The Science of Sustainability

I.  A False Choice

Many assume that economic interests and environmental interests are in conflict. But new research makes the case that this perception of development vs. conservation is not just unnecessary but actively counterproductive to both ends. Achieving a sustainable future will be dependent on our ability to secure both thriving human communities and abundant and healthy natural ecosystems.

The Nature Conservancy partnered with the University of Minnesota and 11 other organizations to ask whether it is possible to achieve a future where the needs of both people and nature are advanced. Can we actually meet people’s needs for food, water and energy while doing more to protect nature? 

II.  Two Paths to 2050

This vision is not a wholesale departure from what others have offered. A number of prominent scientists and organizations have put forward important and thoughtful views for a sustainable future; but often such plans consider the needs of people and nature in isolation from one another, use analyses confined to limited sectors or geographies, or assume that some hard tradeoffs must be made, such as slowing global population growth, taking a reduction in GDP growth or shifting diets off of meat. Our new research considers global economic development and conservation needs together, more holistically, in order to find a sustainable path forward.

What could a different future look like? We’ve used as our standard the United Nations’ Sustainable Development Goals (SDGs), a set of 17 measures for “a world where all people are fed, healthy, employed, educated, empowered and thriving, but not at the expense of other life on Earth.” Our analysis directly aligns with ten of those goals. Using the SDGs as our guideposts, we imagine a world in 2050 that looks very different than the one today—and drastically different from the one we will face if we continue in business-as-usual fashion.

To create our assessment of business-as-usual versus a more sustainable path, we looked at 14 measurements including temperature change, carbon dioxide levels, air pollution, water consumption, food and energy footprints, and protected areas.

Over the next 30 years, we know we’ll face rapid population growth and greater pressures on our natural resources. The statistics are sobering—with 9.7 billion people on the planet by 2050, we can expect a 54 percent increase in global food demand and 56 percent increase in energy demand. While meetings these growing demands and achieving sustainability is possible, it is helpful to scrutinize where the status quo will get us.

The World Health Organization, World Economic Forum and other leading global development organizations now say that air pollution and water scarcity—environmental challenges—are among the biggest dangers to human health and prosperity. And our business-as-usual analysis makes clear what many already fear: that human development based on the same practices we use today will not prepare us for a world with nearly 10 billion people.

To put it simply, if we stay on today’s current path, we risk being trapped in an intensifying cycle of scarcity—our growth opportunities severely capped and our natural landscapes severely degraded. Under this business-as-usual scenario, we can expect global temperature to increase 3.2°C; worsened air pollution affecting 4.9 billion more people; overfishing of 84 percent of fish stocks; and greater water stress affecting 2.75 billion people. Habitat loss continues, leaving less than 50 percent of native grasslands and several types of forests intact.

However, if we make changes in where and how we meet food, water and energy demands for the same growing global population and wealth, the picture can look markedly different by mid-century. This “sustainability” path includes global temperature increase limited to 1.6°C—meeting Paris Climate Accord goals—zero overfishing with greater fisheries yields, a 90 percent drop in exposure to dangerous air pollution, and fewer water-stressed people, rivers and agricultural fields. These goals can be met while natural habitats extend both inside and outside protected areas. All signatory countries to the Aichi Targets meet habitat protection goals, and more than 50 percent of all ecoregions’ extents remain unconverted, except temperate grasslands (of which over 50 percent are already converted today).

III. What's Possible

Achieving this sustainable future for people and nature is possible with existing and expected technology and consumption, but only with major shifts in production patterns. Making these shifts will require overcoming substantial economic, social and political challenges. In short, it is not likely that the biophysical limits of the planet will determine our future, but rather our willingness to think and act differently by putting economic development and the environment on equal footing as central parts of the same equation.

Climate, Energy and Air Quality

Perhaps the most pressing need for change is in energy use. In order to both meet increased energy demand and keep the climate within safe boundaries, we’ll need to alter the way we produce energy, curtailing emissions of carbon and other harmful chemicals.

Under a business-as-usual scenario, fossil fuels will still claim a 76 percent share of total energy in 2050. A more sustainable approach would reduce that share to 13 percent by 2050. While this is a sharp change, it is necessary to stanch the flow of harmful greenhouse gases into the atmosphere.

The reduction in carbon-based energy could be offset by increasing the share of energy from renewable sources to 54 percent and increasing nuclear energy to one third of total energy output—delivering a total of almost 85 percent of the world’s energy demand from non-fossil-fuel sources.

Additionally, we will only achieve the full extent of reduced climate impacts if we draw down existing carbon from the atmosphere. This can be done through greater investment in carbon capture and storage efforts, including natural climate solutions—land management strategies such as avoiding forest loss, reforestation, investments in soil health and coastal ecosystem restoration.

The net benefit of these energy redistribution efforts is twofold. First, they lower the rate at which greenhouse gases are flowing into the air—taking atmospheric carbon projections down to 442 parts per million, compared to business-as-usual estimates that put the level closer to 520 ppm.

Second, these energy source shifts would create a marked decline in particulate air pollution. Our models show that the higher fossil fuel use in the business-as-usual scenario is likely to expose half the people on the planet to poorer air quality by 2050. Under the sustainable scenario, that figure drops to just 7 percent of the world’s inhabitants, thanks to lower particulate emissions from renewable and nuclear energy sources.

Case Studies: 

• Forests That Fight Climate Change: Brazil’s Serra da Mantiqueira region demonstrates how reforestation can tackle climate change, improve water supplies, and increase incomes in rural communities. Learn More
• Can Trees Be a Prescription for Urban Health?: Conservationists, community organizations and public health researchers joined forces to plant trees in Louisville, Kentucky and monitor their impact on air quality and residents’ health. Learn More

Food, Habitat and City Growth

Meeting the sustainable targets we propose requires a second front on land to shift how we use available real estate and where we choose to conduct necessary activities. Overall, the changes we include in our more sustainable view allow the world to meet global food, water and energy demands with no additional conversion of natural habitat for those needs—an outcome that is not possible under business as usual.

While transitioning away from fossil fuels is essential to meet climate goals, new renewable energy infrastructure siting will present land-use challenges. Renewable energy production takes up space, and if not sited well it can cause its own negative impacts on nature and its services to people. In our more sustainable path, we address this challenge by preferencing the use of already converted land for renewables development, lessening the impact of new wind and solar on natural habitat. We also exclude expansion of biofuels, as they are known to require extensive land area to produce, causing conflicts with natural habitat and food security.

Perhaps most encouraging, we show that it is possible to meet future food demands on less agricultural land than is used today. Notably, our scenario keeps the mix of crops in each growing region the same, so as not to disrupt farmers’ cultures, technologies, capacity or existing crop knowledge. Instead, we propose moving which crops are grown where within growing regions, putting more “thirsty” crops in areas with more water, and matching the nutrient needs of various crops to the soils available.

Unlike some projections used by others, for this scenario we left diet expectations alone, matching meat consumption with business-as-usual expectations. If we were able to reduce meat consumption, especially by middle- and high-income countries where nutritional needs are met, reducing future agricultural land, water and pollution footprints would be even easier.

Meanwhile, on the land protection front, our analysis is guided by the Convention on Biological Diversity, the leading global platform most countries have signed. Each signatory country has agreed to protect up to 17 percent of each habitat type within its borders. While many countries will fall short of this goal under business as usual, it can be achieved in our more sustainable option.

 Case Study:

• Managing Sprawling Soy: A partnership between businesses and nonprofit groups in Brazil will help farmers plant soy in the areas where it is has the smallest impact on natural habitats. Learn More

Drinking Water, River Basins and Fisheries

Water presents a complex set of challenges. Like land, it is both a resource and a habitat. Fresh water resources are dwindling while ocean ecosystems are overburdened by unregulated fishing and pollution. Business-as-usual projections estimate that 2.75 billion people will experience water scarcity by 2050 and 770 water basins will experience water stress. Africa and Central Asia in particular would see fewer water stressed basins in the sustainable scenario.

Changes in energy sources and food production (see above sections) would lead to significant water savings by reducing use of water as a coolant in energy production and by moving crops to areas where they need less irrigation. Thanks to these changes, our more sustainable option for the future would relieve 104 million people and biodiversity in 25 major river basins from likely water stress.

Meanwhile, in the seas, we find an inspiring possibility for fisheries. Continuing business-as-usual fisheries management adds further stress to the oceans and the global food system as more stocks decline, further diminishing the food we rely on from the seas. But more sustainable fisheries management is possible, and our projections using a leading fisheries model shows that adopting sustainable management in all fisheries by mid-century would actually increase yield by over a quarter more than we saw in 2010.

And, while we know that aquaculture is a certain element of the future of fish and food, many questions remain about precisely how this industry will grow, and how it can be shaped to be a low-impact part of the global food system. Given these unknowns, we kept aquaculture growth the same in both our views of the future.

 Case Studies:

• Cities and Farmers Find Common Ground on Water: Smarter agricultural practices in the Kenya’s Upper Tana River Watershed are resulting in better yields for farmers and more reliable water supplies for the city of Nairobi. Learn More
• Technology Offers a Lifeline for Fish: A new mobile application being piloted in Indonesia is helping fill a crucial gap in fisheries management—providing accurate data about what species are being caught where. Learn More

IV.  The Way Forward

This analysis does not represent a panacea for the growing need for economic development across the planet or for the environmental challenges that are ahead. But it does provide an optimistic viewpoint and an integrated picture that can serve as a starting point for discussion.

Our goal is to apply new questions—and ultimately new solutions—to our known problems. We present one of many possible paths to a different future, and we welcome like-minded partners and productive critics to share their perspectives with us. We encourage people from across society to join the conversation, to fill gaps where they exist, and to bring other important considerations to our attention. Most of all, we call on the development (e.g. energy, agriculture, infrastructure), health, and financial communities—among others—to work with us to find new ways of taking action together.

Ultimately, by illustrating a viable pathway to sustainability that serves both the needs of economic and environmental interests—goals that many have long assumed were mutually exclusive—we hope to inspire the global community to engage in the difficult but necessary social, economic and political dialogue that can make a sustainable future a reality.

Protecting nature and providing water, food and energy to the world can no longer be either-or propositions. Nature and human development are both central factors in the same equation. We have at our disposal the cross-sector expertise necessary to make informed decisions for the good of life on our planet, so let’s use it wisely. Our science affirms there is a way.

Join us as we chart a new path to 2050 by helping people and nature thrive—together.

Opportunities to Engage

Designing strategies to address global challenges for people and nature requires integration of diverse bodies of evidence that are now largely segregated. As actors across the health, development and environment sectors pivot to act collectively, they face challenges in finding and interpreting evidence on sector interrelationships, and thus in developing effective evidence-based responses.

Learn more about these emerging coalitions that offer opportunities to engage and connect with shared resources.