The safe island retreat of Okinawa will this year witness the annual ritual hand-wringing of the heads of state of the Group of Eight industrialised nations over the seemingly intractable poor country debt crisis. But in the future they may look back at the barrage of criticism about the slow pace of relief as a halcyon period. 

Ten years from now, a beleaguered G8 may be sitting down to work out how to account for the enormous carbon debt they owe the developing world for the consequences of climate change, and how they intend to settle their arrears. This is no abstract theoretical exercise. The economic costs of global warming are rising sharply. According to Munich Re, the reinsurance group, the number of great climate-related and flood disasters quadrupled during the 1990s compared with the 1960s; resulting economic losses increased eight-fold  during the same period. If that trend continued we would arrive at the absurd situation just  after the middle of this century of the costs from global warming overtaking the value of  gross world product. 

The problem is that the damage to human life is very unevenly distributed. Poor people in  poor countries suffer first and worst from extreme weather conditions linked to climate  change - a fact highlighted in the Red Cross World Disasters Report 2000. Today, 96 per  cent of all deaths from natural disasters occur in developing countries. By 2025, more than  half of all people living in developing countries will be "highly vulnerable" to floods and  storms. They are also likely to be most affected by the results of conventional foreign debt. 

Servicing foreign debt in Mozambique, which suffered immeasurable damage and loss of life  as a result of floods this year, has drained the country of precious resources for many  years. Even after relief, Mozambique could still have to spend Dollars 45m a year on debt  servicing - more than it spends on primary healthcare or basic education. Similar examples  occur from Central America to Bangladesh. 

Yet apart from imposing harmful debt servicing, industrialised countries are responsible for a  larger and potentially more damaging ecological debt - a debt for which, as yet, no  accounting system exists to force repayment. Reckless use of fossil fuels has created the  spectre of climate change. The issue produces unlikely allegiances. A survey of corporate  chief executives at last year's Davos summit came to the same conclusion as a recent  survey of 50 leading environmentalists: global warming is real and the biggest issue we  face. 

A letter co-signed by the under secretary of the US National Oceanic and Atmospheric  Administration and the chief executive of the UK Meteorological Office concluded: "The rapid  rate of warming since 1976 - approximately 0.2 degrees Celsius per decade - is consistent  with the projected rate of warming based on human-induced effects." 

To solve the problem or, at least, mitigate its worst effects, all nations will have to live within  one global environmental budget. We all depend on the atmosphere and we all have an equal  right to its services, an equal right to pollute. If we add more than our fair share of pollution  we are running up a carbon debt. Currently, industrialised countries generate over 54 times  more carbon dioxide pollution per person than the least developed countries. A typical G8  citizen uses fossil fuels at a rate 10 times above the threshold for sustainable per capita  consumption. 

Each day that passes without a radical shift in consumption, the carbon debt to the global  community grows. So, 10 years from now, as the G8 sit and argue about how to repay their  debt to the world's poor, what advice should we give them? 

Faced with conventional debts, the poorest countries were told, and expected, radically to  restructure their economies. Poor countries should now, in the face of climate change, be  able to propose a reverse form of economic adjustment on the carbon debtors. 

Instead of old-style structural adjustment programmes, the challenge will be to devise  sustainability adjustment programmes for the rich. Klaus Topfer, executive director of the UN  Environment Programme, called for a 90 per cent cut in consumption of fossil fuels in rich  countries to meet the challenge, adding: (that) "a series of looming crises and ultimate  catastrophe can only be averted by a massive increase in political will." 

Any solution will need to be based on reductions in carbon emissions, otherwise known as  contraction. We will also have to move towards equally sharing the atmosphere, known as  convergence. The contraction and convergence approach was recently endorsed by the  UK's Royal Commission on Environmental Pollution. 

The G8 has for years issued stern economic warnings to the poorest countries. Now,  climate change and the growing carbon debt of industrialised countries might make the G8  ask if it is wise for people who live in greenhouses - and hide on islands - to throw stones. 

The writer heads the global economy programme at the New Economics Foundation.