DEFINITION STATEMENT 'CONTRACTION & CONVERGENCE'
(Copied from www.gci.org.uk)

1. “Contraction and Convergence” (C&C) is the science-based, logically constructed global climate-policy framework, proposed to the United Nations since 1990 by the Global Commons Institute (GCI). [1,2,3,4]
2. The objective of safe and stable greenhouse gas concentrations in the atmosphere and the principles of precaution and equity, as already agreed in the “United Nations Framework Convention of Climate Change” (UNFCCC), provide the formal calculating basis of the C&C framework that proposes: -
* A full-term contraction budget for global emissions consistent with stabilising atmospheric concentrations of greenhouse gases (GHGs) at a pre-agreed concentration maximum deemed to be safe, following IPCC WG1 carbon cycle modelling. GCI sees higher than 450 parts per million by volume [ppmv] CO2 equivalent as ‘not-safe’.

* The international sharing of this budget as ‘entitlements’ results from a negotiable rate of linear convergence to equal shares per person globally by an agreed date within the timeline of the full-term contraction-concentration agreement. GCI suggests: -
[a] between the years 2020 and 2050, or around a third of the way into a 100 year budget, for example, for convergence to complete and
[b] that a population base-year in the C&C schedule is agreed.

* Negotiations for this at the UNFCCC should occur principally between regions of the world. This would leave negotiations between countries primarily within their respective regions. For example 'the European Union', the Africa Union, the United States, etc.
* The inter-regional, inter-national/regional and intra-national/regional tradability of these entitlements, in an appropriate currency such as Energy Backed Currency Units, could be encouraged, but within the overall C&C framework.
As scientific understanding of the relationship between an emissions-free economy and concentrations develops, so rates of C&C can evolve under periodic revision and be renegotiated.
3. Presently, the global community continues to generate dangerous climate change faster than it organises to avoid it. The international diplomatic challenge is to reverse this. The purpose of C&C is to make this possible.
It enables scenarios for safe climate to be calculated and shared by negotiation so that policies and measures can be internationally organised at rates that avoid dangerous global climate change.
4. GHG emissions have so far been closely correlated with economic performance. To date, this growth of economies and emissions has been mostly in the industrialised countries, creating recently a global pattern of increasingly uneconomic expansion and divergence [E&D], environmental imbalance and international insecurity.
5. The C&C answer to this is full-term and constitutional, rather than short-term and stochastic. It addresses inertial argument about ‘historic responsibilities’ for rising concentrations recognising this as a development opportunity cost to newly industrialising countries. C&C enables an international pre-distribution of these tradable and therefore valuable future entitlements to emit GHGs to result from a rate of convergence that is deliberately accelerated relative to the global rate of contraction agreed.

("Contraction & Convergence" and "C&C" are trademarks of Aubrey Meyer/Global Commons Institute.)