Peter Lilley, a British Member of Parliament, seems to have rather missed the point of climate change legislation. He is kicking up a fuss about how the UK’s Climate Change Bill might have costs larger than benefits in the period between now and 2050. Of course, the whole point of climate change mitigation is to avoid the worst effects of climate change and not leave future generations with a severely damaged planet. Almost by definition, the majority of the benefits associated with such an approach will accrue in the distant future.
Even if mitigating climate change has serious net costs between now and 2050, we still need to do it, at least if we care at all about the welfare of future generations and the integrity of the planet. That being said, we can certainly hope to mitigate effectively at a relatively low cost (taking advantage of mechanisms like carbon pricing to secure the lowest cost emission reductions first). We can also work to maximize the co-benefits of climate change mitigation, such an enhancing energy security and reducing other types of air pollution.
It is also entirely possible that we will end up spending more money on climate change than we should have, or than would have been possible if we had taken the best possible approach from the outset. To use an analogy, it is possible for a speeding car to brake too sharply to avoid hitting a pedestrian. Doing so jostles the driver and may damage the car, but it is a less undesirable outcome than braking too hesitantly and ploughing right into the person. When you are making a decision with important consequences and lots of uncertainty, erring on the side of caution and expense is the prudent and ethical approach.