CO2 Past, Present, Future

3 Earths: Past, Present, Future


The CO2.Earth site brings big, planetary climate numbers together in a context so the changes are understandable by most anyone.  This page introduces some of those big numbers and how they relate to one another.


CO2 Past

Studying ice cores and other proxy data tells us a lot about how the slow and fast earth system have adjusted to changes in the past.  These records tell us about atmospheric CO2 levels and climate that go back befre the development of human civilization.  They go back long before the appearance of homo sapiens on earth.  Among other things, they show the unpredented rate of change that has occured since the industrialization of human societies.

The International Panel on Climate Change uses 1750 as its pre-industrial baseline to show changes in atmospheric CO2, global temperature and other climate indicators in the post-industrial era after 1750.  The study of past climates before human influence became signficant helps us understand how different parts of the earth system change over short and very long time scales.  In particular, it gives us a good understanding of the implications that expected changes are likly to have for humanity and the wider community of life.

We know that atmospheric CO2 has ranged between 172 and 300 part per million (ppm) for the past 1 million years.  The earth cycled through cold glacial and warm inter-glacial periods without atmospheric CO2 exceeding 300 ppm.  The first time in human history that atmospheric CO2 exceeded 300 ppm was about the time the Titanic sank in the North Atlantic Ocean.  Now, the crossover to concentrations that stay above 400 ppm CO2 is nearly complete.


CO2.Earth  CO2 Ice Core Data

CO2.Earth  CO2 Proxy Data



CO2 Now


CO2.Earth uses the most current data from the atmosphere to show the planetary trend for Earth's backgrond CO2 level.


CO2.Earth  Daily CO2 Data

CO2.Earth  Weekly CO2 Data

CO2.Earth  Monthly CO2 Data

CO2.Earth  Monitoring CO2

CO2.Earth  Track The Trend



CO2 Future 


"Trend is not destiny."

 ~ René Dubos (1981)


Two decades ago, the international community agreed on an ultimate climate objective to stabilize the concentration of CO2 and other greenhouse gases in the atmosphere.  Today, past and current readings show the continuing, relentless rise in the background level of CO2 in the atmosphere.   Other greenhouse gas levels are rising too.   Despite the current trend, is humanity taking steps now that are sufficient to stop the rising trend?

CO2.Earth helps you answer that question by featuring quantified projections of scientists and modellers at Climate Interactive.  CO2.Earth spotlights Year 2100 projections for atmospheric CO2, atmospheric GHGs (CO2-equivilent), GHG emissions, and global temperature.  It also incorporates this information into the CO2.Earth page introducing the 2015 Paris Climate Talks.


CO2.Earth  2100 Projections

CO2.Earth  COP 21 | 2015 Paris Climate Talks





Dubos, R. (1981). Celebrations of Life (1982 paperback ed.). New York: McGraw-Hill.



Discovery of Global Warming

the discovery of global warming 2nd ed ablestock 150w

The Discovery of Global Warming is both a book and a series of online articles (see Table of Contents). 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). 





spencer weart photo copyright christian bibas 150wBackground

About the author  (Dr. Spencer Weart)


CO2 Past.  CO2 Present.  CO2 Future.