STEP 1: Problem Identification


If we focus on climate change as the problem, the key driver is accumulating CO2 emissions that keep pushing atmospheric concentrations higher.


"Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Projections of greenhouse gas emissions vary over a wide range, depending on both socio-economic development and climate policy."

~ IPCC (2014, p. 8)


CO2.Earth brings focus to the critical problem of 'rising CO2.'  It also situates this problem among a broader array global environmental problems.  This broader context is provided by content related to the Annual Greenhouse Gas Index, "The Great Acceleration" (see "The GA" tab on this page) and Planetary Boundaries.  Each problem appears to identify a problem in the relationship between humankind and the earth system.  Learning about the problems may offer an opportunity to improve our collective relationship with the earth. 

This "problem identification" sets out some of the dimensions of the climate and other global environmental problems. It offers a starting place to answer questions like these:

  • 'What problem or problems exist?
  • "What are the risks?
  • How do we know these things?



IPCC Assessment Reports


The Intergovernmental Panel on Climate Change (IPCC) has given government policy makers the most authoritative and objective scientific and technical assesments of changes to earth's climate system.  The reports it publishes are the product of work by thousands of experts and scientists around the world who represent a wide range of views and disciplines. 

The following excerpt summarizes the 2014 Synthesis Report (SYR) in one paragraph.


The SYR confirms that human influence on the climate system is clear and growing, with impacts observed across all continents and oceans. Many of the observed changes since the 1950s are unprecedented over decades to millennia. The IPCC is now 95 percent certain that humans are the main cause of current global warming. In addition, the SYR finds that the more human activities disrupt the climate, the greater the risks of severe, pervasive and irreversible impacts for people and ecosystems, and long-lasting changes in all components of the climate system. The SYR highlights that we have the means to limit climate change and its risks, with many solutions that allow for continued economic and human development. However, stabilizing temperature increase to below 2°C relative to pre-industrial levels will require an urgent and fundamental departure from business as usual. Moreover, the longer we wait to take action, the more it will cost and the greater the technological, economic, social and institutional challenges we will face.




IPCC 2013  Press Release (2013) Human influence on climate clear





IPCC. (2014). Climate change 2014: Synthesis report. Contribution of working groups I, II and III to the fifth assessment report of the Intergovernmental Panel on Climate Change. (Core Writing Team, R. K. Pachauri, & L. A. Meyer Eds.). Geneva, Switzerland: IPCC. [web + .pdfChinese + Korean]


The Great Acceleration


The Great Acceleration (Sample Charts)

Source image  IGBP Great Acceleration (high res.; full image)


"The second half of the twentieth century is unique in the entire history of human existence on Earth. Many human activities reached take-off points sometime in the twentieth century and have accelerated sharply towards the end of the century. The last 50 years have without doubt seen the most rapid transformation of the human relationship with the natural world in the history of humankind."

~ Will Steffen et al. (2004, p. 131)


Rising CO2 is a critical disturbance that humans are making in the biosphere.  But it's not the only one.

The start of the Industrial Revolution is often referenced as the point when our speicies begain to exert notable pressure on the functionning of the earth system.  A lot has changed since the late 1700s when James Watt brought steam engines into the world. 

Early in the 21st Century, researchers at the International Geosphere-Biosphere Programme (IGBP) in Sweden set out to record a trajectory of the 'human enterprise' in recent centuries.   They chose 12 indicators that tracked changes in the human enterprise, and 12 that tracked changes in the function and structure of natural systems.  They wanted "to build a more systematic picture of the human-driven changes to the earth system" (Steffen et al., 2015, p. 2).  To their surprise, they found a "dramatic change in magnitude and rate of the human imprint from about 1950 onwards" (p. 2).

This was not news among historians, but not generally recognized among earth system scientsts.  Nonetheless, scientists consolidated and quantified the changes.  They aimed "to capture the holistic, comprehensive and interlinked nature of the post-1950 changes simultaneously sweeping across the socio-economic and biophysical spheres of the earth system, encompassing far more than climate change" (p. 2).

Below, you can see latest charts for indicators the IGBP posted in January 2015.


24 'Great Acceleration' Indicators

Planetary Dashboard  |  IGBP


Will Steffen and his research team report that "The Great Acceleration" was first used in 2005 at a workshop in Berlin after the publication of the 24 planetary indicators. The quote below is taken from the workshop report.


"The “engine” of the Great Acceleration is an interlinked system consisting of population increase, rising consumption, abundant energy, and liberalizing political economies. Globalization, especially an exploding knowledge base and rapidly expanding connectivity and information flow, acts as a strong accelerator of the system. The environmental effects of the Great Acceleration are clearly visible at the global scale: changing atmospheric chemistry and climate, degradation of many ecosystem services (e.g., provision of freshwater, biological diversity), and homogenization of the biotic fabric of the planet. The Great Acceleration is arguably the most profound and rapid shift in the human–environment relationship that the Earth has experienced."

~ Charles Redman et al. (2007, p. 131)




IGBP  Great Acceleration

IGBP  Press Release (2015) Planetary dashboard shows "Great Acceleration"

IGBP  POWERPOINT (2015) Great Acceleration (21 MB)

IGBP  Great acceleration data [Excel 2007]

IGBP + YouTube  VIDEO (2014) Welcome to the Anthropocene




Critical Angle  Skuce (2015) The history of emissions and TGA

NY Times  Revkin (2015) Can humanity's 'Great Acceleration' be managed?




Costanza, R., van der Leeuw, S., Hibbard, K., Aulenbach, S., Brewer, S., Burek, M., . . . Steffen, W. (2012). Developing an integrated history and future of people on earth (IHOPE). Current Opinion in Environmental Sustainability, 4(1), 106-114. doi:10.1016/j.cosust.2012.01.010 [COES + researchgate .pdf]

Redman, C., Crumley, C. L., Hassan, F. A., Hole, F., Morais, J., Riedel, F., . . . Yasuda, Y. (2007). Group report: Millennial perspectives on the dynamic interaction of climate, people, and resources. In R. Costanza, L. Graumlich, & W. Steffen (Eds.), Sustainability or Collapse? 96th Dahlem Workshop on Integrated History and Future of People on Earth (IHOPE) (pp. 115-148). Cambridge, MA: The MIT Press and Freie Universität Berlin. [MIT]

Steffen, W., Broadgate, W., Deutsch, L., Gaffney, O., & Ludwig, C. (2015). The trajectory of the Anthropocene: The Great Acceleration. The Anthropocene Review. doi:10.1177/2053019614564785 [ANR]

Steffen, W., Sanderson, R. A., Tyson, P. D., Jäger, J., Matson, P. A., Moore III, B., . . . Turner, B. L. (2004). Global change and the earth system: A planet under pressure. Berlin: Springer Science & Business Media. [IGBP + .pdf book]



Factors (detection & attribution)


"Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, and in global mean sea level rise; and it is extremely likely to have been the dominant cause of the observed warming since the mid-20th century. In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans."

~ IPCC (2014, p. 47)


The earth system is large, complex and dynamic.  Detecting planetary changes and attributing causes requires collaboration among many skilled researchers who make many kinds of observations and use many kinds of instruments and plus computer models to expand knowosed about the earth sytem.

Individuals are learning within a cooperative context.   Consider Dave Keeling as an example of an individual scientist.  Keeling is well known for starting the longest-running instrument record for CO2 measurements at the Mauna Loa Observatory, 3400 metres above sea level.  The first monthly average he reported, 315.71 parts per million for March 1958, remains an important datapoint that is still incorporated into studies and models by scientists today.  Over time and around the world, this kind of earth monitoring work ultimately forms the basis for what scientists know about the earth system and how it behaves.

There are perhaps many ways of learning how earth system scientists learn what they know about the earth system.  To explore these issues further, consider looking into the use of quantitative statistics for detection and attribution of factors contributing to climate changes.  And consider looking into modelling methods scientists use to test and expand knowledge about the earth system.




NASA GISS 2015  Accounting for climate's backseat drivers

NASA GISS  Simple climate model for high school classrooms

RealClimate  The CO2 problem in 6 easy steps



Climate Forcings


Forcings are factors outside the climate system that force or drive changes to the climate system.  This essentially means that a measurable external change is forcing a change in average temperatures, either warmer or cooler.

Forcings can be natural, such as changes in energy output from the sun.  And they can be caused by humans, such as changes in atmospheric concentrations of heat-trapping gases, especially carbon dioxide and methane.  The chart below shows changes in different forcings since 1880.


Climate Forcings 1750-2000

Source graphic  NASA GISS




NASA GISS  Forcings in GISS climate model

OSS  Climate forcing

NOAA Paleoclimatology  What are climate forcings?





"In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans. Impacts are due to observed climate change, irrespective of its cause, indicating the sensitivity of natural and human systems to changing climate."

~ IPCC (2014, p. 47)


As certain human activities continue to drive multiple changes in the earth system, we may expect impacts that cascade and worsen the longer we continue the activities that warm, acidify and degrade the biosphere.  Because human institutions have not committed to a plan that will stabilize the concentraion of greenhouse gases in the atmosphere, we don't know the extent of future global changes.  This signficantly reduces certainty of a stabilized future. 

To be blunt about the situation, the following perspective comes from Professor Kevin Anderson, Deputy Director of the Tyndall Centre for Climate Change Research.


"We are in ‘injury time’ for 2°C – and things are not looking good. However, time will continue regardless even if we blow the 2°C carbon budgets, we still need to drive even harder for deep and rapid mitigation alongside preparing for the regional impacts of a 4, 5 or even 6°C future. But we must note that adaptation to such a future scenario will never be sufficient for the many millions who will suffer and die as a consequence of the fossil fuelled hedonism enjoyed by relatively few of us – including me and very likely anyone reading this; we are the high emitters who have explicitly chosen not to care."

~ Kevin Anderson [See Páll Ormarsson (2015)]


The IPCC made a statement that seems scientifically compatible, but the tone is less personalized.


"Without additional mitigation efforts beyond those in place today, and even with adaptation, warming by the end of the 21st century will lead to high to very high risk of severe, widespread and irreversible impacts globally."

~ IPCC (2014, p. 18)


Nature and Extent of Impacts


Accumulating evidence from a variety of past crises suggests that humanity may be moving increasingly toward a future marked by multiple global and interconnected risks.  When a risk to a financial, social or ecological system materializes as a crisis, the changes are sometimes non-linear, abrupt, surprising and even irreversible. Such crises are often triggered by a mix of interacting social, environmental and technological factors. [See Galaz et al. (2011)]

To see examples of social and economic impacts at CO2.Earth,  jump to the page about people and communities on the front lines of global climate change.

Below, a list of links has been started for scientific data, indexes and images that show the types of changes that are happening worldwide on land and in the oceans.  To begin, the following graphic is updated each day to show cumulative days of ice melt in Greenland.


Greenland Ice Melt YTD

Greenland Ice Sheet Today  |  NSIDC

Greenland Cumulative Melt Days as of Today
Source Image
  NSIDC Greenland Ice Sheet Today [high resolution .png]


Data Links


Ice Sheets

NSIDC  Ice sheets database records



NSIDC  Snow database records



NSIDC  Permafrost database records


Soil Moisture

NSIDC  Soil moisture database records

NOAA NCEI  Crop moisture stress index (CMSI)



NSIDC  Glacier database records

NSIDC  Glacier photo database (since 1880)  [search]

NSIDC  Antarctic Glaciological Data Center


Sea Ice

NSIDC  Sea ice index [web graphics + data portal)

NSIDC  Daily sea ice extent--Northern Hemisphere

NSIDC  Arctic sea ice news & analysis


Sea Level

CSIRO   Sea level data  [GTh sea level + global ocean heat content]


Arctic Change

NSIDC  Satellite observations of arctic change

ELOKA  Exchane for local observations and knowledge of the arctic


More Data Sets

NOAA-NCEI  Societal Impacts

NOAA-NCEI  Extremes (North America & USA)

NOAA-NCEI  Snow and Ice Data (Global & USA)

NOAA-NCEI  Teleconnections: Variability in atmospheric circulation

IGBP  2011 Climate Change Index


Other Data Portals

NSIDC & Google Earth  NSIDC data (KML files) for Google Earth

NASA EOSDIS  Earth data website [search portal]

NASA  Earth Observatory website




Folke, C., Jansson, Å., Rockström, J., Olsson, P., Carpenter, S. R., Chapin, F. S., . . . Westley, F. (2011). Reconnecting to the biosphere. AMBIO, 40(7), 719-738. doi:10.1007/s13280-011-0184-y

Galaz, V., Galafassi, D., Tallberg, J., Boin, A., Hey, E., Ituarte-Lima, C., . . . Westley, F. (2014). Connected Risks, Connected Solutions. Stockholm: Stockholm Resilience Centre, Stockholm University, and the Global Challenges Foundation. Retrieved from [web]

IPCC. (2014). Climate change 2014: Synthesis report. Contribution of working groups I, II and III to the fifth assessment report of the Intergovernmental Panel on Climate Change. (Core Writing Team, R. K. Pachauri, & L. A. Meyer Eds.). Geneva, Switzerland: IPCC. [web + .pdfChinese + Korean]

Páll Ormarsson, O. (2015, October 20). Arctic 2015: Things are not looking good! Iceland Monitor. Retrieved from [web]



CO2 Stabilization Prerequisites

Reposted from ScienceDaily (Feb. 18, 2008)   Now that scientists have reached a consensus that carbon dioxide emissions from human activities are the major cause of global warming, the next question is: How can we stop it? Can we just cut back on carbon, or do we need to go cold turkey? According to a new study by scientists at the Carnegie Institution, halfway measures won’t do the job. To stabilize our planet’s climate, we need to find ways to kick the carbon habit altogether.

In the study, to be published in Geophysical Research Letters, climate scientists Ken Caldeira and Damon Matthews used an Earth system model at the Carnegie Institution’s Department of Global Ecology to simulate the response of the Earth’s climate to different levels of carbon dioxide emission over the next 500 years. The model, a sophisticated computer program developed at the University of Victoria, Canada, takes into account the flow of heat between the atmosphere and oceans, as well as other factors such as the uptake of carbon dioxide by land vegetation, in its calculations.

This is the first peer-reviewed study to investigate what level of carbon dioxide emission would be needed to prevent further warming of our planet.

“Most scientific and policy discussions about avoiding climate change have centered on what emissions would be needed to stabilize greenhouse gases in the atmosphere,” says Caldeira. “But stabilizing greenhouse gases does not equate to a stable climate. We studied what emissions would be needed to stabilize climate in the foreseeable future.”

The scientists investigated how much climate changes as a result of each individual emission of carbon dioxide, and found that each increment of emission leads to another increment of warming. So, if we want to avoid additional warming, we need to avoid additional emissions.

With emissions set to zero in the simulations, the level of carbon dioxide in the atmosphere slowly fell as carbon “sinks” such as the oceans and land vegetation absorbed the gas. Surprisingly, however, the model predicted that global temperatures would remain high for at least 500 years after carbon dioxide emissions ceased.

Just as an iron skillet will stay hot and keep cooking after the stove burner’s turned off, heat held in the oceans will keep the climate warm even as the heating effect of greenhouse gases diminishes. Adding more greenhouse gases, even at a rate lower than today, would worsen the situation and the effects would persist for centuries.

"What if we were to discover tomorrow that a climate catastrophe was imminent if our planet warmed any further? To reduce emissions enough to avoid this catastrophe, we would have to cut them close to zero — and right away," says Caldeira.

Global carbon dioxide emissions and atmospheric carbon dioxide concentrations are both growing at record rates. Even if we could freeze emissions at today’s levels, atmospheric carbon dioxide concentrations would continue to increase. If we could stabilize atmospheric carbon dioxide concentrations, which would require deep cuts in emissions, the Earth would continue heating up. Matthews and Caldeira found that to prevent the Earth from heating further, carbon dioxide emissions would, effectively, need to be eliminated.

While eliminating carbon dioxide emissions may seem like a radical idea, Caldeira sees it as a feasible goal. “It is just not that hard to solve the technological challenges,” he says. “We can develop and deploy wind turbines, electric cars, and so on, and live well without damaging the environment. The future can be better than the present, but we have to take steps to start kicking the CO2 habit now, so we won't need to go cold turkey later.”


Journal reference: Matthews, H. D., and K. Caldeira (2008), Stabilizing climate requires near-zero emissions, Geophysical Research Letters, doi:10.1029/2007GL032388, in press.  |  Stabilizing climate requires near-zero emissions  |  ABSTRACT:  Stabilizing climate requires near-zero emissions



COP 21 | 2015 Paris Climate Talks

Christina Figueres: "The stars are aligning..."

Image The Climate Group 2014 / Flickr / cc-by-nc-sa 2.0
Downloaded from


"I don't know that it is possible to say right now are we going to end up with 1.5, 1.6, 1.7, 1.8, 1.9°C?  But it's got to be within that range. There is no doubt that it has to be below 2°C."
"It’s very obvious that lower temperatures provide more security and more safety.  That is unquestioned."

~ Christiana Figueres, Executive Secretary, UNFCCC [See Hickman (2015, June)]


The United Nations climate conference in Paris, France (November 30 - December 11, 2015) went one day extra to reach a deal.   


UNFCCC   195 Nations Set Path to Keep Temperature Rise Well Below 2 Degrees Celsius

UNFCCC  Paris climate change conference 2015

UNFCC   Paris Agreement: Library Webpage + Agreement .pdf


Tabs below connect you to resources that are relevant for understanding the Paris conference and the outcomes.



STEP 4: World Engagement

To address the global environmental problems that our species and planet faces, the world needs to be engaged.  All of humanity needs to be engaged.  National governments are engaged. 


196 countries

195 Parties to the Convention



Nature 2005  Kyoto Protocol comes into force


7 Billion People




Non-Governmental Organizations








STEP 5: World Targets

The world has an ultimate objective to avoid dangerous interference with the climate system.  Prior pages cover some climate system basics and forums to engage for learning, responding and innovating solutions.  What's missing?  What's still needed?  We need to quantify a target and put date on it.  As with anything, this can generate focus and energy among diverse individuals and groups to move quickly toward an outcome that is widely seen as desirable and important.

For climate change, world institutions, UNFCCC member states in particular, have indicated strong support for a measurable target (avoid 2°C) and a date (now and forever).   On the other side of the coin, the temperature trajectory is powerful and will exceed 2°C if sufficient changes in human activities are not implemented soon enough.

Here, 'Stabilization Step 5' takes a step back to introduce the 'avoid 2°C' target, other temperature targets and some other types of targets.  Whether or not 'avoid 2°C' maintains the wide support it has now, it may help to move forward with eyes wide open.  Further, multiple targets may be complementary and useful.


Carbon Budgets

A carbon budget quantifies remaining CO2 or greenhouse gas (CO2 equivalent) emissions that may occur before breaching a guardrail target like 'avoid 1.5°C' or 'avoid 450 ppm CO2'.  Adopting a cumulative carbon budget reflects a choice to cease emissions before a particular guardrail is reached.

CO2 persists in the atmosphere for periods of time that exceed multiple human lifetimes.  Thus, carbon budgets are cumulative over a period of centuries or millenia.  They are not reset each year like many financial budgets.




Meinshausen et al. (2009). Greenhouse-gas emission targets for limiting global
warming to 2C. Nature, 458 1158-1163. [.pdf + resources]

Zickfeld, K., Eby, M., Matthews, H. D., Weaver, A. J., & Schellnhuber, H. J. (2009). Setting cumulative emissions targets to reduce the risk of dangerous climate change. Proceedings of the National Academy of Sciences of the United States of America, 106(38), 16129-16134. [abstract + .pdf]



2°C Guardrail


 Paris Climate Talks: The 2°C Limit
Nature video examines the science behind the warming target

 Source:  Nature | November 19, 2015



Tracking Temperature  Global warming update




FiveThirtyEight '16  When will it actually be hotter than 2 degrees?

Carbon Brief '14  Two degrees: Will we avoid dangerous climate change?

Carbon Brief '14  Two degrees: History of the climate change limit


Pathways to 2°C


"There are multiple mitigation pathways that are likely to limit warming to below 2°C relative to pre-industrial levels. These pathways would require substantial emissions reductions over the next few decades and near zero emissions of CO2 and other long-lived greenhouse gases by the end of the century. Implementing such reductions poses substantial technological, economic, social and institutional challenges, which increase with delays in additional mitigation and if key technologies are not available. Limiting warming to lower or higher levels involves similar challenges but on different timescales."

~ IPCC (2014, p. 20)







"UN negotiations on climate change aim to limit warming to 2 °C above pre-industrial temperatures. There is, however, no agreement on how to define pre-industrial temperature."

~ New Scientist, 2015 (attributed to Ed Hawkins, University of Reading, UK)



STEP 7: Stabilization Watch


Stabilization Watch
o Create via excel x 2, how it works, proposal,
refer to this triple a problem. chief greenhouse gas. Job 1 is to stabilize the concentration of Co2 in the atmosphere.

Stabilization Watch

o   Create via excel x 2, how it works, proposal,

refer to this triple a problem.  chief greenhouse gas.  Job 1 is to stabilize the concentration of Co2 in the atmosphere.

CO2 Past.  CO2 Present.  CO2 Future.