The issues are of immense importance to our daily lives. If climate change is a reality, and is caused by human emissions of greenhouse gases such as carbon dioxide and methane, then it is clear what needs to be done. We need to reduce our greenhouse gas emissions through solutions such as relying less on private transport, buying smaller, more fuel efficient vehicles and appliances, using less energy, and shifting our energy supply to renewable sources.

But, the skeptics cry, the changes would be enormous! We cannot afford these actions for something which is so uncertain. We have a right to use as much energy as we need, they claim.

Fair enough. But how much energy do we actually need? Surely it is cheaper for an individual or a business to save energy and to purchase their supplies from cheaper, cleaner sources?

The pennies enter a simple equation. If you turn out your lights, you save money. If you walk a kilometer to buy milk rather than driving, you save fuel. These economics would be even truer if all energy sources were competing on the same basis by using the true costs to determine the market price of energy sources.

But the impacts are wider. If you walk rather than drive a kilometer every day, you will be healthier. In addition to feeling better, you will have fewer sick days off work which increases your employer's productivity. And the less you are sick, the less you or the government needs to pay for your health care.

These wide advantages also apply to the other suggestions to counter climate change. Using less energy, increasing fuel efficiency, and reducing greenhouse gases means that less pollution is being emitted and less local and regional environmental consequences result. Greenhouse gases are not the only emissions from energy sources which harm us and the environment.

Particulate matter and fuel additives are good examples. These not only lead to respiratory ailments and harm the health of children, but they can stunt the growth of animals and plants. The solutions to reduce greenhouse gases are also solutions to improve health and the environment. Healthier people lead to a more productive economy and a happier population while a healthier environment means more resources which can be used sustainably or enjoyed for their intrinsic value.

So, yes, climate change may be happening and we may be contributing to it. If so, we know what to do: use less energy, reduce greenhouse gas emissions, and tackle pollution. On the other hand, climate change may not be happening or we may not be contributing to it. If not, we still know what to do: use less energy, reduce greenhouse gas emissions, and tackle pollution.

The uncertainty in climate change and its impacts are important scientific questions, but answering them is not needed for developing policy. We have enough certainty in areas other than climate change to know what we should be doing.