When the explorers first set foot upon the continent of North America, the skies and lands were alive with an astonishing variety of wildlife. Native Americans had taken care of these precious natural resources wisely. Unfortunately, it took the explorers and the settlers who followed only a few decades to decimate a large part of these resources. Millions of waterfowl ( 水禽 ) were killed at the hands of market hunters and a handful of overly ambitious sportsmen. Millions of acres of wetlands were dried to feed and house the ever-increasing populations, greatly reducing waterfowl habitat.

In 1934, with the passage of the Migratory Bird Hunting Stamp Act (Act), an increasingly concerned nation took firm action to stop the destruction of migratory ( 迁徙的) waterfowl and the wetlands so vital to their survival. Under this Act, all waterfowl hunters 16 years of age and over must annually purchase and carry a Federal Duck Stamp. The very first Federal Duck Stamp was designed by J.N. “Ding” Darling, a political cartoonist from Des Moines, lowa, who at that time was appointed by President Franklin Roosevelt as Director of the Bureau of Biological Survey. Hunters willingly pay the stamp price to ensure the survival of our natural resources.

About 98 cents of every duck stamp dollar goes directly into the Migratory Bird Conservation Fund to purchase wetlands and wildlife habitat for inclusion into the National Wildlife Refuge System — a fact that ensures this land will be protected and available for all generations to come. Since 1934, better than half a billion dollars has gone into that Fund to purchase more than 5 million acres of habitat. Little wonder the Federal Duck Stamp Program has been called one of the most successful conservation programs ever initiated.

"What would the world be if there were no hunger?" It's a question that Professor Crystal would ask her students. They found it hard to answer, she wrote later, because imagining something that isn't part of real life—and learning how to make it real—is a rare skill. It is taught to artists and engineers, but much less often to scientists. Crystal set out to change that, and helped to create a global movement. The result一an approach known as systems thinking—is now seen as essential in meeting global challenges.

Systems thinking is crucial to achieving targets such as zero hunger and better nutrition because it requires considering the way in which food is produced, processed, delivered and consumed, and looking at how those things intersect (交叉) with human health, the environment, economics and society. According to systems thinking, changing the food system—or any other network- requires three things to happen. First, researchers need to identify all the players in that system, second, they must work out how they relate to each other, and third, they need to understand and quantify the impact of those relationships on each other and on those outside the system.

Take nutrition. In the latest UN report on global food security, the number of undernourished (营养不良) people in the world has been rising, despite great advances in nutrition science. Tracking of 150 biochemicals in food has been important in revealing the relationships between calories, sugar, fat and the occurrence of common diseases. But using machine learning and artificial intelligence, some scientists propose that human diets consist of at least 26,000 biochemicals—and that the vast majority are not known. This shows that we have some way to travel before achieving the first objective of systems t hinking - which,in this example, is to identify more constituent parts of the nutrition system.

A systems approach to creating change is also built on the assumption that everyone in the system has equal power. But as some researchers find, the food system is not an equal one. A good way to redress (修正) such power imbalance is for more universities to do what Crystal did and teach students how to think using a systems approach.

More researchers, policymakers and representatives from the food industry must learn to look beyond their direct lines of responsibility and adopt a systems approach. Crystal knew that visions alone don't produce results, but concluded that "we'll never produce results that we can't envision".

Live with roommates? Have friends and family around you? Chances are that if you're looking to live a more sustainable lifestyle, not everyone around you will be ready to jump on that bandwagon.

I experienced this when I started switching to a zero waste lifestyle five years ago, as I was living with my parents, and I continue to experience this with my husband, as he is not completely zero waste like me. I've learned a few things along the way though, which I hope you'll find encouraging if you're doing your best to figure out how you can make the change in a not-always-supportive household.

Zero waste was a radical lifestyle movement a few years back. I remember showing my parents a video of Bea Johnson, sharing how cool I thought it would be to buy groceries with jars, and have so little trash! A few days later, I came back with my first jars of zero waste groceries, and my dad commented on how silly it was for me to carry jars everywhere. It came off as a bit discouraging.

Yet as the months of reducing waste continued, I did what I could that was within my own reach. I had my own bedroom, so I worked on removing things I didn't need. Since I had my own toiletries (洗漱用品), I was able to start personalising my routine to be more sustainable. I also offered to cook every so often, so I portioned out a bit of the cupboard for my own zero waste groceries. Perhaps your household won't entirely make the switch, but you may have some control over your own personal spaces to make the changes you desire.

As you make your lifestyle changes, you may find yourself wanting to speak up for yourself if others comment on what you're doing, which can turn itself into a whole household debate. If you have individuals who are not on board, your words probably won't do much and can often leave you feeling more discouraged.

So here is my advice: Lead by action.