Mankind 'can't influence' climate

[Vegas]

http://www.news.com.au/story/0,23599,21542564-2,00.html

MANKIND is naive to think it can influence climate change, according to a prize-winning Australian geologist.

Solar activity is a greater driver of climate change than man-made carbon dioxide, argues Ian Plimer, Professor of Mining Geology at the University of Adelaide and winner of several notable science prizes.

“When meteorologists can change the weather then we can start to think about humans changing climate,” Prof Plimer said.

“I think we really are a little bit naive to think we can change astronomical and solar processes.”

Speaking last night after presenting his theory for the first time, to the Australasian Institute of Mining and Metallurgy in Sydney, Prof Plimer said he had researched the history of the sun, solar and supernovae activity and had been able to correlate global climates with solar activity.

“But correlations don't mean anything, you really need a causation,” Prof Plimer said.

So he then examined how cosmic radiation builds up clouds.

A very active sun blows away the cosmic radiation, while a less active sun allows radiation to build up, he said.

“So you can very much tie in temperature, cloud formation, cosmic radiation and the sun,” he said.

The next part of Prof Plimer's research was to examine the sources of carbon dioxide.

He said he found that about 0.1 per cent of the atmospheric carbon dioxide was due to human activity and much of the rest due to little-understood geological phenomena.

Prof Plimer also argued El Nino and La Nina were caused by major processes of earthquake activity and volcanic activity in the mid-ocean ridges, rather than any increase in greenhouse gases.

Nor does the melting of polar ice have anything to do with man-made carbon dioxide, he said.

“Great icebergs come off, not due to temperature change but due to the physics of ice and the flow of ice,” Prof Plimer said.

“There's a lag, so that if temperature rises, carbon dioxide rises 800 years later.

“If ice falls into the ocean in icebergs that's due to processes thousands of years ago.”

On the same basis, changes to sea level and temperature are also unrelated to anything happening today, he said.

“It is extraordinarily difficult to argue that human-induced carbon dioxide has any effect at all,” he said.

Prof Plimer added that as the planet was already at the maximum absorbance of energy of carbon dioxide, any more would have no greater effect.

There had even been periods in history with hundreds of times more atmospheric carbon dioxide than now with “no problem”, he said.

The professor, a member of the Australian Skeptics, an organisation devoted to debunking pseudo-scientific claims, denied his was a minority view.

“You'd be very hard pushed to find a geologist that would differ from my view,” he said.

He said bad news was more fashionable now than good and that people had an innate tendency to want to be a little frightened.

But Prof Plimer conceded the politics of greenhouse gas emissions meant that attention was being given to energy efficiency, which he supported.

The professor, who is writing a book on the subject, said he only used validated scientific data, published in reputable peer-reviewed refereed journals, as the basis of his theories.

[LSU]

I've heard the naive thing before regarding us thinking we can change the environment. I would pose that it's equally naive to think that we can't affect the environment.

[Vegas]

I've heard the naive thing before regarding us thinking we can change the environment. I would pose that it's equally naive to think that we can't affect the environment.

What is the total amount of energy usage per day that comes from fossil fuels and how does that compare to one hour of sunlight hitting the earth?

[LSU]

What is the total amount of energy usage per day that comes from fossil fuels and how does that compare to one hour of sunlight hitting the earth?


Couldn't tell you.

Are you making the argument that man's actions can't affect the environment?

[Vegas]

Couldn't tell you.

Are you making the argument that man's actions can't affect the environment?

Not really. I've seen some lousy areas where there are leftover mines and such, which I find deplorable. I lived in Southern California for 20 years and the air quality was pretty bad for a good part of that time. It has improved greatly even though we had Republican presidents.

But as far as the climate change, the amount of energy that we use compared to the energy that hits the earth from the sun it's pretty insignificant.

[Vegas]

But I should mention that the amount of solar energy intercepted by the Earth every minute is greater than the amount of energy the world uses in fossil fuels each year.

[LSU]

But I should mention that the amount of solar energy intercepted by the Earth every minute is greater than the amount of energy the world uses in fossil fuels each year.



I don't think global warmists deny that. What they say is the energy can't bounce back away into the coldness of space because of the insulation of greenhouse gases.

Now, I could make a simple observation regarding that claim, but I'll see if anyone else thinks the same way I do...

[Land_Shark]

I've heard the naive thing before regarding us thinking we can change the environment. I would pose that it's equally naive to think that we can't affect the environment.

I suppose it is naive to think that people will read the article before they reply.

“When meteorologists can change the weather then we can start to think about humans changing climate,” Prof Plimer said.

“I think we really are a little bit naive to think we can change astronomical and solar processes.”

Clearly, the Prof is not saying that we can't affect our environment. The Prof is speaking only to climate change. That said, no intellectually honest person could state that we can't affect the environment. One need only look to the myriad of superfund sites listed on the NPL (National Priorities List). However, no intellectually honest person can say that the available science supports the existence of man-made global climate change. At best, in my opinion, the data supports further investigation into the cause of some of the changes we are seeing. Ultimately, as many have postulated, there are far more variables involved than we currently understand. Which poses a problem - we are at the limit on our computing power as it relates to GCMs and we still can't account for all of the known variables.

Then there is this:

http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html

Then looking beyond the science, I must focus on the self-ordained and media supported leader of this movement - Al Gore. Mr. Gore simply and politely put is absolutely uneducated with regard to sound environmental practice. As a prima facie example offered in support of my statement look at his light bulb proposal. The light bulbs he has suggested that everyone switch to qualify as hazardous waste when they are disposed. That is if you are subject to RCRA (Resource Conservation and Recovery Act). Specifically, these bulbs contain mercury. Fortunately, for individuals there is a household exemption in RCRA, however, unfortunately, for the environment if people use these bulbs they will end up in a landfill. Once in the landfill the bulbs will shatter and contaminate the soil with mercury which will then leach into groundwater.

Sometimes I just want to walk up to Al Gore, hand him a yo-yo, and say, "Some people have a hard time with Environmental Science. Here's a yo-yo, it goes up and down."

Just my two cents...okay, its more like five.

[LSU]

I suppose it is naive to think that people will read the article before they reply.

“When meteorologists can change the weather then we can start to think about humans changing climate,” Prof Plimer said.

“I think we really are a little bit naive to think we can change astronomical and solar processes.”

Clearly, the Prof is not saying that we can't affect our environment. The Prof is speaking only to climate change. That said, no intellectually honest person could state that we can't affect the environment. One need only look to the myriad of superfund sites listed on the NPL (National Priorities List). However, no intellectually honest person can say that the available science supports the existence of man-made global climate change. At best, in my opinion, the data supports further investigation into the cause of some of the changes we are seeing. Ultimately, as many have postulated, there are far more variables involved than we currently understand. Which poses a problem - we are at the limit on our computing power as it relates to GCMs and we still can't account for all of the known variables.

Then there is this:

http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html

Then looking beyond the science, I must focus on the self-ordained and media supported leader of this movement - Al Gore. Mr. Gore simply and politely put is absolutely uneducated with regard to sound environmental practice. As a prima facie example offered in support of my statement look at his light bulb proposal. The light bulbs he has suggested that everyone switch to qualify as hazardous waste when they are disposed. That is if you are subject to RCRA (Resource Conservation and Recovery Act). Specifically, these bulbs contain mercury. Fortunately, for individuals there is a household exemption in RCRA, however, unfortunately, for the environment if people use these bulbs they will end up in a landfill. Once in the landfill the bulbs will shatter and contaminate the soil with mercury which will then leach into groundwater.

Sometimes I just want to walk up to Al Gore, hand him a yo-yo, and say, "Some people have a hard time with Environmental Science. Here's a yo-yo, it goes up and down."

Just my two cents...okay, its more like five.



I've gotten this far by not reading the articles. I'm here for the pictures.

[BoredWithNoSB]

I've gotten this far by not reading the articles. I'm here for the pictures.

BTW is that your fighting cock in your avatar?

[LSU]

BTW is that your fighting cock in your avatar?




Big and vicious he is.

[Vegas]

BTW is that your fighting cock in your avatar?

LOL Good one.

That reminds me of the Howie Mandell routine when he says he went to his first cock fight in Mexico and then couldn't walk for a week. But you should see the other guy.

[Nixon's Head]

I've seen proof that global warming is directly related to a decline in the world's pirate population.

[LSU]

I've seen proof that global warming is directly related to a decline in the world's pirate population.



Sounds arrrrrrrrrguable.

[i_hate_righties]

I suppose it is naive to think that people will read the article before they reply.

“When meteorologists can change the weather then we can start to think about humans changing climate,” Prof Plimer said.

“I think we really are a little bit naive to think we can change astronomical and solar processes.”

Clearly, the Prof is not saying that we can't affect our environment. The Prof is speaking only to climate change. That said, no intellectually honest person could state that we can't affect the environment. One need only look to the myriad of superfund sites listed on the NPL (National Priorities List). However, no intellectually honest person can say that the available science supports the existence of man-made global climate change. At best, in my opinion, the data supports further investigation into the cause of some of the changes we are seeing. Ultimately, as many have postulated, there are far more variables involved than we currently understand. Which poses a problem - we are at the limit on our computing power as it relates to GCMs and we still can't account for all of the known variables.

Then there is this:

http://news.nationalgeographic.com/news/2007/02/070228-mars-warming.html

Then looking beyond the science, I must focus on the self-ordained and media supported leader of this movement - Al Gore. Mr. Gore simply and politely put is absolutely uneducated with regard to sound environmental practice. As a prima facie example offered in support of my statement look at his light bulb proposal. The light bulbs he has suggested that everyone switch to qualify as hazardous waste when they are disposed. That is if you are subject to RCRA (Resource Conservation and Recovery Act). Specifically, these bulbs contain mercury. Fortunately, for individuals there is a household exemption in RCRA, however, unfortunately, for the environment if people use these bulbs they will end up in a landfill. Once in the landfill the bulbs will shatter and contaminate the soil with mercury which will then leach into groundwater.

Sometimes I just want to walk up to Al Gore, hand him a yo-yo, and say, "Some people have a hard time with Environmental Science. Here's a yo-yo, it goes up and down."

Just my two cents...okay, its more like five.

Copyright New Statesman Ltd. Apr 2, 2007

It's getting hot in here Johann Hari Six Degrees: our future on a hotter planet Mark Lynas Fourth Estate, 358pp, £12.99

During the cold war, every person on earth knew what the worst endgame would look like: the three-minute warning, the futile scrambling under desks, and universal incineration. With the just-as-real, just-as-dangerous threat of global warming, there is a vague sense of doom, but no clear mental picture of what meltdown would look like - until now.

Mark Lynas is, along with George Monbiot and Bill McKibben, the best writer about global warming working today. In Six Degrees, he does something so obvious and so necessary it is hard to believe nobody has done it before. He pores through the peer-reviewed scientific literature and describes, calmly and plainly, what scientists say will happen on earth as each degree of global warming occurs.

One of the last jeers of the dwindling band of climate change "sceptics" is that a world that is six degrees warmer sounds rather nice, thank you very much. John Redwood, a leading figure in David Cameron's fake-green New Tories, wheeled this canard out only last month. At first glance, they're right: a warming of 1°C to 6°C which is what the authoritative Intergovernmental Panel on Climate Change (IPCC) predicts - doesn't sound like much.

It is. Lynas talks us through the six degrees of separation between us and a planet we do not recognise and cannot survive on. Some 18,000 years ago, the world was six degrees cooler. It was an ice age. Most of England was a freezing polar desert where winter temperatures went as low as -40°C. There were almost no animals, and the only plants to be found were a few species of lichens and mosses. It was possible to walk to France across the channel. No agriculture was possible, because the climate fluctuated too wildly. So what happens as we move in the opposite direction, up to six degrees warmer?

With just one degree of warming, here's what happens: the Great Barrier Reef bleaches and dies, the Greenland ice sheet melts, the Maldives and many islands in the South Pacific disappear beneath the waves, rockfalls from the Alps multiply as the mountains melt, the seasonal rainfalls in sub-Saharan Africa change leaving millions at risk of drought and famine, and hurricanes start to hit Brazil for the first time in millennia. One degree.

At three degrees, the Amazon rainforest - the planet's lungs - will die. Lynas explains: "The trees in the Amazon are used to constant humidity, and have no resistance to fire." Once the humidity dries out, so does the forest. They will burn and turn to ash.

And at six degrees - the IPCC's higher-end predictions for this century - humanity enters its endgame. "An entirely new planet comes into being - one unrecognisable from the Earth we know today," Lynas writes. The rainforests are gone, the world's ice supplies are only a memory, the seas are encroaching, and inland cities see temperatures ten degrees higher than today. In the world's major crop-growing areas - India, Australia, the inland United States most crops are dying, and mass starvation is a perennial risk.

It becomes likely that the vast stores of methane lodged on sub-ocean shelves will bubble to the surface. Since methane is highly flammable, these could quickly be sparked - by lightning, or through human action - into vast fireballs tearing across the sky. The chemical engineer Gregory Ryskin calculates that this methane "could destroy terrestrial life almost entirely", with a major oceanic methane eruption having a force 10,000 times greater than the world's stockpiles of nuclear weapons.

The planet has been here before. Geologists have discovered that at the end of the Permian period, 251 million years ago, the world warmed rapidly by six degrees. It was the worst crisis ever endured by life on earth, "the closest this planet has come to losing its wonderful living biosphere entirely and ending up a dead and desolate rock in space". The earth was racked by "hypercanes" - hurricanes so strong they even left their mark on the ocean floor. Oxygen levels in the atmosphere plunged to 15 per cent - low enough to leave any fast-moving animal gasping for breath.

The only survivors were a few shelled creatures in the oceans, and a pig-like creature that had the land to itself for millions of years. (Whoever thought geological findings could give you nightmares?)

Six Degrees will make some readers want to sink into survivalism, but Lynas wisely warns: "Getting depressed about the situation now is like sitting inert in your living room and watching the kitchen catch fire, and then getting more and more miserable as the fire spreads throughout the house - rather than grabbing an extinguisher and dousing the flames."

[i_hate_righties]

very long, but very good article.....



Copyright Penny Publications Apr 2007
[Headnote]
How our ancestors may have held the ice at bay.

Anyone who pays attention to the news knows that the Earth is warming. As I write this, the latest report is that the rate of ice flow from Greenland's glaciers has doubled in the past decade. But by the time you read it, the only certainty is that this will be old news.

The main question is the extent to which humans have caused this wanning. The Earth, the conventional wisdom goes, is rebounding from an ice age, but in the past 150 or 200 years, we have accelerated the pace as a byproduct of our use of fossil fuels. Prior to that, we were puny creatures incapable of affecting the global environment, and it is only modern technology that changed this.

But is that true? Not the modern technology part-few Analog readers would disagree that we have the ability to geoengineer the Earth on a large scale, and that the future will give us ever greater power. "Our leverage [over climate] keeps growing as our science gets better," David Keith, of the University of Calgary, put it at the Fall 2005 meeting of the American Geophysical Union.

But until recently, climate had a much more obvious effect on us than we had on it. Harvey Weiss, an archaeologist from Yale University, goes so far as to argue that civilization was created in reaction to a climate fluctuation that occurred about 8,200 years ago. He bases this argument on the fact that humans have been on the planet a long time, but it was only then, in ancient Mesopotamia (today's Iraq), that they began banding together into anything more complex than scattered tribes and villages.

"The biggest question in Mesopotamian archaeology is why there even is a Mesopotamian archeology," he said at a 2003 geophysics meeting. That's because, at first glance, Mesopotamia isn't the most inviting place. It's a desolate area "that looks like what you see on CNN every night. Bleak, dismal, and parched, only watered where the Euphrates has its course." It can be firmed, but only at the cost of a lot of work, building and maintaining irrigation canals. Cooperating to do this was obviously a boost to civilization-but why bother?

Weiss argues that the answer lay in the aforementioned climate change: an abrupt cold shift and drought that lasted 200-300 years.1 This forced people to migrate to the water, where they had to work together to learn irrigation. By the time the climate moderated, civilization was established.

Sara Parcak, of the University of Cambridge, believes that another abrupt shift, about 4,200 years ago, produced droughts that contributed to the collapse of Egypt's once-powerful Old Kingdom. Similarly, many archaeologists believe that drying climate in the American Southwest may have forced the Anasazi to abandon the cliff dwellings that delight today's tourists. More recently, a series of wet decades in the early twentieth century lured farmers to places as unlikely as California's Mojave Desert and the sagebrush steppes of eastern Oregon, where ghost towns still dot the land. And in early 2006, South African scientists calculated that global warming would eliminate a sizeable percentage of the continent's arid-region creeks by the end of this century-a potential catastrophe for some of the world's poorest countries.

Swamp Gas

But dependent as humans were (and are) on weather, were our distant ancestors really too weak to make an impact?

Not so, says William F. Ruddiman, a retired professor from the University of Virginia. That's because. 12,000 years ago, they discovered agriculture. And within a few thousand years, that gave them so much (unintended) power over climate that the Earth wouldn't be "naturally'' warming without them.

Ruddiman begins by noting that ice ages are caused by variations in the Earth's orbit that alter the amount of sunlight reaching Canada, Siberia, and Alaska during the brief arctic summer. During high sunlight cycles, there's enough warmth to melt the previous winter's snows. During cold ones, there isn't, and snow gradually accumulates into glaciers.

These orbital variations occur in three well-understood cycles.

1. A 41,000-year variation in the tilt of the Earth's axis. Discovered in the 1840s by French astronomer Urbain Leverrier, this is produced by the gravity of the outer planets and causes the tilt to vary from 22.2° to 24.5°. That changes the angle of the midsummer sun by 2.3°-small, but enough to significantly affect snow melting in the far north. Right now, we're in the middle of the range, at 23 ½°, but we're heading toward the cold end.

2. A 26,000-year precession of the Earth's orbit around the sun.2 Basically, this is like a top wobbling on its axis. The angle of the Earth's tilt doesn't change (except for the small variation noted above), but the direction slowly shifts. If the Earth's orbit were circular, this wouldn't matter. But it's elliptical, which means that sometimes the arctic summer comes when the Earth is closest to the sun, sometimes when it's farthest. Again, the effect is small but significant. In the first case we get warm summers and lots of melting.3 In the other, we get cooler summers and less melting. And guess what: For the last several thousand years, we've been heading for the cold-summer end of this cycle, too.

3. A 100,000-year variation in the eccentricity of the Earth's orbit.4 In some ways, this is most important because it exaggerates the effect of the precession cycles, making them more pronounced when the Earth's orbit is least circular. This one is also shifting toward its colder realm.

[i_hate_righties]

During the heart of the most recent ice age, 20,000 years ago, all three cycles combined to plunge the planet into the icehouse. By 11,000 years ago, when the glaciers were in full retreat, solar radiation reached a glacier-melting peak. Afterward, glaciers continued to melt (just as summer days continue to get hotter after June 21, the longest day of the year), but solar energy has been steadily decreasing: a trend that normally would lead into the next cold cycle.

All of this is reinforced by changes in the Earth's atmosphere, particularly regarding two important "greenhouse" gases, methane and carbon dioxide.

Greenhouse gases are ones that trap atmospheric heat. Carbon dioxide (CO2) is the most plentiful, but molecule for molecule, methane (CH^sub 4^) is a good deal more powerful.

We can trace the levels of these gases back for thousands of years by measuring their concentrations in air bubbles trapped in arctic and Antarctic ice. At the time Kuddiman proposed his theory, scientists had used cores from Russia's Vostok station in Antarctica to do this for the past 400,000 years.

These cores reveal that during eras when the Northern Hemisphere receives weaker summer sunlight (i.e., ice ages), methane is lower. In eras when solar energy is higher in the arctic, methane increases.

This makes sense because methane is produced when vegetation decays beneath swamps and marshes. Many of these marshes are in the arctic, where, if the sun is weak, they're locked up in permafrost. If it is strong, permafrost melts, and swamps and marshes expand.

But that's only one factor. Another, probably more important, lies in Africa, China, and Eurasia.

It's long been known that these areas were a lot wetter 11,000 years ago than today. It's a fact attested to by dry lake valleys in the Sahara and huge reserves of groundwater in regions that sec virtually no rain today.

Ruddiman argues that it is not by coincidence that these lakes existed when the northern summers were at their strongest. Even at moderate latitudes north of the equator (such as the Sahara and large areas in southern Eurasia), he says that summer sunlight was eight percent more intense than today. That produced stronger thunderstorms, a wetter climate, and lots of marshes, as well as lakes.

All of this appears to have been the case throughout the last several million years: Methane levels fluctuate with the 100,000-, 41,000-, and 22,000-year sunlight cycles, peaking when the northern summers are strongest and declining when they weaken.

This pattern means that the atmosphere's methane level should have reached a peak 11,000 years ago and been dropping ever since. And that's exactly what happened until 5,000 years ago. Then something went awry, and it began to rise.

"You have to throw 395,000 years of history out the window to come up with a natural explanation for this," Ruddiman said when he unveiled his theory in a lecture at the 2003 fall meeting of the American Geophysical Union.5 "Something has overridden the natural system."

His not-so-natural alternative? Five thousand years ago was just about when people started creating artificial marshes to grow rice in Southeast Asia. Weeds, stems, and rice roots decomposing in these paddies would have released considerable amounts of methane. Since then, rice farming has continued to expand. As far back as 2,000 years ago, rice farmers had already used up the flat land of the valleys and were beginning to build the hillside terraces we see today, increasing their methane releases with each new terrace.6

The result is that preindustrial methane levels were about the same as those 11,000 years ago, when African and Eurasian thundershowers were at their highest and marshlands were spreading behind retreating glaciers. That's about 25 percent higher than they were at the time the trend reversed and 60 percent higher than would be expected if the "normal" cycle had persisted.

The current level is about 1750 parts per billion. That may not sound like much (carbon dioxide levels are more than 200 times higher), but methane is a powerful enough greenhouse gas (twenty times as powerful as carbon dioxide, according to the website of Oak Ridge National Laboratory) that this is enough to play a major role.

[i_hate_righties]

Wrong-Way CO2

Atmospheric concentrations of carbon dioxide have shown a similar deviation. Antarctic ice cores reveal that CO2 levels fluctuate on natural cycles of 22,000, 41,000, and 100,000 years. The reasons aren't well understood, but the pattern is quite evident, especially for the 100,000-year cycle, which has thrice produced 80 ppm (40 percent) oscillations in the past 350,000 years.

One theory is that carbon dioxide is affected by the extent of pack ice in the oceans. That's because the ice reduces the amount of water coming into contact with the air, thereby reducing the rate at which carbon dioxide can be transferred from the atmosphere to the oceans. Less ice equals more CO2 removal, which means a gradual decline in atmospheric CO2 between ice ages. Another theory is that big ice sheets affect ocean circulation patterns in ways that produce a similar effect.

A third theory says that because ice ages are dusty, more dust blows into the ocean when glaciers are at maximum. This dust is rich in nutrients, particularly iron, which fertilizes the growth of plankton. That removes carbon dioxide from the water, then sequesters it in the depths when the plankton die and sink to the bottom. Deliberately dusting the ocean with iron (a key nutrient) has even been proposed as a method of fighting global wanning, but in a pilot-scale test, called the Southern Ocean Fertilization Experiment (SOFeX), it looked to be impractical.7

All three mechanisms would produce CO2 levels that fluctuate cyclically with the glaciers: exactly what the ice cores show. Thus, carbon dioxide, like methane, should have reached a peak 11,000 years ago and dropped ever since. But it, too, dropped for only the first part of that cycle, then started to rebound-so much so that at the start of the industrial age, the level was already 15 percent too high.

Other scientists have posited a variety of natural theories for this reversal. One is that changes in ocean chemistry are causing the seas to disgorge large quantities of previously absorbed carbon dioxide. Another is that it is due to a natural decline in forests, which remove CO2 from the air to form branches, leaves, bark, and roots. But Ruddiman again suggests that humans might be the cause.

Studies of pollen particles trapped in lakebed sediments allow scientists to trace the spread of wheat, peas, lentils, flax, and barley across regions that were naturally forest. They reveal that as far back as 10,000 years ago, people were beginning to cut down forests to make room for farming. These bogs, Ruddiman says, also reveal increasing levels of sun-loving weeds from cleared land, plus soot from slash-and-burn agriculture.

These facts may have been overlooked by climate modelers, but Ruddiman discovered that they are well known to historical geographers. In 1989, Ian G. Simmons of the University of Durham, England, wrote that by 2,000 years ago, large segments of Southeast Asia, China, Southwestern Asia, and the Mediterranean region were "greatly" deforested. And in a 2003 book, Deforesting the Earth, Oxford geography professor Michael Williams reported that humans were already cutting down European forests 6,000 years ago.

Even North America was affected. As far back as 7,000 years ago, Williams wrote, Native Americans were clearing forests in the Mississippi River Valley to plant squash, sunflowers, maize, and beans.

By the time of the Roman and Chinese empires, the effect had become quite pronounced. "Most of Eurasia was deforested by the time of Christ," Ruddiman said in his 2003 lecture.

In an effort to quantify the amount of preindustrial deforestation, Ruddiman turned to the Domesday Book, a census of Britain conducted by William the Conqueror in 1086 AD. In addition to counting people, William's census-takers tallied the extent of forests, fields, and pastures. According to figures in the Domesday Book, the 1.5 million people then living in England had already cut down 85 percent of their nation's trees.

Extrapolating these per-capita landclearing figures to the 57 million people living in China a thousand years earlier, plus the 140 million more in India, Southeast Asia, and the Roman Empire, Ruddiman calculates that 2,000 years ago, tree-cutting had released 700 to 900 billion tons of carbon dioxide to the air-enough to offset the natural decline and start driving levels of the gas back up again, thousands of years before anyone was using significant quantities of oil.8

Ruddiman's bottom line: All those years ago "humans were doing things at a scale that can explain why the natural trends went haywire."

He backs up his tree-cutting theory by pointing to several dips in the atmospheric level of carbon dioxide that occurred over the past 2,000 years. None was large-only a few parts per million-but they appear to be too much to be explained by natural factors such fluctuations in the rate of volcanic emissions.

One dip occurred during the late years of the Roman Empire. Another was in the 1400s, and a third was between 1500 AD and 1750 AD. All three, Ruddiman says, link to periods when plagues killed off sizeable fractions of the world's population.

The first occurred at a time when bubonic plague killed 20 million people in China and the Roman Empire: roughly one-tenth of the world's then-population. The second correlates to the Black Death, which killed one-third of the people of Europe in its first year alone. The third was during an era when 90 percent of the 50 million to 120 million people living in Central and South America died of smallpox, measles, and other European diseases: the single largest mass mortality in history.

When that many people die, farms are abandoned, and trees grow back quickly enough to take significant amounts of carbon dioxide back out of the air. Historical accounts of the Black Death, Ruddiman says, are full of stories about millions of abandoned farms. "These accounts don't give numbers of farms or acreage," he said, "but it's immense."

[i_hate_righties]

Another intriguing aspect of these plagues is that the last one more or less coincides with an era called the Little Ice Age. During the heart of that period, from about 1550 to 1850, northern climates saw a temperature drop of about one or two degrees. That may not sound like a lot, but it allowed glaciers to surge in Alaska and froze the canals of Holland memorably enough that the Dutch are still speedskating fanatics. Could the Little Ice Age have represented the Earth's attempt to return to its normal cooling trend, thanks to the reduction in human-caused CO2? If so, a lot of low technology alternate-history books and fantasy novels need to be rewritten to include more ice and snow.

Bye-bye Ice Age

The timing of these wiggles adds yet another line of support to Ruddiman's claim that land clearing was the driving force behind the preindustrial increase in carbon dioxide. Over the course of 8,000 years, he says, enough of the Earth was deforested to raise CO2 levels by 40 ppm over what they "should" be.9

Combined with the increase in methane, Ruddiman argues, that's enough to warm the Earth by about 1.4°F-roughly the same amount that industrial-era emissions are believed to have wanned it to date (but not as much as today's emissions are expected to warm it in the future).

At the start of his 2003 lecture, Ruddiman announced that he would present four "outrageous propositions." So far, we've discussed three:

1. Several thousand years ago, atmospheric levels of methane and carbon dioxide started an upswing that is contrary to their normal cycles.

2. These changes were caused by puny, preindustrial humans.

3. Humans have had twice as much effect on climate as was previously believed. (The unrecognized half was before the Industrial Revolution. The other half is modern.)

His fourth claim is the true kicker. "The most in-your-face statement I can make is that humans stopped a glaciation," he said. "And I think there's a strong case that can be made for that."

A 1.4° warming may not sound like much, but (as with all climate-change scenarios) the effects are magnified at high latitudes. They're strong enough, he argued, that climate models show that if people hadn't irrigated rice and cut down so many trees, huge areas of North America would see mean annual temperature decreases of 5°F to 7°F. The result would be year-round snow cover in Canada's Baffin Island, and eleven-month winters in the Labrador highlands: the two areas from which prior glaciations appear to have originated.

If anything, the models Ruddiman used to calculate these effects may have understated the impact. That's because they weren't sophisticated enough to take account of climate-driven changes in arctic vegetation.

By comparing old photos with present landscapes, researchers in Alaska have noted that today's warming trend has produced significant vegetation shifts, most notably a dramatic increase in the prevalence of woody shrubs in lands that previously were tundra. This changes the amount of solar heating. In an article published in the September 7, 2005 issue of the Journal of Geophysical Research-Biogeosciences, Matthew Sturm of the U.S. Army Cold Regions Research and Engineering Laboratory and colleagues reported that the dark branches of these shrubs, protruding above the snow, absorb a lot more sunlight than do low-lying tundra grasses. In his experimental plots, Sturm discovered that spring melting began several weeks earlier in shrubby regions than in unbroken tundra.10

During a cooling period, the same factors would work in reverse. Rather than expanding their range, shrubs would retreat. The same would happen to evergreen forests, whose dark needles also absorb a lot of sunlight. These vegetation shifts would amplify the effects found by Ruddiman's climate model, quite possibly by enough to produce incipient glaciers in Labrador, as well as Baffin Island. Whether these glaciers would now be spreading south remains an open question-and a fruitful topic for an alternate history story.

Latest Cores

It will be years before scientists can be sure whether Ruddiman's theory is correct. Shortly after he unveiled it, I talked to Ralph Keeling, a professor of geochemistry at Scripps Institution of Oceanography in La Jolla.

"At some level," Keeling said, "it seems inevitable that early agriculture would have had an impact on the atmosphere. The question is simply how big." But he added that confirmation of Ruddiman's theory would require the drilling of ice cores going back more than 400,000 years.

The problem was that the Antarctic ice cores on which Ruddiman was relying only went back far enough to capture the three most recent repetitions of the 100,000-year cycle. And (in one of those Murphy's Law, "of course" realities) the one just before that turns out to be the one in which the orbital parameters were most akin to today's. If that earlier era showed the same methane and CO2 anomalies we see in the current cycle, then the cause is natural and Ruddiman's theory goes down the drain.

Luckily, it turned out that there were a few feet at the bottom of the old cores that hadn't previously been studied due to difficulties in figuring out their age. That problem was resolved while Ruddiman was writing his book, allowing the chronology of methane and carbon dioxide levels to be pushed back just barely far enough to get him the information he needed. The result: a slight change in the numbers, but confirmation of his overall hypothesis.

This brings us full circle to Weiss's theory of the early Mesopotamian civilizations. The 6200 BC cold snap-called the 8.2 Kya event by geophysicists-was an anomaly that had nothing directly to do with global climate change. But it did much to boost farming-fed civilizations by creating that ancient world's most powerful kingdoms. And that, in turn, instituted a long-term shift in climate.

Except during the cold snap, the Earth was warmer then than now, but steadily cooling. Since then, we've had one of the most stable climate periods in the last several million years. Anthropologists have long pointed to this as a fortuitous circumstance that helped prevent civilization from being erased by the next major climate change. But if Ruddiman is correct, this stability wasn't the result of some nicely timed Earth process, but rather the result of two offsetting factors: the Earth's slow, natural cooling, and the human-caused buildup in greenhouse gases. Thus, while the Earth was trying to enter a new ice age, it did not, and except for a few minor blips such as the Little Ice Age and the drought that may have toppled Egypt's Old Kingdom, nothing truly untoward happened for 8,000 years.

For science-fictional world builders, this raises all kinds of interesting questions. What if the two rates of change hadn't been so nicely balanced? Could the Romans have coped with an ice age? What would have happened if the world had been in a warming trend when farming was discovered, rather than a cooling one? Then, rather than offsetting, the two factors might have reinforced each other-and melting Antarctic and Greenlandic glaciers might have forced many low-lying civilizations to continually seek higher ground.

Now, the human factor is overwhelmingly powerful. As of 2006, the carbon dioxide level has overshot anything the Earth has seen since the dinosaurs and is heading off into what Ruddiman calls "terra incognita. "

What exactly this entails is open for debate, but in the final chapters of his book, Ruddiman poses an interesting argument. The next few centuries might be a bit warm, he suggests, but eventually we'll run out of coal and oil. Soon enough (geologically speaking) the atmosphere will start purging itself of the extra greenhouse gases... and we'll still be in the present orbital cycle ...

Get the book. It's one of the most intriguing climate hypotheses to come along in years.

[Land_Shark]

I must surmise that this and the previous posts were in response to mine as you quoted me initially. As you really haven't said much I can only guess as to the purpose of your posts, however, they fail to address my comment regarding the lack of valid science on the topic. As I stated, there is enough science to justify investigation but noon to support the fear-mongering that has occurred with regard to this topic. So my statements stands, you have failed to present any science here, if that was your intent. Taking these in turn:

The first post refers to Mark Lynas, his blog is at: http://www.marklynas.org/ I initially note hat he does not list his credentials on his blog site. So I did some digging, http://en.wikipedia.org/wiki/Mark_Lynas indicates that Mr. Lynas holds a degree in History and Politics. Further, he is apparently a journalist. Please explain to me, as a holder of a M.S. in Environmental Science focusing on technology and assessment, Mr. Lynas’ qualifications as a scientist and any substantive research he would have conducted in the relative fields such as geophysics, climatology, environmental chemistry, paleontology, etc.

You second through fifth posts, appear to be an article/book entitled, “How our ancestors may have held the ice at bay.” Whatever this publication is, if placed in quotes, it returns a single Google return. I can’t convey how insignificant that is. Further, a quick search through the scientific research resources I have at my disposal returned nothing which tells me one thing. This is not peer reviewed. Having briefly reviewed your post it appears that it is a string of quotes from various people. Quotes are like statistics, you can make them say anything once you remove the context. Actually, I could probably make Ghandi sound like Pol Pot.

At this point, there seems to be a fundamental disconnect in what qualifies as Science. This link will direct you to a good layout of the requirements for scientific literature: http://en.wikipedia.org/wiki/Scientific_literature Please note the absence of op eds, journalistic research, and generally anything that is not published by an individual with multiple advanced degrees in one or more scientific disciplines.

Further, the scientific method can be condensed into four basic steps: 1. characterization of observations, 2. formulation of a hypothesis based upon those characterizations, 3. predictions based upon the developed model, and 4. conduction of experiments to test the hypothesis. Everyone seems to stop at #3.

So to conclude, if you can direct me to some scientific research verifying the prediction of Mr. Lynas, et al. I would be pleased to pour through it.

[pnkpanther]

I've heard the naive thing before regarding us thinking we can change the environment. I would pose that it's equally naive to think that we can't affect the environment.

see

the aral sea

[IBC]

It is funny to say that IHR's article isn't peer reviewed, seeing as Vegas can't post a single peer-reviewed article that denies Global Warming. You know why? There isn't any anymore.

[Vegas]

It is funny to say that IHR's article isn't peer reviewed, seeing as Vegas can't post a single peer-reviewed article that denies Global Warming. You know why? There isn't any anymore.

I posted several at the old boards. You should pay more attention and try to turn down the anger. Seriously.

[IBC]

I posted several at the old boards. You should pay more attention and try to turn down the anger. Seriously.

I am not angry. I don't want it to come out that way. I actually quite enjoy a good debate. I haven't seen anything peer reviewed.

[Land_Shark]

It is funny to say that IHR's article isn't peer reviewed, seeing as Vegas can't post a single peer-reviewed article that denies Global Warming. You know why? There isn't any anymore.

Why is it funny? I have not said Vegas' articles pass muster. Now it might be funny if Vegas made the comment and then went on to post or had historically posted the equivalent of opeds and tried to pass them off as science.

Turning to the rest of your comment - I am confused. Are you saying that peer reviewed journal articles no longer exist, that there are no peer reviewed journal articles on Global Climate Change, or that the whole peer review process is a sham?

[Jiddy78]

Mankind 'can't influence' climate

Smoke 'em if ya got 'em!!!

Hey!

What's this?

Uh...That's a barrel of toxic waste dude...

Dude, probably not the best idea to smoke that stuff...

Dude, it says right here in the "rules of life" handbook.

Rule #1: All following rules are in order of priority.

Rule #2: Get yours at all costs.

Rule #3: Smoke it if you're not sure.


See?

[Nixon's Head]

This debate is simple, like I mentioned earlier, global warming is a result of the decline in the world's pirate population.