for more on where we are-- and where we might be going-- i'm joined by astrid caldas. she's a senior climate scientist at the union of concerned scientists. welcome. >> thank you. e skeptics are going to say, look, it's summertime, ofrt course it's hot. what can you say -- what does the ience say about this particular kind of app -- a heatwave over the unitedstates. >> this particular heatwave is due totw a meteorogical phenomenon happening in the atmosphere, so this can happen independently of climate changec however, the heat dome leading to this heatwave is trappingpp warmer air because, as we know, the last 18 years, all the years in this century have been record-breaking years in terms of warming.ng so the thermometer is gng up, temperatures are going up, so the heatwaves are likely going up, also. >> reporter: and this trend of mo, longer and hotter heatwaves is what the cmate models have projected. that is what we are seeing.in >> that's correct. we are seeing more extreme heat days, more consecutive extreme heat days and we are slated to a seot more of these ex