Leading article: Climate of technological hope

There is something viscerally attractive about large-scale engineering projects that promise to mitigate the process of climate change, whether by reflecting the Sun's rays away from the Earth, or sucking C02 out of the atmosphere. Various schemes ranging from injecting sea salt into the air using floating pontoons to placing giant mirrors in space are attractive because they suggest that technological innovation can save us from the damage that unchecked climate change threatens to inflict on our planet.

Who, when faced with disaster, could fail to be enthused by talk of a potential saviour in the form of a technological fix? And now the respected Royal Society has declared that such large-scale engineering projects, which some assumed to be pie-in-the-sky, are "technically possible" and that research into them ought to be pursued. We can draw some measure of encouragement from this. But we must also heed the very clear caveats in the Society's report. First, simply because some of these ambitious schemes have been judged "technically possible" does not mean that they would actually work in practice. Second, there is considerable uncertainty about their wider environmental impact and the costs involved.

Most important of all, the report does not suggest that any of these projects constitute a "solution" to climate change, and they certainly do not give us the green light to scrap our efforts to decarbonise our economies. The authors of the report are very clear. Reducing our industrial, domestic and transport carbon emissions must be the first priority of all governments. It envisages these engineering projects as a "Plan B" in the event that mankind fails to get its carbon emissions under control in the coming years.

What these scientists are doing is looking into the future, preparing for dire contingencies. This is a responsible approach. It is infinitely better to plan early, rather than wait until the crisis is upon us. But it is also vital that governments and citizens around the world are not distracted from the overriding priority of the moment which is to reduce drastically the amount of carbon dioxide our societies pump into the atmosphere in the first place.