It did occur to me that perhaps the site itself had localised it. That would be odd for a science site given that science is usually done in metric, but as the New Scientist is pop sci they might have thought it would help grow US readership.

Was it really difficult?

Assuming this is referring to my comment about making life difficult, you had to either do the maths or use a conversion tool. You made it (now fixed, thanks) so that half (I expected a higher %age tbh) of the people reading it had to do that.