bombs exploding every day. if we can get to net zero emissions, it would be three, four years before the switch is flipped and the temperatures stop going up and we can start bringing it down again. >> that is going to take a worldwide effort with the cooperation of not just americans but also other countries like china, which is such a big contributor. before we get more on that, you mentioned just the terrible tragedy unfolding in florida right now. there was a professor with florida international university institute of environment that told cnn he determined in a study last year that the condo tower was sinking about 2 millimeters a year from 1993 to 1999. i want to be clear. we do not know if that contributed to the collapse in any way, but how much of a warning should this serve about rising sea levels and those buildings that are there on the coastal lines? >> yeah, well, as you said, we