Rate of change, how can it be included in emission metrics? Terje Berntsen CICERO/University of Oslo, Norway Workshop on common metrics, Bonn, April 2012

Rate of Change and the UNFCCC ARTICLE 2: OBJECTIVE The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.

Rate of Change and the UNFCCC ARTICLE 2: OBJECTIVE The ultimate objective of this Convention and any related legal instruments that the Conference of the Parties may adopt is to achieve, in accordance with the relevant provisions of the Convention, stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system. Such a level should be achieved within a time-frame sufficient to allow ecosystems to adapt naturally to climate change, to ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner.

Point of departure: Keep to the cost-effective framework indicated in UNFCCC article 2 Use global mean temperature as indicator Keep the constraint of a long-term stabilization target (i.e. the 2°C target) Add a constraint on rate of temperature change

Basic question (all metrics): When are the constraint(s) binding Basic question (all metrics): When are the constraint(s) binding?  Time horizon

Basic question (all metrics): When are the constraint(s) binding Basic question (all metrics): When are the constraint(s) binding?  Time horizon tL

Basic question (all metrics): When are the constraint(s) binding Basic question (all metrics): When are the constraint(s) binding?  Time horizon Rate limit 0.02K/yr tR

Basic question (all metrics): When are the constraint(s) binding Basic question (all metrics): When are the constraint(s) binding?  Time horizon

Similar approach as Manne & Richels (Nature, 2001)

Numerical examples based on pulse AGTP (ΔT(t))

Construction of a rate and level based metric MR&L Rate term Level term tR=2040 tL=2070

Construction of a rate and level based metric MR&L Rate term Level term Combined and relative to CO2   f = 0.5 for t<tR and f=0 for t> tR

MR&L for methane GWP100 Manne & Richels, 2001

MR&L also for BC (Direct effect)

Summary A purely physical metric including both rate and level based constraint can be constructed Requires additional value judgments E.g. weighting factor rate vs. Level Rate constraint MR&L ≤ GWP100 in the early phase for SLCFs Alternatively Consider rate of change as a independent environmental issue Regulate SLCFs in a separate basket, could use MR as metric for this basket