Amongst the main issues to be solved is the long-standing difference of opinion between poor and rich countries over who pays for the required mitigation measures. The poor countries' view is that since the wealthy nations put most of the planet-warming gases into the atmosphere, then they should pay for it. These rich nations in turn do not dispute this, but argue that many of the poorer countries are now producing a huge and growing amount of the gases, and themselves must accept a share of the responsibility.
Then there are the extent to which all nations will be bound by whatever agreement is reached, and, crucially, how it will be monitored, since many nations, such as China, have said they would regard it as a breach of national sovereignty were their emissions to be scrutinized by outsiders. Instead, they demand to be trusted, something which others are uncomfortable about.
Then there is the collapse in the price of oil, which is almost back at $50, previously thought unreachable again. This makes the cost of renewable energy and energy efficiency measures seem much more expensive by comparison. It is leading some to call for stronger taxes on carbon to redress the balance.
On the positive side, the evidence of the reality of climate change is now hitting home in peoples' minds, despite the increasingly hollow-sounding voices of sceptics. 2014 was the hottest year on record - and 10 of the warmest have been since 1998.
Graph of yearly global temperature increases.
We are increasingly seeing more of a push by cammpaigners, scientists, artists, writers and musicians, as well as religious leaders such as the Pope, to build a mass, global consensus that we have to act, and do what the science demands.
If an agreement is reached then we can expect a huge mobilization of activity, but not staight away because an agreement reached in Paris in eleven months would not become binding for another four years.
In order to achieve the 2 °C climate target with a likely probability (>67%), cumulative global CO2 emissions in the 2010–2100 period need to be constrained to about 1000 GtCO2 (range of 800–1200 GtCO2). The projected global 2020 greenhouse gas emission level is now around 10% above the 2010 level.
The ‘least-cost’ 2°C scenarios show lower 2020 emission levels, in the range of 38 to 47 GtCO2eq. But these typically assume immediate implementation of mitigation policies in all countries and sectors.
If large emission reductions by 2020 are unlikely it will become increasingly harder to reach the 2°C target; global emission reduction rates will need to be much higher, and so, therefore, will the mitigation costs.
This in turn raises the risk of missing the 2°C target and the requirement for deploying technologies that often meet with public resistance.
A new analysis of the models (Long-term climate policy targets and implications for 2030 a Dutch PBL Policy Brief) shows that achieving the 2°C target critically depends on well organised international policies, in the short term, to realise stringent reductions during the 2020–2030 period.
This means formulating ambitious mitigation goals and increasing the participation of all parties in climate policy.
And it necessitates taking real action; implementing long-term incentive structures to reduce emissions (given the inertia in economic and energy systems) and stimulating innovation.
The biggest challenge is, in a tough economic climate, with a low price for oil, how to increase the motivation to implement ambitious climate mitigation policies.
It is therefore useful to look at ways of doing so that additionally achieve synergies with other policy areas, such as job creation, poverty relief, food provision, energy security, economic opportunities and risks, air pollution and ecosystem degradation.
The costs of meeting the 2°C target would be lowest if the global emissions level were to peak within the next 10 years.
Can we achieve this? Right now, emissions are increasing, but the rate of increase is slowing. The average growth in emissions over the last decade – excluding the global financial crisis between 2007-2012 was 3.8% per year. A 2.5% growth is projected by PwC and the International Monetary Fund in 2015.
What can cities and regions do? They can set unilateral targets and work with partners on their own strategies. Individuals can put pressure on their local representatives. All can help to put pressure on national governments to reach a firm and proper agreement in the Paris talks.
To borrow two clichés: all hands on deck – it will be touch and go.
David Thorpe's book, The 'One Planet' Life: A Blueprint for Low Impact Development has received the following praise:
"An excellent and immensely practical step by step guide" – George Marshall, author of Don't Even Think About It, Why Our Brains Are Wired To Ignore Climate Change.
“This year’s must have book.” Jane Davidson, former Environment Minister for Wales and Director of INSPIRE
"There is much inspiration to be had from this comprehensive and beautifully illustrated book. David Thorpe is a master of lucid writing on one of the most important topics of our time. I highly recommend this book to anybody who is interested in assuring that we leave a habitable planet to our children." Herbert Girardet, founder of The World Future Council.
"Makes the irrefutable case for ‘one planet living’" – Oliver Tickell, editor, The Ecologist