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The geographical distribution of fossil fuels unused when limiting global warming to 2 °C
Christophe McGlade & Paul Ekins, Nature volume 517 8 januari 2015
Abstract
Policy makers have generally agreed that the average global temperature rise caused by greenhouse gas emissions should not exceed 2 °C above the average global temperature of pre-industrial times.
It has been estimated that to have at least a 50 per cent chance of keeping warming below 2 °C throughout the twenty-first century, the cumulative carbon emissions between 2011 and 2050 need to be limited to around 1,100 gigatonnes of carbon dioxide (Gt CO2).
However, the greenhouse gas emissions contained in present estimates of global fossil fuel reserves are around three times higher than this, and so the unabated use of all current fossil fuel reserves is incompatible with a warming limit of 2 °C.
Here we use a single integrated assessment model that contains estimates of the quantities, locations and nature of the world’s oil, gas and coal reserves and resources, and which is shown to be consistent with a wide variety of modelling approaches with different assumptions, to explore the implications of this emissions limit for fossil fuel production in different regions.
Our results suggest that, globally, a third of oil reserves, half of gas reserves and over 80 per cent of current coal reserves should remain unused from 2010 to 2050 in order to meet the target of 2 °C.
We show that development of resources in the Arctic and any increase in unconventional oil production are incommensurate with efforts to limit average global warming to 2 °C.
Our results show that policy makers’ instincts to exploit rapidly and completely their territorial fossil fuels are, in aggregate, inconsistent with their commitments to this temperature limit. Implementation of this policy commitment would also render unnecessary continued substantial expenditure on fossil fuel exploration, because any new discoveries could not lead to increased aggregate production.
toelichting
CO2-equivalent: hoeveelheid van een bkg met gelijk opwarmend effect als een hoeveelheid CO2
opwarmend effect van qx van bkg x = opwarmend effect van qy CO2
qy = CO2-equivalent van qx
ppm = parts per million, concentratie van broeikasgas in atmosfeer
opwarming
≤ 2 ºC . . . . . . . . ≤ 450 ppm . . . . . . . . . . . . . . . . . . . . 50% kans
. . . . . . . . . . . . . met ontrekking CO2 aan atmosfeer. . . . . 66% kans
≤ 1,5 ºC . . . . . . . ≤ 430 ppm
(De waarschijnlijkheid bij 430 ppm staat niet in de cijfers die ik nu heb.
De variant "450 ppm met onttrekking CO2 aan atmosfeer" snap ik niet, want dan is het aantal ppm niet 450 maar lager.)
Om onder 450 ppm te blijven mag er in de periode 2011-2050 maximaal 1100 gigaton CO2 uitgestoten worden.
De nu bekende wereldreserves aan fossiele brandstoffen bevatten ± 3300 gigaton CO2 of CO2-equivalent.
Daarvan moet ⅔ (gemeten in CO2-waarde) ongeëxploiteerd blijven.
De auteurs verdelen dit in ⅓ van de olie, ½ van het gas en 4/5 van de kolen.
Om onder 430 ppm te blijven moeten meer fossiele brandstoffen ongeëxploiteerd blijven.
Bladwijzers