Latest Climate Change Research

Source: Emory University Health Sciences Center

Posted: January 31, 2006

Increasing Plant Enzyme Efficiency May Hold Key To
Global Warming

Global warming just may have met its match. In
research recently completed at Emory University School
of Medicine, scientists have discovered a mutant
enzyme that could enable plants to use and convert
carbon dioxide more quickly, effectively removing more
greenhouse gasses from the atmosphere.

The findings were published online on January 19 and
will appear in the February issue of the journal
"Protein Engineering Design and Selection." Ichiro
Matsumura, PhD, assistant professor of biochemistry at
Emory University School of Medicine, is the senior
author and principal investigator. The first author is
research specialist Monal R. Parikh.

During photosynthesis, plants, and some bacteria,
convert sunlight and carbon dioxide into usable
chemical energy. Scientists have long known that this
process relies on the enzyme rubulose 1,5-bisphosphate
carboxylase/oxygenase, also called RuBisCO. While
RuBisCO is the most abundant enzyme in the world, it
is also one of the least efficient. As Dr. Matsumura
says, "All life pretty much depends on the function on
this enzyme. It actually has had billions of years to
improve, but remains about a thousand times slower
than most other enzymes. Plants have to make tons of
it just to stay alive."

RuBisCO's inefficiency limits plant growth and stops
organisms from using and assimilating all the carbon
dioxide in the atmosphere. Since the spread of
photosynthesis has not kept pace with the amount of
gas in the atmosphere, the gas builds up. The
resulting gas buildup is one cause of global warming.
A 2004 report by the National Science Foundation
estimates that atmospheric carbon dioxide
concentrations remained steady at between 200 and 280
parts per million for thousands of years, but that
carbon dioxide levels have risen dramatically since
the Industrial Revolution of the 1800s, leading to 380
parts per million of carbon dioxide in the atmosphere
today.

For decades, scientists have struggled to engineer a
variant of the enzyme that would more quickly convert
carbon dioxide. Their attempts primarily focused on
mutating specific amino acids within RuBisCO, and then
seeing if the change affected carbon dioxide
conversion. Because of RuBisCO's structural
complexity, the mutations did not have the desired
outcome.

For their own study, Dr. Matsumura and his colleagues
decided to use a process called "directed evolution"
which involved isolating and randomly mutating genes,
and then inserting the mutated genes into bacteria (in
this case Escherichia coli, or E. coli). They then
screened the resulting mutant proteins for the fastest
and most efficient enzymes. "We decided to do what
nature does, but at a much faster pace." Dr. Matsumura
says. "Essentially we're using evolution as a tool to
engineer the protein."

Because E. coli does not normally participate in
photosynthesis or carbon dioxide conversion, it does
not usually carry the RuBisCO enzyme. In this study,
Matsumura's team added the genes encoding RuBisCO and
a helper enzyme to E. coli, enabling it to change
carbon dioxide into consumable energy. The scientists
withheld other nutrients from this genetically
modified organism so that it would need RuBisCO and
carbon dioxide to survive under these stringent
conditions.

They then randomly mutated the RuBisCO gene, and added
these mutant genes to the modified E. coli. The
fastest growing strains carried mutated RuBisCO genes
that produced a larger quantity of the enzyme, leading
to faster assimilation of carbon dioxide gas. "These
mutations caused a 500 percent increase in RuBisCO
expression," Dr. Matsumura says. "We are excited
because such large changes could potentially lead to
faster plant growth. This results also suggests that
the enzyme is evolving in our laboratory in the same
way that it did in nature."
---

Source: Penn State

Posted: February 10, 2006

Frozen Methane Chunks Not Responsible For Abrupt
Increases In Atmospheric Methane

Icy chunks of frozen methane and water are not
responsible for the periodic increases in atmospheric
methane recorded in Greenland ice cores, according to
a Penn State geoscientist.

The ice core samples from the Greenland Ice Sheet
Project II cover the last 40,000 years and present a
picture of the Earth's climate over that time span.

"There are two hypotheses for the cause of the rapid
increase in methane seen in the ice core records,"
says Dr. Todd Sowers, research associate in
geosciences. "Some researchers believe that clathrates
were the source of the methane while other researchers
believe it was generated in wetlands."

Clathrates are icy balls of methane and water found in
the continental margin sediments -- 200 miles out to
sea. They form when methanogenic bacteria deep in
marine sediments generate methane which rises through
the sediment and, if the temperatures and pressures
are right, form balls of ice.

Conveniently, methane in clathrates and methane
produced from wetlands are produced by different
biochemical processes and consequently have differing
ratios of the two stable hydrogen isotopes -- hydrogen
and deuterium. Methanogenic bacteria in marine
sediments convert carbon dioxide into methane and
water while wetland methane is a byproduct of
fermentation. If clathrates suddenly released methane
into the atmosphere, the ratio of the heavier isotope
of hydrogen, deuterium, to the normal hydrogen would
increase due to the elevated nature of the
deuterium/hydrogen ratio associated with clathrates.

Sowers looked at methane trapped in the layers of ice
preserved in the GISP II ice core. He sampled the
layers every 1,000 years between 8,000 and 25,000
years, and every 30 years during periods when
atmospheric methane levels increase abruptly to
provide a finer assessment of the cause of the
elevated methane levels.

"Hydrogen isotope ratios were stable during these
abrupt warming episodes," says Sowers in his report in
today's (Feb. 10) issue of Science. "The increased
methane that accompanied the warming did not come from
marine clathrates."

While Sowers can rule out clathrates during the abrupt
events, his data do provide new information on the
sources of methane that caused the long-term methane
increase during the last glacial termination. Sowers
observed elevated isotope ratios during the last
glacial period compared to today.

There are a handful of factors that may have
contributed to the observed change in the isotope
ratios. These factors include a change in terrestrial
vegetation type, lowered sea level and/or a
temperature dependent isotope effect associated with
colder glacial temperature.

"Even if these things happened, the total impact on
the isotope budget would have been very small and
would not account for the elevated isotope ratios
during the last glacial period," says Sowers. "That
leaves us with two other possibilities, changes in
wetland systematics and/or increased natural gas
emissions during the glacial period."

If natural gas seeping out of deposits beneath the
oceans decreased throughout the glacial termination,
then the methane isotope signature would follow the
observed record. Methane emissions from natural gas
might be higher during the glacial period due to
lowered sea level that reduced the pressure on the
undersea natural gas seeps allowing more gas to escape
directly to the atmosphere.

"This possibility cannot be discounted," says Sowers.
"However, I think the answer probably lies in changes
in wetland methane emissions."

Climate could alter wetlands in two ways. First,
during the termination, methane emissions from
wetlands would increase if the areal extent of
wetlands increased with warmer climates. Second, if
the wetlands were drier during the glacial period,
then the methane generated at depth would have a
greater chance of being consumed by methanotrophic
bacteria inhabiting the oxygenated region immediately
above the lowered water tables.

"Methane eating bacteria prefer to consume methane
with the lighter hydrogen isotope, which tips the
ratio of heavy to light hydrogen in the methane
emitted to the atmosphere toward heavy," says Sowers.
"This would create a higher hydrogen isotope ratio
that is consistent with that found during the last
glacial period."
###

The National Science Foundation funded this work.
----

Source: University of East Anglia

Posted: February 10, 2006

Medieval Diaries Aid Scientists Ascertain Increase In
Hot Spots Due To Global Warming

The temperature of the northern hemisphere has
increased over a larger area in the last century than
at any time in the past millennium a report published
in Science reveals this week.

The study finds that the number of 'hot spots' has
increased dramatically in the Northern Hemisphere in
the last century compared to the past 1200 years,
adding to the growing evidence of wide-scale global
warming.

Dr Tim Osborn and Prof Keith Briffa, of the Climatic
Research Unit team at the University of East Anglia,
analyzed thermometer measurements of temperature from
1856 onwards to establish the spatial extent of recent
warming, and compared it with evidence from as far
back as AD 800 (from tree rings, ice cores and
shells).

The study found evidence for periods of significant
warmth (890 - 1170) in the Northern Hemisphere during
medieval times and for clearly colder periods (1580 -
1850) during the so-called "Little Ice Age".

Their key conclusion was that the 20th century stands
out as having unusually widespread warmth, compared to
all of the natural warming and cooling episodes during
the past 1,200 years.

The research team gathered climate change data from a
number of regions in the Northern Hemisphere
especially:

Long life evergreen trees growing in Scandinavia,
Siberia and the Rockies, which had been cored to
reveal the patterns of wide and narrow tree rings over
time -- wider rings relating to warmer temperatures.

Ice from cores drilled in the Greenland ice sheets
revealed which years were warmer than others by the
chemical composition of the ice.

They also used a record developed from diaries of
people living in the Netherlands and Belgium over the
past 750 years that revealed for example the years
when the canals froze.
----

Source: University of Alberta

Posted: February 7, 2006

Thousands Of Barges Could Save Europe From Deep Freeze

It is ironic that one consequence of global warming is
that Europe might plunge into a deep freeze. This
possibility stimulated an unusual research project at
the University of Alberta.

Dr. Peter Flynn, the Poole Chair in Management for
Engineers in the U of A Department of Mechanical
Engineering, has studied whether down-welling ocean
currents can carry more dissolved carbon into the deep
ocean. He learned they can't, but in the course of
this research he found some evidence that the ocean
currents that bring warm water to the oceans off
northern Europe may be weakening.

The results of the research have been published
recently in the journal Climatic Change.

"The current is like an ocean conveyor belt," Flynn
explained. "It starts in the north Atlantic, where
down-welling, cold, arctic water flows south at the
bottom of the ocean, and then warm, tropical water
flows north to fill in the vacuum created by the cold
water, and this warm water helps ensure a mild climate
in northern Europe,"

The melting of fresh water ice due to global warming
can reduce the flow of the down-welling current, and a
study published recently in the journal Nature by
researchers at the University of Southhampton in
England reported evidence of weakening down-welling
currents.

Flynn and a graduate student evaluated seven different
methods to enhance down-welling currents. They found
one way was far more cost effective than the others:
making thicker sea ice by pumping salty ocean water on
top of ice sheets.

They envisioned more than 8,000 barges moving into the
northern ocean in the fall, speeding the initial
formation of sea ice by pumping a spray of water into
the air, and then, once the ice is formed, pumping
ocean water on top of it, trapping the salt in the ice
and reaching a thickness of seven meters.

In the spring, water would continue to be pumped over
the ice to melt it, forming a vast amount of cold,
salty water that sinks and adds to the down-welling
current to re-strengthen it.

The estimated cost is about $50 billion.

"When we first did this study we thought this idea was
way too expensive--we were shocked by the numbers,"
Flynn said. "But let's say conservatively that there
are 100 million people in Europe affected by this
current. Fifty billion dollars would come to 500
dollars per person, and we don't think that is an
unreasonable price if the glaciers are at your
backdoor and your way of life is disappearing."

Flynn emphasizes that his group does not propose this
scheme as the first or best choice, since all
geo-engineering projects have a risk of unforeseen
circumstances.

"The best way to deal with global warming is to deal
with the causes, fossil carbon in the atmosphere, not
the symptoms," he said. "However, if our efforts to
control CO2 levels in the atmosphere fail and we reach
a crisis, we can contemplate emergency action."
----

Antarctic Krill Provide Carbon Sink In Southern Ocean

New research on Antarctic krill (Euphausia superba), a
shrimp-like animal at the heart of the Southern Ocean
food chain, reveals behaviour that shows that they
absorb and transfer more carbon from the Earth's
surface than was previously understood. The results
are published this week in the journal Current
Biology.

New research on Antarctic krill (Euphausia superba), a
shrimp-like animal at the heart of the Southern Ocean
food chain, reveals behaviour that shows that they
absorb and transfer more carbon from the Earth's
surface than was previously understood. (Image
courtesy of British Antarctic Survey)

Scientists from British Antarctic Survey (BAS) and
Scarborough Centre of Coastal Studies at the
University of Hull discovered that rather than doing
so once per 24 hours, Antarctic krill 'parachute' from
the ocean surface to deeper layers several times
during the night. In the process they inject more
carbon into the deep sea when they excrete their waste
than had previously been understood.

Lead Author Dr Geraint Tarling from BAS says, "We've
known for a long time that krill are the main food
source for whales, penguins and seals, but we had no
idea that their tactics to avoid being eaten could
have such added benefits to the environment. By
parachuting down they transport carbon which sinks
ultimately to the ocean floor -- an amount equivalent
to the annual emissions of 35 million cars -- and this
makes these tiny animals much more important than we
thought."

Krill feed on phytoplankton near the ocean surface at
night but sink deeper in the water column during the
day to hide from predators. By knowing how these
animals behave, we can understand better the
contribution they make to removing carbon from the
Earth's atmosphere and upper ocean.

###

Background

Satiation gives krill that sinking feeling by Geraint
A. Tarling and Magnus L. Johnson is published in
Current Biology on 7 February 2006.

Antarctic krill (Euphausia superba), are shrimp-like
crustaceans that are one of the most important animals
in the Southern Ocean. They feed on phytoplankton and
are in turn eaten by a wide range of animals including
fish, penguins, seals and whales. Phytoplankon are the
starting point for the marine food chain and use
photosynthesis to extract carbon from carbon dioxide.

Krill live in the open ocean, mainly in large swarms
and reach particularly high numbers in Antarctica. The
migrations that they perform (called Diel Vertical
Migrations, DVM) are a way of transporting carbon to
the ocean's interior because they eat phytoplankton at
the surface and excrete their waste at depth.
Antarctic krill can grow up to a length of 6cm and can
live for 5-6 years. They are one of the largest
protein resources on Earth and can be fished easily
with large nets for human consumption.

There is enough Antarctic krill to fill the total
volume of the new Wembley stadium 1500 times. Spread
out on the floor, they would cover the entire area of
Scotland. The total weight of Antarctic krill is
calculated between 50-150 million tonnes.

The krill migrate from the ocean surface by fanning
out their swimming legs and enter a controlled
descent, akin to parachuting. The behaviour is most
apparent when their stomachs are full and may be an
effective means of getting out of harms way when they
can eat no more.

Numbers of Antarctic krill have dropped by about 80%
since the 1970's. The most likely explanation is a
dramatic decline in winter sea-ice. Krill feed on the
algae found under the surface of the sea-ice, which
acts as a kind of 'nursery'. The Antarctic Peninsula,
a key breeding ground for the krill, has warmed by
2.5¡C in the last 50 years, with a striking decrease
in sea-ice. It is not fully understood how the loss of
sea-ice there is connected to the warming, but could
be behind the decline in krill.

The study was carried out aboard the British Antarctic
Survey ship RRS James Clark Ross from December 2004 -
January 2005 around the islands of South Georgia in
the South Atlantic. The krill were caught with nets
and transferred to tanks for observations. The tanks
were continuously supplied with water (and therefore
food) from the sea surface.

British Antarctic Survey is a world leader in research
into global issues in an Antarctic context. It is the
UK's national operator and is a component of the
Natural Environment Research Council. It has an annual
budget of around £40 million, runs nine research
programmes and operates five research stations, two
Royal Research Ships and five aircraft in and around
Antarctica. More information about the work of the
Survey can be found at: www.antarctica.ac.uk

Centre for Coastal studies is based at the Scarborough
campus, at the University of Hull. The Centre for
Coastal Studies is a small but vibrant centre,
specialising in teaching and research with a strong
emphasis on fieldwork. The centre attracts around 50
students a year from a wide range of backgrounds who
study degrees in Coastal Marine Biology, Environmental
Science and Ecology. Students acquire strong
theoretical knowledge of their subject combined with
skill and expertise in the field. Academics and
postgraduates in the centre are currently working on a
diverse range of topics including intertidal ecology,
krill morphometrics, fisheries management and tropical
fish biology. For more information visit:
www.ccs.hull.ac.uk
----