Originally trained in Quaternary and glacial geology, my interests turned to oceanography after noting the profound influence of ocean heat transport on ice sheet growth and retreat in the Arctic. I was amongst the first to show that the timing and speed of changes in the large scale overturning circulation of the oceans matched that predicted by paleo-temperature records from Greenland ice cores and (the then) nascent numerical models of ocean circulation. In the run-up to the 1992 Rio Earth Summit (at which the United Nations Framework Convention on Climate Change was opened for signing) I gave testimony to the U.S. Senate warning that unmitigated warming could lead to changes in the overturning circulation of the northern North Atlantic—a phenomenon now clearly visible in regional air and sea temperatures 25 years later. For the last two decades my work has focused on studies of the ocean’s role in determining Ice Age (natural) CO2 variations and on the use of 14C as a tracer in the contemporary carbon cycle and for direct quantification of anthropogenic CO2 emissions.