Strong action essential to avoid climate change disaster

The Stern Review on the Economics of Climate Change, commissioned by the British Government, states bluntly: "The scientific evidence is now overwhelming: climate change is a serious global threat, and it demands an urgent global response."

The possibility of avoiding a global catastrophe is "already almost out of reach", warns Sir Nicolas Stern, former Chief Economist of the World Bank, in his 700-page report.

"This Review has assessed a wide range of evidence on the impacts of climate change and on the economic costs, and has used a number of different techniques to assess costs and risks. From all of these perspectives, the evidence gathered by the Review leads to a simple conclusion: the benefits of strong and early action far outweigh the economic costs of not acting."

Satellites are used to map the extent and duration of snowmelt on the Greenland ice sheet. The dark red area represents the extent of snowmelt in 2005. It is the most extensive in the 27 year history of data collection. © NOAA and CIRES)

Costs of warming

Hundreds of millions of people could suffer hunger, water shortages and coastal flooding as the world warms. Using the results from formal economic models, the Review estimates that if we don�t act, the overall costs and risks of climate change will be equivalent to losing at least 5% of global GDP each year, now and forever. If a wider range of risks and impacts is taken into account, the estimates of damage could rise to 20% of GDP or more.

In contrast, the costs of action � reducing greenhouse gas emissions to avoid the worst impacts of climate change � can be limited to around 1% of global GDP each year.

"The investment that takes place in the next 10-20 years will have a profound effect on the climate in the second half of this century and in the next," says Sir Nicholas.

Major disruption

"Our actions now and over the coming decades could create risks of major disruption to economic and social activity, on a scale similar to those associated with the great wars and the economic depression of the first half of the 20th century. And it will be difficult or impossible to reverse these changes."

If no action is taken to reduce emissions, the concentration of greenhouse gases in the atmosphere could reach double its pre-industrial level as early as 2035, virtually committing us to a global average temperature rise of over 2�C. In the longer term, there would be more than a 50% chance that the temperature rise would exceed 5�C. This rise would be very dangerous indeed, according to the report. It is equivalent to the change in average temperatures from the last ice age to today. "Such a radical change in the physical geography of the world must lead to major changes in the human geography � where people live and how they live their lives."

Emission paths to stabilisation

But the report adds that the risks of the worst impacts of climate change can be substantially reduced if greenhouse gas levels in the atmosphere can be stabilised between 450 and 550ppm CO2 equivalent (CO2e). The current level is 430ppm CO2e today, and it is rising at more than 2ppm each year.

Stabilisation in this range would require emissions to be at least 25% below current levels by 2050, and perhaps much more. Ultimately, stabilisation � at whatever level � requires that annual emissions be brought down to more than 80% below current levels.

Manageable

This is a major challenge, Sir Nicholas admits, but sustained long-term action can achieve it at costs that are low in comparison to the risks of inaction.

"Central estimates of the annual costs of achieving stabilisation between 500 and 550ppm CO2e are around 1% of global GDP, if we start to take strong action now. This is manageable. We can grow, and be green."

The costs of taking action are not evenly distributed across sectors or around the world. Even if the rich world takes on responsibility for absolute cuts in emissions of 60-80% by 2050, developing countries must take significant action too.

Non-energy emissions

Cuts in non-energy emissions, such as those resulting from deforestation and from agricultural and industrial processes, are also essential, says the report. With strong, deliberate policy choices, it is possible to reduce emissions in both developed and developing economies on the scale necessary for stabilisation in the required range while continuing to grow.

Deforestation continues to rage in Asia. © Henrylito Tacio

International action is essential. "The UN Framework Convention on Climate Change and the Kyoto Protocol provide a basis for international co-operation, along with a range of partnerships and other approaches. But more ambitious action is now required around the world."

The report spells out key elements of future international frameworks:

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• Emissions trading: Expanding and linking the growing number of emissions trading schemes around the world is a powerful way to promote cost-effective reductions in emissions and to bring forward action in developing countries: strong targets in rich countries could drive flows amounting to tens of billions of dollars each year to support the transition to low-carbon development paths.
  
• Technology cooperation: Informal co-ordination as well as formal agreements can boost the effectiveness of investments in innovation around the world.
  
• Action to reduce deforestation: The loss of natural forests around the world contributes more to global emissions each year than the transport sector. Curbing deforestation is a highly cost-effective way to reduce emissions; large-scale international pilot programmes to explore the best ways to do this could get underway very quickly.
  
• Adaptation: The poorest countries are most vulnerable to climate change. It is essential that climate change be fully integrated into development policy, and that rich countries honour their pledges to increase support through overseas
  development assistance. International funding should also support improved regional information on climate change impacts, and research into new crop varieties that will be more resilient to drought and flood.

Links:

Failure to tackle global warming could cost trillions

Stern Report on the economics of climate change

Stern Report: Summary of Conclusions

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