2°C-målsætningen: De fleste lande skal fordoble deres klimaindsats
29. oktober 2015
Forud for den forestående Paris-konference får vi i morgen får fremlagt en syntesrapport af de indleverede INDC. Det står allerede nu klart, at summen af de indberettede nationale klimaplaner ikke kommer til at leve op til den 2°C-målsætning. Og selvom vi via IPCC store klimastatusrapport AR5 sidste år fik defineret et carbon budget for en 2°C-løsning, har FNs klimaforhandlinger valgt i første omgang ikke at håndtere det heraf følgende kernespørgsmål, hvem som så må udlede hvor meget, og hvem som skal reducere hvor meget hvor hurtigt for at holde 2°C-målsætningen. I den anledning har jeg hentet nedenstående artikel af Anita Talberg og Malte Meinshausen fra University of Melbourne fra The Conversation. Her præsenterer de en artikel, som de netop har publiceret i Nature Climate Science, som ser på forskellige fordelingsnøgler for det globale carbon budget, hvis vi samlet set skal kunne holde 2°C-målsætningen. Den manglende diskussion af denne fordelingsnøgle er stærkt medvirkende til, at de fleste lande har indleveret klimaplaner, som anerkender 2°C-målsætningen samtidig med at de er helt utilstrækkelige til opnåelsen af 2°C-målsætningen.
For EU, som ikke behandles særskilt i artiklen, vil der ved en metrisk lige fordeling skulle reduceres med 41% i 2030, og hvis man tager udgangspunkt i en korrigeret nøgle, hvor udviklingslande har ret en forholdsvis større del af carbon budgettet end de industrialiserede lande, står EU til at skulle reducere med 49% i 2030 – begge tal i forhold til 2010. EUs nuværende reduktionsmål er 40% i forhold til 1990, så uanset hvilken fordelingsnøgle, man benytter, er også EUs reduktionsmål helt utilstrækkelige i forhold til 2°C-målsætningen.
Talberg & Meinshausens artikel, Most countries need to at least double their efforts on climate: study, er gengivet her ifølge The Conversations vilkår for common licence.
Most countries need to at least double their efforts on climate: study
Developed nations would need to double or triple their current efforts to limit global warming to a “safe” level of 2⁰C. That’s the finding of a study published today in Nature Climate Change assessing countries’ post-2020 climate pledges ahead of December’s international climate summit in Paris.
As an example, Australia would need to reduce emissions 50-66% below 2010 levels to be considered to be doing its fair share (its current target, when converted to 2010, is a 23-25% reduction).
Countries have agreed to limit warming to 2⁰C above pre-industrial levels. But how do we divide up the necessary reductions in emissions fairly?
Developing nations often argue that developed nations need to do more, because they are responsible for more greenhouse gas emissions historically.
This new paper shows that these debates about fairness will inevitably cause us to go beyond 2⁰C, however it also shows a way to fix the problem.
You can read more in a Briefing Note, and all the underlying data is available on a new website.
Are we on track for 2⁰C?
How much the world warms is determined by the total amount of greenhouse gases that go into the atmosphere, what’s known as the “carbon budget”. To have a 66% chance of limiting warming to 2⁰C the Intergovernmental Panel on Climate Change shows that after 2011 we can only emit 1,010 billion tonnes of greenhouse gases.
Converting the budget to yearly emissions is not easy. However, by analysing hundreds of emissions scenarios, the new study found that to meet the carbon budget, global emissions need to be reduced to 1990 levels by 2030.
We are not on track for this.
The same conclusion was reached by a paper published in 2010, and more recently by Climate Action Tracker that projects 2.7⁰C of warming by 2100.
