Last week we were treated to the ridiculous story about Genghis Khan having an impact (or apparently not enough) with his impact on humanity. This week, a “new interpretation”; it’s the Romans and Christopher Columbus who are the ghosts of climate injustices past by daring to enable use of forest resources. I got quite the chuckle from this part, emphasis mine:
Ignoring the progress in agriculture, the preceding models implied that the same area of land is required to feed a European living in the fifth century as in the 20th century. This is why scientists struggled in trying to estimate the amount of CO2 produced by man before the industrial era. The work of Jed Kaplan’s team now enables us – for the first time – to travel back thru time.
Wow, time travel! Here is the press release in full:
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Man has been provoking climate change for thousands of years!
24.01.11 – The Roman Conquest, the Black Death and the discovery of America – by modifying the nature of the forests – have had a significant impact on the environment. These are the findings of EPFL scientists who have researched our long history of emitting carbon into the environment.
“Humans didn’t wait for the industrial revolution to provoke environment and climate change. They have been having an influence for at least 8000 years.” Jed Kaplan is putting forward a new interpretation of the history of man and his environment. This SNSF professor at EPFL and his colleague Kristen Krumhardt have developed a model that demonstrates the link between population increase and deforestation. The method enables a fairly precise estimate of human-origin carbon emissions before the advent of industrialization.
The story of our influence on the climate began with the first farmers. At that time, the prevailing technology didn’t allow an optimal use of the soil. “For each individual, it was necessary to clear a very large area of forest”, explains Jed Kaplan. However, with time, irrigation, better tools, seeds and fertilizer became more effficient. This development was a critical factor, which would partially counterbalance the increase in population, and contain the impact of human pressure on the natural environment.
Animation commented by Jed Kaplan
Agriculture – the story of a race for productivity
The relationship between population levels and agricultural land-use is therefore not simply proportional, as was formerly believed. In the Middle Ages, Europe had fewer forests than today, although since then the population has increased more than five fold. “The real innovation in our research has indeed been the taking into account of the improvements in farming techniques. Standard models simply state that the bigger the population, the more forest is cleared; but this doesn’t correspond to the historical reality.
Ignoring the progress in agriculture, the preceding models implied that the same area of land is required to feed a European living in the fifth century as in the 20th century. This is why scientists struggled in trying to estimate the amount of CO2 produced by man before the industrial era. The work of Jed Kaplan’s team now enables us – for the first time – to travel back thru time.
The influence of the Roman Empire and the Black Death on the climate
The results of this research tell a very different story from that which has been circulating up until now. They show, for example, a first major boom in carbon emissions already 2000 years before our era, corresponding to the expansion of civilizations in China and around the mediterranean.
Certain historical events, almost invisible in the preceding models, show up strongly in the data produced by the scientists. A good example is the re-growth of the forests as a consequence of the fall of the Roman Empire. The Black Death, a plague which resulted in the death of more than a third of the European population, also led to a fall in carbon emissions.
From the decline of the American indians to the minor ice age
Lastly, a significant decrease in emissions began in the 16th century – the one which would herald the minor ice age. Jed Kaplan has an audacious hypothesis to explain the dip in the data curve: “Thanks to the reports of the early explorers, we know that the forests were less abundant on the American continent. Then the settlers gradually eliminated the indigenous population.” Threatened with extinction, these populations effectively deserted the forested areas, which – by taking up the carbon in the atmosphere – in turn set off the legendary frosts of the 19th century. “Of course, it’s only a hypothesis”, he concludes, “but given the data we have gathered, it’s entirely plausible”.
Jed Kaplan’s model is not in contradiction with the previous ones on one critical point: the enormous increase in emissions from the beginning of the industrial era, and the massive use of fossil fuels. “We are just saying that our influence on the climate began a lot earlier than we thought. In 6000 BC, we were already accumulating significant quantities of carbon in the atmosphere, even though it was nothing compared to the situation today”, adds the scientist. A conclusion that could turn out to be critical in the future for the improved evaluation of the decisive impact of the forests on the climate.
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This story was released via Eurekalaert. The study authors: Prof. Jed Kaplan and Kristen Krumhardt have interesting bios.
Here’s the abstract:
Holocene carbon emissions as a result of anthropogenic land cover change
Kaplan, Jed Oliver ; Krumhardt, Kristen ; Ellis, E. C. ; Ruddiman, W. F. ; Lemmen, C. ; Goldewijk, K. K.
In: The Holocene, 2010
Date: 2010
Humans have altered the Earth’s land surface since the Paleolithic mainly by clearing woody vegetation first to improve hunting and gathering opportunities, and later to provide agricultural cropland. In the Holocene, agriculture was established on nearly all continents and led to widespread modification of terrestrial ecosystems. To quantify the role that humans played in the global carbon cycle over the Holocene, we developed a new, annually resolved inventory of anthropogenic land cover change from 8000 years ago to the beginning of large-scale industrialization (ad 1850). This inventory is based on a simple relationship between population and land use observed in several European countries over preindustrial time. Using this data set, and an alternative scenario based on the HYDE 3.1 land use data base, we forced the LPJ DGVM in a series of continuous simulations to evaluate the impacts of ALCC on terrestrial carbon storage during the preindustrial Holocene. Our model setup allowed us to quantify the importance of land degradation caused by repeated episodes of land use followed by abandonment. By 3 ka BP, cumulative carbon emissions caused by anthropogenic land cover change in our new scenario ranged between 84 and 102 Pg, translating to c. 7 ppm of atmospheric CO2. By ad 1850, emissions were 325–357 Pg in the new scenario, in contrast to 137–189 Pg when driven by HYDE. Regional events that resulted in local emissions or uptake of carbon were often balanced by contrasting patterns in other parts of the world. While we cannot close the carbon budget in the current study, simulated cumulative anthropogenic emissions over the preindustrial Holocene are consistent with the ice core record of atmospheric d13CO2 and support the hypothesis that anthropogenic activities led to the stabilization of atmospheric CO2 concentrations at a level that made the world substantially warmer than it otherwise would be.
Keyword(s): agricultural intensification, anthropogenic land cover change, dynamic global vegetation model, global carbon cycle, Holocene CO2, prehistory
Reference: EPFL-ARTICLE-161674
Full paper:
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“I doubt that the very few human beings in ancient periods could burn forests on a continental scale.”
Australian Aborigines changed the entire ecosystem, continent-wide, leaving only fire-friendly trees like eucalypts in a previously much more diverse ancient Australia forest spread. Pines were wiped out eg.
Angry Exile says:
January 24, 2011 at 9:14 am
I’m guessing the Roman and Medieval Warm Periods are about to be rehabilitated once they think they can sell them as being anthropogenic. Nero drove a Volvo while Rome burned, you know?
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Nero was not much of a risk-averse, safety-first kind of guy. I’m thinking a Hummer.
This may have been pointed out already, I’ve not time to read the comments now, but is it not odd how over the past 8K years, humans have ever increased CO2 emissions, yet the climate has cooled over the same period? WUWT?
http://i45.tinypic.com/2yo1hsy.jpg (from some crummy US gov’t science website)
Mike D. says:
January 24, 2011 at 2:20 pm
vigilantfish says: …how do you distinguish between the effects of anthropogenic and natural forest fires?
Anthropogenic fires were frequent, seasonal, and purposeful. They were set in specific locations, including lowlands. Purposeful landscape fire has been the key way that humanity has altered ecosystems during our entire existence, and were set for survival and sustenance reasons. Anthropogenic fires induced prairies, savannas, and open and park-like forests. Frequent burning eliminated most trees, but those that survived lived to very old ages.
Lightning fires are infrequent, generally occur during summer (hot dry weather), and generally start on ridgetops or other high places. Infrequency leads to biomass build-up, and lightning fires tend to be more severe because of the larger fuel loadings. Without frequent human fires to reduce fuels, lightning fires tend to be stand-replacing; that is, they kill all the trees. No trees grow to very old ages. Often fire-type brush replaces forests and prairies.
For example, many areas of the Southwest and California were subjected to anthropogenic fire for millennia. Those led to the open, park-like forests of old-growth ponderosa pine, punctuated by open meadows, encountered by the early Euro-American explorers to that region. But in the absence of the former frequent, tending fires set by the indigenous residents, biomass accumulated. Modern fires in those areas kill all the trees and convert the burned areas to chaparral.
Without frequent anthropogenic fire, forest development pathways are altered. Short-lived thickets of trees and brushfields result. Old-growth trees do not develop. Shade-tolerant species such as true firs tend to dominate, and shade-intolerants such as ponderosa pine are all but eliminated. Meadow and prairie areas become overgrown with brush and small trees. Savannas are invaded by trees and the former dominant species die out.
It may not be obvious to all, but a trained eye can readily detect the differences between anthropogenic and lightning fire regimes.
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Honestly, I don’t know where to begin after reading this gobbledygook. I can only speak about Australia, a place where devastating bushfires are almost an annual event, and where uber-fires which kill hundreds of people in settled areas have happened more than once in 210 years of European occupation of this sparsely populated continent.
Before, and since, European settlement, the two sources of fire were anthropogenic (Aboriginal fires to clear land for hunting) and natural (lightning strikes and possibly other sources of combustion). The man-made component was limited by the low number of indigenous people and their small geographical range. They tended to stay in the same area and burn the same area, over thousands of years.
The naturally caused fires were, and are, more frequent in the high country. Yet, it is there that the oldest trees are found. The predominant species, eucalypts, are not only adapted to fire, many of them require it to reproduce – and that goes for many of the other species in fire prone areas as well. The heat of a bushfire opens the seed pods, which can sit on the forest floor for decades.
After a big fire, many of the old trees, which look dead, start resprouting leaves within weeks.
Sport, you and your ‘trained eye’ know nothing about fire ecology in Australia. Perhaps your views are more valid for the rest of the world – I will leave that to others who know something about it. But, let me stress again the size of the Australian continent, and the tiny number of people (less than 500,000 pre European settlement about 200 years ago). We are now up to 22 million, and like Californians, have little control over naturally occurring bushfires.
Mike D. says:
January 24, 2011 at 2:20 pm
Actually, lightening strike forest fires aren’t unique to ridges. Quite a few in Australia are not much above sea-level. One fire, at a neighbour’s property, was caused by lightening, on river flats. Luckily it was spotted and dealt with in time to save the neighbour’s home and shedding, not to mention cattle.
I really would like to refer to the speech made by President Vaclav Klaus in october 2010 and what he said about climate change.
So in short, the climate change doctrine and the environmental movement are the new Communism and the environmentalist’s want a human empty planet.
That’s exactly the crap we’re going to hear much more about the next years.
Better to ignore it or provide every wacko who comes up with such ideas with a gun so they can shoot themselves.
We have found a clear indication that Europe is preparing for energy rationing and even prohibition. President Klaus has warned us about this:
http://www.europol.europa.eu/publications/Scenarios/Organised_crime_in_energy_supply.pdf
http://wattsupwiththat.com/2010/10/20/president-vaclav-havel-climate-control-or-freedom/
One thing I do not see having been raised above is the use of fire for hunting. As well as driving herds of animals off cliffs, fire were ignited up wind of animals with hunters downwind waiting for the fleeing animals.
The main take-away I get after reading this is “humans=evil”. If, as their premise suggests, even medieval man is responsible for such drastic climate change as MWP and LIA, the ONLY remaining logical method to prevent anthropogenic climate change of any sort would be the extermination of all mankind.
This is actually a good study as it reveals many things. The first thing it reveals is the ignorance of the authors. In order to accept their hypothesis, one has to agree that man is “extra-terrestrial” and therefore any actions man has on the environment is against nature or natural cycles. I find this hypothesis fascinating as I am a big fan of Arthur C. Clarke and “2001: A Space Odyssey”.
The second revelation revealed is that this study now opens the door for the AGW group to admit to the existance of the MWP. Something that a “vast consensus” of scientists have agreed for a long time really did exist. Now they can admit to it, without destroying their premise. Of course the Hockey stick will have to undergo a minor revision, but I am sure we can all start talking about the “Kayak Oar” that will replace it.
johanna;
Eucalypts are unique, as is the environment they’re suited for. Other areas that make the mistake of transplanting them learn that fast.
Just my 2c worth. Dr Pielke Snr has been talking about Land Use Change and it’s effect on (at least local) climate. Disregarding CO2 issues completely, he has written that UHI, change of land from forest or, I believe, prairie to farmed land has distinct impact on the environment. Of course he has been pooh-poohed by the ‘Team’, so doesn’t this actually support his hypothesis? Cetainly supports it better than any CO2 change as climate change mediator.