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 | | From: | Edmund Fitzgerald | | Subject: | 'Greenhouse Humans May Have Averted New Ice Age' | | Date: | Sun, 23 Jan 2005 00:22:18 -0500 |
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 | It may be too late. It's fucking cold.
From:
http://news.scotsman.com/latest.cfm?id=4035704
Sun 23 Jan 2005
2:50am (UK)
'Greenhouse Humans May Have Averted New Ice Age'
By John von Radowitz, PA Science Correspondent
Humans may have unwittingly saved themselves from a looming ice age by
interfering with the Earth's climate, according to a new study.
The findings from a team of American climate experts suggest that were it
not for greenhouse gases produced by humans, the world would be well on the
way to a frozen Armageddon.
Scientists have traditionally viewed the relative stability of the Earth's
climate since the end of the last ice age 10,000 years ago as being due to
natural causes.
But there is evidence that changes in solar radiation and greenhouse gas
concentrations should have driven the Earth towards glacial conditions over
the last few thousand years.
What stopped it has been the activity of humans, both ancient and modern,
argue the scientists.
Over the last 8,000 years carbon dioxide levels in the atmosphere have
gradually risen, when previous trends indicated that it should have dropped.
Methane, another greenhouse gas, had also increased instead of fallen.
The unexpected trends could be explained by massive early deforestation in
Eurasia, rice farming in Asia, the introduction of livestock, and the
burning of wood and plant material, all of which led to an outpouring of
greenhouse emissions.
The United States researchers, led by William Ruddiman from the University
of Virginia in Charlottesville, used a climate model to test what would
happen if these greenhouse gases were reduced to their "natural" level.
They wrote in the journal Quaternary Science Reviews: "In the absence of
anthropogenic contributions, global climate is almost 2C cooler than today
and roughly one third of the way toward full glacial temperatures."
At the peak of the last ice age, which began 70,000 years ago, 97% of Canada
was covered by ice.
The research showed that without the human contribution to global warming,
Baffin Island would today be in a condition of "incipient glaciation".
"Portions of Labrador and Hudson Bay would also have moved very close to
such a state had greenhouse gas concentrations followed natural trends,"
said the scientists.
The experiment had probably underestimated the amount of ice that would
exist today in north-east Canada without human interference, they said.
The number of potential influences on the model was deliberately limited in
order to highlight the effect of greenhouse gases.
It did not take into account the effect of increased ice cover, which would
have caused further cooling by reflecting back the sun's rays. Dynamic ocean
processes were also not accounted for.
Anthropologist Dr Benny Peiser, from Liverpool John Moores University, said:
"If the research findings are correct, a radical change in the perception of
anthropogenic greenhouse gas emissions will be required.
"Instead of driving us to the brink of environmental disaster, human
intervention and technology progress will be seen as vital activities that
have unintentionally delayed the onset of a catastrophic ice age."
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| | From: | Leonard Evens | | Subject: | Re: 'Greenhouse Humans May Have Averted New Ice Age' | | Date: | Sun, 23 Jan 2005 12:51:36 -0600 |
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| Edmund Fitzgerald wrote:
> It may be too late. It's fucking cold.
>
> From:
> http://news.scotsman.com/latest.cfm?id=4035704
>
> Sun 23 Jan 2005
> 2:50am (UK)
> 'Greenhouse Humans May Have Averted New Ice Age'
>
> By John von Radowitz, PA Science Correspondent
>
> Humans may have unwittingly saved themselves from a looming ice age by
> interfering with the Earth's climate, according to a new study.
>
> The findings from a team of American climate experts suggest that were it
> not for greenhouse gases produced by humans, the world would be well on the
> way to a frozen Armageddon.
>
> Scientists have traditionally viewed the relative stability of the Earth's
> climate since the end of the last ice age 10,000 years ago as being due to
> natural causes.
>
> But there is evidence that changes in solar radiation and greenhouse gas
> concentrations should have driven the Earth towards glacial conditions over
> the last few thousand years.
>
> What stopped it has been the activity of humans, both ancient and modern,
> argue the scientists.
>
> Over the last 8,000 years carbon dioxide levels in the atmosphere have
> gradually risen, when previous trends indicated that it should have dropped.
We know from ice core data that the concentration of these gases in the
atmosphere has been relatively constant during this time, and only
started rising significantly with the advent of the industrial
revolution. The great bulk of the increase has been in the 20th
century. It seems highly conjectural to me to assume that these
greenhouse gases would have declined during this period absent
anthropormorphic contributions. It is an interesting idea, but should
be taken with more than a grain of salt. compare for example with the
conjectured destruction of large mammals in the Americans by humans.
That is still quite controversial among people who have studied the matter.
In any event, it seems to say little or nothing about the significance
of recent increases in greenhouse gas contributions.
>
> Methane, another greenhouse gas, had also increased instead of fallen.
>
> The unexpected trends could be explained by massive early deforestation in
> Eurasia, rice farming in Asia, the introduction of livestock, and the
> burning of wood and plant material, all of which led to an outpouring of
> greenhouse emissions.
>
> The United States researchers, led by William Ruddiman from the University
> of Virginia in Charlottesville, used a climate model to test what would
> happen if these greenhouse gases were reduced to their "natural" level.
>
> They wrote in the journal Quaternary Science Reviews: "In the absence of
> anthropogenic contributions, global climate is almost 2C cooler than today
> and roughly one third of the way toward full glacial temperatures."
>
> At the peak of the last ice age, which began 70,000 years ago, 97% of Canada
> was covered by ice.
>
> The research showed that without the human contribution to global warming,
> Baffin Island would today be in a condition of "incipient glaciation".
>
> "Portions of Labrador and Hudson Bay would also have moved very close to
> such a state had greenhouse gas concentrations followed natural trends,"
> said the scientists.
>
> The experiment had probably underestimated the amount of ice that would
> exist today in north-east Canada without human interference, they said.
>
> The number of potential influences on the model was deliberately limited in
> order to highlight the effect of greenhouse gases.
>
> It did not take into account the effect of increased ice cover, which would
> have caused further cooling by reflecting back the sun's rays. Dynamic ocean
> processes were also not accounted for.
>
> Anthropologist Dr Benny Peiser, from Liverpool John Moores University, said:
> "If the research findings are correct, a radical change in the perception of
> anthropogenic greenhouse gas emissions will be required.
>
> "Instead of driving us to the brink of environmental disaster, human
> intervention and technology progress will be seen as vital activities that
> have unintentionally delayed the onset of a catastrophic ice age."
>
>
>
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