"A turning point"

After two weeks, and just a day late, the COP21 climate summit produced a historic agreement. It attempts to keep global temperatures "well below 2°C above pre-industrial levels and to pursue efforts to limit the temperature increase to 1.5 °C above pre-industrial levels". 

To achieve this a rapid decarbonisation of the global economy must start immediately. 

Centre director Johan Rockström describes the agreement as a turning point.

"This sends the signal to the global economy that decarbonisation starts today. The Global Carbon Project’s carbon budget published during the conference gives the first sign that this is underway."

Centre partner Future Earth’s Global Carbon Project published the global carbon budget on 7 December at another major press conference. Remarkably, the researchers announced carbon emissions grew just 0.6% in 2014 and are predicted to fall slightly in 2015 (-0.6%) - the first time emissions have stalled during a period of global economic growth. The scientists warn this hiatus may not last long as India and elsewhere industrialise rapidly.

Rockström belives the penny has dropped for many, particularly since the last climate summit in Copenhagen in 2009.

"We are starting to see that sustainable solutions not only exist but they are also adaptable and deliverable on various levels in society as a whole."

For any change of limiting the temperature increase 1.5 °C Rockström argues that the richest nations such as the EU, US, Australia and other oecd countries must lead the way to zero fossil fuel use by 2030.

Agreement in line with Earth Statement
In advance of COP21, the Earth League, a network of leading institutions working to respond to some of the most pressing environmental issues published the Earth Statement. Lead by Johan Rockström, the statement was a scientific assessment of the key elements required for a climate agreement to meet the goal of reducing the risk of crossing the 2°C threshold. The Paris agreement reflects most of the elements within the Earth Statement.

Here is a summary of the agreement:

• The agreement aims to keep temperatures "well below 2°C” but the introduction of a 1.5°C target into the agreement surprised many. This language reflects an increased awareness of the vulnerability many nations now feel. During the negotiations a new alliance emerged - the high ambition coalition. Over 100 nations have now joined this informal group, including the US and Australia, to push for deep emissions cuts.
  
  
• The first paragraph of Article Four states "to achieve the long-term temperature goal...Parties aim to reach global peaking of greenhouse gas emissions as soon as possible." No date is given and the agreement recognises developing countries should peak later than developed nations.
  
  
• The agreement goes on to say greenhouse gas emissions must fall rapidly "in accordance with best available science...to achieve a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century." This sentence is under intense scrutiny by scientists.
  
  
• National emissions commitments - the Intended Nationally Determined Contributions (INDCs) - received by the UN in advance of the summit fall short of the ambition of the agreement. Estimates suggest this will cause global temperatures to rise at least 2.7°C above pre-industrial. To deal with this, the agreement calls for a review every five years with each review requiring deeper emissions cuts than the previous period - the so-called "Ratchet mechanism".