Welcome back to our sustainable future. In the first two modules of the course, we spent a lot of time talking about climate change and the science behind global warming. All to convince us that we need to change as if we really needed any convincing, but also to give us the background on why we need to change. In this module, we'll start looking at things a little differently. If we know we have to reduce greenhouse gases on a global scale, then how do we do that? And that brings in questions of equity, something I call carbon equity, and that's the topic of our first lesson. We then turn our attention to growth and why everyone from business to governments think growth is the solution to just about any problem. Of course, with just one planet, there's a finite limit to how much growth we can have and that's the topic of lesson two. We then talk about how we got to our current state of so few people around the world owning so much of all the wealth, resulting in today's social inequity and wealth inequality. That means we need to talk about business, economic growth, governmental policies, and the transition from the economic thinking from the last century to new and a more inclusive ideas for this century. We'll continue lesson three talking about doughnuts, introducing Kate Raworth and her novel ideas about doughnut economics. Representing a whole new way of thinking about business, growth, and making sure everyone on the planet has opportunities for a fulfilling life. With all this discussion of a sustainable future, perhaps we should define what we even mean by sustainable or sustainability, and that's the topic for lesson four. We also introduced two new terms that you'll no doubt be hearing, regenerative and restorative, and the reasons these terms are gaining momentum in sustainability circles. Lesson five presents a simple model put forward several years ago called the iPad equation, an idea that helps clarify the role of consumption and technology on our collective environmental impacts. And finally, it's important to know that we're not alone in wanting to make a difference. In fact, the United Nations has established what are called sustainable development goals that help provide the roadmap for a more sustainable future for all of us, and that's our final topic in lesson six. So with this module, we start turning the corner from a discussion on why we need to change, to beginning thoughts on how to change, and that's where things get really exciting. Are you ready? Let's get started. Do you remember this curve from module two? It shows the collective global greenhouse gas emissions from 1990 to 2018. The last year, these were reported as of when this lecture was created. It shows that one, greenhouse gases have continued to increase, even with all the knowledge we've learned about global warming and subsequent climate change. Two, this curve shows the major greenhouse gases that we need to worry about. Mostly carbon dioxide CO2, followed by methane CH4, nitrous oxide N2O, and those pesky F gases or florenated gases like hydrofluorocarbons found in air conditioners and refrigerants. At the end of 2018, we see that the global greenhouse gas emissions were about 48.9 gigatons of carbon dioxide equivalent, which we said takes into account the different global warming potentials or GWPs of methane, nitrous oxide, and the F gases relative to carbon dioxide. Last time, we also said that the latest report from the Intergovernmental Panel on Climate Change or the IPCC indicated that in order to limit global warming to a much more manageable 1.5 degrees Celsius or 2.7 degrees Fahrenheit. We needed to aggressively reduce greenhouse gas emissions and quickly. This is a plot that shows the actual greenhouse gas emissions from 1990 to 2018, the blue dots, which is essentially the same curve as before, just without all the details. Then we project forward to show what we need to accomplish. For instance, net greenhouse gas levels need to be reduced by approximately 50% by 2030 from 2010 levels, otherwise, there's no way we'll hit our 1.5 degree target no matter what we do after that. The reason for this is that carbon dioxide, one of the most important greenhouse gases, stays in the atmosphere for quite a long time, potentially several 100 years or so. So even if we stopped putting any more anthropogenic CO2 into the atmosphere starting tomorrow, the CO2 we've already emitted would largely still be there locking and warming for quite a while. So as we said at the end of module two, 2030 is an incredibly important date for all of us. Once we achieve that goal, we need to reduce net global greenhouse gases, the other 50% to 0 by 2050. Note that we said net greenhouse gas emissions need to come down 50% by 2030 and then to 0 by 2050. Well, what does net mean? Well, according to the IPCC, pathways to get to these targets include more than just reducing our fossil fuel use. We also need to draw down carbon dioxide that might be up there already. Think of it this way, one day you drive your gasoline powered car around town potentially emitting ten kilograms of carbon dioxide. Of course, you're bothered by this, so you plant a tree in your backyard and that tree absorbs one kilogram of carbon dioxide per day. Your net carbon dioxide emissions are nine kilograms that day. The ten that you emitted by driving around less, one absorbed by the tree that you planted just for this purpose. That's the idea behind net emissions getting to zero by 2050. We might still emit some, but those would have to be absorbed by something else we do, like planting more trees a lot of trees. One way we can think about how to reduce our collective greenhouse gas emissions is to simply divide up the challenge equally among everyone on the planet, that way we know exactly what we have to do to reach our targets. Well, that sounds rather equitable, so let's calculate what that looks like. In 2018, global greenhouse gas emissions were about 49 gigatons or 49 billion metric tons overall. At about the same time, the world's population was just about 7.6 billion people. So you divide the emissions by the number of people and you have your own personal emissions value of 6.4 tons of greenhouse gases in 2018 for each one of us living on the planet. That also personalizes the challenge quite a bit. Now we don't have to talk in somewhat abstract units like gigatons or billion metric tons, just 6.4 tons per year that we can understand. Okay, so now all we have to do is reduce that to about 3.2 tons per year by 2030 and get to zero by 2050 and we're good to go, right? Well that's certainly one approach, but there's a problem with this line of reasoning. Well, 6.4 tons of greenhouse gases per person is a good average number. We know already that the world is not made up of averages. People have different lifestyles and different consumption patterns across the globe. And those differences lead to rather dramatic differences in our own personal contributions to greenhouse gases. Yes, some people are average contributors to GHGs, like those bike riding business folks like you might see in many Northern European countries. But other people and certainly other cultures have much lower contributions to greenhouse gases. Or as we so often hear these folks have a much smaller carbon footprint. A topic we'll soon get into. Take these folks, for example, they understand the need to live sustainably and have adjusted their lifestyle and consumption patterns to fit their values. They are low GHG contributors. On the other hand, there are many people on the planet that due to their very lavish consumption based lifestyles, they tend to be associated with very large carbon footprints. In effect contributing much more to greenhouse gas emissions than anyone else. Thus by taking such an averaging approach to greenhouse gases, we are immediately penalizing those that are already on the path to a sustainable future. And we let those off the hook that are the main culprits and that's just not equitable. We need a different way to figure out how to reduce emissions to limit warming to 1.5°C. So if calculating greenhouse gas emissions per person doesn't seem fair, how about we look at emissions by individual countries. The chart here shows the Global Greenhouse gas emissions in 2018, this time by country. What we see is that 65% of all Greenhouse gas emissions come from just 10 countries or collection of countries like the European Union, with each of the remaining 184 or so countries, each contributing less than 1.5% of the total. You can see immediately that China has led the way, with nearly 24% of all emissions, followed by the United States, with 12%. India and the 27 countries making up the European Union, each contributed to about 7% of all global greenhouse gas emissions. Every other country making up the top 10 list contributed a lot less. So maybe we should just say that 50% of all global greenhouse-gas emissions come from China, the United States, the European Nations and India. One conclusion people often come to when they see a plot like this is, wait a minute, China is the real guilty party here. They need to clean up their act. But of course that's not thinking about things too deeply. For one China's rise to the top spot is a fairly recent event, only surpassing the United States in 2004 as the world's largest contributor to greenhouse gases. Until that point, the United States was by far the greatest emitter of greenhouse gases and for decades in fact. Second, let's not forget that China has about 1.4 billion people living there. More than four times the number that live in the United States. And considering that many of those people have risen out of poverty with China's economic growth, it only makes sense that their greenhouse gas emissions would also increase. Since greenhouse gas emissions typically rise with higher standards of living. Of course, let's also not forget that starting about 30 or 40 years ago, China set itself the goal to become the manufacturer to the world. How many products do you use that were made in China? And why were they made their because it was cheaper to make them there than in the home country where they were often designed. And at least for many businesses in the United States, they simply outsource their production to countries like China and India as part of the trend of globalization of the economy. Of course, millions of lives benefited from this new opportunity. But how did countries like China gear up for all this new business? They built coal fired power plants, and lots of them. Because that's what you did in the last century, when you needed a lot of energy and fast. A short footnote here, over the last few decades, China has also installed more renewable energy than many other nations around the globe. Something we'll discuss in future lessons. So while maybe those of us living in the United States and perhaps the European Union feel good about having lower greenhouse gas emissions than China. Is this really a fair comparison? Not really, particularly when much of China's emissions are related to manufacturing the products that we want to buy, but more on that later. Okay, if looking at each country's greenhouse gas emissions doesn't tell us the whole story either, then what else can we do? Let's take into account each country's population and calculate a country's greenhouse gas emissions per person. Also known as a per capita emissions. Looking at the same 10 countries as before and now dividing their 2018 emissions by their population in 2018, we come up with the graph you see here. Greenhouse gas emissions per capita. Interestingly, Canada pops out as number one, in this case. With more than 20 tons of greenhouse gases emitted for every one of the nearly 40 million people that are living there. The United States is a close second with nearly 18 tons of greenhouse gases per person. Looking down the list, you finally see China, which comes in at number six. So using emissions per person is our metric, it doesn't seem that China is the loan bad guy after all. Another group we should take a look at is the European Union, made up of those 27 countries, such as Germany, France Spain and Italy. Close examination shows us that the average European has an emissions footprint of less than half of what the average person has in the United States. Why is that? That's a good question. Something we're going to explore in future lessons. Another thing to point out here is that there are countries not shown that actually have higher emissions per person than Canada. These tend to be smaller countries where their overall contributions are not very high. So for now we won't consider them. Of course another question is why would Canada have such high greenhouse gas emissions per person? Maybe it's because they are so far north, they spend a lot more energy on heating during the winter. But we'll come back to this later when we look at how people around the world contribute to global greenhouse gas emissions based on their lifestyles. So stay tuned. Another important fact, when trying to figure out how we individually reduce our greenhouse gas emissions is who has contributed the most over time. Remember that carbon dioxide stays up in the atmosphere for hundreds of years. So while it's important what a country in its today, it's also important to know the cumulative emissions by a country over time. And that is what this plot shows, the total amount of carbon dioxide emitted into the atmosphere determined from the start of the Industrial Revolution in 1750 to 2019. By this measure, the United States is clearly the country that has contributed the most carbon dioxide and, therefore, is the country most responsible for global warming and subsequent climate change. Yes, China is up there as well, but there is no doubt that it is the United States that needs to step up and take responsibility for its actions or inactions as the last several decades have shown. Let's summarize our discussion with a few main takeaways. For one, in order to limit global warming to a more manageable 1.5° Celsius, we need to reduce our greenhouse gas emissions by at least 50% by 2030, and then keep on going to achieve net zero greenhouse gas emissions by 2050. That's a tall order, and one that only gets more challenging every year we simply talk about it. We need to be conscious of what I call carbon equity, meaning people around the world have very different lifestyles and consumption patterns which ultimately leads to very different contributions to global greenhouse gases. We definitely can't penalize those that are already limiting their emissions while we let the major contributors off the hook. We hear a lot about China as the number one contributor of greenhouse gases today, and that is indeed important because it means we need China to be part of the solution. But let's not forget that their ascendancy to number one is a recent phenomenon and mostly because they have become the world's manufacturing center. Such economic growth has raised the standards of living for millions of people in China. So how can we fault them for that? Besides when we take China's 1.4 billion people into account, their per capita emissions contributions start to look rather average. Rather than look at emissions one year at a time, we need to remember that greenhouse gases especially carbon dioxide stay in the atmosphere for a very long time, therefore, we need to consider cumulative emissions over time. And under that metric, the United States is by far the top contributor to global warming and by a lot. So in the end, we in the United States are the ones mostly responsible for global warming and therefore, it's our responsibility to implement the solutions to fix it before it gets too late. By setting the example for the rest of the world, we can show how such a challenge can be overcome and lead the way to a more sustainable future. One last thought on this topic. So we now know who bears most the responsibility in getting us to where we are today. Yet across the globe our politicians continue to debate the significance of climate change while pushing obvious solutions off into the future. Businesses on the other hand want to preserve the status quo and often see such disruptive change as a threat. Although as we'll see in future lessons, there are some enlightened companies out there challenging the way we do business today. And that means any significant change has to start with us. We vote the politicians in the office and we buy the products from the companies that make them for us. To be sure this is the reason I created this course and put it on coursera to reach as many of us as possible, who take this seriously and want to take individual responsibility in order to make a difference. Maybe if enough of us take up the challenge the rest of the world will follow. There's no time to waste, if indeed it's up to us now, then let's get going. For our next lesson, we're going to shift gears a bit and talk about some of the other challenges we face. For one, most of us live in what is known as a linear economy, where businesses extract minerals from the earth, create the products that we buy, and then we use them until we're done, whereby we toss them into the trash. That's the way our economy has been built from the early days of the Industrial Revolution. We're happy to get new stuff and business is happy that they continue to grow. But there's a problem with this model today, and that's the topic of our next session. I'm Michael Reidy, and thanks for joining me. I'll see you next time.