Kathryn Kelly: We know the boundary currents carry a lot of warm water from the tropics towards the poles and participate in the heat budget, the global heat budget. And we thought maybe these changes that we see in sea level from the altimeter are associated with changes in the heat budget in those regions, maybe in the amount of heat that the currents transport. So we came up with some simple ways to model this and did some direct calculations and we showed that basically the changes in amount of the heat in those regions are primarily coming from the changes in the current structure itself, not from the atmosphere. A lot of people thought the heat in the ocean would be from local heating: In most areas the ocean is not moving that much and so if the ocean gets warmer, it's because of heat coming from the sun through the atmosphere, from air-sea fluxes. But in the western boundary currents, the current itself is so strong that it is the dominant contributor to the amount of heat there, heat is brought in sideways by the currents. We established that we could get the heat budget in the boundary currents, which without satellites is impossible to do. With the satellite observations for those regions we could show that the dominant term in the heat budget was from the changes in the boundary current.