* Any views expressed in this opinion piece are those of the author and not of Thomson Reuters Foundation.The climate deal needs a way to rachet up whatever ambition comes out of Paris
With just a day to go until nations agree on a global climate deal in Paris, it is fast becoming clear there is one issue which needs to be included in the agreement if a pollution-free and prosperous planet is to be ensured.
Already 183 countries have submitted their national action plans outlining the steps they will take to reduce green house gas emissions and build resilience. With rich countries also indicating the support they will provide to those on the front line of climate change.
Added together, these plans alone will make a significant contribution to keeping average global temperature rise in check. The UN Environment Programme has reported that if implemented these Intended Nationally Determined Contributions (INDCs) will keep average temperature rise between 2.7 to 3.5 degrees Celsius above pre-industrial levels. This is considerably better than the hellish 5 degrees or more we're currently heading towards but still way above the 2 degrees of global warming scientists have warned will lead to dangerous impacts. This is simply not good enough.
So how do we get from a 2.7-3.5 degree world to a 2 degree one? Or ideally one with just 1.5 degrees of warming as called for the by more than 120 most vulnerable countries.
The vital element UK Energy and Climate Change Secretary, Amber Rudd, and other ministers must deliver is an 'ambition accelerator', a mechanism to regularly review national commitments and increase them like a ratchet. That way, governments leaving the Paris talks at the weekend will be able to genuinely claim to have achieved a purposeful outcome. Everyone agrees our destination is a decarbonised world and a limit on global temperatures way below 2 degrees. But if our starting point is 2.7-3.5 we need a vehicle to get us there. That vehicle is the 'ambition accelerator'.
What this would look like is a review of current INDCs by 2019 and new plans submitted no later than 2023 which would come into force by 2025. This process would then repeat on a five year basis. This would make the Paris deal not just revolutionary but also evolutionary. It would evolve to keep pace with the falling costs of renewable energy and other changes in the geopolitical landscape.
As well as controlling emissions (mitigation) this cyclical approach should also include adaptation, the support rich countries have promised poor climate vulnerable nations to not only adapt to a climate they didn't cause but also help them develop along a clean pathway.
Government ministers have until Friday night to make sure this ratchet mechanism is agreed and in place. If it is then we have a good chance of reaching our destination - a fossil fuel free world at a temperature which will allow everyone to prosper.
Mohamed Adow is a senior climate change advisor for Christian Aid.