(I) Water vapour is the most common greenhouse gas in the atmosphere, accounting for about 60 to 70 per cent of the natural greenhouse effect. (II) Humans do not have a direct effect on water vapour levels in the atmosphere. (III) But human activities do increase the concentration of other greenhouse gases in the atmosphere, producing warmer temperatures. (IV) Indeed, global warming has now become one of the most passionately argued issues of our time. (V) This results in an increase in the evaporation of oceans, lakes, and rivers, raising the amount of water vapour in the atmosphere.