Another Look at Closing the Gigatonne Gap

6 October 2010


In narrowing the negotiating text here in Tianjin, delegates should focus on a shared vision of limiting global temperature rise to 1.5° C and atmospheric concentrations of carbon dioxide of no more than 350 ppm. 

Anything above these levels would result in a host of severe impacts, including the inundation of low-lying island nations, the complete loss of coral reefs and summer Arctic sea ice, as well as the potential triggering of irreversible feedbacks adding massively to climate disruption. 

For this reason, more than 110 countries support reducing carbon dioxide to 350 ppm.  A shared vision that accomplishes anything less would surely consign future generations to ecological and economic

As indicated by several scientific assessments, emission reduction pledges made at Copenhagen fall far short of the action needed to limit temperature rise to 2° C, much less to 1.5° C/350 ppm.  Even viewed in the most optimistic light, the Copenhagen Accord would increase global temperatures by more than 3° C and push carbon dioxide levels past 650 ppm, a recipe for disaster. 

To provide a 50/50 chance of limiting warming to an average of 2º C above pre-industrial levels, emissions by 2020 should be no more than 44 gigatonnes (Gt) CO2e globally.  For the safer 1.5º C/350 ppm target, global emissions would need to be no greater than 40 Gt. 

The Copenhagen Accord pledges, on the other hand, would end up at 48 to 55 Gt in 2020, so there is your ‘gigatonne gap’.  And it’s not a pretty sight.  Parties must formally acknowledge this gap in Cancun and adopt a firm process to close it.  The laws of physics and chemistry will not bend to fit political convenience.

There are many potential measures to close the gigatonne gap, including increased emission reduction commitments by developed countries, dealing with excessive use of AAUs, capping emissions from bunkers, closing loopholes in greenhouse gas accounting, and additional financing to facilitate greater emissions reductions from
developing countries. 

Because there is a shrinking window of time to address the climate crisis, expressly acknowledging the need to close the gigatonne gap is critical, and bold action will be needed to meaningfully address the climate crisis. There is no more time to lose.

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