On July 9, leaders of the world's largest economies will meet in L'Aquila, Italy, at the Major Economies Forum (MEF) to discuss progress toward a new global climate agreement. In six months, a deal is supposed to be struck in Copenhagen, so the MEF meeting comes at a vital moment.

When many of the same leaders met in April to address the global economic crisis, they rightly pledged to do "whatever is necessary". The same spirit needs to animate the L'Aquila meeting.

There is enormous goodwill to do so. The new US administration is supporting strong American action. China is setting ambitious targets for reducing energy intensity and making massive investments in renewable energy. India has put forward its own action plan. Europe has set a goal of cutting greenhouse gas (GHG) emissions by 30 percent below 1990 levels by 2020 if there is an ambitious global agreement. Japan has published its proposals for major carbon reductions. Across the world, commitments are forthcoming.

But practical challenges remain. What is being asked is that global GHG emissions be less than half their 1990 levels by 2050, having peaked before 2020. Since emissions from the developing countries are on the whole lower than those of the developed world - and will need to continue to rise in the short-term as they maintain economic growth and address poverty - it has been proposed that developed countries cut emissions by at least 80 percent by 2050, taking 1990 as the base year, with major steps towards this goal over the next decade.

Developing countries will also need to play their part, significantly slowing emissions growth in the coming decades. For the US, such commitments would mean cutting emissions to around one-tenth of today's per capita level, while for China it would mean creating a new low-carbon model of economic development. For all countries, this is a major challenge - a revolution that implies a huge shift in policy.

The good news is that if we focus on clear, practical, and achievable goals, major reductions can be made in order to ensure that, whatever the precise interim target, the world will fashion a radical new approach within a manageable timeframe. A new report from Breaking the Climate Deadlock project, a strategic partnership between my office and The Climate Group, shows how major reductions even by 2020 are achievable if we focus action on certain key technologies, deploy policies that have been proven to work, and invest now in developing those future technologies that will take time to mature.

Perhaps the most interesting fact to emerge is that fully 70 percent of the reductions needed by 2020 can be achieved by investing in three areas: increasing energy efficiency, reducing deforestation, and the use of lower-carbon energy sources, including nuclear and renewables. Implementing just seven proven policies - renewable energy standards (for example, feed-in tariffs or renewable portfolio standards); industry efficiency measures; building codes; vehicle efficiency standards; fuel carbon content standards; appliance standards, and policies for reduced emissions from deforestation and forest degradation - can deliver these reductions.

All seven policies have already been successfully implemented in countries around the world, but they need scaling up. While cap-and-trade systems or other means of pricing carbon emissions can help provide incentives for businesses to invest in low-carbon solutions, in the short term at least, these seven policy measures - and direct action and investment by governments - are needed to achieve the targets.

In the longer term, we also need technologies such as carbon capture and storage (CCS), expanded nuclear power, and new generations of solar energy, together with the development of technologies whose potential or even existence is still unknown. The important thing for Copenhagen is that decisions are taken now for investments that will yield benefits later.

For example, the overwhelming majority of new power stations in China and India - necessary to drive the industrialization that will lift hundreds of millions out of poverty - will be coal-fired. That is just a fact. So developing CCS or an alternative that allows coal to become clean energy is essential for meeting the 2050 goal. But we need to invest now, seriously and through global collaboration, so that by 2020 we are in a position to scale up CCS or be ready to use other options.

Renaissance of nuclear power will require a big expansion of qualified scientists and engineers. Electric vehicles will need large adjustments to infrastructure. Smart grid systems can enable big savings in emissions, but require a plan for putting them into effect. These measures will take time, but require investment now.

In the short term, low energy lighting and efficient industrial motors may sound obvious, but we are nowhere near using them as extensively as we could.

So we know what we need to do, and we have tools available to achieve our goals. MEF leaders can therefore have confidence in adopting the interim and long-term targets recommended by the scientific community: keeping warming to below 2 C; peaking emission cuts within the next decade; and at least halving global emissions by 2050, taking 1990 as the base year.

Developed countries will be able to commit to reducing their emissions by 80 percent versus 1990 by mid-century, as many have already done, and provide the necessary financial and technology support for developing countries to adapt to climate change and fight it. With that support, developing countries in turn will need to design and implement "low-carbon growth plans" that significantly slow their emissions growth. By making these commitments, the MEF leaders, whose countries account for more than three-quarters of global emissions, would lay a firm foundation for success in Copenhagen.

Between L'Aquila and Copenhagen, there will undoubtedly be difficult discussions over interim targets for developed countries. While such targets are important, what matters most is agreement on the measures that ultimately will set the world on a new path to a low carbon future.

For years, the emphasis has rightly been on persuading people that there must be sufficient "will" to tackle climate change. But leaders, struggling to cope with this challenge even amidst the economic crisis, need to know that there is also "a way". Only by combining the two will we succeed. Fortunately, such a way - immensely challenging but nonetheless feasible - exists.

The author is a former Prime Minister of the United Kingdom.

(China Daily via Agencies July 8, 2009)