The Gulf Stream plays a significant role in maintaining the climate of the US East Coast and Western Europe. "We conclude with a high degree of confidence that Gulf Stream transport has indeed slowed by about 4% in the past 40 years." The full study is Here
Is this not the only tipping point that can actually reduce energy held by the biosphere due to increased ice in the northern hemisphere, and therefor increasing Earth's albedo?
Not sure there'll still be ice in the north by then.