image title

Conversations on the future of water spring up in the desert

March 20, 2018

ASU hosts national economic anthropology conference, bringing world’s top social scientists studying water to Phoenix

In early March, the Center for Global Health in ASU’s School of Human Evolution and Social Change hosted this year’s Society for Economic Anthropology (SEA) international conference, with participation and support from many other units at the university and beyond.

Each year, the SEA conference draws economic anthropologists from around the world to explore how they can use their unique insights to address challenges and embrace opportunities on various societal, cultural and economic issues.

This year’s theme was “Water and Economy” — with a particular focus on water scarcity. Below, Professor Amber Wutich, director of the Center for Global Health, explained why this gathering was a crucial first step in aligning the world’s top minds on water.

amber wutich

Amber Wutich.

Question: Why has resource management become a big concern for scientists globally, and why is water often at the forefront of these discussions?

Answer: Water is a basic human resource, perhaps our most fundamental need. Managing scarce resources effectively has been a major problem through all of human history. But today, the increasing inequality, complexity and interconnectedness of human organization poses new problems, and stressors like climate change make equitable and sustainable resource management even more challenging.

The reality is that many communities all around the world now face water issues — from overuse and conflicts over water rights, to underinvestment and inequalities in infrastructure and delivery. These scarcities can trigger humanitarian disasters and political instability and poor sanitation also means outbreaks of infectious diseases like cholera. Not having reliable access to water, it turns out, is so stressful for people that it's also a major trigger for mental illnesses like depression. This is why water is increasingly on the radar of not just scholars, but governments, businesses and human rights activists.

These are issues in Arizona too. Because of Arizona’s arid climate and dependence on the Colorado River, we are in constant negotiation with our surrounding states over water rights. And we always need to pay close attention to water management within Arizona as well — a major challenge is making sure our farmers have what they need to grow food, while still serving our growing urban centers too. It can help the state a lot to have such a diverse set of scholars come together here to help design new solutions.

Q: How did this year’s conference come about?

A: I’ve worked on water issues my whole career, starting from my dissertation research nearly two decades ago in urban Bolivia. Having worked closely with the Center for Global Health since it was established, I have always pushed for water to be a central part of the global health agenda for the university.

In 2006, I began working as a postdoctoral fellow with ASU’s Decision Center for a Desert City. They and Future H2O helped provided support for this conference. Those collaborations helped me to better understand the connections between water and governance in the Arizona area, and connect to the very wide net of people at ASU who work on water.

A conference dedicated solely to this topic also offered an incredible opportunity to bring together anthropologists and allied scholars from around the world. It gave us the chance to debate major questions, find new ways to approach how humans use, manage and value water globally, and help establish how we should approach water problems in the future.

Q: How many attendees and participants took part?

A: Over 100 scholars, from senior to emerging, participated from all over the world. Some of the star water scholars who joined us were Raul Pacheco-Vega (CIDE, Mexico), a leading voice in this community; Chad Staddon (University of the West of England, Bristol), the director of the International Water Security Network; and Wendy Jepson (Texas A&M), an AAAS Leshner Fellow on water and food security.

Our keynote speaker was Jessica Budds, a geographer from the University of East Anglia in the U.K. who studies the connections between poverty and exclusions from water systems in the global south. Leila Harris, the co-director for University of British Columbia’s program on water governance, also gave an excellent presentation on indigenous water rights in Canada. Her talk provoked a discussion that is needed and relevant to the long history of tribal stewardship of, and rights to, water in our state.

Much work is being done by scholars outside the U.S., especially in the middle and lower income countries where water equity issues are often severe. By live-tweeting to over 20,000 people under the hashtag #EconAnth2018, our conversations here reached a wider international audience, which helped raise the exposure of many key debates.

Q: How does this topic align with and overlap with the work of your peers at the school and center?

A: ASU’s Center for Global Health specializes in methodologically-innovative research on the economic, political and cultural processes that produce health inequalities.

For example, President’s Professor and Center for Global Health Founding Director Alexandra Brewis Slade is leading a team that is studying water sharing between households as a type of informal economic behavior. That project is starting to demonstrate this behavior as a crucial survival strategy in water-scarce areas of some countries, something never before documented systematically.

The School of Human Evolution and Social Change’s work on the archaeological front is also incredibly important because it allows us to examine these causes and consequences with much greater time depth. The school’s archaeologists have done amazing work over the last two decades looking at the very long-term resilience of people in the Valley of the Sun around water management, from the prehistoric Hohokam communities up through today.

Q: How was diversity of perspective critical in an event like this?

A: These water scholars came from a range of scholarly fields, but also many different countries and personal backgrounds. Many grew up or live in communities faced with severe water challenges. For example, we talked about what has happened around lead contamination of the water supply in Flint, Michigan, with researchers who live and work in the state. We watched and engaged in discussion around an outstanding ethnographic film about Flint called “Nor Any Drop to Drink.”


Conference attendees check out poster presentations during a break between panels.

We all came away with a much better understanding about what went wrong there, such as why water managers chose to switch the city’s water source and expose the residents of Flint to lead. The discussion also helped clarify why residents are so distrustful of both lead testing and remediation efforts to fix the problem. It takes bringing together and digging into all of these different pieces and perspectives to begin to understand how we might avoid or address such tragedies in the future.

Q: Were there any other “aha” moments?

A: Tennille Marley, an assistant professor of American Indian Studies at ASU, discussed her research with American Indian communities in Arizona. She made the key point that not all water is the same — for example, water with sacred or ceremonial properties may need to be understood as a different thing altogether from water intended for regular household consumption. This is really important for understanding the many ways people experience water shortages, and suggests that one-size-fits-all solutions may not work well for water problems.

Q: What other areas will you be focusing on in 2018 and beyond?

A: We are bringing together some of the key scholarly findings from the conference in a special issue of the journal Economic Anthropology in 2019. But more generally, the Center for Global Health is helping to lead a new massive network of international scholars working on what we are calling Household Water Insecurity Experiences (HWISE), together with Texas A&M University, Northwestern University, and University of Miami.

The network has grown quickly to include over 100 collaborators across the globe, and we are about to publish an innovative scale to allow us to better measure household water insecurity in lower income countries. Together with these partners, ASU’s Center for Global Health will be able to better define and then address water struggles around the globe, including showing how alleviating basic struggles for water has amazing positive ripple effects on human health. 

Aaron Pugh

Manager of Marketing and Communications , School of Human Evolution and Social Change


TRAPPIST-1 planets provide clues to the nature of habitable worlds

ASU study on planets' water composition published in Nature Astronomy

March 20, 2018

TRAPPIST-1 is an ultra-cool red dwarf star that is slightly larger, but much more massive, than the planet Jupiter, located about 40 light-years from the sun in the constellation Aquarius.

Among planetary systems, TRAPPIST-1 is of particular interest because seven planets have been detected orbiting this star, a larger number of planets than have been than detected in any other exoplanetary system. In addition, all of the TRAPPIST-1 planets are Earth-sized and terrestrial, making them an ideal focus of study for planet formation and potential habitability. Artist's concept shows what the TRAPPIST-1 planetary system may look like Artist's concept shows what the TRAPPIST-1 planetary system may look like, based on available data about the planets' diameters, masses and distances from the host star, as of February 2018. Credit: NASA/JPL- Caltech Download Full Image

ASU scientists Cayman Unterborn, Steven Desch and Alejandro Lorenzo of the School of Earth and Space Exploration, with Natalie Hinkel of Vanderbilt University, have been studying these planets for habitability, specifically related to water composition. Their findings have been recently published in Nature Astronomy.

The calculations equal water

The TRAPPIST-1 planets are curiously light. From their measured mass and volume, all of this system’s planets are less dense than rock. On many other, similarly low-density worlds, it is thought that this less-dense component consists of atmospheric gasses.

“But the TRAPPIST-1 planets are too small in mass to hold onto enough gas to make up the density deficit,” geoscientist Unterborn explained. “Even if they were able to hold onto the gas, the amount needed to make up the density deficit would make the planet much puffier than we see.”

So scientists studying this planetary system have determined that the low-density component must be something else that is abundant: water. This has been predicted before, and possibly even seen on larger planets like GJ1214b, so the interdisciplinary ASU-Vanderbilt team, comprised of geoscientists and astrophysicists, set out to determine just how much water could be present on these Earth-sized planets and how and where the planets may have formed.

But how much is there? 

To determine the composition of the TRAPPIST-1 planets, the team used a unique software package, developed by Unterborn and Lorenzo, that uses state-of-the-art mineral physics calculators. The software, called ExoPlex, allowed the team to combine all of the available information about the TRAPPIST-1 system, including the chemical makeup of the star, rather than being limited to just the mass and radius of individual planets.

Much of the data used by the team to determine composition was collected from a dataset called the Hypatia Catalog, developed by contributing author Hinkel. This catalog merges data on the stellar abundances of stars near to our sun, from over 150 literature sources, into a massive repository.

What they found through their analyses was that the relatively “dry” inner planets (“b” and “c”) were consistent with having less than 15 percent water by mass (for comparison, Earth is 0.02 percent water by mass). The outer planets (“f” and “g”) were consistent with having more than 50 percent water by mass. This equates to the water of hundreds of Earth-oceans. The masses of the TRAPPIST-1 planets continue to be refined, so these proportions must be considered estimates for now, but the general trends seem clear.

“What we are seeing for the first time are Earth-sized planets that have a lot of water or ice on them,” said Steven Desch, ASU astrophysicist and contributing author.

But the researchers also found that the ice-rich TRAPPIST-1 planets are much closer to their host star than the ice line. The “ice line” in any solar system, including TRAPPIST-1’s, is the distance from the star beyond which water exists as ice and can be accreted into a planet; inside the ice line water exists as vapor and will not be accreted. Through their analyses, the team determined that the TRAPPIST-1 planets must have formed much farther from their star, beyond the ice line, and migrated in to their current orbits close to the host star.

There are many clues that planets in this system and others have undergone substantial inward migration, but this study is the first to use composition to bolster the case for migration. What’s more, knowing which planets formed inside and outside of the ice line allowed the team to quantify for the first time how much migration took place.

Because stars like TRAPPIST-1 are brightest right after they form and gradually dim thereafter, the ice line tends to move in over time, like the boundary between dry ground and snow-covered ground around a dying campfire on a snowy night. The exact distances the planets migrated inward depends on when they formed.

“The earlier the planets formed,” Desch said, “the farther away from the star they needed to have formed to have so much ice.” But for reasonable assumptions about how long planets take to form, the TRAPPIST-1 planets must have migrated inward from at least twice as far away as they are now.

Orbital Radius of Ice Line

This graph shows the minimum starting distances of the ice-rich TRAPPIST-1 planets (especially f and g) from their star (horizontal axis) as a function of how quickly they formed after their host star was born (vertical axis). The blue line represents a model where water condenses to ice at 170 K, as in our solar system's planet-forming disk. The red line applies to water condensing to ice at 212 K, appropriate to the TRAPPIST-1 disk. If planets formed quickly, they must have formed farther away (and migrated in a greater distance) to contain significant ice. Because TRAPPIST-1 dims over time, if the planets formed later, they could have formed closer to the host star and still be ice-rich.

Too much of a good thing

Interestingly, while we think of water as vital for life, the TRAPPIST-1 planets may have too much water to support life.

“We typically think having liquid water on a planet as a way to start life, since life, as we know it on Earth, is composed mostly of water and requires it to live,” Hinkel explained. “However, a planet that is a water world, or one that doesn't have any surface above the water, does not have the important geochemical or elemental cycles that are absolutely necessary for life.”

Ultimately, this means that while M-dwarf stars, like TRAPPIST-1, are the most common stars in the universe (and while it's likely that there are planets orbiting these stars), the huge amount of water they are likely to have makes them unfavorable for life to exist, especially enough life to create a detectable signal in the atmosphere that can be observed. “It's a classic scenario of ‘too much of a good thing,’” said Hinkel.

So, while we’re unlikely to find evidence of life on the TRAPPIST-1 planets, through this research we may gain a better understanding of how icy planets form and what kinds of stars and planets we should be looking for in our continued search for life.  

Karin Valentine

Media Relations & Marketing manager, School of Earth and Space Exploration