REDEM

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 trends),
• 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 (early-mid-late).

Currently, there exist two versions of REDEM based on the same algorithm.

• 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.

Authors:

REDEM is developped by independent academic researchers.

The original version of REDEM has been implemented by

• Emmanuel Prados (INRIA), Patrick Criqui and Constantin Ilasca (CNRS)

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").