Thom Hartmann: For tonight's Green Report we go to Phoenix Arizona where temperatures have been over 100 degrees Fahrenheit for most of this month of June - and nine of the first 22 days of the month were 110 degrees or hotter - including five consecutive days. And thanks to climate change, that kind of extreme heat is becoming more and more normal across much of the United States. The National Weather Service estimated that between June 16th and June 22nd, 32 million people saw temperatures in excess of 100 degrees Fahrenheit in the United States - 7 million people saw temperatures at or above 110 degrees Fahrenheit and 159,000 people saw temperatures of 120 degrees Fahrenheit or more.

This particular heat event is caused by what's called a "heat dome" - which is also driving the historically large wildfires in the western United States. According to ClimateSignals.org - looking at records going back to 1958 - researchers have found that almost all of the high-intensity heat domes like the one we're seeing right now have occurred since 1983 - and an overwhelming majority have occurred since 1990.

For more on this I'm joined now by Dr. Michael Mann - Distinguished Professor of Meteorology - Director of the Earth System Science Center at Penn State University and author of Dire Predictions - Understanding Climate Change. Dr. Mann, welcome back to the program.

Michael Mann: Thanks, Thom, it's good to be with you.

Thom Hartmann: Thanks for joining us. You recently told members of the Democratic National Committee that there isn't much need for climate data and models anymore - because we're seeing the impacts of climate change everywhere. Can you give me some examples?

Michael Mann: Yeah, well, what I said wasn't quite that dismissive of data and models. What I actually said was that we no longer need the sophisticated sorts of tools that we used to have to use to detect the signal of climate change because that signal has now fully emerged from the noise. So as you allude to, the record-breaking heat that we've seen in the U.S. We see all time records broken for the hottest day on record for various locations around the country. Those records are being broken at twice the rate that they were a few decades ago.

We have seen a tripling in the extent of wild fires in the Western U.S. And so when you see those sorts of numbers - the doubling of extreme heat, the tripling of wildfire - the signal has emerged from the noise. You don't need fancy sophisticated statistical tools to see the impacts of climate change as they are playing out. And we are indeed seeing those impacts play out in real time.

Thom Hartmann: So we have this heat dome over much of the United States right now that is drying out the West and causing all these problems. What exactly is a heat dome and what are the impacts of that sort of thing on our climate and on our weather?

Michael Mann: So, a heat dome typically is a large high pressure center. So low pressure areas, as you know, those are associated with storms and have lots of cloudiness and you have rainfall. High pressure is associated with fair weather and often we think of high pressure conditions as being fair weather conditions, good conditions. Unfortunately, in the summer, those high pressure systems are also where we find some of the warmest temperatures on the face of the Earth. Typically, you find a very strong, well-pronounced belt of high pressure in the sub tropics, somewhere in the vicinity of thirty degrees north or thirty degrees south of the equator - the Sahara desert, the desert south west of the U.S., those are the...

Thom Hartmann: The Tropics of Cancer and Capricorn, you are talking about.

Michael Mann: Yeah, that's where you tend to see the high pressure and it's associated with sinking air. It's the sinking of the same air that rises within the band of storminess that we call the inter-tropical convergent zone. All that rainfall and cloudiness in the deep tropics. Eventually that air sinks and it sinks as dry air with clear conditions, high pressure at the surface. Now, that sub-tropical band of desert-like conditions is literally expanding. So the sorts of conditions that we associate with the Sahara desert or the desert south west, those conditions are expanding into higher latitudes, well into the middle latitudes of North America. The 2003 epic heat wave in Europe which killed 30,000 people - they don't have the sort of resources to deal with heat like we do here in the U.S. - they don't have widespread air conditioning, for example, in many parts of Europe and 30,000 people perished. That was an example of one of these high pressure subtropical systems that migrated to very high latitudes, all the way into the UK. And that is consistent with what the models have been predicting for decades. For decades we've said that one of the clearest responses of the circulation of the atmosphere, of climate change, is going to be a forward migration of that belt of high pressure sinking air, and that's what we're seeing.

Thom Hartmann: Wow. How much of a factor is the El Niño in this particular heat dome that the US west in particular is experiencing?

Michael Mann: So, the El Niño signal has pretty much subsided. El Niño is no longer playing a dominant role in the weather patterns that we're seeing in North America or elsewhere. In fact, typically the strongest influence of El Niño on weather patterns is in the winter, is in the northern hemisphere in winter. So what we're seeing right now can't really be related to El Niño in any meaningful way. But again, it is consistent with the increased prevalence of dry hot conditions that we expect to see as we continue to warm the planet and change the climate.

Thom Hartmann: Do the forest fires that are happening underneath this heat dome, I mean, they're generating their own heat and they are also putting particulate matter in the air, I don't know if that cools or if it traps heat, are they part of a feedback loop or is this merely the secondary effect of all this heat drying out the wood so it'll burn?

Michael Mann: No, you're exactly right. There are very important feedback mechanisms here where, you know, you warm the soil, the soil evaporates, more moisture, what little moisture it has in the case of California, back into the atmosphere. It becomes dryer, and that means that the surface has one less means of cooling off. Evaporation is one way that the surface tries to cool off. If you take away that ground moisture, that soil moisture, then those soils are going to warm up. The surface is going to warm up even faster and it's therefore going to dry out even more. And so it is indeed a positive feedback loop. It sounds like a good thing. It's not. What we mean there is a vicious cycle where the process just intensifies itself.

And so it's not coincidental that in the midst of the worst drought in California in 1200 years - that's what the paleo climate scientists tell us - and even a big El Niño event wasn't enough to really make much of a dent in that drought. And now we have the summer conditions, we're seeing record level heat, record level drying, it's not rocket science. When you have record heat, when you have record drought and you have all of this fuel, these weakened trees and plants from the drought serving as fuel, well, you're going to get more and more intense wildfires, and that's what we're seeing play out.

Thom Hartmann: You said the worst event in 1200 years. You know, when I would say something like that to people like Marc Morano, he'd say, "Yeah, 1200 years ago, see, the climate change has always been with us".

Was 1200 years ago a local event or is there some pattern here that is additive to the man made stuff?

Michael Mann: Yeah, well, you know, it's indicative of the the science speak that we scientists tend to lapse into. So when we say the worst drought in 1200 years what we really mean is, we can only go back 1200 years with the data we have, with the tree rings we have, with the pale-...

Thom Hartmann: Ah!

Michael Mann: We can only go that far back. And as far back as we can go, this is the worst drought on record. So that's really what it's telling us.

Thom Hartmann: So, wow, so it's the worst record that we have any evidence of in that era. What other kinds of events that we're seeing on our televisions can be directly attributed to man-made climate change?

Michael Mann: Well, it sometimes seems counter-intuitive, even paradoxical, but it's quite clear, Thom, that as you warm the planet, as we've already said, you're going to get more widespread drought in the summer over a large part of not just the sub tropics but the middle latitudes. But at the same time, a warmer atmosphere can potentially hold more water. And so if the conditions are conducive to rainfall - if you have a rising motion in the air - then you're going to have more moisture that can be condensed into what we call rainfall and you get more intense rainfall, you get more flooding. So while it might seem like a paradox, it isn't. You get more widespread summer drought in the middle latitudes, but you also get more intense flooding events like what we're seeing in West Virginia - a thousand year event. Like what we saw earlier this year in South Carolina, a thousand year event. Texas, another thousand year event of flooding we saw earlier this year there. When you get this many thousand year events, events that shouldn't happen more often than once in a thousand years, you know something is happening.

Thom Hartmann: I was in France the week before last and the French news, when they talked about the flooding that was going on, they would just routinely put in the context of climate change. I mean, it's just part of the normal discussion, the dialogue there. Why do you think that the mainstream American media, the corporate American media, is totally avoiding making the connection to climate change? There's the floods in West Virginia, the wildfires out west, all this stuff, those words 'climate change' just seem to be absent from our television screens.

Michael Mann: Yeah, and that is true to some extent. There are some media outlets that do a great job, RT America obviously being one of them, MSNBC Chris Hayes and others there have done a pretty good job in my view of connecting those dots, Thom, with these sorts of events and talking about climate change in that context.

And, but, at the same time, a lot of, when you watch these networks, you'll see a lot of advertisements from Exxon Mobil, from the American Petroleum Institute, from the Koch brothers. Koch Industries now is advertising on these channels. And so they're getting a lot of money from the fossil fuel industry in the form of advertising and whether that may lead them to not want to upset their sponsors by talking about climate change, 'cause Exxon Mobil doesn't want them talking about climate change, the Koch brothers don't want the networks talking about climate change. They don't want them connecting those dots for the American people and so there is a potential conflict of interest there.

Thom Hartmann: Yeah, it would certainly seem so. Dr. Michael Mann, it's always a pleasure to have you with us, sir. Thank you.

Michael Mann: You too, Thom. Thanks.

Transcribed by Sue Nethercott.