C-ROADS is designed to broaden decision-maker understanding of the
climate system’s responses to human intervention through
What is the structure of C-ROADS?
The C-ROADS (Climate Rapid Overview and Decision Support) simulator is based on the biogeophysical and integrated assessment literature and includes representations of the carbon cycle, other greenhouse gases, radiative forcing, global mean surface temperature, and sea level change. The simulation is grounded in the established literature yet remains simple enough to run quickly on a laptop computer.
What sorts of tests can users make in C-ROADS?
Model users determine the path of net GHG emissions (e.g., CO2 from fossil fuels and land use, non-CO2 GHGs including CH4, N2O, F-Gasses, Montreal Protocol Gasses and CO2
sequestration from afforestation), at the country or regional level,
through 2100. The model calculates the path of atmospheric CO2 and other GHG concentrations, global mean surface temperature, and mean sea level rise resulting from these emissions.
The user can choose the level of regional aggregation. Currently, users may choose to provide emissions inputs for one, three, or six different blocs of countries with C-ROADS World Climate. C-ROADS Pro enables greater disaggregation. Graphs of other key variables such as per capita emissions, energy and carbon intensity of the economy (tonnes C per dollar of real GDP), and cumulative emissions are also available.
Where has C-ROADS been used?
C-ROADS has been used worldwide by thousands of people ranging from strategic planning sessions for decision-makers from government, business and civil society to interactive role-playing policy exercises.
Is C-ROADS a “GCM” like MAGICC?
Relative to the General Circulation Models or GCMs, C-ROADS is a
highly-aggregated simulation. And it has a different purpose – it
intends to give policymakers and others access to the insights first
discovered in the GCMs.
How did you build confidence in or validate C-ROADS? What sorts of tests did you do?
As described in the C-ROADS Reference Guide, we conducted a full suite of tests to build our confidence in the simulation, guided by section 21.4 in Business Dynamics by John Sterman.
Given the existence of many other climate models, one of the most important tests was the comparison of C-ROADS output to the output of disaggregated simulations from the SRES database (e.g., MAGICC) given a range of emissions input scenarios. As part of the ongoing work to keep C-ROADS updated comparison tests have been run against the RCP and SSP scenario sets from the IPCC.
How did you test the scientific validity of the simulation with scientists outside your team?
C-ROADS underwent a scientific review, which concluded, in part:
C-ROADS … is a timely simulation tool that provides policymakers
and policy analysts … a better understanding and intuitive feel for the
broad brush, long term consequences of climate change given various GHG
reduction strategies. This very rapid simulation model reproduces the
response properties of state-of-the-art three dimensional climate models
very well – well within the uncertainties of the high resolution models
– and with sufficient precision to provide useful information for its
intended audience. Given the model’s capabilities and its close
alignment with a range of scenarios published in the Fourth Assessment
Report of the IPCC we support its widespread use among a broad range of
users and recommend that it be considered as an official United Nations
Dr. Robert Watson, Review Chair, the UK Department for Environment,
Food and Rural Affairs (DEFRA) and the Tyndall Centre at the University
of East Anglia (UK)
Mr. Eric Beinhocker, McKinsey Global Institute (UK)
Dr. Bert de Vries, Netherlands Environmental Assessment Agency (The Netherlands)
Dr. Klaus Hasselmann, Max-Planck Institut für Meteorologie (Germany)
Dr. David Lane, London School of Economics & Political Science (UK)
Dr. Jorgen Randers, Norwegian School of Management (BI) (Norway)
Dr. Stephen Schneider, Stanford University (US)
Note – The review panel’s endorsement of C-ROADS represents the views of the members of the review panel in their individual capacity and does not necessarily imply any endorsement by the organizations with which they are affiliated.
What are your biggest criticisms of the model’s accuracy?
While C-ROADS includes multiple feedback processes (e.g., carbon fertilization and carbon saturation), it does not include the effects of various economic feedback loops on economic growth (GDP) that would come from climate impacts and/or large scale climate change mitigation.
Additionally C-ROADS is based upon and calibrated to the results of models from the IPCC’s Fifth Assessment Report. Recent science suggests that AR5 may underestimate the speed and magnitude of some climate change impacts. For example, scientific understanding of global seal level rise is changing as observed sea level rise and arctic melting are accelerating faster than previously expected.
About the developers and development process
Who created C-ROADS?
C-ROADS is based on research originally conducted in the mid 1990s at MIT, and has been developed by a partnership of MIT’s Sloan School of Management, Ventana Systems, and Climate Interactive. Ventana Systems is a leading simulation and consulting firm. The lead modeler at Ventana Systems on the project is Dr. Tom Fiddaman, whose 1997 MIT doctoral dissertation, supervised by Prof. John Sterman, forms the foundation of the C-ROADS model. Today C-ROADS is largely maintained by Climate Interactive, with ongoing input from Prof. John Sterman, Tom Fiddaman, and many others.
Who is on the C-ROADS development team?
– Dr. Lori Siegel, Climate Interactive
– Dr. Tom Fiddaman, Ventana Systems
– Dr. John Sterman, MIT System Dynamics Group
– Dr. Travis Franck, Climate Interactive
– Andrew Jones, Climate Interactive
– Stephanie McCauley, Climate Interactive
– Dr. Phil Rice, Climate Interactive
– Dr. Elizabeth Sawin, Climate Interactive
Where does the financial support behind C-ROADS come from?
The development and use of C-ROADS has been supported by ClimateWorks, Active Philanthropy, Zennström Philanthropies, The Morgan Family Foundation, The Rockefeller Brothers Fund, Citigroup, Fidelity Investments, and others, all via grants and contributions via Climate Interactive. More on our current funders and partners here.
In-kind contributions have been made by multiple project partners.
About the data and the assumptions behind the model
What is the source of the structure of the carbon cycle and climate sector?
The primary sources for the climate and temperature sector are:
Bolin, B. 1986.
Fiddaman. T.S. 1997.
Goudriaan, J. and P. Ketner. 1984.
Nordhaus, W. D. 1992, 1994, 2000.
Oeschger, H., U. Siegenthaler, et al. 1975.
Rotmans, J. 1990.
Schwartz, S.E. 2007.
Schneider, S.H., and S.L. Thompson. 1981.
Wullschleger, S. D., W. M. Post, et al. 1995.
For the complete up to date bibliography, please consult the C-ROADS Reference Guide. Structural diagrams of the sectors are below.
What assumptions do you make when calculating sea level rise?
We use the equations in (Rahmstorf, S. 2007), and allow users to
examine the impact of higher or lower future SLR per degree of warming
through a sensitivity parameter, so that users can examine, for example,
the impact of higher future rates of SLR due to accelerating melt and
calving from the Greenland and West Antarctic ice sheets.
The model uses historical data through the most recent available figures, including country-level GDP and population and GHG emissions from fossil fuels, changes in land use, and other sources.
Scenarios for the future are calculated in the C-ROADS simulation and based on UN population medium fertility projections with GDP per capita rates converging to 1% over time (consistent with other IAMS), and GHG per capita projections for each gas. The emissions per GDP rates reflect trends over the last decade, converging to business as usual rates of decreasing improvements over time. The resulting projections are consistent with trajectories between RCP8.5 and 6.0.
Projected N2O, CH4, and other non-CO2 gas atmospheric concentrations
IPCC Fifth Assessment Report. RCP 8.5
What are the assumptions behind the “business as usual” or “reference scenario?”
We build our reference scenario (business as usual scenario) based on UN population medium fertility projections with GDP per capita rates converging to 1% over time (consistent with other IAMS), and GHG per capita projections for each gas. The emissions per GDP rates reflect trends over the last decade, converging to business as usual rates of decreasing improvements over time. The resulting projections are consistent with trajectories between RCP8.5 and 6.0. For more information, please consult the C-ROADS Reference Guide.
What is your assumption about the sensitivity of climate to CO2 concentration?
C-ROADS uses a climate sensitivity of 3 (that is 3°C of temperature increase for a doubling of CO2 concentration.) Users can modify this parameter in the assumptions to explore the impact of higher or lower values.
More information on C-ROADS
Where can I learn more about the organizations that created the simulation?
The Potsdam Institute for Climate Impact research provides a similar model. Other simulations that are designed for use by policy-makers and/or on the web include the Java Climate Model (JCM – Matthews 2003), FAIR (den Elzen & Lucas 2005), Good Enough Tools (Socolow & Lam 2007), IASSA’s RAINS model, DICE (Nordaus 1994, 1999+) and MAGICC/SCENGEN.
What press coverage has there been about C-ROADS?
C-ROADS has been featured in hundreds of media outlets and ahead of the Paris climate change negotiations in 2015 it was part of a featured story on the front page of the New York Times.
Countries in the 6 region mode are the United States, European Union, China, India, all Other developed countries and all Other developing countries. For the specific countries in the “other developed” and “other developing” groups please refer Table 3-9 in the C-ROADS Reference Guide
The 15 region mode (available in C-ROADS Pro) is comprised or the United States, European Union, Russia, Canada, Japan, Australia, South Korea, all other Developed non-MEF, Mexico, China, India, Indonesia, Brazil, South Africa, all other Developing non-MEF countries.
How can I see a bigger version of a graph?
In C-ROADS World Climate – Go to “Window” in the menu bar and select “Large Left Graph” or “Large Right Graph”.
In C-ROADS Pro – Below each graph pane is a “Large Graph” button. Clicking the “Large graph” will open a window containing a larger copy of the graph above it. You may open a large graph from each pane. Within the large graph window, you may select other graphs to view. The graphs selections are the same as in the parent graph pane. You may also export the image of the graph and the data used to create the graph.
How can I view the numbers behind the graphs?
In C-ROADS World Climate – this feature will be added in a future version.
In C-ROADS Pro –
To see the numbers underlying a graph, click the “Data table” button. This brings up a window containing the graph’s data with choices to “Export all” or “Export Range”. There is also a check box to select to transpose the data before exporting it. When you click “Export all” the entire data set for the graph is placed on the clipboard ready to be pasted into an appropriate application of your choosing.
If you click the “Export Range” button you have an additional choice
to select the date range of the data you wish to export. The default
range is the same as the graph you are viewing. The data are placed on
the clipboard for you to paste in your application of choice
Below each graph pane is a “Large Graph” button. Clicking the “Large graph” will open a window containing a larger copy of the graph above it. You may open a large graph from each pane. Within the large graph window, you may select other graphs to view. The graphs selections are the same as in the parent graph pane. You may also export the image of the graph and the data used to create the graph.
What is the best way to share a simulation run with another C-ROADS Pro user?
The most efficient means would be to send a copy of the “my run.cin”
file that was saved into My Documents/C-ROADS-CP/MODEL/my run.cin. It is
a small file for emailing purposes. The recipient places it in the
C-ROADS-CP/MODEL folder and runs the simulation and selects “Load stored
settings” from the opening screen it will be available for them to
load. If they then wish to, then may create a copy of the data file by
choosing “Save run”.
You could also send them a copy of the data file, “my run.vdf.” They
could view this using the “Review runs(s)” button – which doesn’t allow
the run to be altered – or they could use ‘”Update run” and view or
modify the run further and create their own settings file using the
“Save run” function.
How can I save the settings of a scenario so I can load it and build upon it later?
This feature is not available in C-ROADS World Climate.
With C-ROADS Pro, after you have set up a run, simply click the “Save run” button and name the run. Two files are created in the C-ROADS/Models folder, a data file, “my run.vdf”, and a settings file, “my run.cin”. The data file contains all of the data output of the simulation and the settings file contains all of the settings to replicate the run when you wish. Settings files are much smaller (~5 KB) than data files (~5 MB).
How can I make an Excel file of the numbers behind the graphs?
Select the graph from which you would like the numbers. Use “Export
image/data” to open a dialog for the graph you are viewing which will
allow you to export a picture or data in a variety of formats. The data
export allows you to export data as an excel file.
An alternate method is to select “Data table” and choose either
“Export all” or “Export Range” to place the data onto the clipboard.
Switch to your spreadsheet program and paste the data into a worksheet.
I am in 15 region mode, but I only see four regions on the graph. How can I add more?
There are two ways to change the regions that are displayed on your graphs. In the C-ROADS Pro main screen select “Set graph defaults” where you can set the default country/regions you would like to view on graphs that display data “by country”. These default settings will be used each time you select “Create new run.” You may reset them as you wish.
In the simulation control window you may override the default settings made in “Set graph defaults.” Click the “Select regions” button to add or remove the regions displayed on the data by country graphs. This override remains effective until you end the current simulation run either by “Returning to main” or choosing “Reset to baseline”.
How can I look at fewer lines on one of the comparative graphs?
Click “Load/Unload run” to go to the Dataset Control dialog. The set
of “Available” or viewable runs is on the left panel and the runs that
are “Loaded” in your comparative graph are in the right panel.
Double-click on a run in the “Available” column and it will move into
the “Loaded” column and vice versa. You may also single click on a run
name and then click on the arrow button between the columns to move runs
back and forth between “Loaded” and “Available”.
You may also control the order of the runs in the graph. A single click moves any run to the top of the loaded column.
How can I look at fewer lines on one of the graphs that shows multiple countries?
Each of the lines on a graph has a checkbox next to it. Un-checking the box will cause the line to be removed from the graph. The data label and checkbox remain; the graph line may be reactivated by checking the box again. The set of lines that are included is controlled from the “Select regions” or by the “Set graph defaults” buttons (see “I am in 15 region mode, but I only see four regions on the graph. How can I add more?”).
When I view a non-comparative graph, how can I select which of the runs I see?
In a non-comparative graphs you can tell which run you are viewing by the text at the bottom, “Showing values from run_name.vdf”. If you wish to view a different run, click the “Load/Unload run” button to go the Dataset Control dialog. The data set that is showing in a non-comparative graph is the one at the top of the “Loaded” list in the right panel. To move a run to the top of the list, click on it and it will rise to the top of the list. Click “Close” and the graph will show the run that is at the top of the “Loaded” list.
How do I change the Reference Scenario? What are my options for doing so?
This is under development and not available at this release. The intent is to allow the user to specify an alternative reference scenario to A1FI and have that used in the simulation and the reference scenario.
How can I input emissions via an Excel file?
The Excel file, “Emissions for C-ROADS-CPv2….xls”, contains two worksheets into which you may put data, “User 15 Region Inputs” and “User 6 Region Inputs”. You may specify your data inputs to the model using the area on the worksheet (15 Region inputs– A3:P22 and 6 Region inputs– A3:G22). When you have made the changes to the spreadsheet, you must save the file so the simulation can read the changes from the file.
I changed the date in the “Emissions for C-ROADS-CP.xls” file but I don’t see any difference in the simulation output.
When you make a change to the excel data file, “Emissions for C-ROADS-CP.xls”, it is important that the changes are to the correct sheet that corresponds to the aggregation level in the simulation you are using — 6 region or 15 region. The excel file must be saved so that the simulation program can read it from the disk. The simulation must be started from the main menu from any of the three buttons, “Create new run”, “Update run” or “Load stored runs(s)”. Entering the simulation in these three modes reads the excel file information in to the simulator so that it may be used.
How can I input emissions via a graph?
If you select “Graphical” as an input method you can enter data by modifying a graph by dragging or by entering data points as pairs of “Year” and “Gtons CO2/year”. You may also redraw the graph by clicking by the line and not on one of the points and slowly dragging a new line. This simultaneously creates the (year,Gtons CO2 emissions/year) data points. Play around with it to get the hang of it. Hit reset to undo any mess you make.
I am setting emissions for countries one-by-one. How can I see all of them together?
Select the “Summary” button to produce a table of all the inputs in a row and column format. Numerical inputs may be entered in this table. Arrow keys, tab and Return will move from cell to cell.
What are other gases like methane doing in this simulator? Where do I change what they do?
You can set whether the emissions controls are controlling “CO2
equivalents” or controlling “CO2 only” in the NON-CO2 GHGs portion of
the “Settings” pane. When ‘Set controls to regulate “CO2 equivalents”’
is selected, user inputs are in the form of CO2 equivalents. If you
select 50% below a reference point (Ref year or Ref scenario) The 50%
reduction will be applied across the GHG gases according to their
prevalence at the Reference time.
If you choose Set controls to regulate “CO2 only”, a 50% reduction
will be applied only to CO2. All the other greenhouse gases will
continue to grow according to the reference scenario.