Hi, I want to talk about context based sustainability. I've mentioned it several times already in these classes. It's important to me because until I learned about it from Mark McElroy at the Center for Sustainable Organizations, sustainable business seemed like a lot of almost random decisions. But context based sustainability links ecological limits to business activities so things make sense. In this lecture, I want to introduce context based sustainability as it relates to climate change. I've given this talk a couple times, and I call it my sad or mad baby lecture. You'll see why in just a second. In context based sustainability, we use the best scientific evidence that we have about the ecological limits related to a particular activity. Case of climate change, we're interested in how carbon dioxide emissions are related to temperature changes. A very influential paper was published in 2009 that made this connection. It estimated that from the year 2000 to the year 2050, humans could emit about 1,437 gigatons of CO2 to have a 50% chance of global temperatures, not increasing more than 2 degrees centigrade. To increase the probability to 80%, that is having an 80% chance of there being less than 2 degrees of warming, the 50 year carbon budget was estimated at 886 gigatons. A gigaton is a billion tons. To give this some perspective, about 30 to 35 billion tons of CO2 are emitted every year. From the year 2000 until 2016, we've emitted about 525 gigatons of CO2. That means that for the next 34 years, we have a remaining carbon budget of about 912 gigatons, or just under 27 billion tons a year. Now remember, we're emitting 35 billion tons a year. In 2014, it was 35.9 billion tons. This is for a 50% chance of staying under the 2 degree warming ceiling. At an 80% probability, we only have about 360 gigatons remaining in the budget for the next 34 years or about 11 billion tons per year. This is where we get our first sad or mad baby. Now again, I want to put this into perspective. In 2015, which is the most recent data available, and it might be subject to some adjustment, China and the US combined emitted 15 billion tons of CO2. That absolutely overwhelms the 11 billion ton annual budget for an 80% chance to stay below the 2 degrees of warming. And it absorbs over half of the 50% probability budget. Looked at a little differently, at a 50% chance of staying under the 2 degree warming target, all of the countries get to share an annual carbon emission budget of 12 billion tons. For those 180 countries has about 60 million, not billion, but million tons, are a tiny fraction of what some are now emitting. Here's another mad baby. So we figured out what nature allows, giving a warming target of 2 degrees C or less. But now we have to do the hard part and figure out how to allocate that budget. There are a lot of possible ways to share the budget. Some people think we should look at historical emissions, and those countries that have emitted the most should get the least in the future. Basically what this means is that the US would get none. While that might seem fair to some people, since the US is a key driver of the global economy, it would probably bring the entire world economy to a grinding halt, harming everybody. Some people argue for sharing based on relative contributions to the global economy. This would sort of lock in a status quo with little room for expansion by poorer countries. Others have argued that a per capita allocation is best. That model has every person getting an equal share. If some countries had excess, they could sell or barter the excess, holding onto the option in the future to use their emissions for economic growth. With my colleague at the University of Colorado, Denver Beth Cooperman, we've estimated the reductions needed to shift to a per capita allocation over 20 years. The reductions vary by country depending on current emissions, current population, and population growth estimates. For the US, we'd have to make reductions in the range of 6% per year to begin with and then increase those reductions over time to almost 16%. There are lots of different trajectories that'll get to the same end point. Here are a couple of them. Now this won't be easy, and now we get a really, really sad or mad baby. Of course, there could be extra emissions available for purchase, so the reductions might not be quite like this, but it's still going to be really hard. I want to touch on two related topics. First, science-based targets, a number of companies are setting science-based sustainability targets. I'll post a video from Autodesk about how it sets its target. It uses a contribution to GDP allocation or sharing role. Other companies use slightly different approaches. These are great first steps towards true context based sustainability target setting. Most of the targets I've looked at, actually, all of the targets I've seen, did not take a global view of the allocation of the budget. But again, it's a first step. At least companies are acknowledging that there's ecological limits that have to be respected. If you could help your company develop science-based targets for its carbon or greenhouse gas emissions, that would be a great contribution, a huge step forward. If you really want to make a splash, maybe even make headlines, your company could adopt the Byrd-Cooperman reduction pathway to per capita sharing. Your company would be the first company in the world, even in the universe, to have a globally equitable carbon emission target. That would be absolutely great. The second topic I want to mention is applying context to other situations. It turns out climate is a simple situation to address in terms of context, except for the sharing part, of course. Water has all sorts of complexities. The amount varies seasonally, ecosystem needs can be hard to determine, and so on. Other situations like fertilizer overuse and agriculture and soil depletion may also be more complicated than climate. But we're just starting to think in terms of context. So we can't expect perfection. We can't expect recognition that context and ecological limits matter. If you can instill this notion in your company, that'd be a great contribution to make, thanks.