Declarations of interest are now standard practice for scientists who publish their work in recognised peer-reviewed journals. In medical research, for instance, it is important to know not just the findings and methodology of a particular study, but who actually paid for the work. And it would be unacceptable for scientists to put their names to a study involving a certain kind of drug if they refused to say whether they were paid by the drug company.

The same is true of climate research. If an organisation such as Greenpeace commissioned a climate study that was then published in a journal, we would expect the scientists involved to make it clear who funded the work. That, indeed, is the definition of declaration of interest.

It is clear, however, that some wealthy individuals feel they can hide behind anonymity when it comes to the funding of climate "scepticism" (we use the word advisedly, as science is, by its nature, sceptical). As an example, we document today the curiously labyrinthine route through which an American billionaire industrialist, Charles Koch, funds US climate scepticism in order to preserve his anonymity.

In Britain, the climate-sceptic Global Warming Policy Foundation has received as much as £1m in anonymous donations since it was set up in 2009. The organisation has repeatedly refused to name its backers, yet the foundation has pursued climate scientists relentlessly for their alleged lack of transparency over data and methodology.

The foundation, which is registered as an educational charity, could just as well be described as an attack dog of the wealthy climate sceptics who have supported it. Yet the public does not know the identity of these individuals and can only guess at their motives. Surely, if the Global Warming Policy Foundation was genuinely concerned about the transparency of climate research, it should also tell us whose money it is relying upon.