CO2 Now

Historical CO2
Discovery of Atmospheric CO2 Levels PDF Print E-mail


Rewards and Penalties of Monitoring the Earth by Charles David Keeling

Charles David Keeling (SIO Archives)Rewards and Penalties of Monitoring the Earth is a 1998 autobiographical account of Dave Keeling's discovery of background levels of carbon dioxide in the atmosphere.  It describes events that led to this discovery, and events that followed.  It is a story of perserverence in the face of scientific and institutional challenges to push open the door of understanding of the rising levels of atmospheric CO2.  A review in the scientific Journal, Nature, declares that Keeling's article "should be compulsory reading for politicians and science administrators."  The reviewer adds that "idealistic young scientists, as yet unscarred, should read it and take note: courage and perseverance are required."

The Scripps Institution of Oceanography has reprinted the paper with the permission of the Annual Review of Energy and the Environment.  Click here for more citations and republication information.  Click here to download the paper directly from the Scripps website.

Discovery of Global Warming PDF Print E-mail


The Discovery of Global Warming (AbleStock photo)

The Discovery of Global Warming is both a book and a series of online articles.  Both are kept up to date by climate science historian Dr. Spencer Weart.  

The highly-acclaimed book tells the history of climate science, and the discovery of climate change, as a concise, single story.  As a retired physicist, Spencer Weart supplements the information in the book with ongoing updates to a series of inter-linked articles on the website of the American Institute of Physics (AIP). 

To help people who want to know more about the historical aspects of global warming and climate change, a list of links to Spencer Weart’s articles is made available at 

 The following links take you from to the Discover Global Warming section of the AIP website.
Click "read more" to see the full list of links. 

Getting Started

Summary of the history of climate change science [pdf]

Search all of Spencer Weart’s online articles

CO2 Ice Core Data PDF Print E-mail
800,000 Years


"The farther backward you can look,
the farther forward you are likely to see."
   - Winston Churchill

Ice Core Data and Links

This ice core data page gives you links to composite data sets going back as far as 800,000 years ago.  You also get links to scientific findings as published in May 2008 when the ice core data set was extended from 650,000 years before present to 800,000 years before present.   

High-res. CO2 concentration record 650,000–800,000 years ago 

NatureDieter Lüthi et al  Published in Nature, Vol. 453, pp. 379-382, 15 May 2008. 

ABSTRACT  Changes in past atmospheric carbon dioxide concentrations can be determined by measuring the composition of air trapped in ice cores from Antarctica. So far, the Antarctic Vostok and EPICA Dome C ice cores have provided a composite record of atmospheric carbon dioxide levels over the past 650,000 years. Here we present results of the lowest 200m of the Dome C ice core, extending the record of atmospheric carbon dioxide concentration by two complete glacial cycles to 800,000 yr before present. From previously published data and the present work, we find thatatmospheric carbon dioxide is strongly correlated with Antarctic temperature throughout eight glacial cycles but with significantly lower concentrations between 650,000 and 750,000 yr before present. Carbon dioxide levels are below 180 parts per million by volume (p.p.m.v.) for a period of 3,000 yr during Marine Isotope Stage 16, possibly reflecting more pronounced oceanic carbon storage. We report the lowest carbon dioxide concentration measured in an ice core, which extends the pre-industrial range of carbon dioxide concentrations during the late Quaternary by about 10 p.p.m.v. to 172–300 p.p.m.v.


Atmospheric CO2 Concentrations over the Last Glacial Termination

A record of atmospheric carbon dioxide (CO2) concentration during the transition from the Last Glacial Maximum to the Holocene, obtained from the Dome Concordia, Antarctica, ice core, reveals that an increase of 76 parts per million by volume occurred over a period of 6000 years in four clearly distinguishable intervals. The close correlation between CO2 concentration and Antarctic temperature indicates that the Southern Ocean played an important role in causing the CO2 increase. However, the similarity of changes in CO2 concentration and variations of atmospheric methane concentration suggests that processes in the tropics and in the Northern Hemisphere, where the main sources for methane are located, also had substantial effects on atmospheric CO2 concentrations.


CO2 Ice Core Data



Ice Core



 0 - 22 KYr

Dome C 

Monnin et al. 2001 

Dome C, Antarctica Carbon Dioxide Data
Monnin et al. Science v.291 pp112-114

University of Bern


Excel: see Luethi

22 - 393 KYr 


Petit et al. 1999
Pepin et al. 2001 Raynaud et al. 2005 

LGGE in Grenoble

Text  |  MS Excel 

393 - 416 KYr 

Dome C 

Siegenthaler et al. 2005 

LGGE in Grenoble

Text  |  MS Excel

416 - 664 KYr 

Dome C 

Siegenthaler et al. 2005 

University of Bern

Text  |  MS Excel

664 - 800 KYr 

Dome C 

Luethi et al. 

University of Bern

Text  |  MS Excel


Timescale:  EDC3



CO2 800,000 Years

Lüthi et al. (2008) 800KYr CO2 Data  |   text or Microsoft Excel format.



More Ice Core Data (NOAA Paleoclimatology / NCDC)

EPICA Dome C Ice Core Data Page

Ice Cores

Ice Core Data Gateway

Antarctica Ice Core Timescales (EDC3) PDF Print E-mail
800,000 Years


Scientists use the EDC3 chronology (2007) to establish the age of gases that are extracted from ice core samples.   The EDC3 is described in the following paper.  

The EDC3 chronology for the EPICA Dome C ice core

Parrenin et al. |  Published in Climate of the Past, Issue 3, pp. 485-497, 2007

Abstract   The EPICA (European Project for Ice Coring in Antarctica) Dome C drilling in East Antarctica has now been completed to a depth of 3260 m, at only a few meters above bedrock. Here we present the new EDC3 chronology, which is based on the use of 1) a snow accumulation and mechanical flow model, and 2) a set of independent age markers along the core. These are obtained by pattern matching of recorded parameters to either absolutely dated paleoclimatic records, or to insolation variations. We show that this new time scale is in excellent agreement with the Dome Fuji and Vostok ice core time scales back to 100 kyr within 1 kyr. Discrepancies larger than 3 kyr arise during MIS 5.4, 5.5 and 6, which points to anomalies in either snow accumulation or mechanical flow during these time periods. We estimate that EDC3 gives accurate event durations within 20% (2σ) back to MIS11 and accurate absolute ages with a maximum uncertainty of 6 kyr back to 800 kyr.

Climate of the Past  |  Journal & Abstract   Full article (pdf)   Supplement (zip)   Discussion Paper



CO2Now  |  800,000 Years

CO2Now  |  CO2 Ice Core Data