What is C-Learn?
C-Learn is a simulation tool to see how changes in greenhouse gas emissions from different groups of countries will affect the Earth’s climate. The tool is developed from the scientifically reviewed, C-ROADS model, which allows users to explore how changes in fossil fuel emissions, deforestation, and afforestation will affect atmospheric carbon dioxide levels, global temperature, sea level rise, cumulative emissions, and emissions per capita.
Who should use C-Learn?
C-Learn is designed for people exploring the human impacts on climate change, from students and teachers to researchers and policymakers.
Who created C-Learn?
C-Learn was built by Climate Interactive, Ventana Systems, and MIT Sloan School of Management’s System Dynamics Group, building off of Dr. Tom Fiddaman’s (of Ventana Systems) PHD dissertation at MIT. For more information, see the Credits page.
Does it cost anything to use it?
There is no cost associated with using C-Learn. In fact, we actively encourage you to share your findings and we hope that you may use the graphs and tables from the site in presentations and projects. For additional resources and more information on Climate Interactive’s open-source efforts, please visit our website.
What is the purpose of the site?
We hope that you will use C-Learn to try out different scenarios to see what it will take to reach your goals on climate change and that you will then share these results with others. Second, we hope to inspire other organizations and individuals to develop their own interfaces and uses for the scientifically-rigorous equations in the simulation. For more information, see the Motivations page.
Questions About Climate Change
What is global warming?
According to the EPA Climate Change Basic Information, “Global warming is an average increase in the temperature of the atmosphere near the Earth’s surface and in the troposphere, which can contribute to changes in global climate patterns. Global warming can occur from a variety of causes, both natural and human induced. In common usage, “global warming” often refers to the warming that can occur as a result of increased emissions of greenhouse gases from human activities.”
How dire is the problem?
According to the Intergovernmental Panel on Climate Change (IPCC), over the last century, average global temperature has increased by 1.2 to 1.4 degrees Fahrenheit, and over the next century, estimates put the temperature increase at 3 to 7 degrees Fahrenheit (Source: IPCC Climate Change 2007: The Physical Science Basis)
What is the current level of CO2 in the atmosphere?
The CO2 concentration in the atmosphere is about 390 parts per million. On average the level of CO2 in the atmosphere has been rising at around 2 parts per million per year.
What are the results of sea-level rise?
Sea-level rise erodes coastlines and makes communities vulnerable to large-scale flooding during storms. Low lying coastal areas like New York City, Shanghai, Bangladesh, and the Netherlands are just some of the many areas that face disastrous consequences from flooding. Impacts range from devastating economic losses to loss of lives.
What are different ways for countries to reduce emissions?
Governments can take action by putting a price on carbon emissions through taxes or cap and trade programs, investing in clean energy technologies, and incentivizing businesses to reduce their emissions. In countries like the United States, government action to reduce emissions must have widespread public support to overcome the inertia of business as usual.
How can I find out more?
Check out the following sites, if you’re looking for more information on climate change:
This site is an excellent place to start learning more about the climate system and climate science, the latest in the news, energy and sea level rise.
This site is an excellent resource for debunking misinformation about climate science and about explaining climate science. The site also produces excellent graphics that help explain climate trends and produces smartphone apps that catalog rebuttals to climate skeptic myths.
This site answers several elementary questions about climate change, emissions, and their effects.
The US National Oceanic and Atmospheric Administration (NOAA) National Climate Data Center provides data, reports, and images covering many aspects of climate change.
Provides a general overview of climate change data and issues
Here you can find educational materials to aid teachers and others learning about climate change.
This recently released report is available for review. “Climate change, once considered an issue for a distant future, has moved firmly into the present. This report of the National Climate Assessment and Development Advisory Committee concludes that the evidence for a changing climate has strengthened considerably since the last National Climate Assessment report, written in 2009. Many more impacts of human-caused climate change have now been observed.”
The Intergovernmental Panel on Climate Change (IPCC) is a broad-based international panel of leading climate experts that assembles scientific assessments on the causes and consequences of climate change.
RealClimate, “climate science from climate scientists” provides commentary on current issues in climate change science and policy by climatologists and other scientists. They work to separate what is science from what is advocacy and misinformation.
About the C-Learn Climate Model
How was the model made?
The model was made using a methodology known as system dynamics, which examines the relationships of different parts of a system to each other through feedback loops that can be used to model complex systems to help us understand how one thing can impact another, like CO2 emissions on sea level rise.
What is the scientific basis of the assumptions in the C-Learn model?
Since C-Learn is a version of C-ROADS please refer to the technical reference materials for C-ROADS here. The C-ROADS technical review explains that: “The simulation model is based on biogeophysical and integrated assessment literature and includes representations of the carbon cycle, other GHGs, radiative forcing, global mean surface temperature, and sea level change.” The report continues, “The core carbon cycle and climate sector of the model is based on Dr. Tom Fiddaman’s 1997 MIT dissertation. The model structure draws heavily from Goudrian and Ketner and Oeschger and Siegenthaler, et al. The sea level rise sector is based on Rahmstorf. In the current version of the simulation, temperature feedbacks to the carbon cycle are not included.” For the entire report, check the following link: C-ROADS technical review.
What data are used?
The C-ROADS technical review, explains that “the model uses historical data through the most recent available figures, for values such as country-level GDP and population, CO2 emissions from fossil fuels and from changes in land use. Scenarios for the future including Business As Usual CO2 emissions projections are calibrated to the IPCC SRES scenarios with the World Energy Outlook growth allocations between regions.”
Why are there so many graphs, and what do they show?
The graphs on the home page show the basic information regarding the emissions projections, carbon dioxide concentration, and global temperature change over the 21st century resulting from the input changes made by the user. Clicking on the menu items provides more specific graphs such as: emissions, atmospheric GHG concentration, temperature change, and sea level change.
Are there limitations in what inputs we may use?
|Variable||Minimum input value||Maximum input value|
|Stop Growth Year||2005||2100|
|Reduction Start Year||2005||2100|
|% Annual Reduction||0||10|
Are we allowed to copy the graphs from the site?
Yes. To copy a graph, take a screenshot of the graph by using a screen copy software or, if available, press “print screen” on your keyboard. This is a change from the previous version of C-Learn. The data for generating graphs using your own graphing software are also available from the table view of each graph.
Questions from Investigating the C-Learn Climate Model
Do deforestation and afforestation really have that small a difference?
Based on the model, the difference they make is fairly minor. There is a limit to how many forests can be created and how long they take to sequester carbon dioxide from the atmosphere.
Why is there an awkward jump/change in the otherwise smooth graphs?
The policy changes only begin to take place from the “start year”. However, the graphs begin in 2000. Consequently, the graphs will always have a sudden change, resulting from the policy decision, whenever it starts.
Why do the emissions for Developing A and B peak around 2080 in the default scenario?
The default scenario follows the assumptions of the IPCC’s A1F1 pathway.
Why, when I peak greenhouse gas emissions but do not choose a reduction, does the main graph on the control panel show emissions falling slowly after the peak year?