The paper surely can’t mean that water vapour is an inactive greenhouse gas. But as the bulk of Professor Hunter’s AGW “evidence” is focused on fossil fuels, he probably means this statement to be limited to carbon dioxide. Even then, it is not immediately obvious that an increase from 0.022% to 0.028% should be described as “significant”.

The greenhouse gases of greatest concern to New Zealand are methane and nitrous oxide. The concentration of atmospheric methane raced upwards in the eighteenth century, then plateaued during the huge population increases of the nineteenth and twentieth centuries. It spiked upwards in the 1990s and then went flat for a decade. There is no reason to assume any of these gyrations had anything to do with human activities.