Nicholas Stern

The United Nations Climate Change Conference in Copenhagen begins on 7 December and we can see the outline of a global agreement emerging. However, the crucial specifics of that agreement, including emissions reduction targets for the major emitters and finance for mitigation and adaptation in developing countries, are not yet settled and will require strong political commitment to conclude.

The world faces a stark choice. Do we collaborate and agree a strong framework agreement that decisively cuts the devastating risks posed by climate change and rapidly opens up the opportunities offered by low-carbon economic growth to overcome poverty and promote prosperity? Or, do we give way to division, lack of ambition and delay, allowing the risks to the climate to grow to dangerous levels?

Given what is at stake, essentially the future peace and prosperity of the planet, world leaders must now recognise that Copenhagen is the most important international gathering of our time. A strong framework agreement with the necessary political commitment at the highest level of government can and must be reached in Copenhagen. There can be no excuses for failure.

There is both a fierce urgency for leadership, and a big opportunity for both poor and rich countries. The developed world must face up to its responsibilities on both development and climate change. Action on the necessary scale will require radical change, and significant finance and investment. If we choose to, wisely and decisively, we can not only manage the profound risks of climate change, we can also find a much more attractive and stronger form of growth: a growth that can last and that helps us overcome world poverty. Indeed we must approach this discussion by recognising that the two defining challenges of our century are managing climate change and overcoming poverty. And if we fail on one we will fail on the other. I believe that the developing world, if the rich world plays its part, will accelerate its actions and we can together create an international collaboration which can transform the way the world works together.

Three issues are the key to agreeing an effective and equitable framework in Copenhagen.

First, we must recognise what we have to achieve in terms of global emissions of greenhouse gases. In order to have a reasonable, around 50 per cent, chance of avoiding an increase in global average temperature that exceeds 2°C above preindustrial levels, we must reduce annual worldwide emissions from the present level of just under 50 billion tonnes of carbondioxide-equivalent to well below 20 billion tonnes by 2050 (or as sometimes expressed, at least 50 per cent below 1990 levels).

There are a number of possible emissions paths which could meet this target and control total cumulative emissions over the period to the level necessary, but all of them require us to reduce global annual emissions to well below 35 billion tonnes by the mid-point of 2030 and much less than 20 billion tonnes by 2050.

These are the key figures that must guide any agreement on national targets for emissions reductions. By focusing on these totals for global annual emissions, and not percentages relative to earlier levels, we can concentrate on where the science takes us, on the overall path of annual emissions over the next few decades. In other words, we must focus on whether the planned national emissions targets are consistent with the constraints of the global emissions totals implied by responsible action on the climate, and whether the total emissions planned by each country, when ‘added up’, meet these constraints.

If we are to have a path which meets these constraints, has cumulative emissions consistent with 2°C, and does not imply implausibly large or rapid cuts before or after 2020, then global annual emissions should be around 44 billion tonnes by 2020.

Second, the need for national targets both to add up and to be equitable means that rich countries, including the European Union, Japan and the United States, should achieve emissions reductions of at least 80 per cent by 2050 compared with 1990. Developing countries, including China and India, also need to limit the growth of, and start to decrease, their emissions, but in ways that are consistent with their ambitions for continued economic growth and the reduction of poverty. By 2050 the world average of per capita emissions must be around 2 tonnes of carbon-dioxide-equivalent, compared with around 7 tonnes per capita now (and the USA is over 20, Europe around 10 and China around 6).

Third, given the relative wealth of rich and poor countries, the rich countries’ responsibility for the bulk of past emissions, and the urgent need for action, developing countries must receive reliable and substantial support from the rich nations for their climate action plans. This is necessary both for these plans to deliver emissions reductions on the scale required, and to overcome the additional challenges that climate change will pose for their efforts to tackle poverty.

Developed countries should show the extent of their commitment by providing US$50 billion per year by 2015, rising to US$100 billion in 2020, and progressing to around US$200 billion during the 2020s as effective low-carbon and adaptation programmes are developed and implemented. Whilst these sums are substantially smaller than the overall investments that are necessary, as developing countries would also be making substantial investments, they are crucial and help to realise great benefits to the entire world.

Crucially, financial support should be additional, beyond existing official development assistance. While these might sound like large sums, US$50 billion is around 0.1 per cent of the likely gross domestic product of the rich countries in 2015, and is very small compared with the likely costs we will face if we do not secure a strong international agreement to tackle climate change.

The immediate priorities for spending should be halting deforestation, supporting adaptation in African and other vulnerable nations, and supporting technological change throughout the developing world.

We have seen major advances and a gathering momentum over the past few weeks and months. At Copenhagen, we are now seeking an organisational framework with strong political commitment rather than a formal treaty. A formal treaty can follow in 2010 if the political framework is clear. But without such a framework, settled at the highest level, progress on a treaty or similar agreement will be impossible. Now is the time for heads of government to take charge – only they can forge such an agreement.

Country after country have been raising their ambitions for controlling emissions. Assembling these ambitions, it is now clear that if countries move together and find extra margins of action, we can reduce global annual emissions to 44 billion tonnes of carbon-dioxide-equivalent by 2020, and set the world on a responsible path. If current ambitions for emissions reductions across the world are settled, financed and delivered, we may be only a few billion tonnes short of where we need to be. But enhancing finance and delivery are major tasks, and finance, in particular, remains contentious.

We can now see that it is possible to achieve an agreement that is effective, efficient and equitable. It will allow us to avoid the biggest risks of climate change, to overcome poverty worldwide, and to usher in an exciting new era of prosperity based on sustainable low-carbon growth. Through innovation and investment in new greener and more energy efficient technologies in the next two or three decades, the transition to the low-carbon economy can be the most dynamic period of growth in economic history. And the low-carbon world we can create will also be quieter, cleaner, more energy-secure and more biologically diverse.

Let us not allow mistrust, pessimism and lack of ambition to take us stumbling into profound dangers. Instead, let us have real vision and leadership in both developing and developed countries which seize the opportunities offered by Copenhagen, for us, our children and future generations.

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