Rows of solar panels sit amid crops on a farm.
An initiative called The World in 2050 seeks to apply science-based knowledge to make achieving the United Nations’ 17 Sustainable Development Goals (SDGs)—which focus on clean and accessible energy, sustainable production, and ending hunger, among many other objectives—more practical and equitable. Credit:

In recent years, international organizations have sounded alarms that if rapid and global progress isn’t made on a myriad of sustainability fronts, generations to come—and even already born—could face a future steeped in inequity and climate crises. In 2015, for example, the United Nations (UN) adopted the 2030 Agenda for Sustainable Development, which includes 17 Sustainable Development Goals (SDGs) and 169 associated targets for countries to work toward by 2030. These goals cover a vast range of issues such as ending poverty and hunger, ensuring clean energy supplies are ample and accessible, and acting to mitigate climate change.

But are these goals realistic? And how viable are ongoing efforts to achieve them? Since before the SDGs were officially adopted, these questions have motivated a group of researchers working together through an initiative called The World in 2050 (TWI2050).

The Sustainable Development Goals were “a great gift to humanity” when they were adopted, but much work is still needed to develop science-based pathways to show how they can be effectively and equitably implemented.

The UN’s aspirational SDGs were “a great gift to humanity” when they were adopted, but much work is still needed to develop science-based pathways to show how they can be effectively and equitably implemented, said Nebojsa “Naki” Nakicenovic, professor emeritus at the Vienna University of Technology and former deputy director general of the International Institute for Applied Systems Analysis (IIASA).

Also, the tight, 15-year timeline makes the goals “so ambitious that they’re unlikely to actually be achieved by 2030,” said James Edmonds, a chief scientist at the Joint Global Change Research Institute, a collaboration between the Pacific Northwest National Laboratory and the University of Maryland, College Park.

The World in 2050, a global research initiative launched by the IIASA, the Sustainable Development Solutions Network, and the Stockholm Resilience Centre (SRC), seeks to make the aspirational SDGs more practical and equitable. Nakicenovic is the initiative’s executive director, and Edmonds is a collaborator.

The initiative has received input from more than 150 experts—including research contributors, report authors, and independent experts from academia, business, government, and intergovernmental and nongovernmental organizations from around the world—many as volunteers.

Rather than setting goalposts for 2030 and then trying to decipher how to meet them, the TWI2050 team delineated what constitutes a sustainable 2050 in a broad sense: environmentally, economically, socially, and governmentally. They then began working backward, or “backcasting,” to develop sustainable development pathways to guide actions, policies, and shifts in attitudes and norms that must be adopted today to reach that desired future.

Embracing Six Transformations

The initiative’s targets for achieving a sustainable future are designed to account for nine planetary thresholds related to stratospheric ozone depletion, biodiversity loss and extinctions, chemical pollution, climate change, ocean acidification, freshwater consumption and the global hydrological cycle, changes to land systems, flows of nitrogen and phosphorus into the oceans and biosphere, and atmospheric aerosol loads. Crossing those thresholds “increases the risk of generating large-scale abrupt or irreversible environmental changes,” according to the SRC.

In addition to these planetary thresholds, researchers have also identified six key transformations “that empirical evidence, global assessments and analyses, show are necessary and potentially sufficient to attain the SDGs on a sustainable planet,” the TWI2050 team wrote in a 2018 report. The six transformations, detailed in the report and in a 2019 perspective in Nature Sustainability, concern “education, gender and inequality; health, well-being and demography; energy decarbonization and sustainable industry; sustainable food, land, water and oceans; sustainable cities and communities; and the digital revolution and sustainable development.”

Numerous plastic containers and other pieces of garbage line a beach in Accra, Ghana.
Plastic bottles and other garbage pollute a beach in Accra, Ghana. The World in 2050 identified six key transformations—including the sustainable treatment of food, land, water, and oceans—that it describes as necessary to meet the UN’s SDGs. Credit: Muntaka Chasant, CC BY-SA 4.0

The transformations were introduced in part to address concerns about the large number and interrelatedness of SDGs and associated targets, according to Jerry Miller, a contributor to the project and president of Science for Decisions, which promotes science-based information for policy and management decisions related to natural resources. And they were created through analysis of large-scale drivers, such as population growth and urbanization, that will affect efforts to achieve the SDGs, according to Kristie Ebi, a professor of global health at the University of Washington in Seattle and a contributor to the project.

The transformations aren’t meant to reduce or replace the SDGs, but instead to provide a new way of thinking about how to reach the SDGs. They are “mutually exclusive and collectively exhaustive” and call for action by governments, scientists, business leaders, and the public, Nakicenovic and his collaborators noted in their perspective.

Pursuing the transformations also provides opportunities to consider their complex benefits and trade-offs. For instance, the energy decarbonization and sustainable industry transformation requires steps to be taken to modernize energy sources for all, alignment with the Paris Agreement by decarbonizing the energy system by 2050, and controlling industry-driven pollution of air, water, and soil, according to the perspective. The authors also pointed out that potential negative effects of pursuing this transformation could arise if efforts to reach it are poorly designed, for example, if they focus on decarbonization while neglecting the need for universal, affordable energy access.

From Evaluating Examples to Developing Comprehensive Assessment Models

TWI2050’s modeling, conclusions, and recommendations are informed by integrated assessment modeling, with researchers running new experiments with different inputs on previously developed models, Edmonds and Ebi said.

Integrated assessment modeling, first used more than 30 years ago in emissions work, according to Ebi, is an approach used to pull together threads of information from different disciplines to study interactions between society and the environment.

Most integrated assessment models aren’t currently designed to examine the multitude of factors influencing the achievement of the full suite of SDGs, although modeling teams associated with The World in 2050 are working toward that goal.

Most integrated assessment models aren’t currently designed to examine the multitude of factors influencing the achievement of the full suite of SDGs, Ebi said, although modeling teams associated with the project are working toward that goal.

These teams, run by the IIASA, the Potsdam Institute for Climate Impact Research, and the PBL Netherlands Environmental Assessment Agency, have been running experiments “to generate insights on the synergies and trade-offs across the SDGs,” Ebi said. Results from sustainable development pathway modeling can be used as inputs in the group’s integrated assessment models, as can data from Shared Socioeconomic Pathways, which are used to study intersections of environmental, social, and economic changes in communities of varying size, from towns and municipalities to the entire planet.

Some of these are optimization models that focus on finding the best path toward a sustainable 2050 and beyond, whereas others are designed to evaluate potential impacts of different policies and inputs on sustainable development, Edmonds said.

Many of the modeling experiments that TWI2050 has done to date have focused on specific situations—narrowed down by geography or the number of interacting goals evaluated in a system—rather than evaluating the entire suite of SDGs or sustainable development transformations.

“We’re doing a lot of work to run [models of] these systems in a coupled manner,” Edmonds said, but the level of detail needed to do so is daunting. The details informing these models, such as specific types of fuels used for cooking or types of engines used in vehicles, also often vary by geographic location. Furthermore, there aren’t widely agreed upon indicators for success toward some of the goals, such as those concerning peace and justice, making it challenging to quantify progress toward those goals.

Overall, the amount of work that still must be done to determine how to reach the SDGs in an optimal way was a motivating factor for introducing the 2050 timeline rather than focusing on 2030, Edmonds said. The UN’s timeline is probably overambitious, he said. On the other hand, “you can imagine a path that gets us there by the middle of the century,” although it won’t be easy.

The Challenge Ahead

“We know to a large extent what needs to be done” to reach a sustainable future, “but we don’t know how” to do it yet.

“We know to a large extent what needs to be done” to reach a sustainable future, “but we don’t know how” to do it yet, Nakicenovic said. Critically, he said, human well-being must be decoupled from negatively impacting Earth. This change involves viable science-based plans, which TWI2050 is working to create, but it also involves changing the behavior and thinking of the world’s inhabitants, he said.

Rather than expecting others to provide visions for the future, everyone needs to grasp the impacts an unsustainable future will have on their own lives, and then societal values need to change to align with a sustainable future, Nakicenovic noted.

Starting in communities or even at dinner tables, he said, “we all need to be visionaries.”

—Rachel Crowell (; @writesRCrowell), Freelance Science Journalist


Crowell, R. (2020), The World in 2050 pursues paths to a sustainable future, Eos, 101, Published on 16 January 2020.

Text © 2020. The authors. CC BY-NC-ND 3.0
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