by the year 2030.

http://www.brightsurf.com/news/headl...omb_blast.html

[Antaletriangle]

The literature that i engaged in is known as a 'bible' for geolgists-i have the third edition which maybe somewhat redundant now Arthur Holmes,principles of phys. geology.
It's all about limited observational viewpoints-this applies to all sciences,especially as it's become a religion to most;meaning never stop learning but sit back,and also understand that it's as a a child wishing to know how to use and what are multi-coloured building blocks...

http://books.google.co.uk/books?id=v...um=1&ct=result


What can midges tell us about climate change? Ted Nield at the BA finds out more than he ever thought possible about the flies that bite.
Geoscientist Online 8 September 2008

Chironomidae are a family of two-winged flies (Diptera) that are closely related to mosquitoes and biting midges. However, unlike their cousins, who can be a scourge for any one taking a holiday in Scotland or elsewhere in the north of Europe, adult chironomids do not require a blood meal.

Britain boasts about 600 species of chironomids, and there are about 10,000 world-wide. The larvae of most species are aquatic, and abundant in lakes and rivers. The familiar 'blood-worms', which can occur in huge numbers in nutrient-enriched waters (because of their ability to tolerate low oxygen concentrations) are the larvae of one of the subfamilies of Chironomidae. Although they have a worm-like appearance and wriggle when they swim, they are in fact insects. A full-grown blood worm may reach 2cm long - but many species never reach more than 5mm.

Steve Brooks, an entomologist working at the Natural Histry Museum in London, told the BA: “Chironomidae are sensitive indicators of environmental change and recently have become pre-eminent in reconstructing past climate change.”
This is because the heads of chironomid larvae are well-preserved in lake sediments and can be used to identify the midge species. By taking a sediment core from a lake and sieving out the heads, which may be less than one tenth of a millimetre in size, changes in chironomid assemblages through time can be analysed and related to climatic change.

“We know from the modern distribution of chironomids that some species are typical of warm climates whereas others only occur in cold regions” said Brooks. “We can estimate the summer air temperature optimum of European chironomid species and use this information to reconstruct past summer temperatures from fossil chironomid assemblages in our lake sediment cores. By applying the chironomid-temperature inference model to modern species assemblages (collected from the surface sediments of lakes where we know the present-day mean July air temperature) we know that our 'chironomid thermometer' has an accuracy of plus or minus one degree Celsius! We also know that the chironomid larvae have developed in the lakes that are sampled so they must be responding to local climatic conditions.”

This is a distinct advantage over pollen as a climate indicator, because pollen may have been blown over long distances before it was deposited. Because chironomids are so abundant in lakes, only a few grams of mud need to be sampled to obtain enough chironomid heads for a robust temperature reconstruction. This means that the lake sediments can be sliced at fine intervals (1 cm or less) which often equates to one sample every 10 years or fewer, and provides scientists with detailed estimates of the size and rapidity of climate change in the past.

Says Brooks: “Beetles are also frequently used as climate indicators, but they are relatively rare in sediments and so kilograms of sediment are required for analysis. This means that studies at high temporal resolution are not usually possible and short-term climate oscillations may not be detected. Adult chironomids are weak fliers but they are carried by the wind so they can travel hundreds of kilometres very short amount of time and so they respond very quickly to abrupt climate change - much more quickly than trees can, for example, which may take hundreds of years to migrate across the landscape!”


Context

The quantitative evidence that chironomids provide about past climate helps to put modern climate change in context. For example, is the scale of modern global warming unprecedented, or have natural fluctuations of this kind occurred before? These chironomid-inferred temperature estimates can be used to test the reliability of global climate models by seeing how well the models perform in reconstructing past climate. Reconstructions of past climate also help provide scientists with a better understanding of climate dynamics, global climate teleconnections, feedback mechanisms and tipping points.

Brooks told the BA: “With Professor John Birks from the University of Bergen, Norway, I have developed a chironomid-mean July air temperature inference model that has been applied widely to fossil chironomid assemblages from throughout northern Europe covering the last 15,000 years - the period since the last ice age, known as the late-glacial and Holocene. We already know something of the rapidity and relative magnitude of climate change during this period from oxygen isotope analysis of the ice cores collected from Greenland. However, it can be problematic to convert these oxygen isotope records into actual temperature estimates. Also, we cannot be sure how representative the Greenland record is of the past European climate. This is where the midge-inferred temperatures from European lakes are useful.”

Chironomid-inferred summer air temperatures from lakes in northern Europe show broad similarities to the temperature trends found in Greenland ice cores. All these records show that there was rapid warming towards the end of the last ice age, which reached a peak in the early Interstadial after about 15,000 years ago. Temperatures then began a general downward decline, punctuated by two sudden short-lived cold oscillations about 13,800 and 13,000years ago. Then about 12,800 years ago ice age conditions returned to northern Europe for a period of about 1000 years. This episode is known as the Younger Dryas because of the return of tundra vegetation including the plant Dryas (the Mountain Aven).

Dryas

It is thought to have been caused by a shutdown of the Thermohaline Circulation in the north Atlantic (the Gulf Stream) due to the release of huge quantities of cold freshwater from the melting Scandinavian ice cap. The Younger Dryas came to an equally abrupt end when the Gulf Stream returned, marking start of the Holocene and the period of human expansion. Chironomid-inferred temperature estimates indicate that summer temperatures fell by about five degrees Celsius over a period of about a decade at the start of the Younger Dryas and increased at a similar rate and magnitude at the end of this period.

Chironomid-inferred temperatures for the first and second cold oscillations during the Interstadial are about 1.5 and 0.8 degrees Celsius respectively. There are subtle but consistent differences between the oxygen isotope records from Greenland and chironomid-inferred temperatures in northern Europe which suggest that the Greenland ice core record cannot be assumed to indicate late-glacial temperature trends for the whole region. North European chironomid-inferred temperature records indicate that summer temperatures declined much less strongly during the Interstadial than those inferred from the Greenland ice cores. Also, it appears that the first Interstadial cold oscillation was cooler than the second - which is the reverse of what is indicated in the Greenland ice core records.

The consistency of north European chironomid-inferred temperature reconstructions is well-illustrated by a recent study carried out by researchers at the Natural History Museum and the Universities of Liverpool and Exeter on five lakes in the English Lake District. At all five sites, similar summer temperature trends and estimates were inferred by chironomid analysis, and these estimates also agreed closely with climate inferences derived from oxygen isotope analysis of the carbonate sediments in the lakes that were studied. While showing remarkable consistency between each other and other northern European estimates there were consistent differences in details between these records and the oxygen isotope records from Greenland.

Recently, chironomid-inferred summer air temperatures have been used to infer, for the first time, precipitation gradients in Scotland at the end of the Younger Dryas. The equilibrium-line altitude of glaciers is determined by the balance between the amount of winter precipitation and the summer temperature. If the summer temperatures and the maximum extent of the Younger Dryas glacial moraines are known, then the winter precipitation can be calculated.

Chironomid assemblages have recently been analysed from sediment cores taken from a lake in the Cairngorms and a lake on the Isle of Skye and temperatures for the late-glacial were estimated. The equilibrium line altitudes of Younger Dryas terminal moraines from nearby sites were calculated and these data were used to estimate winter precipitation. This study showed that winter precipitation was similar to modern values in the eastern Highlands but about 400mm per year higher in the Western Isles of Scotland at the end of the Younger Dryas than today and that the west-east precipitation gradient was also greater at that time than today.

Chironomid analysis has also been used recently for the first time in Europe to estimate temperatures from periods before the late-glacial. Until now temperature estimates from these earlier periods were only available from beetle analysis. A recent study of midges from a lake sampled in northern Finland, which contained sediments dating to the height of last ice age about 50,000 years ago, revealed that summer temperatures at that time were about the same as they are today.

Despite this, the surrounding vegetation was typical of arctic tundra, even though it would have been warm enough to support birch and pine forest. Presumably the warm period did not last long enough for trees to migrate into the area from further south. These results indicate that northern Scandinavia was not continually covered in ice during the last ice age but that the ice sheet fluctuated in response to climatic oscillations.

Future midge research

Brooks told the BA that past climate changes in Russia are relatively poorly known at present, and no chironomid-inferred temperature estimates are currently available. To address this, a new project is currently underway to develop a chironomid-temperature inference model for arctic Russia. Current modern chironomid distributional data has been assembled from over 100 lakes from the north Urals, the Putoran Plateau, Yakutia and the Lena River delta, and the relationship with summer temperature has been used to create a chironomid-temperature inference model for the region.

The model has been used to reconstruct summer temperatures during the late Holocene from three lakes on the Putoran Plateau. The study has confirmed the results of climate models, which suggest that there has been little increase in summer temperatures during this period. However, recent significant changes in the chironomid assemblages suggest a response to increased lake productivity - which may be a result of spring ice melt occurring earlier in the year.


Conclusion

Analysis of chironomid midges preserved in lake sediments can produce low error summer temperature estimates at high temporal resolution over tens of thousands of years, and are one of the best indicators of past climate change.

Comparison of midge-inferred temperature trends with those from the Greenland ice cores show that, although there are similarities in the records, the ice core record does not provide an accurate summary of climate change in northern Europe. These midge-inferred temperature estimates, when used in combination with evidence from glaciers, can also provide information on past changes in rainfall.

Analysis of midges in arctic Russia has confirmed evidence that the high artic has already been seriously impacted by modern climate change. Midge-inferred temperature estimates from ice age lake sediments has revealed that even in northern Finland there were periods when temperatures were similar today and the ice retreated.

Midge-inferred temperature estimates, when used in combination with evidence from glaciers, can also provide information on past changes in rainfall. Analysis of midges in arctic Russia has confirmed evidence that the high artic has already been seriously impacted by modern climate change. Midge-inferred temperature estimates from ice age lake sediments has revealed that even in northern Finland there were periods when temperatures were similar today and the ice retreated

http://www.dur.ac.uk/geochem.www/group/arthurholmes.htm


Arthur Holmes (January 14, 1890 – September 20, 1965) was a British geologist. As a child he lived in Low Fell, Gateshead and attended the Gateshead Higher Grade School which later became Gateshead Grammar School[1]

He performed the first uranium-lead radiometric dating specifically designed to measure the age of a rock during his undergraduate studies. His result was 370 mya for a Devonian rock from Norway. He graduated in 1910, and the result was published 1911,[2] after he had already travelled to Mozambique for six months to prospect for minerals. He contracted blackwater fever and malaria so severe that an obituary was telegraphed back to Britain. However, he immediately left for home and recovered, and, because of this managed to avoid military service during World War I.

He joined the staff at Imperial College, where he pursued doctoral studies, obtaining a PhD in 1917.

He then took a job with an oil company in Burma, but the company went bankrupt and he had to return to England penniless in 1924. To make matters worse, his son had died of dysentery in Burma. He then became Professor of geology at the University of Durham, but moved on to the University of Edinburgh later in his career (1943), retiring in 1956.

He greatly furthered the newly created discipline of geochronology and published the world renowned book The Age of the Earth in 1913 in which he estimated the Earth's age to be 1.6 billion years.

He championed the theory of continental drift, even when he was in a small minority. He proposed that Earth's mantle contained convection cells that dissipated radioactive heat and moved the crust at the surface. His second famous book Principles of Physical Geology was published in 1944, which concludes with a chapter about continental drift. His later measurements of the age of the Earth (4,500 +/- 100 Ma) were based on measurements of the relative abundance of uranium isotopes by Alfred O. C. Nier.

He won the Wollaston Medal in 1956 and the Penrose Medal in the same year. The Arthur Holmes Medal of the European Geosciences Union is named after him.

A crater on Mars was named in his honour.

The Durham University Department of Earth Sciences' Arthur Holmes Isotope Geology Laboratory is named after him, as is the students' Geology society.