A new study looking at past climate change asks if these changes in the future will be spasmodic and abrupt rather than a more gradual increase in the temperature. Today, deep waters formed in the northern North Atlantic fill approximately half of the deep ocean globally. In the process, this helps moderate the effects of global warming. Changes in this circulation mode are considered a potential tipping point in future climate change that could have widespread and long-lasting impacts. Until now, this pattern of circulation has been considered relatively stable during warm climate states such as those projected for the end of the century. A new study suggests that Atlantic deep water formation may be much more fragile than previously realized....