About / Introduction
What is the REDEM?
REDEM is a tool which allows to build benchmarking
of GHG emission reduction trajectories for individual states, groups of
states or the entire world, and which fulfills a set of fundamental
principles. It seeks to reconcile bottom-up aspirations and top-down
constraints existing in the negotiations on climate change.
The obtained curves are benchmark curves (of future
GHG emissions until 2100). They are not prospective curves based on
simulations of complex economic phenomena.
REDEM draws on the concept of “soft landing in
emissions” to compute national or world CO2 emission trajectories
in order to generate trajectories that are compatible with
- observed CO2 emissions until 2014 (emissions and their
- exogenous cumulative CO2 emissions to 2100.
REDEM main parameters are the date of the peak in the emission
declining rate and a curvature factor.
REDEM derives trajectories for different probabilities of reaching a
given temperature level, according to the timing of action
Currently, there exist two versions of REDEM based on the same
- The original version is devoted to the analyses carried out at
the scales of individual states or at groups of states. It allows
the countries to evaluate and compare themselves to others. The
comparisons are done in a framework ensuring the consistency with
the global objective of GHG emissions. This framework verifies some
common equity rules which are the simplest and the most objective
possible and which allow to differentiate the countries according
to their capacity and responsibility.
- The "REDEM World" version has been specifically designed for
assessing the adequacy of the INDCs (Intended Nationally Determined
Contributions) with the 2°C trajectories (or eventually with the
2.5°C or 3°C trajectories) in preparation for the COP21 in Paris.
This last version also allows to handle a pool of negative CO2
emissions. Non CO2 gas are introduced on top of CO2 emissions,
based on the median of IPCC RCP2.6 scenarios.
REDEM is developped by independent academic researchers.
The original version of REDEM has been implemented
- Emmanuel Prados (INRIA), Patrick Criqui and Constantin Ilasca
The simplified version called "REDEM World" has been
specifically adapted for the COP21 in Paris and the analyses of the
INDCs proposed for this event. This version has been implemented by
- Emmanuel Prados (INRIA), Olivier Boucher, Hélène Benveniste
(IPSL), Patrick Criqui (CNRS)
in framework of the work carried out by the GICN ("Groupe
Interdisciplinaire sur les Contributions Nationales").