 Scientists have interrogated many, many different aspects of the climate system, not just looking at one number, the average temperature or average moisture or average pressure, but looking at complex patterns of change in hard observations, the latest greatest satellite observations, the latest greatest climate model simulations. And the red thread running through all of this fingerprinting work is, natural causation alone doesn't cut it. It doesn't explain the changes in all of these things that we've actually observed. If you look from the surface of the Earth right up into the stratosphere, 20 miles above the surface of the Earth, what we've actually observed in weather balloon measurements and satellite measurements is this complex pattern of warming low down and cooling up high. The only thing that we know of that can generate that distinctive fingerprint is human-caused increase in heat-trapping greenhouse gases and human-caused depletion in the upper atmosphere of stratospheric ozone. The best information we have now from our most recent research is that the chances of getting a fingerprint match between that human fingerprint pattern of warming low down and cooling up high and purely natural causes is infinitesimally small. What we're now exploring is whether one can use these formal fingerprinting techniques that we've successfully applied to things like water vapor and temperature to the seasonal cycle. And the answer seems to be yes. We know why that should be. We know in the case, say, of ozone depletion, that has a really clear signature in terms of the seasonal cycle. Other things like biomass burning or changes in sea ice. Again, there's some clear expectation that these things should affect the seasonal cycle, both the size of the seasonal cycle, the timing of the seasonal cycle. And to first order, that's what we're seeing. Some identifiable human fingerprint in the March of the Seasons, which is scientifically gratifying. But as a human being and as a citizen of this planet, it's kind of disturbing to think that we're now at a point where humans have a detectable signature on the seasons themselves. I have been interested in scientific consensus for a long time and the question of how scientists come to consensus, how they decide to have enough evidence to say, yes, we know this. And also the question of, well, if scientists have a consensus, how do we know they're right? And so I read the IPCC reports and the National Academy of Sciences reports, and it was clear that these reports were very clear that climate change was underway and it's being driven by human activities. But I thought, well, yeah, but just because the leadership of a scientific society say it, that doesn't really prove that it's what the rank and file believe. I mean, that's sociology 101 just because the leaders say it doesn't make it true for the people. So I thought, how could I test that? How could I judge whether or not the IPCC reports and the National Academy of Sciences reports are accurate reflections of what working scientists actually think? And I thought, well, I could do a science citation index survey. I could do a sample of a thousand papers, look at them and see what they say. And so that's what I did. So the paper essentially just says that if you look at what scientific experts have to say on the subject of whether or not climate change is underway and whether it's mostly caused by human activities, the scientific community is clear. The answer to that question is yes. And so the paper was simply just saying that. That's it. That was the whole thing. Nothing more. Yes, this is what scientists have to say. Because I thought that was an important message because it seemed like a lot of people didn't actually know that and because the media was presenting it as a great big debate. One day I read the statistic about the public opinion in the U.S. on climate change and how many people thought that humans were responsible and it was disturbingly low. I think at the time it was 58% or something like that. And I thought, hey, well, let's do this as a questionnaire. It's an idea I hadn't back in my head for a while. There's a couple of key questions. One was, is the planet warming? And more people obviously agree with that than the second question, which is, are humans responsible for that? And the overall numbers were only in the 80s for people, for scientists believing, and these are Earth scientists, and it's all Earth scientists, not just climate people. It's geologists. It's seismologists. It's all kinds of different people. And the response was in the 80s, are we responsible? Are humans responsible? And that was a little lower than I thought it would be. But then you start picking apart the data and you start looking at what's their expertise. And it turns out that the people that are publishing climate scientists, the real experts, that self-identify themselves as climatologists, that's 97. I think it was 98%. It's a small group. You get down to only about 100 people that are in that expert group, but they are overwhelmingly in support that humans are causing global warming. I don't know how much more we have to do to prove that there is a consensus. It seems like a silly argument at this point, that we've proved it over and over and over, and clearly there is a strong consensus. It's time to take the next step, whatever that is.