Scenarios
Real, unsolved problems in real places, each one a test a digital twin should be able to take on.
Talk about digital twins drifts easily to the very large, "the climate crisis", which is too big to model and too tangled to act on. The scenarios here are smaller and harder in a useful way. Each one is a real situation in one place: a strait closed to tankers, a river that owes water to its neighbour, a sea whose midwater emptied after a spill. Each has people who must decide something soon, and each runs across several domains at once, so no single model answers it.
That makes them a test. A twin worth building should be able to hold one of these situations, couple the domains it runs across, and let the people involved try the what-ifs listed on its page. The list is also a check on what we think twins can do: where none of the tools on this site would get far, the gap is worth knowing.
The scenarios run along a continuum of scale. At the world end are problems carried by global trade and shipping, where a closed strait reaches a rice farmer in Bangladesh. In the middle are bioregional problems, a river basin or a sea or a stretch of wetland, bounded by the land and the water rather than by borders. At the local end are single communities: a town that dissolved over its water tank, a lagoon in one city's river, one ranch. A twin may suit one end better than the other, and where it stops working along the way says something about it.
The two ends test a twin differently. A world-scale problem draws the most interest, and its model is the hardest to fault, because few people can check it against anything they know first hand. A local problem draws fewer people, but they know the place: a farmer knows which wells run low, and whoever paid for the last repair knows what it cost. They will see an error at once. That makes the local end the harder test and the more useful one, since a twin that holds up in front of the people who live there has earned some trust.
Each page says what happened, who needs an answer, which domains the problem chains together, what a twin should let people try, and what data and tools exist to start. The general questions behind them, such as where a flood will go, are under Use cases.
World scale
For nearly two decades soy traders agreed not to buy soy grown on newly cleared Amazon land. The pact has been abandoned, and researchers project at least 1.4 million hectares of extra forest loss in Brazil by 2036. What would hold it back?
Bangladesh grows about 7% of the world's rice and imports much of its fertiliser through the Strait of Hormuz. If trade through the strait stays disrupted, how much of next year's crop is at risk, and who else feels it?
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More than 1,500 ships sat idle in the Gulf for months after Hormuz closed, growing sea life on their hulls in very warm water. When they sail, which ports are most at risk of new invasive species, and which hulls should be cleaned first?
Since March 2026 foreign-flagged tankers may carry fuel between US ports, a trade the Jones Act normally reserves for US-built, US-crewed ships. How much fuel has it moved, and has it changed prices?
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With Hormuz closed, Saudi Arabia moved its oil exports to the Red Sea, and in September 2026 the Houthis seized islands and a port near the Bab el-Mandab strait. Which routes are left for Saudi crude to reach Asia?
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Since the war with Iran began on 28 February 2026, traffic through the strait that carries about a fifth of the world's oil has fallen to a fraction of normal. Who gets through, how much oil reaches market, and what happens when it reopens?
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The United States imports most of its aluminium and taxes it at 50%, while building a new smelter takes years. What does that do to the price American manufacturers pay, and can domestic smelting come back?
Bioregional
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Canada banned strychnine for Richardson's ground squirrels over the risk to burrowing owls and other wildlife; Alberta pushed back, and an emergency use is now allowed to 2027. Which control keeps crops and predators both whole?
Bali's rice terraces are watered by about 1,200 farmer collectives coordinated through water temples, a World Heritage landscape since 2012. Rice fields shrank from 70,996 to 64,474 hectares between 2019 and 2024 as land goes to hotels and housing. What keeps the system working?
WaterFood & landCities & placesPeople & societyLiving systems
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The Philippines has backed bamboo since 2010 for reforestation, school furniture and farm income, and Mindanao is now its designated bamboo hub. Growers in Bukidnon must choose which bamboo to plant, where, and when to cut it, as engineered timber, plastic substitutes and carbon credits change what a culm is worth.
Living systemsWaterWeather & climateFood & landPeople & society
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The rules for sharing the Colorado River's shortages expired with 2026, and the seven basin states could not agree on new ones. The federal government imposed two-year rules instead, with Lake Powell and Lake Mead at record lows and two states suing. How should the cuts be shared?
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After an exceptionally dry July, much of England is in drought, reservoirs are far below normal and hundreds of abstraction licences are restricted. Can farm reservoirs refill this winter for 2027?
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Mussels keep disappearing from rivers that are cleaner and less dammed than they were, and no one is sure why. Biologists suspect an invasive clam. Which streams can be restored, and what would it take?
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The Great Lakes hold about a fifth of the world's surface fresh water, but by Earth.com's account less than 1% of it is replaced each year, while the climate around them warms and their ice shrinks. How much can be drawn and diverted safely?
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Sixteen years after the spill, the fish, krill and squid of the Gulf's open water are still 60 to 85% below their 2011 numbers, and the whales that eat them are down too. Is it recovering, and what would help?
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Private land bought and restored by Kristine and Doug Tompkins was given to Argentina on condition it stay protected for at least 99 years, making or enlarging six national parks. Jaguars are back in the Iberá wetlands, next to cattle country. What happens next?
Fires in Sumatra and Kalimantan, many of them set to clear land, spread through drained peat in dry El Niño years and send haze across Southeast Asia. 2026 is another such year. Which peat, rewetted or protected, would cut the smoke the most?
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A century of tree planting has covered about 100,000 hectares of Israel, much of it shrubland, grassland and loess plain that was naturally open. Ecologists found many open-country species gone from the plantings. Where should planting go, and what should happen to the forests already there?
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A Supreme Court settlement gives New Mexico until May 2036 to pump 18,200 acre-feet a year less groundwater along the Lower Rio Grande, and the state hopes to do it by buying farmers' water rights. Who gives up water, and is it enough?
The Middle East and North Africa have warmed about 1.5°C since pre-industrial times, some parts three times as fast as the world. Gulf states stop outdoor work at midday each summer on fixed dates and hours. Do those windows still match the heat, and will they later?
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A flesh-eating fly larva eradicated from the United States in 1966 moved north through Central America and Mexico and was found in calves in Zavala County, Texas, in June 2026. Can sterile flies push it back again?
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California's Delta feeds the pumps that send water across the state, holds a delta smelt whose index in the state's autumn survey has been zero since 2018, and sits behind 1,100 miles of aging levees with islands sunk below sea level. In 2025 and 2026 the federal pumping rules, the state's flow rules and a 45-mile tunnel were all being decided at once.
WaterLiving systemsFood & landPeople & societyCities & placesWeather & climate
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Grand Coulee and Chief Joseph dams were built without fish passage and have kept salmon out of the upper Columbia since the 1940s. Tribes on both sides of the border are now releasing salmon above them to test whether runs can come back, and what passage would have to be built.
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California's 2014 groundwater law gives the valley's most overdrafted basins until 2040 to stop drawing down their aquifers. Two are now on state probation, wells keep going dry and the land is still sinking. Which fields go dry, and who pays?
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Wolves returned to Yellowstone National Park in 1995, and the park held 84 of them at the end of 2025. Inside the park they are protected; across the boundary they are hunted under state rules. How many can be taken next to the park, what do wolves cost ranchers, and how much did they change elk, willows and streams?
Local community
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Villages in Alwar district, Rajasthan, rebuilt earthen rainwater dams from 1985 and saw dry wells and the Arvari River flow again, yet the district as a whole still pumps about 1.8 times the groundwater it can safely draw each year. Which choices by villages and the state would move the water table?
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A Montana cattle ranch of about 114,000 acres was turned over to bison in 1989 and now carries about 4,500 of them. What did the switch change for grass, streams and wildlife, and could other ranches do it?
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A small town in south-eastern Colorado lost its whole government while its water tank failed and residents boiled their water for months. The county now owns the system. Who should run it, and what will it cost?
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A tidal lagoon in the middle of Oakland, opened wider to San Francisco Bay in 2013, still runs short of oxygen in late summer and winter, and a Bay algal bloom killed thousands of its fish in 2022. Which mix of tide gate operation, aeration and other measures keeps its fish alive?
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A stagnant lagoon left by gravel mining in the Willamette River breeds cyanobacteria blooms that close the river to swimmers and pets. Researchers propose cutting channels to flush it. Which design, and who pays?
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Mowi's Huar Norte salmon site in southern Chile added floating solar and batteries in 2025 to cut the diesel its generator burns, with about 57% of the site's power expected from the sun. How far can that go, here and at other pens with no cable to shore?
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Tuvalu's islands average barely two metres above the sea. Its groundwater is turning salty, new raised land has been built on the capital islet, and since 2025 up to 280 Tuvaluans a year can move to Australia. How much land, water and food will hold those who stay?
WaterCities & placesPeople & societyFood & landLiving systemsWeather & climate