Subscription Center
Jun 18, 2009 02:30 PM | 9
Despite vast changes in climate since the early Pleistocene, 2.1 million years ago, carbon dioxide levels have stayed pretty stable until lately, according to a study published online today in Science.
All of that consistency, in which peak CO2 levels averaged 280 parts per million, makes today's concentration—385 parts per millions, which is 38 percent higher—all the more stunning, the authors report. Previous work showed stable CO2 levels going back about 650,000 years.
For the new estimate, the researchers analyzed ancient plankton shells beneath the Atlantic Ocean floor, rather than relying on data from polar ice cores, which can only give readings for the past 800,000 years. The tiny shells provided info on CO2 levels as well as temperature and ocean acidity.
The findings suggest that previous ice ages may have had more to do with other forces, such as changes in the Earth's orbit, than with plummeting levels of carbon dioxide in the atmosphere. But, spikes in CO2 levels did match up with periods of warming.
"Our data continues to suggest that greenhouse gases and global climate are intimately linked," lead study author Bärbel Hönisch, a geochemist at Columbia University's Lamont Doherty Earth Observatory, said in a statement.
Image of Bärbel Hönisch diving for plankton courtesy of Steve Doo
Tags:
carbon dioxide
More News Blog:
Next: China wants Web filters placed on all PCs, to the chagrin of U.S. PC makers
Previous: Carbon counter unveiled in New York City
See what we're tweeting about
Deadline: Aug 31 2013
Reward: $100,000 USD
The Geoffrey Beene Foundation Alzheimer’s Initiative (GBFAI) is launching the 2013 Geoffrey Beene Global NeuroDiscovery Challenge whose
Deadline: Jul 15 2013
Reward: $5,000 USD
SciBX: Science-Business eXchange, a joint publication from the makers
Powered By: 
YES! Send me a free issue of Scientific American with no obligation to continue the subscription. If I like it, I will be billed for the one-year subscription.
9 Comments
Add CommentContradiction 1: "stable CO2 levels for 2.1 million years" vs. "spikes in CO2 levels" - logic: spikes negate stability.
Reply | Report Abuse | Link to thisContradiction 2: "previous ice ages may have had more to do with other forces, such as changes in the Earth's orbit" vs. "greenhouse gases and global climate are intimately linked" - logic: global ice ages are a subset of global climate.
Is it me or does this report contradict its own conclusion?
It's you. Spikes don't negate stability - it's not an either/or thing. Most curves aren't smooth. Your comment on 'Contradiction 2" is nit-picking.
Reply | Report Abuse | Link to thisThe article would be improved by an explanation of how shells of oceanic plankton reliably indicate atmospheric CO2 levels from the time the plankton were alive (as opposed to, say, the more intuitive conclusion that they would indicate oceanic CO2 levels)... and how we are confident that atmospheric CO2 information is retained in the shells for 2 million years or more without some other force tending to skew the data toward uniformity.
Reply | Report Abuse | Link to thisUnderstanding -- and writing to explain -- the methodology upon which your sources rely is helpful.
sapbucket: It is not entirely you. The conclusion was poorly phrased. Still one needs to be somewhat obtuse not to realise that.
Reply | Report Abuse | Link to thissapbucket is correct;
Reply | Report Abuse | Link to this"The findings suggest that previous ice ages may have had more to do with other forces, such as changes in the Earth's orbit, than with plummeting levels of carbon dioxide in the atmosphere. But, spikes in CO2 levels did match up with periods of warming."
The articles conclusions do not fit the facts presented.
The fact is CO2 in the atmosphere follows temperature. Temperature goes down,CO2 goes down. Temperature goes up, CO2 in atmosphere goes up.
Go look at the raw data, ice cores,seabed deposits etc.
pgtruspace,
Reply | Report Abuse | Link to thisYou're correct for the previous temperature/co2 relationship for the earth's history. As the earth warmed caused by slow changes in the earth's orbit, a variety of geological/oceanographic processes caused the release of more CO2. The current situation of CO2 leading temperature is a tell tale sign of anthropogenic influence. Again, neither of these cases in anyway refute the fact that CO2 is still a greenhouse gas.
For those wondering how calcifying plankton can be use to determine past CO2 concentrations, this is one of the paragraphs directly from the science article which pertains to this method. There is more, but since this is a secure source, I don't feel comfortable linking the majority of it.
"The boron
isotopic composition of planktic foraminifera shells
is a proxy for past seawater pH. This proxy is
based on the equilibrium reaction between the
two dominant species of dissolved boron in seawater
and the isotope fractionation between the
two species [supporting online material (SOM)].
Atmospheric pCO2 can be estimated from the
boron isotopic composition of those shells if (i)
aqueous partial pressure of CO2 (PCO2) at the
core site is in equilibrium with atmospheric pCO2,
and (ii) another carbon parameter of the water in
which the foraminifers grew is known. Using reasonable
assumptions about seawater alkalinity,
quantitative replication of select intervals of the
Vostok pCO2 record from boron isotopes in the
planktic foraminifer Globigerinoides sacculifer
(15) has demonstrated the validity of this method."
It does not matter if you believe in climate change caused by humanity or not. What I believe everyone can agree on is; we need high paying jobs and we need to stop paying big bucks for energy. Now is the time to exploit space power and resources. Sunlight is available in high Earth orbit 24/7, 365 days a year. We have had the technology since the late 60’s to transmit via microwave all the energy we could ever use, to Earth, from orbit. The material for constructing the space end of the system is available on the near Earth asteroids and the Moon. We the people need the government to fund the project just as the government funded World War II. Our survival as a people with liberty was threatened by mad men with weapons during WWII. Today our survival is threatened by mad men with oil. If we as a people shrink from the task at hand we will lose our liberty.
Reply | Report Abuse | Link to this"It does not matter if you believe in climate change caused by humanity or not."
Reply | Report Abuse | Link to thisYou don't have to believe in anything. Anthropogenic global warming is a scientific fact.
"Sunlight is available in high Earth orbit 24/7, 365 days a year"
A worldwide grid can accomplish the same thing without the expense of putting things into orbit. That worldwide grid can also distribute other forms of renewable energy: wind, small/dam-less hydro, combined heat and power from biomass (agricultural waste, municipal waste, etc) and others.
Seriously, we can derive almost all of our energy needs from sustainable, pollution-free, GHG-free electricity without major technological breakthroughs.
The fact that ice ages (and the warming periods that followed them may have resulted from orbital changes more than greenhouse gas changes does not negate current science. Those climate changes were considerably more gradual, in most cases, than the changes that we are observing now.
Reply | Report Abuse | Link to this