1 February 2011 – Global action is not going to stop climate change, wrote The Economist on 25 November last year. The world needs to look harder at how to live with it.

From The Economist –On November 29th representatives of countries from around the world will gather in Cancún, Mexico, for the first high-level climate talks since those in Copenhagen last December.

The organisers hope the meeting in Mexico, unlike the one in Denmark, will be unshowy but solid, leading to decisions about finance, forestry and technology transfer that will leave the world better placed to do something about global warming. Incremental progress is possible, but continued deadlock is likelier. What is out of reach, as at Copenhagen, is agreement on a plausible programme for keeping climate change in check.

The world warmed by about 0.7°C in the 20th century. Every year in this century has been warmer than all but one in the last (1998, since you ask). If carbon-dioxide levels were magically to stabilise where they are now (almost 390 parts per million, 40% more than before the industrial revolution) the world would probably warm by a further half a degree or so as the ocean, which is slow to change its temperature, caught up. But CO2 levels continue to rise.

Despite 20 years of climate negotiation, the world is still on an emissions trajectory that fits pretty easily into the “business as usual” scenarios drawn up by the Intergovernmental Panel on Climate Change (IPCC).

The Copenhagen accord, a non-binding document which was the best that could be salvaged from the summit, talks of trying to keep the world less than 2°C warmer than in pre-industrial times—a level that is rather arbitrarily seen as the threshold for danger. Many countries have, in signing the accord, promised actions that will or should reduce carbon emissions. In the World Energy Outlook, recently published by the International Energy Agency, an assessment of these promises forms the basis of a “new policies scenario” for the next 25 years (see chart 1).

According to the IEA, the scenario puts the world on course to warm by 3.5°C by 2100. For comparison, the difference in global mean temperature between the pre-industrial age and the ice ages was about 6°C.

The IEA also looked at what it might take to hit a two-degree target; the answer, says the agency’s chief economist, Fatih Birol, is “too good to be believed”. Every signatory of the Copenhagen accord would have to hit the top of its range of commitments. That would provide a worldwide rate of decarbonisation (reduction in carbon emitted per unit of GDP) twice as large in the decade to come as in the one just past: 2.8% a year, not 1.4%. Mr Birol notes that the highest annual rate on record is 2.5%, in the wake of the first oil shock.

But for the two-degree scenario 2.8% is just the beginning; from 2020 to 2035 the rate of decarbonisation needs to double again, to 5.5%. Though they are unwilling to say it in public, the sheer improbability of such success has led many climate scientists, campaigners and policymakers to conclude that, in the words of Bob Watson, once the head of the IPCC and now the chief scientist at Britain’s Department for Environment, Food and Rural Affairs, “Two degrees is a wishful dream.”
The fight to limit global warming to easily tolerated levels is thus over. Analysts who have long worked on adaptation to climate change—finding ways to live with scarcer water, higher peak temperatures, higher sea levels and weather patterns at odds with those under which today’s settled patterns of farming developed—are starting to see their day in the uncomfortably hot sun. That such measures cannot protect everyone from all harm that climate change may bring does not mean that they should be ignored. On the contrary, they are sorely needed.

Public harms
Many of these adaptations are the sorts of thing—moving house, improving water supply, sowing different seeds—that people will do for themselves, given a chance. This is one reason why adaptation has not been the subject of public debate in the same way as reductions in greenhouse-gas emissions from industry and deforestation have. But even if a lot of adaptation will end up being done privately, it is also a suitable issue for public policy.

For a start, some forms of adaptation—flood barriers, for instance—are clearly public goods, best supplied through collective action. Adaptation will require redistribution, too. Some people and communities are too poor to adapt on their own; and if emissions caused by the consumption of the rich imposes adaptation costs on the poor, justice demands recompense.

Furthermore, policymakers’ neat division of the topic of climate change into mitigation, impact and adaptation is too simplistic. Some means of adaptation can also act as mitigation; a farming technique which helps soil store moisture better may well help it store carbon too. Some forms of adaptation will be hard to distinguish from the sort of impact you would rather avoid. Mass migration is a good way of adapting if the alternative is sitting still and starving; to people who live where the migrants turn up it may look awfully like an unwelcome impact.

Its frequently private and slightly blurry nature is not the only reason why adaptation has been marginalised. The green pressure groups and politicians who have driven the debate on climate change have often been loth to see attention paid to adaptation, on the ground that the more people thought about it, the less motivated they would be to push ahead with emissions reduction. Talking about adaptation was for many years like farting at the dinner table, says an academic who has worked on adaptation over the past decade. Now that the world’s appetite for emissions reduction has been revealed to be chronically weak, putting people off dinner is less of a problem.
Another reason for taking adaptation seriously is that it is necessary now. Events such as this year’s devastating floods in Pakistan make it obvious that the world has not adapted to the climate it already has, be it man-made or natural. Even if the climate were not changing, there would be two reasons to worry about its capacity to do more harm than before. One is that it varies a lot naturally and the period over which there are good global climate records is short compared with the timescale on which some of that variability plays out.

People thus may be ignoring the worst that today’s climate can do, let alone tomorrow’s. The other is that more lives, livelihoods and property are at risk, even if hazards do not change, as a result of economic development, population growth and migration to coasts and floodplains.

The three-degree difference
In a late 21st-century world 3°C warmer than the pre-industrial norm, what changes are most marked? Start with the coldest bits. Arctic summer sea ice goes, allowing more shipping and mining, removing a landscape of which indigenous peoples were once an integral part. Permafrost warms up, and infrastructure built on it founders. Most mountain glaciers shrink; some disappear. Winter snows melt more quickly, and the risks of spring floods and summer water shortages on the rivers they feed increase.

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https://www.economist.com/node/17572735?story_id=17572735