joining me from college town princeton university michael mann. here in new york jeffrey sachs the director of the earth institute of columbia university and also michael oppenheimer a professor at prime stop and one of the main authors of the icct study. please to do have all of them here. i said to jeffrey when he sat down it's worse than we thought. and he said you can be it's true. the piece that said ice caps are melting. sea ice in the arctic is collapsing, water supplies are coming under stress, heat waves and heavy rains are intensifying, coral reefs are dying and going extinct. oceans are arising at a pace that threatens coastal oceans are becoming more acidic as they absorbed co2 and organic matter frozen in soils is not melting. what's going on? >> what's going on in fact is in a way somewhat predictable because in the science community, these facts have been known for at least a couple decades. not everyone but the dangers have been understood. it has been true that the more refined the measurements you can, the more careful the observa

climate scientist michael mann on how a changing climate may affect our future. >> sometimes you'll hear from the critics. they'll say, "we demand proof that humans are causing this." and my response is that proof is reserved for alcoholic beverages and mathematical theorems." it doesn't characterize how science works. science works through weights of evidence, through likelihoods, through confidence levels, and so we're about as certain that humans are causing global warming as we are about any scientific proposition, but we never say we've proven something in science because there's always the outside chance that we could discover some new piece of information that would change our perspective. it's absolutely true that critics of sort of the forces of antiscience, those looking to confuse the public about the science will always draw upon that vulnerability, that as scientists we're never comfortable in stating things in absolutes because that's not the way the world works, that's not the way science works. unfortunately our detractors, those looking to sort of pollute the public disc

michael mann is a professor at penn state university. here in new york, jeffrey sachs is director of the earth institute at columbia university. also michael oppenheimer. a professor at princeton and one of the main authors of the study. i am pleased to have all of them here. i said to jeffrey when he sat down it is worse than we thought and he said, you can be sure that is true. the piece that says guys caps on areing, -- ice caps melting, ice waves and heavy rain are intensifying. species are going extinct. oceans are becoming more acidic as the observed co2. melting frozenis in soils. what is going on? >> what is going on in fact is in a way somewhat predictable because in the science community, these facts have been known for at least a couple of decades. not everyone but the dangers have been understood. it has been true that the more refined the measurements, the more careful the observation. the more the risks have been confirmed. as the world economy has continued to grow, even though we see it crisis, china is continuing to grow

climate scientists michael mann addressed that urgency on the show recently. if we want to avoid crossing that two degree c. threshold where the locomotive that is headed down the tracks full speed ahead if we slam on the brakes right now it may take a mile into we stop and that's what's going on with the climate system right now if we are going to avoid passing the two degree celsius threshold we've got to bring our global carbon emissions to peak within the next couple years and start ramping them down several percent per year we can still avoid crossing that four hundred fifty parts per million c o two level in the atmosphere but we have to start acting now there is an urgency to acting unlike anything we've seen before if we're going to avoid committing to those truly damaging potentially irreversible changes and here's professor guy mcpherson from friday's show discovery discussing his thoughts on how dire the climate change situation is. professor mcpherson it just to summarize the last. segment we were talking essentially you were suggesting that we cou

and quick change to a much more sustainable system in the middle of a half or so we have loved michael mannrecently wrote a piece for scientific american suggestion that within twenty years or so we will have passed points of no return first and i mentioned earlier the university of arizona has said we've already passed those points. in your thoughts on how far we can go before we basically you were screwed. well the climatologists the negotiators who've been working with the science tell us that two degrees really is the threshold of warming that we should stay but the thing we wish to avoid the worst consequences of climate change were on the threshold of that now in a few more years of burning fossil fuels at the current rate that we get into that new territory of risk and the more we burn the higher the risk goes up i wouldn't like to put a timetable on when the point of no return is that when the brits become unmanageable but the longer we continue with our present direction of travel the more we're courting danger and that danger is not only something that's going to fall to future ge

michael." one today, one of the stars of the new movie, "the other woman," leslie mann. e are kelly ripa and michael strahan! [cheers and applause] ♪

mann tomorrow. >> and robin is coming up on "kelly & michael." check your local listings. and have a great day.n a single mission: saving lives. discover how we are advancing medicine at kp.org join us, and thrive. >>> good morning. i'm kristen sze. water officials in the east bay meet today. they say supplies may not meet demands this year. possible solutions include bringing in water from the sacramento river. >>> we had some showers but looks like we're left with the winds. >> 0.04 of an inch at sfo, that was the most we received. winds out of the west 10 to 20 miles per hour will be here all day, may tick up during the evening commute. temperatures in the low to mid-60s, except for upper 50s at the coast. accuweather seven-day forecast, cooler thursday and friday. sue? >>> thanks, mike. we still have slow and go all around the bay area. better news on the peninsula. sigalert lifted, southbound 280 but traffic still jammed from 92. we do have a capital corridor and caltrain delay. kristen? >> thanks so much. and that's going to do it for now. announcer: it's "live! with kelly & michael." tod