How increasing CO2 leads to an increased negative greenhouse effect in Antarctica

CO₂ is the strongest anthropogenic forcing agent for climate change since preindustrial times. Like other greenhouse gases, CO₂ absorbs terrestrial surface radiation and causes emission from the atmosphere to space. As the surface is generally warmer than the atmosphere, the total long-wave emission to space is commonly less than the surface emission. However, this does not hold true for the high elevated areas of central Antarctica. For this region, the emission to space is higher than the surface emission; and the greenhouse effect of CO₂ is around zero or even negative, which has not been discussed so far. We investigated this in detail and show that for central Antarctica an increase in CO₂ concentration leads to an increased long-wave energy loss to space, which cools the Earth-atmosphere system. These findings for central Antarctica are in contrast to the general warming effect of increasing CO₂.