The report, Assessing the costs of adaptation to climate change: a review of the UNFCCC and other recent estimates, adds that costs will be even more when the full range of climate impacts on human activities is considered.

Parry and colleagues warn that this underestimate of the cost of adaptation threatens to weaken the outcome of UNFCCC negotiations, which are due to culminate in Copenhagen in December with a global deal aimed at tackling climate change.

The amount of money on the table at Copenhagen is one of the key factors that will determine whether we achieve a climate change agreement. But previous estimates of adaptation costs have substantially misjudged the scale of funds needed.

—Professor Parry

The UNFCCC has estimated annual global costs of adapting to climate change to be US$40-170 billion. But the report’s authors warn that these estimates were produced too quickly and did not include key sectors such as energy, manufacturing, retailing, mining, tourism and ecosystems. Other sectors that the UNFCCC did include were only partially covered.

Just looking in depth at the sectors the UNFCCC did study, we estimate adaptation costs to be 2-3 higher, and when you include the sectors the UNFCCC left out the true cost is probably much greater.

—Professor Parry

The report’s authors also note that it is not clear what proportion of expected damage would be avoided by the proposed UNFCCC adaptation investment levels. Most impacts are projected to increase non-linearly with climate change, and adaptation costs similarly with impacts.

Therefore it will probably be very inexpensive to avoid some impacts but prohibitively expensive to avoid others; and some impacts we cannot avoid even if funds were unlimited, because the technologies are not available (e.g. in connection with ocean acidification)...but probably common to most cases will be that adaptation to (say) the first 10% of damage will be disproportionately cheaper than for 90% of damage. We need to be clear, then, about how much we are willing to pay for adaptation to avoid damages.

...Implicit in the above is that much damage will not be adapted to over the longer term, because adaptation is either not economic or not feasible. We term this ‘residual damage’. In the UNFCCC report it is not clear how much residual damage might be expected. But it is very important that we start to consider this, because the amount may be significant and is likely to increase over time.

—“Assessing the costs of adaptation to climate change”

The new report’s key findings include:

• Agriculture: The present study concludes that the UNFCCC estimate of $11.3–12.6 billion is a reasonable first approximation of adaptation costs in this sector, but expects the estimate of adaptation costs for agriculture, forestry and fisheries to increase as more detailed studies of specific adaptation actions become available. The study concludes that, with such levels of adaptation, about 80% of the cost of potential impacts might be avoided, but about 20% might not.

• Water: The UNFCCC estimate of US$11 billion excluded costs of adapting to floods and assumes no costs for transferring water within nations from areas of surplus to areas of deficit. The underestimate could be substantial, according to the new report.

• Health: The UNFCCC estimate of US$5 billion excluded developed nations, and assessed only malaria, diarrhoea and malnutrition. This could cover only 30-50% of the global total disease burden, according to the new report.

• Infrastructure: The UNFCCC estimate of US$8-130 billion assumed that low levels of investment in infrastructure will continue to characterize development in Africa and other relatively poor parts of the world. But the new report points out that such investment must increase in order to reduce poverty and thus avoid continuing high levels of vulnerability to climate change. It says the costs of adapting this upgraded infrastructure to climate change could be eight times more costly than the higher estimates predicted by the UNFCCC.

• Coastal zones: The UNFCCC estimate of US$11 billion excluded increased storm intensity and used low IPCC predictions of sea level rise. Considering research on sea level rise published since the 2007 IPCC report, and including storms, the new report suggests costs could be about three times greater than predicted.

• Ecosystems: The UNFCCC excluded from its estimates the costs of protecting ecosystems and the services they can provide for human society. The new report concludes that this is an important source of under-estimation, which could cost over US$350 billion, including both protected and non-protected areas.

The report calls for detailed case studies of what adaptation costs will be, and points out that the few that already exist suggest that costs will be considerable.

It adds that the UNFCCC estimates do not include the cost of bearing ‘residual damage’ that will arise from situations where adaptation is not technically feasible or simply too expensive.

Finance is the key that will unlock the negotiations in Copenhagen but if governments are working with the wrong numbers, we could end up with a false deal that fails to cover the costs of adaptation to climate change.

—Camilla Toulmin, director of the International Institute for Environment and Development, which co-published the report

The new report was reviewed by seven of the world’s foremost adaptation scientists, including the lead authors of the original UNFCCC study. Following this, close to 100 adaptation policy and research experts were invited to comment on the pre-publication draft.

The report’s authors are: Professor Martin Parry (Imperial College London), Professors Nigel Arnell (University of Reading), Richard Tiffin (University of Reading) and Tim Wheeler (University of Reading), Dr Pam Berry (University of Oxford), Drs David Dodman and David Satterthwaite (International Institute for Environment and Development), Dr Sam Fankhauser (London School of Economics), Dr Chris Hope (University of Cambridge), Dr Sari Kovats (London School of Hygiene and Tropical Medicine), Professor Robert Nicholls (University of Southampton).

Resources

• Assessing the costs of adaptation to climate change: A review of the UNFCCC and other recent estimates