The Climate Equity Reference Calculator is implemented as a web applications, and as a supporting database. There are also a number of spreadsheets implicated in parts of the analysis that we have not yet been able to integrate into the Calculator. In general, the algorithms are largely implemented by the Calculator, but the results of the analysis depend in significant ways on the time-series indicators in the database. The treatment of GDP and emissions baselines are notable in this regard.
The database
The Calculator database features a large set of key, national-level, time-series indicators such as historic emissions, GDP, population, PPP and MER exchange rates, embodied carbon flows, and income distribution data. These time-series indicators are taken from, or based upon, the most authoritative data available.
In all cases, the contents of the database are fully documented. In some cases, this simply means that they are sourced. In other cases – for example, national emissions baselines and global mitigation pathways – they are projected from or based upon authoritative, externally-sourced data. In such cases, the algorithms by which they are projected are fully documented as well.
See The Climate Equity Reference Calculator database for more information.
Definition, sourcing, and updating of emissions baselines
The essential framework here is effort-sharing as opposed to a resource sharing. Thus, calculations of fair shares are sensitive to assumptions about baselines – assumptions about “business-as-usual,” or BAU, as projected into the future. This is because effort-sharing approaches, by definition, allocate obligations in terms of reductions below a BAU situation in which no special climate-related efforts are being taken; i.e., a national emissions baseline.
What this means in practice is that a country’s actual mitigation obligation in any given year is relative to a projected baseline. Two countries with the same Responsibility and Capacity Index (or RCI) and thus the same mitigation obligation would have different emission allocations in a given year – say 2030 – if they had different BAU emissions projections for that year.
See Definition, sourcing, and updating of the emissions baselines for more information.
The Climate Equity Reference Calculator web interface
The Climate Equity Reference Calculator web interface is primarily written in PHP, with some javascript for interface interactivity, and is released as open source software under a GNU General Public License. The source code is available on github. Since in the installation of the calculator is a somewhat complicated procedure and requires access to a web server, we also maintain a docker image of the calculator that can be used to run it locally on any relatively modern computer – the docker image is hosted on docker hub and a Dockerfile to generate the image from source is available in the github repository. For most users, however, we recommend using our own installation of the calculator at https://calculator.climateequityreference.org
The Equity Reference Calculator engine
Behind the Calculator‘s web interface is an “engine” written in the C programming language. The full code is available under a permissive Apache license and is documented in detail.
- The Equity Reference Calculator engine is hosted on SourceForge, a site for open-source software projects.
- Source code can be browsed in a Subversion repository.
- Source code documentation can be browsed online (generated by Doxygen).
- A formal description of the Calculator‘s algorithms can be found at Calculations for the Calculator.
Working with the code
To check out the calculator engine’s code from Sourceforge using Subversion, execute the following command:
- svn co https://gdrs.svn.sourceforge.net/svnroot/gdrs/gdrsclib gdrs
The code is developed in NetBeans and can be loaded directly into NetBeans by pointing to the URL above. However, running the code requires a copy of the underlying SQLite3 database. The database is available in the Harvard University Dataverse.
The Web API
The Equity Reference Calculator can be accessed through a web application programming interface (API). This API is useful for web developers who wish to use the Calculator functionality but avoid the calculator interface itself.
The Web API Documentation is available as a PDF (150 kB).