———————————————–
“But there are issues there,” he said. “One is,
do you really think the government should have a
monopoly on tracking changes in the climate?”
“The loss of oxygen in itself isn’t an issue, he
said. There’s plenty of oxygen in the air, and he
is studying tiny changes in the levels. What his
research is clarifying is what is happening to
the CO2.”
“Ralph Keeling’s oxygen studies have shown that
while more CO©— is being pumped into the
atmosphere, land ecosystems are storing more of
it than they were a couple of decades ago, he
said.
“There are four main reasons, he said. Plants
grow a little faster in an atmosphere with more
CO2; a warming climate has extended growing
seasons; some plants are using nitrogen from
pollution and growing faster; and some previously
cut forests have regrown.”
“We need to know how much time we have,” Haymet
said. “That’s what these measurements tell us.”
——–
San Diego Union-Tribune
March 27, 2008
Graphic evidence
Keelings’ half-century of CO2 measurements serves
as global warming’s longest yardstick
http://www.signonsandiego.com/news/science/20080327-9999-1c27curve.html
By Robert Krier UNION-TRIBUNE STAFF WRITER
Fifty years ago this month, geochemist Charles
David Keeling began recording the curve of the
Earth.
That may be stating it a bit grandiosely, but not too much.
Few scientific studies have had a bigger impact,
and not just on people in white lab coats. Like
the carbon dioxide Keeling studied, the results
of his research have circled the globe.
He began monitoring CO2 levels in the atmosphere
at Mauna Loa, Hawaii, in March of 1958. He was
working for Roger Revelle, then director of the
Scripps Institution of Oceanography in La Jolla
and one of the founders of the University of
California at San Diego.
Decades of data from Mauna Loa have been
condensed into one of the most famous scientific
graphs of the 20th century: the Keeling Curve.
The graph demonstrates that CO2 levels rise and
fall each year, and more importantly, that carbon
dioxide is gradually accumulating in the
atmosphere.
The graph has come to represent man’s growing
impact on climate and the environment. Keeling’s
work laid the foundation for the study of global
warming.
The curve was born from his personal curiosity,
but after 50 years, it lives on because a member
of the next generation inherited his
determination and persistence.
Charles David Keeling died in 2005, but his son,
Ralph, has kept the time-series studies alive.
Ralph Keeling’s own measurements of atmospheric
oxygen levels, which he also does at Scripps,
complement the Keeling Curve.
“In a sense, he was the first person to really
commit his career to the problem of global
warming,” Ralph Keeling said of his father. “He
was a pioneer in a new field. While he was not
really doing what geochemists were supposed to
do, he was recognizing that there was something
else that was even possibly more important.”
Keeling’s Curve is “monumentally important for
climate study,” said Tony Haymet, director of the
Scripps Institution of Oceanography.
“When Dave Keeling started, only Dave and his dog
and Roger Revelle knew this was a problem. It’s
quite a journey, and I think it shows the value
of data.”
Carbon counting
In the mid-1950s, before measurements of CO2 in
the atmosphere had been perfected, Charles David
Keeling was working on a project in Big Sur that
examined the carbon content of rivers. To
understand the rivers’ composition, he needed to
learn about the exchange of carbon with the
atmosphere.
Keeling developed an apparatus that measured
carbon dioxide in the air. He built a vacuum
extraction system that isolated CO2; then he
modernized a decades-old device called a
manometer to measure the gas. He designed glass
flasks, about the size of soccer balls, with
small stopcocks to hold a vacuum.
“I weighed them empty and filled them with water
to determine their volume,” the elder Keeling
wrote in a brief autobiography in 1998. He later
took air samples with the flasks.
“I extracted the CO2 with my vacuum line,
measured its amount with my new manometer, and
calculated its concentration in each sample,” he
wrote.
His method was much more precise than what others
had used to examine CO2 in the air.
When looking at the literature on CO2 in the
atmosphere, Keeling had the impression that
carbon dioxide should be quite variable depending
where a person was. He expected fluctuations of
as much as 100 parts per million, depending on
wind direction or other factors. There was no
sense there might be patterns and regularity.
To his surprise, he almost always found the same
number when he measured CO2 in the afternoon.
Samples taken at night showed elevated levels,
because plants release CO2 at night, then
reabsorb it during the day. But the afternoon
samples tended to give nearly the same value:
about 312 parts per million.
He came to believe that he was witnessing the
tendency for the atmosphere well above the ground
to mix with air at the surface because of heating
of the ground in the afternoon.
But to explain the consistent afternoon CO2
levels he was finding, there would have to be a
kind of constant background. Scientists didn’t
know that such a background existed.
This was at a time when Revelle and a few others
were already thinking about the possibility that
carbon dioxide was accumulating in the atmosphere.
“There were discussions about how to do sampling
to see whether it was building up,” said Ralph
Keeling, who is also a professor at Scripps. “He
had the idea that maybe really all you had to do
was to go to a sufficiently clean site and probe
this background. You could do an accurate
determination of trends just by sitting in one
spot and determining what was happening with this
background.”
That spot turned out to be Mauna Loa, which sits
at more than 13,600 feet and is surrounded by
thousands of miles of ocean. Keeling worked with
a man named Harry Wexler at the Weather Service
in Washington, D.C., while simultaneously working
on a related project for Revelle at Scripps.
Daily measurements began in March 1958, and air
samples were shipped back to Scripps. The Mauna
Loa record began shortly after CO©— measurements
started at the South Pole, and Keeling examined
those samples, too. But the Mauna Loa
measurements took advantage of a new,
more-accurate analyzer, and the South Pole
records were spotty.
After he had about two years of data, Keeling was
able to confirm his suspicions: In addition to
daily and seasonal fluctuations, atmospheric CO©—
levels overall were, in fact, rising.
“At that point, it wasn’t even known if it was
increasing or not,” Ralph Keeling said. “That was
a pretty significant discovery, because it
legitimized further work on the carbon dioxide
problem. Until you really knew something was
changing, it was a dangerous investment, in a
way, for scientists to work on this because the
whole problem could not even be there. Very few
people had worked on it.”
Today, there are many CO2 monitoring stations
around the globe. But the Mauna Loa measurements
constitute the longest continuous record of CO2
concentrations anywhere in the world. (Keeling’s
glass flasks are still used for CO2 research
around the globe. The Mauna Loa record, however,
is now based on data from a separate analyzer
that provides a more-detailed, continuous
measurement of CO2.)
Before Keeling’s work, no one knew how much of
the CO2 produced by the burning of fossil fuels –
if any – was being absorbed by the oceans. The
curve proved that not all of that man-made CO2
was going back into the seas; some of it was
accumulating in the atmosphere.
Carbon dioxide is what scientists consider a
greenhouse gas. It occurs naturally, but the
burning of fossil fuels has increased its
atmospheric concentration. Sunlight can pass
through it and warm the Earth, but the gas then
traps some of that heat in the atmosphere. Most
climatologists theorize that as the concentration
of greenhouse gases in the atmosphere increases,
so will global temperatures.
“In a sense, the measure of whether humanity
copes with this problem or not is the Keeling
Curve, the Mauna Loa record,” Ralph Keeling said.
“We’re basically measuring the bottom line of the
planet.”
Oxygen decline
The Keeling Curve did more than simply document
the rise of atmospheric carbon dioxide, which has
climbed from an estimated 280 parts per million
before the Industrial Revolution, to the 312 ppm
Keeling first measured in the ’50s, to more than
380 ppm today.
The seasonal swings in the curve demonstrated
that the Earth sort of breathes. When plants grow
in the spring, they take up carbon dioxide
through photosynthesis, and the global level
dips. In the fall, leaves and decaying plants
return CO2 to the soil, and the level rises.
Ralph Keeling, in addition to carrying on his
father’s work at Mauna Loa, leads a separate
study of oxygen in the atmosphere. He measures
oxygen levels at nine stations around the world,
from the South Pole to near the North Pole, and
from La Jolla to American Samoa and the
northwestern tip of Tasmania.
He has found that as CO2 levels rise globally, O2
levels decline. Ralph Keeling’s curve points
downward, while his father’s points upward.
“The initial goal, for my work, was to document
accurately how fast the oxygen in the atmosphere
was decreasing over time,” he said. “And the
longer the record gets, the better you’re able to
see that.”
The loss of oxygen in itself isn’t an issue, he
said. There’s plenty of oxygen in the air, and he
is studying tiny changes in the levels. What his
research is clarifying is what is happening to
the CO2.
“We see these cycles in oxygen that help us
understand the planetary metabolism,” he said.
“The trend in oxygen helps us understand the
sources and the sinks of carbon dioxide – what’s
controlling the rise in CO2. And with longer and
longer records, you can see more and more detail.”
Ralph Keeling’s oxygen studies have shown that
while more CO2 is being pumped into the
atmosphere, land ecosystems are storing more of
it than they were a couple of decades ago, he
said.
There are four main reasons, he said. Plants grow
a little faster in an atmosphere with more CO2; a
warming climate has extended growing seasons;
some plants are using nitrogen from pollution and
growing faster; and some previously cut forests
have regrown.
“It’s as though the behavior of the planet is
being slowly revealed in its fuller extent,” he
said.
Lasting legacy
Being the son of a famous scientist has been a
bit of a burden for Ralph Keeling, but he said
he’s comfortable with his role, which includes
seeing that the Mauna Loa data-gathering
continues. And that is not as simple as taking
measurements and recording numbers.
Although a fair amount of the effort goes into
collecting the next data point, much of the work
involves trying to figure out what each reading
means and whether it might have been biased in
one way or another, he said. For example, a
volcanic eruption or an equipment failure could
skew the numbers.
“We have to figure out how to make small
corrections in order to make the data better,” he
said. “And that applies to the whole record.
We’re constantly trying to refine our
understanding of what was done in the past and do
things better now. If you’re not doing that,
things are probably sliding in the wrong
direction.”
Peter Guenther, a Scripps researcher who worked
with the elder Keeling beginning in the late ’60s
and now works with Ralph Keeling, said Charles
David Keeling was determined and tenacious.
“He was persistent, even stubborn, in pursuit of
his scientific goal of understanding as much as
possible about the natural cycle of CO2,” said
Guenther, who is responsible for maintaining
Scripps’ CO2 monitoring program. “The emphasis in
his research was on establishing hard facts.”
Ralph Keeling understands the constant budget
battles his father endured, starting in the early
1960s. In general, the research was funded by
various federal agencies, which threatened to cut
off funds at several points, sometimes for
political reasons.
In the 1970s, his father was competing with the
National Oceanic and Atmospherics Administration.
NOAA spun off a program that was designed to
cover some of the same scientific territory. But
the elder Keeling felt the agency wasn’t properly
equipped to monitor CO©—. Funding battles
continue today.
“There has always been a danger it won’t keep
going,” Ralph Keeling said. “It only kept going
because he was there pushing it, and now because
I’m there pushing it. I wish there was a way to
put it on a footing where it didn’t depend on a
Keeling as much.”
At the moment, it looks like the measurements
overlap with similar monitoring programs, Keeling
said. He has been told that in the name of
efficiency, the effort should be cut.
“But there are issues there,” he said. “One is,
do you really think the government should have a
monopoly on tracking changes in the climate?
“We at Scripps are really the caretakers of the
longest records. There’s always a question of
continuity and maintaining the quality so the
records have a uniform value.”
Scripps director Haymet said global measurements
the last three years are showing more rapid
increases in CO2 levels than the United Nation’s
Intergovernmental Panel on Climate Change had
expected.
“We need to know how much time we have,” Haymet
said. “That’s what these measurements tell us.”
Find this article at:
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