——————————————————————————————————————–
” … scientists didn’t know until now whether such ancient, frozen
organisms and their
DNA could be revived at all or for how long cells are viable after
they’ve been frozen.”
———————————————————————————————————————–

Science Daily
Web address: http://www.sciencedaily.com/releases/2007/08/070807084214.htm

Source:         Rutgers, the State University of New Jersey
Date:         August 13, 2007

Ancient Microorganisms May Return To Life As Glaciers Melt

Science Daily – The DNA of ancient microorganisms, long frozen in
glaciers, may return to life as the glaciers melt, according to a
paper published recently online in the Proceedings of the National
Academy of Sciences by scientists at Rutgers, The State University of
New Jersey, and Boston University. The article is scheduled to appear
in the print edition on Tuesday, Aug. 14.

The researchers chose Antarctic glaciers for their research because
the polar regions are subject to more cosmic radiation than the rest
of the planet and contain the oldest ice on the planet. (Credit: Joe
Mastroianni, National Science Foundation)

The finding is significant, said Kay Bidle, assistant professor of
marine and coastal sciences at Rutgers, because scientists didn’t know
until now whether such ancient, frozen organisms and their DNA could
be revived at all or for how long cells are viable after they’ve been
frozen. Bidle is lead author of the article, “Fossil Genes and
Microbes in the Oldest Ice on Earth.”

Bidle and his co-authors, Rutgers colleague Paul Falkowski, SangHoon
Lee of Korea’s Polar Research Institute and David Marchant of Boston
University — melted five samples of ice ranging in age from 100,000
to 8 million years old to find the microorganisms trapped inside.

The researchers wanted to find out how long cells could remain viable
and how intact their DNA was in the youngest and oldest ice. “First,
we asked, do we detect microorganisms at all”” Bidle said. “And we did
— more in the young ice than in the old. We tried to grow them in
media, and the young stuff grew really fast. We recovered them [the
microorganisms] easily; we could plate them and isolate colonies. They
doubled every couple of days.” By contrast, Bidle said, the
microorganisms from the oldest ice samples grew very slowly, doubling
only every 70 days.

Not only were the microorganisms in oldest ice slow to grow, the
researchers were unable to identify them as they grew, because their
DNA had deteriorated. In fact, the DNA in the five samples examined
showed an “exponential decline” after 1.1 million years, “thereby
constraining the geological preservation of microbes in icy
environments and the possible exchange of genetic material to the
oceans.” “There is still DNA left after 1.1 million years,” Bidle
said. “But 1.1 million years is the ‘half-life’ — that is, every 1.1
million years, the DNA gets chopped in half.” Bidle said the average
size of DNA in the old ice was 210 base pairs — that is, 210 units
strung together. The average genome size of a bacterium, by
comparison, is 3 million base pairs.

The researchers chose Antarctic glaciers for their research because
the polar regions are subject to more cosmic radiation than the rest
of the planet and contain the oldest ice on the planet. “It’s the
cosmic radiation that’s blasting the DNA into pieces over geologic
time, and most of the organisms can’t repair that damage.” Because the
DNA had deteriorated so much in the old ice, the researchers also
concluded that life on Earth, however it arose, did not ride in on a
comet or other debris from outside the solar system. “…The
preservation of microbes and their genes in icy comets may have
allowed transfer of genetic material among planets,” they wrote.
“However, given the extremely high cosmic radiation flux in space, our
results suggest it is highly unlikely that life on Earth could have
been seeded by genetic material external to this solar system.”

The five ice samples used in the experiment were taken from two
valleys in the Transantarctic Mountains by Marchant, the Boston
University glaciologist. “He sent us blocks of ice,” said Bidle of
Marchant. “Without them, we couldn’t have done the work. Dave is also
one of the few researchers who is knowledgeable about the age of the
ice, and also important information about the formation and geology of
the ice.”

The actual melting of the ice, growing of microorganisms and
examination of DNA was carried out by Bidle and Lee, who was a
visiting researcher at Rutgers at the time. Falkowski co-directed the
research and helped to write the paper.

The work was funded by a grant to Falkowski and Bidle from the Gordon
and Betty Moore Foundation.

Note: This story has been adapted from a news release issued by
Rutgers, the State University of New Jersey.

Copyright (c) 1995-2007 ScienceDaily LLC  -  All rights reserved

A new entry titled ‘Arctic sea ice watch’ has been posted to RealClimate.org.

http://www.realclimate.org/index.php?p=464

——————————————————

Sample quotes:
“The minimum extent is usually in early to mid September, but this
year, conditions by Aug 9 had already beaten all previous record
minima.”

“The reduction is around 1.2 million square km of ice, a little bit
larger than the size of California and Texas combined.”

———————————————————————-
“The next piece of the equation is to define “dangerous climate
change”. This is a bit of a guessing game, but 2 degrees C (above the
present global average – Lance) seems a reasonable danger limit. This
would be decidedly warmer than the Earth has been in millions of
years….”

“One final note: most of the climate change community, steered by
Kyoto and IPCC, limit the scope of their consideration to the year
2100 …. This calculation seems rather callous, almost sneaky, given
the inevitability of warming once the CO2 is released. I suspect that
many in the community are not aware of this sneaky implication of
restricting our attention to a relatively short time horizon.”
———————————————————————————————————————–

Real Climate   http://www.realclimate.org/
6 Nov 2006

How much CO2 emission is too much?
http://www.realclimate.org/index.php?p=368
David Archer

This week, representatives from around the world will gather in
Nairobi, Kenya for the latest Conference of Parties (COP) meeting of
the Framework Convention of Climate Change (FCCC) which brought us
the Kyoto Protocol. The Kyoto Protocol expires in 2012, and the task
facing the current delegates is to negotiate a further 5-year
extension. This is a gradual, negotiated, no doubt frustrating
process. By way of getting our bearings, a reader asks the question,
what should the ultimate goal be? How much CO2 emissions cutting
would it take to truly avoid “dangerous human interference in the
climate system”?

On the short term of the next few decades, the line between success
and excess can be diagnosed from carbon fluxes on Earth today.
Humankind is releasing CO2 at a rate of about 5 Gton C per year from
fossil fuel combustion, with a further 2 Gton C per year from
deforestation. Because the atmospheric CO2 concentration is higher
than normal, the natural world is absorbing CO2 at a rate of about 2
Gton C per year into the land biosphere and into the oceans, for a
total of about 4 Gton C per year. The CO2 concentration of the
atmosphere is rising because of the 3 Gton C imbalance. If we were to
cut emissions by about half, from a total of 7 down to about 4 Gton C
per year, the CO2 concentration of the atmosphere would stop rising
for awhile. That
would be a stunning success, but the emission cuts contemplated by
Kyoto were only a small step in this direction.

Eventually, the chemistry of the ocean would equilibrate with this
new atmospheric pCO2 concentration of about 380 ppm (the current
concentration), and its absorption of new CO2 would tail off.
Presumably the land biosphere would also inhale its fill and stop
absorbing more. How long can we expect to be able to continue our
lessened emissions of 4 Gton C per year? The answer can be diagnosed
from carbon cycle models. A range of carbon cycle models have been
run for longer than the single-century timescale that is the focus of
the IPCC and the FCCC negotiation process. The models include an
ocean and often a terrestrial biosphere to absorb CO2, and sometimes
chemical weathering (dissolution of rocks) on land and deposition of
sediments in the ocean. The models tend to predict a maximum
atmospheric CO2 inventory of about 50-70% of the total fossil fuel
emission slug. Let’s call this quantity the peak airborne fraction,
and assume it to be 60%.

The next piece of the equation is to define “dangerous climate
change”. This is a bit of a guessing game, but 2 degrees C seems a
reasonable danger limit. This would be decidedly warmer than the
Earth has been in millions of years, and warm enough to eventually
raise sea level by tens of meters. A warming of 2 degrees C could be
accomplished by raising CO2 to 420 ppm and waiting a century or so,
assuming a climate sensitivity of 3.5 degrees C for doubling CO2, a
typical value from models and diagnosed from paleo-data. Of the 420
ppm, 140 ppm would be from fossil fuels (given an original natural
pCO2 of 280 ppm). 140 ppm equals 280 Gton C, which divided by the
peak airborne fraction of 60% yields a total emission slug of about
500 Gton C.

How much is 500 Gton C? We have already released about 300 Gton C,
and the business-as-usual scenario projects 1600 Gton C total release
by the year 2100. Avoiding dangerous climate change requires very
deep cuts in CO2 emissions in the long term, something like 90% of
business-as-usual averaged over the coming century. Put it this way
and it sounds impossible. Another way to look at it, which doesn’t
seem quite as intractable, is to say that the 200 Gton C that can
still be “safely” emitted is roughly equivalent to the remaining
traditional reserves of oil and natural gas. We could burn those
until they’re gone, but declare an immediate moratorium on coal, and
that would be OK, according to our defined danger limit of 2 degrees
C. A third perspective is that if we could limit emissions to 4 Gton
C per year starting now, we could continue doing that for 200/4 = 50
years.

One final note: most of the climate change community, steered by
Kyoto and IPCC, limit the scope of their consideration to the year
2100.  By setting up the problem in this way, the calculation of a
safe CO2 emission goes up by about 40%, because it takes about a
century for the climate to fully respond to rising CO2. If CO2
emission continues up to the year 2100, then the warming in the year
2100 would only be about 60% of the “committed warming” from the CO2
concentration in 2100. This calculation seems rather callous, almost
sneaky, given the inevitability of warming once the CO2 is released.
I suspect that many in the community are not aware of this sneaky
implication of restricting our attention to a relatively short time
horizon.

Bookmark the permalink.

Comments are closed