The venerable global management consultancy McKinsey & Co. has issued a report that takes a macro view of the steps that must be taken over the next two decades to keep the damage from climate change at a reasonably tolerable level. According to the report, there is now scientific consensus that the global temperature increase must be kept below two degrees Celsius, because this is "a threshold when the implications of global warming become very serious.'" The study assesses what must be done to achieve this goal.

Like most analyses of this ilk, the report mixes hope with challenges. On the positive side, it concludes that '"(o)ur analysis finds that there is potential by 2030 to reduce GHG (greenhouse gas) emissions by 35% compared with 1990 levels, or by 70 percent compared with the levels we would see in 2030 if the world collectively make little attempt to curb current and future emissions. This would be sufficient to have a good chance of holding global warming below the 2 degrees Celsius threshold …"

The study also finds that the costs associated with GHG abatement would be tolerable: €250 (US $330) billion

to €350 (US $460) billion annually, or less than 1% of forecasted GDP. As for financing, "the total upfront investment in abatement measures needed would be €530 billion in 2020 per year or €810 billion per year in 2030." This corresponds to 5-6% of what the McKinsey study calls "business-as-usual investments in fixed assets in each respective year." It's a percentage range that strikes the authors as a reasonable proportion of total global investment, especially since there'd be a strong business rationale for doing so: "Many of the opportunities would see future energy savings largely compensate for upfront investments."

So far, so good: but a lot of "ifs" come bundled with the assessment. "Our research finds not only that all regions and sectors would have to capture close to the full potential for abatement that is available to them; even deep emission cuts in some sectors will not be sufficient. Action also needs to be timely. A 10-year delay in taking abatement action would make it virtually impossible to keep global warrming below 2 degrees Celsius."

The language is also full of hedges: note, for instance, the report's assessment that there would be "a good chance" of holding global warming below the 2 degrees Celsius threshold if global GHG emissions are reduced by 35% compared to 1990. A "good chance" is very different from a "sure thing."

Macro studies of this sort are very useful, and they are also, below the requisite mix of hope and somberness, depressing. Over the years, our aspirational baseline has shifted dramatically. We used to believe we could ward off climate change completely; now our much more modest hope is to keep the consequences from being completely catastrophic. Yet the hope-to-doom ratio, as presented in studies like this one, remains constant.

Psychologically we have little choice but to do this. Above all else, we need to act. Without hope there is no reason to take action, yet with too much hope it's all too easy to rest on our laurels and … not take action. This is why we see, in study after study, the same mix of the carrot ("we can do it!") and the stick.

[Flickr photo courtesy of SorbyRock]