I'm here to tell you what we've learned lately from our simulations. Building on the scientifically-reviewed work at Climate Interactive and MIT Sloan, you can go try any of the models yourself. They're all available open source and online. So how much will all the pledges to the UN climate talks in Paris help and what more is needed to prevent climate change? Here's the short version. The nations of the world have committed to the shared goal of limiting warming to no more than 2 degrees C or 2 degrees Celsius. If there's no further progress after 2030, all the pledges will reduce warming from 4.5 down to 3.5 degrees C, a full degree C of progress. And perhaps more importantly, these pledges set up the world to improve the pledges, decrease emissions even more, and limit warming to the goal of 2 degrees C. We're looking at a graph of total greenhouse gas emissions from burning coal, oil and gas, industry and land use from 2,000 to 2,100. So here's what could happen. The European Union says we're not going to grow our emissions throughout the entire century. Instead, we're going to reduce our emissions 40% below 1990 levels by 2030. Note the EU does not declare its pledge after 2030. We don't know if emissions will then stay flat or go down. So what we've assumed is that those emissions will stay constant after 2030, assuming no continued progress. We assume governments will do what they say, but we're not giving governments credit for commitments that they have not yet made. We'll show you the effect of continued reductions later in the video. Next, the US says we won't grow our emissions through the entire century. Instead, we'll reduce our emissions 26% below 2005 levels by 2025. Other developed nations, Russia, Japan, South Korea, Canada, Australia, turn away from fast emissions growth throughout the century and declare that they will reduce their emissions. A bit more modestly, China says we're not going to follow a fossil fuel intensive future and have our emissions grow throughout the century. Instead, it pledges we're going to cap our emissions of carbon dioxide in 2030. Now note that the graph still rises a little bit over time because the pledge does not include emissions of methane, N20, and the F-gases, the other greenhouse gases. This pledge would avoid a large amount of future emissions. Look at the big difference between the business's usual future and the pledge future. This is really key to avoiding future warming. And now we're going to look at the other developing countries, all of Africa, most of Asia, most of South America. Most of the pledges received from the other developing countries except for some like Brazil and Mexico are relative to the business as usual scenario, usually a 10 to 30 percent drop. What that does is it slows the rate of increase of emissions, but it's not an absolute reduction in emissions. We anticipate these steady increases in other developing countries because of rapid population growth and economic growth that lead to significant burning of coal, oil, and gas. Unless they leapfrog a fossil fuel energy system and develop their economies with efficiency and low carbon renewable energy, this would take technology transfer and take financing, cooperation with the developed world. India pledges a 35 to 40 percent reduction in emissions intensity. That's emissions relative to their fast growing GDP. 35 to 40 percent sounds like a big decrease in actual emissions, but it's not. The business's usual case shown here already includes more than a 40 percent reduction in emissions intensity. So in this scenario, we show no net change in emissions due to the pledge. So there it is. This is what we think the pledges to Paris would bring us. In this scenario, a good bit of coal, oil, and gas stays safely in the ground. We reduce temperature in 2100 from 4.5 down to 3.5 C, and avoiding that degree of warming creates a more safe and secure world. But it's not good enough. What if countries reconvene after Paris to improve the pledges? And what if those pledges include continuing reduction in emissions? What if the US and EU reduces emissions after 2030 at the same rate as recent decades? And what if other developed countries, Russia, Japan, South Korea, Australia, Canada, join in as well? If developed countries reductions continue, we would drop the temperature from 3.5 down to 3.2. And what if China says we'll include other greenhouse gas emissions in our pledge as well as reduce up to 2% after 2030? What would that bring us? When we did the calculations, we see that temperature comes all the way down to 3.0 degrees, a big improvement. And then what if other developing nations in India, cap emissions in 2035, it would take tech transfer, it would take financing, it would take really global cooperation. What would that bring us? When we did the calculations, we see that temperature would come all the way down to 2.6 degrees. That's a huge jump. And now for our final what if scenario? What if the developed countries were to peak emissions in 2020 to 2025? And all developing countries soon after 2030 to 2035. And then all nations of the world reduced emissions 3.5 to 4.4% per year. What would that bring us? When we do the calculations, we see it brings us down to a 50-50 chance at 2 degrees, 2 degrees remains possible. 3.5 and 2. We would need to figure out how to meet human needs and keep an enormous amount of coal, oil and gas safely in the ground. The good news is the Paris Agreement looks to be a stepping stone to where we really want to go.