 At first I want to thank Ricky and Philip for the invitation to participate in another urban age event. It's a real pleasure to be here and I'm looking forward to the conversation. So Nick has really set up the stage very nicely. Thank you very much for the remarks that I'm going to make in the next 15 minutes or so. And the answer to this question that I've put up here is a pretty simple yes. And what I'd like to do is actually go through some of the ways in which cities can mitigate climate change and again underlie the urgency of this, what we really need to do. I want to start off with this statistic that came out of the last IPCC report, the Fifth Assessment Report, the AR5. One of the big conclusions of the third working group, which I was a part of, is that greenhouse gas emissions growth continues to accelerate, the growth continues to accelerate despite mitigation efforts in many parts of the world. I'm in an environment school at Yale and when this result came out I will say that it was quite disconcerting because there are many efforts underway. We would like to think that these mitigation efforts are making an impact. Why do we see the emissions growth accelerating despite these mitigation efforts? We see that over the last 10 years or from 2000 to 2010, the growth in emissions was even greater than in the period before. Here you see that from the period of 1970 to 2000 the rate of growth per year was about 1.3% and in contrast from 2000 to 2010 that rate of growth was 2.2% per year. And the economic collapse, you see there's a little blip there but didn't really make that much of an impact in changing the overall trend. And you see in this graph in the yellow that the dominant driver of these emissions is fossil fuel and industrial processes. Now I want to just spend a couple of minutes talking about the changes over the last 40 years in the geography of emissions because it's going to be really important when we get into the discussion about urbanization. What we're seeing is that there's been a significant shift globally in the geographic patterns of greenhouse gas emissions. From 2000 to 2010 these upper middle income countries and these are the World Bank designation, not the IPCC designation. But if you look at the World Bank designation it will give you a list of these countries. These countries were responsible for 75% of the increase in total annual greenhouse gas emissions. So you can see that total emissions per year, this doesn't work, barely works but you can see it's 18.3 gigatons almost catches up to the very high income levels. Now I will say that this is a little bit misleading because if you look at the list of countries it's like when you take introduction to statistics and the teacher says in some cases you might use the average and in other cases you don't want to use the average because if you have someone like Bill Gates as part of your sample your average may be skewed. So these numbers are clearly skewed for the upper middle income numbers by one or two countries that have very high emission rates. But the other thing to notice is that when countries at the lower middle income and upper middle income we see that industry and energy are a very large percentage of their total greenhouse gas profile. But for high income countries we see that transport, those cars that we like, transport becomes a growing portion of the overall profile. I want to just have you keep that in mind in terms of this changing geography what happens to emissions as countries develop from lower income, upper middle income to high income countries. I want to just put this statistic up here because it's probably something that many of you are not familiar with that if the top 50 emitting cities were a single country would rank third in emissions behind China and the United States. So this really underscores the I would say the currency that cities have in effecting climate change that what happens in these 50 countries or 50 cities certainly has a really big impact. Now I'm curious to know how many people here have read the fourth assessment report of the IPCC. Okay you're really dating yourselves now so like there are five people in the room who read the fourth assessment report. So all the previous assessment reports of the IPCC up until the most recent one that was published last year, those assessment reports looked at mitigation primarily through a sectoral lens, energy, buildings, transport. And for those of us who are urbanists in the room it was very clear that there needed to be a chapter on cities and how cities could mitigate climate change. But it wasn't until the most recent assessment report that the IPCC did include a brand new chapter on how cities and especially spatial planning and infrastructure could mitigate climate change. And this entire chapter all hundred plus pages you can download from the IPCC website. I do want to just say very quickly that inclusion of this chapter in the IPCC was not without controversy. Because the IPCC, the constituents, the clients of the IPCC are nation states. They're not cities. So when many of us said there needs to be a chapter on cities and how cities can mitigate climate change, this is one of the biggest trends of the 21st century. It's climate change and it's urbanization. And if we don't have a chapter on climate change we're missing this mega trend. And we can talk offline and maybe during the discussion about the politics of the local versus the national and I'm sure there are many other people in this room more competent than I to talk about this. But clearly this played out in including, simply just including a chapter on cities. So I want to highlight a couple of the main take home messages from this chapter. And one of the take home messages Nick already alluded to or mentioned is that cities account for the majority of fossil fuel based carbon emissions. However, there's a lot of variation between cities and there's a lot of variation between countries. When we assess the literature what we found was that there are basically four drivers of urban emissions. And these four drivers are pretty straightforward. It's the economy. It's the socioeconomic structure of these cities. So if you're a manufacturing city, if you're an export city versus if you're a services city or an import city you'll have very different emissions profiles. In terms of your socioeconomics it depends on the age cohort of your city, the age structure, the household size, income levels. But the third thing that matters is also the technology. What types of technologies does your city use? Technology in terms of heating and cooling, in terms of your building. And so the vintage of your buildings has a very big impact on your total emissions profile. And then last but not least the urban form, the form and structure, the density and I'll talk a little bit more about this in a moment, but the form of a city has a big impact. And all four of these interact together so it's very difficult to parse out one from another. So what you see here are these differences played out at the global level. So what you see on the left are annex one cities and on the right are non-annex one cities. And in blue these are cities where the energy use, the per capita energy use is lower than the national average. So in blue basically you're a city where your energy use is lower than the national average. And in yellow these are cities where energy use is higher than the national average. And if you take those four factors, those four main drivers of urban emissions that I just talked about, you can kind of start to understand why we see these differences. So in some cases, especially for the non-annex one countries, these are cities that are primarily manufacturing cities, they're export cities, they're producing stuff. On the other hand on these annex one cities, these are cities that are service cities, they're service economies. Some of these are cities that have higher density, higher accessibility, more co-location of work with residences, and also much more efficient technology. And so it's these four factors that are playing out. But I think it's really important for us to remember that there are significant differences between cities and that is a really critical thing to think about when we start talking about policies. I will underscore this window of opportunity though, this window of opportunity to shape the environment and to shape not only the urban environment but really the global environment. Nick has already mentioned that we're at a little bit more than 50% of the global population living in urban areas. What does that translate into in terms of land use change, in terms of the built environment we need to support people? We did a study a few years ago and we found that every day for the first 30 years of this century, every day about 20,000 American football fields becomes urban. And I'm sorry, I don't know how big an American football field is relative to a football field is. But someone will quickly do the calculation. But it's quite a large area every single day for the first 30 years. Every 10 days about 1.3 million people move into cities. So this is something that's happening now. It's not something that's happening in the future. But for cities to be part of the solution, the climate change solution, one of the things that they absolutely must do is arrest, reverse the trend of declining densities. And this is a graphic that's taken from the fifth assessment report, which is based on the work of Soli Angel and his colleagues. But basically what he and his colleagues, and this has been corroborated by many other studies, shows that across income levels, across geographies, we see that cities around the world are declining in terms of their densities. So we're not becoming more compact and walkable, we're actually sprawling out and becoming more of transit-based, car-based city. So if cities are going to be part of the solution, this trend has to be reversed. Now, I'm not going to have time to go into this in detail, but I do want to say that urban form, and I've mentioned these four factors that drive urban emissions, urban form is one of the factors, one of the main factors that localities can affect completely within their jurisdiction, whether it's through zoning or land use laws. Four characteristics of urban form are especially important for shaping urban emissions. One of them is density, but density, as we'll get to now, is that increasing density alone is not sufficient for reducing urban emissions. Because these urban form, these factors, there are a number of them. It's not just density, it's also land use. Places that have a higher land use mix tend to have lower emissions. Places that have high connectivity, where you have a lot of inner section density basically makes it easier for people to walk to places. Those are also places that have lower emissions. But then really the one thing that has a big, big impact is this last point here, which is accessibility. And accessibility in the literature can be measured in a number of different ways, but think of it simply as how easy is it for you to get to the services and activities that you're interested in, whether it's school or work or your grocery store. How easy is it to get to? Now we can think of places that are accessible in a number of ways. You can think of a freeway going really fast in a fast car is being very accessible. But then those are places that generally aren't very connected and don't have a lot of high land use mix. You can think of accessibility where residences are co-located or located very close to where people work. And that is probably one of the most defining ambitious characteristics in terms of low carbon urban form is for places to have high accessibility. But I think one of the important things to remember is that density alone is not going to solve our climate problem. Increasing density without intentionally locating people close to jobs and close to services will not lower emissions. One of the things that we're going to see coming in the next, it's happening now, but really over the next 10, 20 years is infrastructure development primarily in lower income and developing country cities. And this infrastructure development is going to result in significant emissions to mine the material, to process the material, to transport the material, and to build the buildings. Oftentimes when we think about climate change and policies to mitigate climate change, we focus on things like energy efficiency of the lights, of our buildings, of our windows, of our cars. But there's an embodied energy, embodied emissions associated with building all this stuff. And so this is another graphic that's taken from the IPCC report which shows differences in infrastructure between annex one countries. You can see the average here for annex one countries. We have a lot of infrastructure in our countries compared to the global average down here, which is relatively low. If developing countries over the next 20 years develop their infrastructure in the same way that we have in annex one countries, this is what the emissions profiles will look like. This is just to build the infrastructure. This is not to operate the infrastructure. So there's a lot of emissions associated with building the infrastructure to support the urban population of tomorrow, even of today. What we're seeing with satellite data, we keep thinking that urbanization, this urban transition, urban revolution is something that's going to happen in the future, but it's already happening now. This is work that we've done with some collaborators at University of New Hampshire where they've used satellite data to look at the growth of infrastructure. And what's interesting here is this is data from 1999 to 2009. And I'm going to give you a crash course in satellite image analysis. So what we have here are two different types of satellite data. On the x-axis, these are the night lights. How many people here have seen the night lights? A lot more than those who've read the fourth assessment report. So this is the night lights that you see the earth from space at night over a 10-year period. And so this arrow, the arrows that move in the horizontal direction basically show how much additional light is there. So this is growth of infrastructure, but also growth in the horizontal direction. And then in the y direction, this is a different satellite. It's a radar scatterometer. It basically is able to characterize the physical structure, the height of the urban area. So what we see in these four Indian cities is Bangalore, Hyderabad, Chennai, and Delhi. They've grown out but not very up. So those of us who've worked or been to India, this is no surprise. African cities, we see a very similar trend. There's a little bit of growing up here in Luanda, a little bit in Lagos. But by and large, these cities are growing out. But this represents real infrastructure development on the ground. And then we get to Chinese cities where we see significant vertical infrastructure development. This is concrete. This is steel. These are embodied carbon emissions. So this lock-in, this infrastructure and carbon lock-in is something that's happening now. It's not something that we have to stop for the future. We have to think about how we change the patterns today. I will end with this positive note because I am ultimately an optimist, which is that there is an urgency. There is this wind of opportunity because once infrastructure is built, it's very difficult to change it. Once you build the backbones of a city, the roads, the transport lines, etc., it's very difficult to change it. And so there is this urgency, this window of opportunity. But more urban areas will be built in the first three decades of this century than all of human history. So those of you who are planners and designers, you have your work set out for you. So with that, thank you very much.