Earth Day was first celebrated in 1970 to call attention to air and water pollution. Over 50 years later, Earth Day is a reminder of the importance of environmental conservation and sustainability and encourages collective action for a healthier planet.

The University of Arizona's Biosphere 2 is the world's largest indoor controlled environment dedicated to understanding the effects of climate change and providing restoration and adaptation solutions for the resilience of Earth, Biosphere 1, said John Adams, Biosphere 2 deputy director. 

The Earth science facility encompasses 3.14 acres and houses five synthetic ecosystems encased in a glass and metal frame. These 30-year-old ecosystems include the world's largest controlled analogs of the tropical rainforest, desert, savanna, mangrove and ocean.

When UArizona acquired Biosphere 2 in 2011, it added the Landscape Evolution Observatory to study how slopes transform from barren to fertile and how the flow of water responds to an ecosystem's transformation.

Biosphere 2 research has also expanded beyond the enclosed facility and now includes projects that weave together agriculture and technology, including agrivoltaics projects and a modular container farm. Biosphere 2's original eight biospherians, who locked themselves under the steel and glass for two years in the early 1990s, have inspired continued work on how to build self-sustaining habitats for eventual use on other worlds. Biosphere 2 is also home to an astronaut training program.

"Biosphere 2's mission is to understand natural and humanmade ecosystems through research for the betterment of all," said Joaquin Ruiz, Biosphere 2 director. 

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The desert's rainforest

Biosphere 2's 20,000-square-foot rainforest hosts over 100 species and is modeled after the Amazon Basin, a region that has been razed by decades of deforestation and will need to adapt to climbing global temperatures and shifting weather patterns.  

In 2020, Biosphere 2 researchers added 50 coffee trees and 75 cacao trees to the facility's rainforest to study how warmer temperatures will affect these crops' production, said Joost Van Haren, interim director of rain forest research.

Researchers are also working to understand how rainforest canopies will react to a warming climate. 

"This project makes use of Biosphere 2's rainforest greenhouse," which traps heat under the Arizona sun, Van Haren said. "At times, it can be the hottest rainforest canopy on Earth. We see temperatures 20 to 30 degrees Fahrenheit higher than in the real world." 

Van Haren and his team are also working to understand how flooding affects tree trunk methane emissions, one of the most potent greenhouse gases. 

Soil bacteria usually go about their day producing methane. Oxygen typically combines with this methane to produce carbon dioxide, which is a less potent greenhouse gas. 

During heavy rain, however, flood waters act as a lid atop the soil, trapping bacteria-produced methane within and keeping oxygen out, Van Haren said. Methane can only escape when small animals disturb the soil and create bubbles, or through tree stems. 

The tree mechanism was only recently rediscovered, he said. Researchers want to understand just how much methane this process can move through the stems and transport to the atmosphere.

Understanding this process is important because global methane levels wax and wane annually, but scientists aren't sure why. This process could potentially account for almost a quarter of the global methane budget – a hypothesis that Van Haren seeks to confirm.

Turning the tides for coral reefs

Coral reefs not only provide a rich ecosystem in which ocean animals thrive, they also are a source of food, shoreline protection, culture, tourism and more. Yet, Earth has lost half of its coral reefs to climate change. 

Biosphere 2's ocean is a 1-million-gallon tank brimming with life under machine-generated waves, dedicated to studying how reefs can be restored.  

Diane Thompson, an assistant professor in the Department of Geosciences and Biosphere 2 director of marine research, is working with a research team to prepare the Biosphere 2 ocean for coral reef introduction. As part of the process, the team has been removing algae from the Biosphere 2 ocean and introducing fish to clean the water. 

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In February, the team deployed Berghia stephanieae, a species of sea slug, into 500-gallon tanks to see if they could successfully rid the ocean of a stinging, competitive coral pest – a sea anemone called Aiptasia. The results look promising for the ocean, said Lia Crocker, a Biosphere 2 research specialist. The team is also experimenting with ways to clear the ocean of another coral-eating pest, called fire worms, which has a venomous sting. 

This spring, a new lighting structure will illuminate the ocean from above. Over the summer, the research team will test which wavelength combinations are best suited for coral growth. 

For now, the team grows and maintains the corals in a nursery in the depths of Biosphere 2's technosphere, which houses the technology used to keep Biosphere 2 running. Corals are expected to populate the ocean by the end of the calendar year. 

'Starting from scratch'

When compared to the 30-year-old, complex synthetic ecosystems housed under Biosphere 2's glass, the Landscape Evolution Observatory, or LEO, which was established in 2011, provides researchers an enlightening juxtaposition, said Aaron Bugaj, a LEO senior research specialist.

"With LEO, we wanted to create something that was simple," he said. "We're literally starting from scratch." 

To understand how water moves through a sloped landscape, researchers installed a uniform, 1-meter-deep layer of crushed volcanic rock and poured artificial rain across its surface, studying how the water weaves through the system or is stored in its depths. 

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Now, the slopes are carpeted in moss, said Bugaj, marking the first step towards the ecological phase of LEO. With the support of bacteria, the moss is harnessing nitrogen from the air and storing it in the basalt, making the slopes nutrient rich for future plants. 

Researchers want to understand how landscapes transform from blank slates to nutritious soil abundant with life. 

Within the next year, researchers aim to integrate different strains of alfalfa into the slopes. 

"Some will have deep roots, others shallow," Bugaj said. "Some will flower, others won't." These characteristics could impact how water is stored or moved through the system.

As the years go by, LEO researchers anticipate the gradual addition of increasingly complex plant life.

A perfect pair

A changing climate will force humans to adapt, especially in their agricultural practices, said Greg Barron-Gafford, professor in the School of Geography, Development and Environment and associate director of the School Garden Workshop.

Agrivoltaics is the strategic combination of solar panels and crops to increase efficiency in crop growth and energy output. Solar panels shade crops from the intense rays of the sun, while the vegetation releases moisture to cool the panels above. 

Barron-Gafford leads a research team running various agrivoltaics projects around Tucson, including atop the Environment and Natural Resources 2 building on the UArizona campus, at Ricardo Manzo Elementary School and the Biosphere 2 campus.

Recently, NextEra Energy Resources, the world's largest generator of renewable energy from the sun and wind and a world leader in battery energy storage, donated 788 solar panels that will cover three quarters of an acre at Biosphere 2. 

Barron-Gafford and team will continue their agrivoltaics research with these panels, but with a focus on native vegetation.

Construction began March 17. The team anticipates the addition of plants over the summer. 

Farms of the future

In another effort to innovate crop production in a changing world, Biosphere 2 has teamed up with a private vertical farm technology company, Freight Farms, to develop sustainable and resilient food systems.

Biosphere 2 runs one hydroponic farm, a 40-foot long, 8-foot-wide shipping container that has been retrofitted to grow leafy greens vertically. 

The farm system includes lighting, climate control and irrigation and uses less than 5 gallons of water daily to produce on average 80 to 120 pounds of food per week when running at maximum capacity. Its annual production is the equivalent of 2 acres or more of land with a footprint of only 320 square feet, said Jason Deleeuw, a Biosphere 2 research specialist.

Biosphere 2 also has a second 20-foot-long container that will be used to produce pharmaceuticals. It will likely be up and running later this year.

"While the Freight Farms system uses very little water to grow crops in a small area, it requires a lot of energy," Deleeuw said. So, the research team is currently working with a local engineering firm to design and construct a small photovoltaic field around the farms that will provide electricity to offset the electrical demand. 

Beneath the solar panels, taller crops that cannot be grown inside the Freight Farm will be cultivated. The two systems – agrivoltaics on the outside and hydroponics on the inside – will complement each other. There are also plans to use water harvesting technologies to close the water loop for both systems. 

From Earth to the moon and beyond

"In order to prosper as an interplanetary species, we must bring with us the complex ingredients for agriculture and bioregeneration, plants to provide both food and clean air to breathe," said Kai Staats, director of research for the Space Analog for the Moon and Mars, or SAM. "We are
experimenting with both at SAM with guidance from Biosphere 2 and the Controlled Environment Agriculture Center."

Staats assembled a team that started building SAM in January 2021.

SAM is a 1,100-square-foot hermetically sealed and pressurized facility built around the renovated 1987 Biosphere 2 Test Module and prototype lung, which is used to maintain the pressure of the enclosed space. SAM includes a crew quarters, an engineering bay and a greenhouse with a hydroponics system. 

Immediately outside SAM's functional airlock is a 2,600-square-foot Mars yard. A Hollywood set construction company is currently engaged in sculpting fine detail into the synthetic Martian crater walls based on images from the Curiosity and Perseverance rovers. Once complete, the indoor Mars yard will provide a high-fidelity approximation of key geological features on Mars. Beyond the indoor Mars yard will be a substantially larger outdoor moon/Mars yard and terrain park designed to host rover competitions and robotic exploration.

SAM has hosted three crews since April 2023. By inviting visiting crews, Staats and his team learn more about how humanity can prepare for the challenges of living and working on other worlds. The next crewed mission is expected in the fall.

The next generation of astronauts

Biosphere 2 is also home to a spaceflight training and research program directed by Trent Tresch.

Since Tresch founded the Center for Human Space Exploration, or CHaSE, in 2022, he has focused on furthering the sustainable presence of humans in the solar system and beyond. With a mission to foster the global space community through accessible and experiential spaceflight training, Tresch is pushing UArizona's presence in human-based space research and technology development. CHaSE held its first astronaut training class in November 2022.

For the last two years, Tresch and the CHaSE team have been growing the program to include training around spacecraft egress, spacesuit operations and emergency response.

Through partnerships with NASA and collaboration with the U.S. Air Force and private space companies, CHaSE aims to help build humanity's future in space.