LISTEN TO THE SCIENCE, PEOPLE!

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sat Nov 16, 2019 1:40 p

Atlantic (period), continued ...

From Wikipedia, the free encyclopedia

Fauna

The best picture of Atlantic Period fauna comes from the kitchen middens of the Ertebølle culture of Denmark and others like it.

Denmark was more of an archipelago.

Humans lived on the shorelines, exploiting waters rich in marine life, marshes teeming with birds, and forests where cervids and suids as well as numerous small species were plentiful.

The higher water levels offset the effects of the submarine toxic zone in the Baltic Sea.

It contained fish now rare there, such as the anchovy, Engraulis encrasicolus, and the three-spined stickleback, Gasterosteus aculeatus.


Also available were pike, whitefish, cod, and ling.

Three kinds of seals were found there, the ringed, harp and grey.

Mesolithic man hunted them and whales in the estuaries.

The main birds were maritime: the red-throated diver, the black-throated diver, and the gannet.

The Dalmatian pelican (Pelecanus crispus), which is now found only as far north as south-eastern Europe, has been found in Denmark.

The capercaillie, as is the case now, was found in forested areas.

In the lofty canopy could be found a continuous zone of smaller animals, such as the ubiquitous squirrel, Sciuris vulgaris.

Daubenton's bat (Myotis daubentonii) was common.

In and around the big trees hunted the wildcat, pine marten, polecat (Mustela putorius), and wolf.

The forest floor was prolific with larger browsers and rooters as well: the red deer, roe deer, and wild boar.

Not all the former plains mammals had abandoned the country.

They remained in the open forest and meadows.

These include the aurochs, ancestor of cattle, and the wild horse which, as a discovery, was something of a revelation.

The horses were not entirely hunted out, were not confined to the plains further east, and were not entirely the property of the Indo-European cultures there.

The Mesolithic Ertebølle people were hunting them in Denmark.

TO BE CONTINUED …

https://en.wikipedia.org/wiki/Atlantic_(period)

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sat Nov 16, 2019 1:40 p

Atlantic (period), concluded ...

From Wikipedia, the free encyclopedia

Human cultures

Human cultures of Northern Europe were primarily Mesolithic.

The Kongemose culture (6400–5400 BC) settled on the coastline and lake margins of Denmark.

Late in the Atlantic, Kongemose culture settlements were abandoned because of the rising water of the Littorina Sea; and the succeeding Ertebølle culture (5400–3900 BC) settled more densely on the new shorelines.


Northeastern Europe was uninhabited in the Early Atlantic.

When the Mesolithic Sertuan Culture appeared there in the Middle Atlantic, around 7000 BP, it already had pottery and was more sedentary than earlier hunter-gatherers, depending on the great abundance of wildlife.

Pottery was being used around the lower Don and Volga from about 8000 BP.

In the Late Atlantic, Sertuan culture evolved into Rudnya culture, which used pottery like that of the Narva and Dnieper-Donets cultures.

That use of pottery upsets the idea that pottery belongs to the Neolithic.

Further to the south, the Linear Pottery culture had already spread into the riverlands of Central Europe and was working a great transformation of the land.

On the steppe to the east, the Samara culture was deeply involved with large numbers of horses, but it is not yet clear in what capacity.

https://en.wikipedia.org/wiki/Atlantic_(period)

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sun Nov 17, 2019 1:40 p

Subatlantic

From Wikipedia, the free encyclopedia

The Subatlantic is the current climatic age of the Holocene epoch.

It started at about 2,500 years BP and is still ongoing.

Its average temperatures were slightly lower than during the preceding Subboreal and Atlantic.


During its course the temperature underwent several oscillations which had a strong influence on fauna and flora and thus indirectly on the evolution of human civilizations.

With intensifying industrialisation, human society started to stress the natural climatic cycles with increased greenhouse gas emissions.

History and stratigraphy

The term subatlantic was first introduced in 1889 by Rutger Sernander to differentiate it from Axel Blytt's atlantic.

It follows upon the previous subboreal.

According to Franz Firbas (1949) and Litt et al. (2001) it consists of the pollen zones IX and X.

This corresponds in the scheme of Fritz Theodor Overbeck to the pollen zones XI and XII.

In climate stratigraphy the subatlantic is usually subdivided into an older subatlantic and a younger subatlantic.

The older subatlantic corresponds to pollen zone IX (or XI in an alternate nomenclature made of more zones) characterized in central and northern Europe by beech or oak-beech forests, the younger subatlantic to pollen zone X (or XII in the alternate nomenclature made of more zones).

In eastern Germany Dietrich Franke subdivides the subatlantic into four stages (from young to old):

youngest subatlantic: 1800 until present: modern history

younger subatlantic: 1250 until 1800: High Middle Ages, Late Middle Ages, Early Modern Period

middle subatlantic: 500 until 1250: migration period and Slavic migrations

older subatlantic: 500 BC until 500 AD: pre-Roman iron age, ancient Rome and start of migration period.

TO BE CONTINUED ...

https://en.wikipedia.org/wiki/Subatlantic

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Fri Nov 22, 2019 1:40 p

SCIENTIFIC AMERICAN

"Like Oceans, Freshwater Is Also Acidifying - Rising CO2 in lakes and reservoirs may harm animals that live in those ecosystems"


By Erica Gies on January 11, 2018

Scientists have known for some time the ocean is acidifying because of climate change.

The seas’ absorption of human-generated carbon dioxide from the atmosphere is well documented, along with the harm it is causing ocean creatures like shellfish.

But what about freshwater?

Is it also soaking up atmospheric carbon?

A new paper published today in Current Biology presents some of the first evidence that the answer may be yes, but perhaps not the same way as occurs in the ocean.

In the new study researchers reported a significant increase of CO2 and a correlating pH decrease of about 0.3 in four reservoirs in Germany over 35 years.


They analyzed data collected from 1981 to 2015 by the local Ruhr region agency that monitors drinking water, and were able to document the rising carbon dioxide levels over time by factoring in changes in temperature, water density, pH, ion species distribution and total inorganic content.

A crucial reason why the study of freshwater acidification has lagged until now is because determining how atmospheric carbon affects these ecosystems requires complex modeling, and is much less clear than that occurring in oceans, according to study author Linda Weiss, an aquatic ecologist at Ruhr University Bochum in Germany.

In oceans CO2 from the atmosphere dissolves into seawater’s surface, forming carbonic acid.

Freshwater such as lakes, though, receive various sources of carbon dioxide from decomposing organic and inorganic matter swept into them, which makes it hard for scientists to distinguish between the direct effects of rising atmospheric CO2 and these other elements.


Carbon dioxide levels in lakes are often high and vary widely from lake to lake based on factors such as the type of nearby ecosystem, land use such as agriculture, sizes of the lake and watershed, amount of precipitation, and because some types of soils and rocks absorb more CO2 than others.

Levels of CO2 also shift seasonally, changing as leaves drop in fall and ice forms in winter or as animals go through their life cycles, and even daily, rising at night due to temperature changes and algae’s inability to photosynthesize at night.

All of this makes it harder to discern long-term trends.

The data set Weiss used was unusual in that it monitored these myriad factors over the 35-year period, allowing the researchers to conclude the increase in CO2 they saw in the reservoirs was indeed due to increased carbon dioxide in the atmosphere.

The primary way freshwater ecosystems absorb CO2 created by humans burning fossil fuels is likely different than what happens in oceans.

In lakes and reservoirs the extra atmospheric CO2 feeds the surrounding vegetation and the rising global temperature lengthens the growing season.

As plants in and around the lake grow larger and/or proliferate, the amount of organic carbon available when they die and the rate at which they break down in soil increases.


Precipitation then washes it into lakes and other freshwater systems.

Although some lakes can also absorb CO2 at their surfaces similar to the way oceans do, the increases in these other sources of organic and inorganic carbon are likely the dominant factor, says Scott Higgins, a research scientist at the International Institute for Sustainable Development’s Experimental Lakes Area, a natural laboratory of 58 small lakes in Ontario.

In fact, some lakes have more CO2 than the atmosphere, so they release CO2 from the water into the air, he says.

For their study, Weiss and her team also documented the impacts of higher CO2 levels on freshwater crustaceans at the bottom of the food web — specifically, two species of Daphnia, also known as water fleas.

Multiple studies have shown increased CO2 makes it more difficult for ocean animals to form shells as well as dulls their senses, making them more vulnerable to predators.

A few studies have shown similar impacts on freshwater species in the lab.

But Daphnias, Weiss’s critters of interest, had not been studied.

When Daphnias sense predators, they raise a helmet and deploy spikes, called “neckteeth,” to protect themselves.

To test how rising CO2 might affect their defense mechanism, Weiss exposed stock Daphnias in the lab to levels of CO2 ranging from just above the maximum level seen in global freshwater to about 60 percent more than that maximum, to mimic a worst-case scenario.

The researchers found that when exposed to higher CO2 levels, the critters were less able to sense predators and deploy their defenses.

Weiss says she used lab animals because they are well studied: “We know what they do or what they’re supposed to do.”

But Higgins notes that could create misleading results: The animals Weiss tested had never been exposed to such high CO2 concentrations before.

That is likely different than the experiences of wild animals, who have to adapt to the regularly changing carbon dioxide levels of lakes and reservoirs from season to season and throughout the day.

“Over time, lakes are experiencing quite variable CO2 concentrations, and all the biota that live in them are, too,” he says.


Although still unknown, it may be that living in such complex water chemistry will ultimately help freshwater plants and animals adapt to the planet’s rising CO2 levels.

ABOUT THE AUTHOR(S)

Erica Gies


Erica Gies writes about science and the environment from Victoria, British Columbia, and San Francisco. Her work appears in the New York Times, the Guardian, the Economist, and elsewhere. She is working on a book that investigates water's past so we can adapt to the future by collaborating with nature.

https://www.scientificamerican.com/arti ... cidifying/

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Fri Nov 22, 2019 1:40 p

From CLIMATE, HISTORY AND THE MODERN WORLD, Second Edition by H.H. Lamb:

Average temperatures over December, January and February in the seven coldest and seven mildest winters in central England between 1659 and 1979 (long-term average for winter 1850–1950 4.0 °C)

Winter

1683–4 = -1.2°C

1739–40 = -0.4°C

1962–3 = -0.3°C

1813–14 = +0.4°C

1794–5 - +0.4°C

1694–5 - +0.7°C

1878–9 - +0.7°C

Winter

1868–9 = 6.8°C

1833–4 = 6.5°C

1974–5 = 6.3°C

1685–6 = 6.3°C

1795–6 = 6.2°C

1733–4 = 6.1°C

1934–5 = 6.1°C

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Fri Nov 22, 2019 1:40 p

From CLIMATE, HISTORY AND THE MODERN WORLD, Second Edition by H.H. Lamb:

Average temperatures over June, July and August in the fourteen hottest and fifteen coldest summers in central England between 1659 and 1979 (long-term average for summer 1850–1950 15.2 °C)

Summer

1826 = 17.6°C

1976 = 17.5°C

1846 = 17.1°C

1781 = 17.0°C

1911 = 17.0°C

1933 = 17.0°C

1947 = 17.0°C

1868 = 16.9°C

1899 = 16.9°C

1676 = 16.8°C

1975 = 16.8°C

1666 = 16.7°C

1719 = 16.7°C

1762 = 16.7°C

Summer

1725 = 13.1°C

1695 = 13.2°C

1816 = 13.4°C

1860 = 13.5°C

1823 = 13.6°C

1674 = 13.7°C

1675 = 13.7°C

1694 = 13.7°C

1888 = 13.7°C

1922 = 13.7°C

1812 = 13.8°C

1862 = 13.8°C

1698 = 14.0°C

1890 = 14.0°C

1920 = 14.0°C

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sat Dec 07, 2019 1:40 p

PennState

Lesson 7: Climates of Africa - Forming of the Sahara Desert


Precipitation and the Inter Tropical Convergence Zone (ITCZ)

The most important component of climate is precipitation, because rainfall provides water for survival.

Equatorial regions have extremely regular annual and inter-annual (short-term and long-term) patterns of rainfall.

These regions include the rain forest areas of Cote d'Ivoire, Ghana, Togo, Cameroon, the Central African Republic, and parts of both the Congo and the Democratic Republic of the Congo.

These regions have between 8 and 12 months where rainfall is >50 mm/month and as many as 200 days of precipitation each year, making the equatorial zone the wettest on the planet.

The equatorial region has no real dry season and is constantly hot and humid.

This idea should sound familiar to you, because the White Nile starts in the equatorial region, and it does not have a major flood season.

As distance from the equator increases, the duration, amount and reliability of precipitation all decrease.

As a result, agricultural enterprises of any type become a riskier business as one moves away from the equator.


The extreme, of course, is the Sahara desert in northern Africa.

So what causes the rain to fall at the equator but not in the higher latitudes?

To answer that question we need to look at the movement of air around the Earth.

On a large scale, there are few air masses which shape the rainfall characteristics of tropical Africa.

Sub-Saharan Africa (excluding the East African coast) gets its precipitation from tropical moist oceanic air that moves from the Atlantic and Indian Oceans toward an equatorial low pressure zone.

This area is the intertropical convergence zone (ITCZ).


The ITCZ is also called the "climate equator" — it lies near the geographic equator, and divides the global air circulation patterns into two mirror images to the north and south.

The ITCZ is an area of low atmospheric pressure that forms where the Northeast Trade Winds meet the Southeast Trade Winds near (actually just north of) the earth's equator.

As these winds converge, moist air is forced upward, forming one portion of the Hadley cell.

The air cools and rises, causing water vapor to be "squeezed" out as rain, resulting in a band of heavy precipitation around the globe.

Air that rises along the ITCZ moves away from the equator and sinks in the subtropics at the Horse Latitudes, rounding out the Hadley Circulation.


This reliable circulation feeds the lush rain forests of central Africa, and also defines the limits of the Sahara desert.

The ITCZ has been called the doldrums by sailors because there is essentially no horizontal air movement, that is, no wind (the air simply rises).

In the US, we are interested in the ITCZ primarily because, under certain circumstances, tropical depressions moving along the ITCZ intensify to hurricanes.

The position of the ITCZ varies predictably throughout the year.

Although it remains near the equator, the ITCZ moves farther north or south over land than over the oceans because it is drawn toward areas of the warmest surface temperatures.


The location of the ITCZ can vary as much as 40° to 45° of latitude north or south of the equator on land.

It moves toward the Southern Hemisphere from September through February and reverses direction in preparation for Northern Hemisphere Summer.

The ITCZ is less mobile over the ocean, although there is one exception: during an El Nino event the ITCZ is deflected toward the unusually warm sea surface temperatures in the tropical Pacific.

Thus the position and migration of the ITCZ are important in defining the Earth's climate on a global scale.

So how does it work in Africa?

The ITCZ migrates latitudinally on a seasonal basis.

In July, when the sun is over the Tropic of Cancer, the ITCZ reaches its northernmost position at about 15°N; in January it reaches ~5° S when the sun is over the Tropic of Capricorn.

The most important consequence of this shifting is the annual alteration of wet and dry seasons in tropical Africa.

Areas near the equator in western and southern Africa have a single intense rainy season from July to September.

In eastern Africa (S. Ethiopia to central Tanzania), however, there are two rainy seasons.

The ITCZ moves northward over this region between February and May, and southward again between October and December.

Since the distance covered by the ITCZ is quite large in this part of the continent, the rainy seasons are less intense than those of western Africa.

That is, the ITCZ dumps the same amount of rain in the east as it does in the west, but that rain gets distributed over a larger area in the east because of the greater movement of the weather system.

The arid and semi-arid regions of Africa (Sahara and Sahel) lie north of about 10°N, near the northern limit of the ITCZ, and receive one rainy season with very little precipitation.

Farther to the north, along the Mediterranean Sea coast, the climate is not affected directly by the ITCZ and rain falls in the winter.

https://courseware.e-education.psu.edu/ ... 07/03.html

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sat Dec 07, 2019 1:40 p

PennState

Lesson 7: Climates of Africa - Forming of the Sahara Desert


Modern Dry Phase

The time period between 5500 and 3500 BC was one of tremendous climate change - all of it toward dryer conditions.

During this transformation, the grass and scrub vanished, the game animals migrated, and the hunters and (eventually) cattlemen who were abundant around the many lakes of the region abandoned their lifestyle and took to a combination of (a) nomadic raiding and (b) settling along the Nile valley.

This climatological change marks the start of centralized residential civilization.


We have great records of the changes in both climate and life style preserved in rock art from the modern Sahara.

This site is where much of the art has been found; it represents the early home of peoples who settled Egypt.

Slideshow image - Contact your instructor if you are unable to see or interpret this graphic.

The Bubalus Period (5500-3500 BC) is named for art that shows animals that later became extinct in the area, including the buffalo (Bubalus antiquus), elephant, rhino, and hippo.

Men are shown armed with clubs, throwing sticks — but never spears.

This giraffe was carved during the Bubalus period on a rock face in Niger.

The presence of this intricate carving tells us more than simply indicating the presence of giraffe in what is now an arid region.

For a group of people to create artwork, they must have enough food.

If food is scarce then everybody spends their time finding and preparing food, not carving images of animals into rock.

And if you have ever tried to carve anything out of granite, you will know that these artists spent a lot of time working on their images.

Between 3500-2000 BC the life style in this region (the modern Sahara; we haven't settled in the Nile valley yet) changed to reflect a fully pastoral economy.

That means we see images of cattle and rams, indicating herding activities, rather than only buffalo, giraffe and other game animals.

We also find pottery, bows and arrows.

The domestication of sheep and goats spread from the Sahara to Khartoum in the early 5th millennium, or about 4500 BC.

We'll talk about the arrival of the horse in more detail soon, in the context of the Egyptians, but I wanted to close the circle on rock art.

The horse was apparently introduced about 1200 BC by people from Crete, who came as allies of the Libyans and hence enemies of the Egyptians.

There were other rivers during the Holocene Wet Phase as well, not just the Nile.

The image below shows Wadi Howar, a huge tributary to the Nile that was not known by modern peoples until this space shuttle image was taken about a decade ago.

Since then researchers have visited sites along the paleo-river and discovered ample evidence of human habitation.

Wadi Howar was 2700 km long, and it flowed from about 9500-4500 years ago, linking together a very richly settled area of lakes and springs.

It was just one of several such large tributaries that formed a trans-continental drainage system that has long since disappeared.

These images show dramatically the evidence for climate change recorded in the artwork and artifacts of the desert.

Course Authors: Dr. Tanya Furman, Associate Professor of Geosciences, and Dr. Laura Guertin, Assistant Professor of Earth Science.

This courseware module is part of Penn State's College of Earth and Mineral Sciences' OER Initiative.

https://courseware.e-education.psu.edu/ ... 07/08.html

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sat Dec 07, 2019 1:40 p

PennState

Lesson 7: Climates of Africa - Forming of the Sahara Desert


Deserts and Oases

First, we're going to visit the modern Sahara desert, and then explore the long-term changes in climate that caused it to form.

The Sahara today receives less than 2 inches of rain each year.

Yet it is home to over 4 million people, who spend all or a large part of their lives within the desert, tending camels, goats, sheep and sometimes cattle.

Some desert peoples mine salt as well, and transport it across trans-Saharan trade routes that go back thousands of years.

So - how do people live in the desert?

They need water.

There are oases scattered throughout the desert, and though their quality and appearance varies tremendously, they provide the bulk of water for people and animals in this region.

This particular oasis is a small clear pond in an area of low topography.

Others, as we will see, are formed in and around ancient rivers that no longer flow.

Most of the romanticized cities in West Africa are in fact Sahelian oases: Timbuktu (Tombouctou), Agadez, Bilma, Bamako, Tamanrasset, and many others.

The water in these oases has been dated in many places, and it is generally between 20,000-30,000 years old.

That is, the water people drink today in places like Libya, Algeria, Tunisia, and throughout the Sahara is incredibly old.

It represents rain that fell in such great quantities that it seeped into the soil and then deeper into porous bed rock, and has stayed there for tens of thousands of years.

It represents a very obvious non-renewable resource.


As you can see on the map, the oases are located in places where the modern rainfall is clearly insufficient to provide adequate drinking water.

So we must be talking about climate change.

There was a time when the Sahara was immensely rainy, and now it is not.

We care because the development of Egyptian civilization and settlement in the Nile Delta was driven by this climate change.

We also care because this huge change in climate was not caused by human activity.


Course Authors: Dr. Tanya Furman, Associate Professor of Geosciences, and Dr. Laura Guertin, Assistant Professor of Earth Science.

This courseware module is part of Penn State's College of Earth and Mineral Sciences' OER Initiative.

https://courseware.e-education.psu.edu/ ... 07/04.html

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Re: LISTEN TO THE SCIENCE, PEOPLE!

Post by thelivyjr » Sat Dec 14, 2019 1:40 p

Roman Warm Period (Europe) -- Summary

Climate alarmists contend that the degree of global warmth over latter part of the 20th century was greater than it has been at any other time over the past one to two millennia.

Why?

Because this contention helps them sell their claim that the "unprecedented" temperatures of the past few decades were CO2-induced.

Hence, they cannot stomach the thought that the Medieval Warm Period of a thousand years ago could have been just as warm as, or even warmer than, it has been recently, especially since there was so much less CO2 in the air a thousand years ago than there is now.


Likewise, they are equally loath to admit that the temperatures of the Roman Warm Period of two thousand years ago may also have rivaled, or exceeded, those of the recent past, since atmospheric CO2 concentrations at that still earlier time were also much lower than they are today.

As a result, climate alarmists rarely even speak of the Roman Warm Period, as they are happy to let sleeping dogs lie.

In addition, they refuse to accept the possibility that these two prior warm periods were global in extent, claiming instead, with respect to the Medieval Warm Period, that it was a purely local phenomenon restricted to lands that surround the North Atlantic Ocean.

In another part of our Subject Index we explore these contentions as they apply to the Medieval Warm Period.

In this Summary, we explore them as they pertain to the Roman Warm Period, beginning with the part of the planet where climate alarmists are willing to acknowledge the Medieval Warm Period's existence, but not its magnitude, i.e., Europe.

We begin this discussion by noting that the studies of Olafsdottir et al. (2001) and Jiang et al. (2002) document the existence of relatively benign weather conditions in Iceland and its oceanic environs up to about 2500 ± 200 years ago (the "beginning of the end" of the Roman Warm Period), after which their data depict the region gradually descending into what has come to be known as the Dark Ages Cold Period.

The first of these research teams also describes the concurrent long-term cooling-induced decline in vegetative productivity on Iceland, which was actually reversed for about four centuries during the Medieval Warm Period but then declined to what they describe as "an unprecedented low" during the Little Ice Age that lasted from about AD 1300 to 1900.

In like manner, Jiang et al.'s data, obtained from the seabed of the north Icelandic shelf, depict a similar post-Roman Warm Period decline in summer sea surface temperature, which exhibited a dramatic increase that peaked around AD 1150 after having risen more than 1°C above the line describing the long-term downward trend.

Thereafter, however, the temperature fell rapidly, by approximately 2.2°C, as the depths of the Little Ice Age were encountered, after which modern warming overcomes some of the dramatic cooling but cannot return the region to the pinnacle of Roman Warm Period warmth.

Further east in Ireland, McDermott et al. (2001) derived a similar picture of post-Roman Warm Period cooling based on ð18O data derived from a stalagmite.

Here, however, the initial climatic deterioration did not begin until about 2000 years ago.

Then, Berglund (2003) documented what he called a great "retreat of agriculture" throughout northwest continental Europe that was coincident with the declining temperature, based on assessments of "insolation, glacier activity, lake and sea levels, bog growth, tree line, and tree growth."

Contemporaneously, in northern Swedish Lapland, Grudd et al. (2002) developed a 7400-year history of summer mean temperature based on tree-ring widths obtained from 880 living, dead and subfossil northern Swedish pines.

The most dependable portion of the record, based upon the number of trees that were sampled, consists of the last two millennia, which the researchers say "display features of century-timescale climatic variation known from other proxy and historical sources, including a warm 'Roman' period in the first centuries AD and a generally cold 'Dark Ages' climate from about AD 500 to about AD 900."

They also note that "the warm period around AD 1000 may correspond to a so-called 'Mediaeval Warm Period', known from a variety of historical sources and other proxy records."

Lastly, they note that "the climatic deterioration in the twelfth century can be regarded as the starting point of a prolonged cold period that continued to the first decade of the twentieth century," which "Little Ice Age," in their words, is also "known from instrumental, historical and proxy records."

Dropping down to northwest Germany, Niggemann et al. (2003) employed petrographical and geochemical techniques to develop a climatic history of the last seventeen millennia from a set of three stalagmites.

This history closely matches the one derived by McDermott et al., with Niggemann et al. explicitly noting that it provides evidence for the existence of the Little Ice Age, the Medieval Warm Period and the Roman Warm Period, which also implies the existence of the Dark Ages Cold Period that separated the Medieval and Roman Warm Periods, as well as the cold period that preceded the Roman Warm Period.

Continuing south, Desprat et al. (2003) studied the climatic variability of the last three millennia in northwest Iberia via a high-resolution pollen analysis of a sediment core retrieved from the central axis of the Ria de Vigo in the south of Galicia.

There they detected "an alternation of three relatively cold periods with three relatively warm episodes."

In order of their occurrence, these periods are described by them as the "first cold phase of the Subatlantic period (975-250 BC)," which was "followed by the Roman Warm Period (250 BC-450 AD)," which was followed by "a successive cold period (450-950 AD), the Dark Ages," which "was terminated by the onset of the Medieval Warm Period (950-1400 AD)," which was followed by "the Little Ice Age (1400-1850 AD), including the Maunder Minimum (at around 1700 AD)," which "was succeeded by the recent warming (1850 AD to the present)."

In light of these findings, Desprat et al. conclude that "a millennial-scale climatic cyclicity over the last 3000 years is detected for the first time in NW Iberia paralleling global climatic changes recorded in North Atlantic marine records (Bond et al., 1997; Bianchi and McCave, 1999; Chapman and Shackelton, 2000)."

Considering that the same findings are reported by the other studies described above, the establishment of the Modern Warm Period in Europe over the course of the past century or so is seen to be nothing more than the most recent manifestation of the warming phase of this ever-recurring cycle of climate, which is totally unrelated to the coincidental historical increase in the air's CO2 content.

References

Berglund, B.E. 2003. Human impact and climate changes - synchronous events and a causal link? Quaternary International 105: 7-12.

Bianchi, G.G. and McCave, I.N. 1999. Holocene periodicity in North Atlantic climate and deep-ocean flow south of Iceland. Nature 397: 515-517.

Bond, G., Showers, W., Cheseby, M., Lotti, R., Almasi, P., de Menocal, P., Priore, P., Cullen, H., Hajdas, I. and Bonani, G. 1997. A pervasive millennial-scale cycle in North Atlantic Holocene and glacial climates. Science 278: 1257-1266.

Chapman, M.R. and Shackelton, N.L. 2000. Evidence of 550-year and 1000-year cyclicities in North Atlantic circulation patterns during the Holocene. The Holocene 10: 287-291.

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