i from the tropics to the tropics| and then it causes the northern hemisphere to cool and i the southern hemisphere to keep the heat. so there is a contrast - between the temperatures in the northern hemisphere i and the southern hemisphere. and this difference in temperature causes a massive disruption in the atmospheric dynamics and changes - the atmospheric circulation . in a way that puts the tropical pacific into a la nina state. so it s quite interesting, because what happens l in the atlantic, it can impact| the tropical pacific and it can have implications for the whole globe, including australia. - back here at imperial college london, i am with dr fredi 0tto again, she leads the world weather attribution group here,