 Scientists have been measuring carbon dioxide in the atmosphere systematically since 1958 during the international geophysical year. We know that the prime driver of global climate change is increased carbon dioxide in the atmosphere from burning fossil fuels and deforestation. How do we know that? It's not a theory, it's not a model, it's not a hypothesis, it's measurements. So there is a steady almost inexorable increase in carbon dioxide that has brought us up to where we are today, which is 400 parts per million. So what this tells us is that there's a very powerful urgency here, particularly in the light of the Paris Agreement, which said we should try to stay well below. This is a map that shows average global increase and what you see is the earth essentially turning red, the earth getting hot. The globe as a whole has increased about just under one degree C since pre-industrial levels and in the Arctic regions it's actually six degrees. And the Arctic is where the ice is obviously and if that ice sheet starts to melt, particularly the ice that's on the land, then that slides into the sea. You get not only the warming of the sea, which is a rather long process, but the sliding of the ice into the sea. If you remember Archimedes principle from your high school days, that is something that pushes up the sea level much more rapidly than simply the thermal expansion. As the earth warms, the oceans warm and they expand due to thermal expansion, that's basic physics, but in addition we also melt ice off the land masses and all of this contributes to sea level rise. We believe that seeing is believing and we find that when people see the impacts of climate change, see the drivers, it has a greater impact on them than if we just talk to them about the scientific theories. We know that the principle driver of greenhouse gases is energy use. About 60% of all greenhouse gases in the atmosphere are directly related to energy use. For most of the world that means oil, gas and coal. So this is a picture of the earth at night and what you're seeing here is not electricity, what you're seeing here is flaring of gas from oil wells. So all of these fires you see are methane being burnt off, not sold, not used, but being burnt, being wasted going directly to the atmosphere and contributing to global warming. We're in the middle of an incredibly rapid transformation of the world's population into cities. We're about 50% in the cities now of around 7 billion people, so roughly we're a little over 3.5 billion people in the cities. That's going to go up to 6.5 billion people in the cities, something like 70% of more than 9 billion in the middle of this century. That's a one-off event in human history. That growth of the cities locks in infrastructure. It settles whether those cities are congested and polluted and wasteful or productive, clean and attractive places to be with low emissions. Cities, especially well-designed cities, are more energy efficient than rural and suburban areas. And cities also sometimes have the political and social capacity to institute reforms and changes that can be hard to institute on a national level. So to the extent to which cities are planned intelligently, to the extent to which cities implement regulations, to the extent to cities foster cultures of efficiency, there are tremendous opportunities in the next 10 to 20 to 30 years to really reformulate the way we use energy, the way we travel, the way we move and really make a very, very big difference in this problem. It shows what the risks are, shows what the drivers are and also points to some of the things we can do. This is an illustration of solar photovoltaic installations in the United States and focusing here, particularly in the Greater Boston area. This is the year 2001, so it's only 14 years ago. And this is really important, and I think probably most people in this audience know this but it's worth underscoring. Change can happen really quickly when you have the right rules, regulations and incentives in place. And that happened in the state of Massachusetts a few years ago. And so now watch what happens to the Boston metropolitan area over the course of the next 14 years. And you can see this rapid transformation. Now let's go to California. And now it's 2000. We see a bit of PV capacity but still not too much. And then California passes AB 32, an emissions control law that had large incentives for renewable energy. I mean, look at this. The whole of California is being lit up by solar PV. And all of that happened in less than 15 years. Sometimes regulation can make a big difference to things happening quickly. Sometimes you want to use the taxes and the subsidies, sometimes the regulations. Policy matters, but credibility of policy also matters. Scientists have been communicating this evidence for a long, long time now. And I think all of us close this issue feel like the time has really come to stop talking about climate change and the evidence of climate change and to really be talking about the solutions. Because we're really at a moment in history when if we don't do that now, the opportunity to fix this problem will really disappear. We'll really slip from our grasp.