Better understanding of rapid climate change is one of the most pressing questions for climate sciences in the 21st century. We now know that human activities are significantly changing important elements of the climate system of our planet such as the composition of the radiative active gases in the atmosphere. However, we are less certain about the responses of the coupled climate system. In particular strong amplifiers of climate perturbations and sources of nonlinear responses have yet to be understood. There are processes in the ocean that could trigger rapid climate change: deep convection and its connection to the global ocean overturning circulation, sea - ice and its impact on the planet's albedo, and regime shifts of coupled ocean atmosphere phenomena such as ENSO.
Modern observations will play three important roles to further our understanding of these topics: (1) they will provide insight into the processes that are thought to play an important role. (2) They provide the data to validate global climate models that are then used for a more complete assessment of possible system responses. (3) If maintained over a long period of time they allow the state of the climate system to be tracked directly and provide the baseline from which predictions can be attempted.
A large number of model studies have shown that most often deep water formation processes are involved in abrupt climate change scenarios. Sites of deep water formation are also sensitive indicators of change and thus provide information for climate predictions or at the minimum exhibit early warning signs of climate change. The Modern Oservations component of CORC-ARCHES combines physical and tracer measurements to track the long term behavior at three sites. Most of the effort concentrates on the outflow region of the Weddell Sea as an index site for the southern hemisphere deep water production. To that end, we maintain a moored array and and a short hydrographic/tracer repeat section in the northwestern corner of the Weddell Sea.
Cross Cutting Themes:
Climate and Society