Revisiting the Thermohaline

Initially we spoke rather passively about the effects of climate change on the thermohaline, however, as the blog progressed I realised that the key to abrupt climate change is in fact this system. It has been viewed in sediment records that during the past glacial periods the cooling is incited by a collapse of the thermohaline as a result of warming. The system is vulnerable from both the North and the South. In regards to the reducing sea ice, this directly impacts the system’s ability to function as it reduces the temperature as well as the salinity in the surface water, this is water that is transported North in the Gulf stream and is destined to sink in the Arctic and form the North Atlantic Deep Water current. A similar process is experienced surrounding the Antarctic continent where warming reduces the sea ice and the process is replicated.

As the key to bringing about abrupt climate change it is important to note the causes of such instances. Several readings were conclusive with this citing that large icebergs breaking off the Greenland Ice Sheet caused a rapid freshening of the Arctic surface water completely inhibiting the AMOC and inciting a period of freezing as a result of mis-distribution of the global heat budget allowing it to occur at the poles. Once, this takes hold the albedo feedback becomes relevant once again in reducing the energy absorbed by the planet.

We addressed the likelihood of such an extreme event occurring in the future as a response to anthropogenic forcing and although unlikely were able to conclude that there will be a significant weakening of the system by 2100 on several emission scenarios, this slowing will bring about a degree of heat distribution that will noticeably alter the climate around the world, perhaps significantly.