There are not many human activities whose impact can reasonably be predicted decades, centuries, or even millennia in advance. The fallout from nuclear waste is one; humans’ contribution to global warming through greenhouse gas emissions from burning fossil fuels, and its impact on rising sea levels, is another. Indeed, the latest Intergovernmental Panel on Climate Change (IPCC) report stated, in uncharacteristically strong terms, that the sea level is “virtually certain” to continue to rise in the coming centuries or millennia. Moreover, the greater our emissions, the higher the seas will rise. But the recent revelations about Antarctica are different. Rather than reacting to global warming with gradual and predictable patterns of change, the West Antarctic ice sheet has suddenly “tipped” into a new state. A relatively small amount of melting beneath the Amundsen Sea’s ice shelf has pushed its grounding line to the top of a sub-glacial hill, from which it is now “rolling down.” Simply put, one thermal kick was enough to initiate an internal dynamic that will now continue under its own momentum, regardless of any action that humans might take to prevent it.
Posted on: Sun, 03 Aug 2014 17:06:00 +0000