please welcome doctor dan cohan. >> thank you susan, well, it's a privilege to be here. i'm really impressed with the gathering that you've all assembled here in and the quality of the discussion. so i know that i don't want to wear out my welcome so i'll try to get through this sort of on time. you know at one time there was a pointer up here, and seems to have disappeared. so, maybe we can go on to the next slide and in the meantime we'll find a pointer. it wasn't very many years ago or not that many audiencesing a that i sort of felt like i was in a slightly different environment than the one i heard this morning. the way i'm going to structure this talk is to - thank you - okay. is to talk about mainly observations first and then models and observations second, and then kind of sum up. so next one. if you look at the traces on this plot, which is a global average version of surface temperature of the earth, the thick dark line in this trace is actually the observe or what we estimate to be the observed temperature of the earths surface, and the other part - the color