CO2, Ca, and Rapid Change in Oceans

—————————————-
“As CO2 increases and weather patterns shift, the
chemical composition of our rivers will change,
and this will affect the oceans,” says co-author
Ken Caldeira of the Carnegie Institution’s
Department of Global Ecology.

“What we learned from this work is that the ocean
system is much more sensitive to climate change
than we have previously appreciated,” says
Griffith.
———————————–

Science Daily
News Release

Climate Change Alters Ocean Chemistry
http://www.sciencedaily.com/releases/2008/12/081211141832.htm

ScienceDaily (Dec. 12, 2008) – Researchers have
discovered that the ocean’s chemical makeup is
less stable and more greatly affected by climate
change than previously believed. Researchers
report that during a time of climate change 13
million years ago the chemical makeup of the
oceans changed dramatically. The researchers warn
that the chemical composition of the ocean today
could be similarly affected by climate changes
now underway – with potentially far-reaching
consequences for marine ecosystems.


“As CO2 increases and weather patterns shift, the
chemical composition of our rivers will change,
and this will affect the oceans,” says co-author
Ken Caldeira of the Carnegie Institution’s
Department of Global Ecology. “This will change
the amount of calcium and other elements in ocean
salts.”

The research team, which included Caldeira,
Elizabeth M. Griffith and Adina Paytan of the
University of California, Santa Cruz, plus two
other colleagues, studied core samples of deep
oceanic sediment recovered from the Pacific Ocean
Basin. By analyzing the calcium isotopes in
grains of the mineral barite in different layers,
they determined that between 13 and 8 million
years ago the ocean’s calcium levels shifted
dramatically. The shift corresponds to the growth
of the Antarctic ice sheets during the same time
interval. Because of the huge volume of water
that became locked up in the ice cap, sea level
also dropped.

“The climate got colder, ice sheets expanded, sea
level dropped, and the intensity, type, and
extent of weathering on land changed,” explains
Griffith.

“This caused changes in ocean circulation and in
the amount and composition of what rivers
delivered to the ocean,” adds Paytan. “This in
turn impacted the biology and chemistry of the
ocean.”

Calcium-bearing rocks such as limestone are the
largest storehouse of carbon in the Earth’s
carbon cycle because they are primarily made up
of calcium carbonate. “The ocean’s calcium cycle
is closely linked to atmospheric carbon dioxide
and the processes that control seawater’s
acidity,” says Caldeira. Acidification of
seawater is already a growing threat to coral
reefs and other marine life.

“What we learned from this work is that the ocean
system is much more sensitive to climate change
than we have previously appreciated,” says
Griffith. “We thought that the concentration of
calcium, which is a major element in seawater,
would change slowly and gradually over tens of
millions of years. But what our data suggests is
that there could be a more dynamic relationship
between climate and ocean chemistry, which can
sometimes result in rapid biogeochemical
reorganization.”

“We see here how dynamic the climate-ocean system
is and that the responses to change are not
always what we would expect” says Paytan. “We
need to keep this in mind when considering future
climate and other anthropogenic changes, like
ocean acidification, and their impact on the
ocean and ocean resources.”

Journal reference:

1. Elizabeth M. Griffith, Adina Paytan, Ken
Caldeira, Thomas D. Bullen and Ellen Thomas. A
dynamic marine calcium cycle during the past 28
million years. Science, December 12, 2008

Adapted from materials provided by Carnegie Institution.
Email or share this story:
Need to cite this story in your essay, paper, or
report? Use one of the following formats:
APA

MLA
Carnegie Institution (2008, December 12). Climate
Change Alters Ocean Chemistry. ScienceDaily.
Retrieved December 12, 2008, from
http://www.sciencedaily.com°©
/releases/2008/12/081211141832.htm

————————————————————————————————————————————————-

Bookmark the permalink.

Comments are closed