TO GO WITH AFP STORY BY RICHARD INGHAM (FILES) -- A file photo taken on October 31, 2013 in Haubourdin, northern France, shows smoke from a factory. More than two dozen scientific institutes, in unprecedented advice to world leaders, on July 8, 2014 urged major economies to unleash an energy revolution for slashing carbon emissions to safer levels by 2050. In a report issued ahead of the September 23 world climate summit, they also warned time was short for meeting the UN's global-warming target but the goal must not be scrapped. AFP PHOTO PHILIPPE HUGUEN Image Credit: AFP

We do not have a Chinese or an American atmosphere. We have a global atmosphere. We cannot run independent experiments upon it. We have instead been running a joint experiment. This was not a conscious decision: It happened as a result of the industrial revolution. But we are consciously deciding not to stop.

Conducting irreversible experiments with the only planet we have is irresponsible. It would only be rational to refuse to do anything to mitigate the risks if we were certain the science of man-made climate change is bogus. Since it rests on well-established science, it would be ludicrous to claim any such certainty.

On the contrary, any reasonably open-minded reader of the Summary for Policymakers from the Intergovernmental Panel on Climate Change would reach the conclusion that any such certainty on the science would be ludicrous. It is rational to ask if the benefits of mitigation outweigh the costs. It is irrational to deny the plausibility of man-made climate change.

In these debates and indeed in climate policy, the US plays a pivotal role, for four reasons. First, the US is still the world’s second-largest emitter of carbon dioxide, though its 14 per cent share of the global total in 2012 puts it well behind China’s 27 per cent. Second, US emissions per head are roughly double those of leading western European economies or Japan. It would be impossible to persuade emerging economies to curb emissions significantly if the US were not to join in. Third, the US has unsurpassed scientific and technological resources, which will be sorely needed if the world is to tackle the challenge of combining low emissions with prosperity for all. Finally, the US is home to the largest number of passionate and committed opponents of action.

Given this, two recent events are encouraging for those (like me) who believe elementary common sense requires us to act. One was the publication of the President’s Climate Action Plan last month. This plan covers mitigation, adaptation and global cooperation. Its goal is to cut greenhouse gas emissions by 17 per cent below 2005 levels by 2020. The other event, also last month, was the publication of a report — aptly titled ‘Risky Business’ — by a heavyweight bipartisan group that included former New York mayor Michael Bloomberg, former US Treasury secretaries Hank Paulson and Robert Rubin and former US secretary of state George Shultz.

Yet, we must temper joy. Even if the US administration successfully implemented its plan, by exploiting its regulatory authority, it would still be just a modest start. Already, atmospheric concentrations of carbon dioxide, methane, and nitrous oxide have risen to levels unprecedented in at least the past 800,000 years, long before homo sapiens emerged. On our present path, the increase would be far bigger by the end of the century, with impacts upon the climate likely to be big, irreversible and perhaps catastrophic. Increases in average temperature of 5 degrees Celsius above pre-industrial levels are conceivable on our current path. It would then be a different planet from today’s.

Risky Business brings out what this may mean for the US. It focuses on the damage to coastal property and infrastructure from rising sea levels. It looks at the risks of greater and more frequent storms. It considers possible changes to agriculture and energy demand, as well as the impact of higher temperatures on productivity and public health. Indeed, some areas of the country could become almost uninhabitable. What makes the report valuable is that it sets this out rightly as a problem in risk management. The aim must be to cut off the risks in the tail of the distribution of possible outcomes. The way to do so is to change behaviour. Nobody can sell us insurance against planetary changes. We have seen what tail risk means in finance. In climate, tails are fatter and likely to be far more damaging.

The question is whether something real and important may come from these modest new beginnings. They may, though halting the rise in concentrations of greenhouse gases is hugely demanding.

I used to think that the way to advance would be via a global agreement to cap emissions, using some combination of taxes and quotas. I now consider this approach hopeless, as the failure of the Kyoto Protocol of 1997 to make any real change to our emissions trajectory demonstrates. The political debate for sensible policy will be won if and only if two things happen: First, people must believe the impact of climate change could be both large and costly. And second, they must believe the costs of mitigation will be tolerable. The latter in turn requires the development of credible and workable technologies for a low-carbon future. Once the concept of such a future is proved, adoption of the needed policies will be far easier.

In this context, the two new documents are mutually supportive. Risky Business documents the potential costs to Americans of unmitigated climate change. The administration’s focus on regulatory standards is then a big part of the answer, not least because standards are sure to force an acceleration of innovation in the production and use of energy. By adding in support for fundamental research, the US government could trigger waves of beneficial innovation in our wasteful energy and transportation systems. Done with sufficient urgency, that could also transform the context for global negotiations. Furthermore, given the failure of mitigation so far, a large part of the response is likely to consist of adaptation. Again, US engagement should help provide more examples of what works.

I have secretly hoped the deniers would be proved right. Only then would failure to respond to this challenge prove costless. But we are very unlikely to be that lucky.

Continuing on our current path is likely to cause irreversible and costly damage. A happier possibility exists. Perhaps it will prove possible to reduce the cost of mitigation to such an extent that it becomes politically palatable. Perhaps, too, we will become far better aware of the risks. Neither seems probable. But if these two reports did bring about a shift in the US approach, the chances of escape from our danger would have risen, though probably too late. That does not merit two, let alone three cheers. But we could try one.

— Financial Times