Under a White Sky

1. The Anthropocene: A Planet Remade by Human Control

So pervasive is man’s impact, it is said that we live in a new geological epoch—the Anthropocene.

Humanity's footprint. Humans have profoundly reshaped Earth, transforming over half of its ice-free land and diverting most major rivers. Our industrial activities, from fertilizer production to power generation, now emit hundreds of times more carbon dioxide than natural sources like volcanoes. This overwhelming influence has led scientists to propose a new geological epoch, the Anthropocene, signifying an era where human activity is the dominant force altering the planet.

Stark statistics. The sheer scale of human impact is evident in biomass ratios:

• People outweigh wild mammals by over 8:1.
• Including domesticated animals (cows, pigs), this ratio climbs to 22:1.
• Humans and livestock combined outweigh all other vertebrates, excluding fish.
  This dominance highlights our role as the primary driver of extinction and, paradoxically, speciation, creating a "no-analog future" for ecosystems and climate.

Unintended consequences. The success of our species has brought about severe environmental by-products, including atmospheric and ocean warming, acidification, sea-level rise, and desertification. These changes are occurring at a pace comparable only to major geological events like the asteroid impact that ended the dinosaur era. The predicament is that having stepped so far into controlling nature, retreat seems impractical, leading to a cycle of more control to manage the consequences of previous controls.

2. Rivers Reversed, Ecosystems Upended: The Chicago Story

First you reverse a river. Then you electrify it.

A city's solution. In the late 19th century, Chicago faced a severe public health crisis due to its waste flowing into Lake Michigan, its sole source of drinking water. To solve this, engineers undertook a monumental public-works project: digging the Chicago Sanitary and Ship Canal, which literally reversed the flow of the Chicago River away from the lake and towards the Mississippi River system. This feat, a "textbook example of what used to be called, without irony, the control of nature," was the biggest public-works project of its time.

New problems emerge. The river reversal, while solving Chicago's sewage problem, inadvertently connected two previously distinct aquatic ecosystems: the Great Lakes and the Mississippi River basin. This created a pathway for invasive species. The round goby, an aggressive fish, quickly crossed into the Mississippi, and later, Asian carp began moving in the opposite direction, threatening the Great Lakes.

More control needed. To combat the Asian carp invasion, the Army Corps of Engineers installed electric barriers in the canal, pulsing electricity into the water to repel fish. This intervention, costing hundreds of millions, is a prime example of "the control of the control of nature." Despite these efforts, the carp continue to spread, leading to further interventions like "barrier defense" (mass fishing) and even proposals for "disco barriers" using loud noise and bubbles, illustrating a never-ending cycle of human intervention.

3. Louisiana's Sinking Coast: The Price of River Control

If control is the problem, then, by the logic of the Anthropocene, still more control must be the solution.

A disappearing landscape. Southern Louisiana, particularly Plaquemines Parish, is one of the fastest-disappearing places on Earth, shrinking by over two thousand square miles since the 1930s. This "land-loss crisis" is a direct consequence of thousands of miles of levees, flood walls, and revetments built to manage the Mississippi River and keep the region dry. These structures prevent the river from naturally depositing sediment, which historically built up the delta and countered subsidence.

The paradox of protection. Historically, the Mississippi would regularly overtop its banks, spreading sediment and building new land. With the "crevasse period" ended by extensive levee systems, this natural land-building process ceased. The very infrastructure designed to protect cities like New Orleans from floods inadvertently caused the land to sink and wash out to sea, leaving the region increasingly vulnerable to rising sea levels and storm surges.

Bold new interventions. In response, Louisiana's Coastal Protection and Restoration Authority (CPRA) is undertaking new, massive public-works projects. Their "bold" scheme involves punching giant, gated holes through the levees—man-made "crevasses"—to redirect sediment-rich water back into the sinking marshes. Projects like the Mid-Barataria Sediment Diversion, costing billions, aim to "reestablish the natural sediment deposition process," but are themselves unprecedented acts of engineering, highlighting the ongoing cycle of human attempts to manage the consequences of previous interventions.

4. Conservation's New Frontier: Engineering Life to Survive

For one species to mourn the death of another is a new thing under the sun.

A history of loss. Humanity's expansion has consistently led to species extinction, from Paleolithic mammoths to 19th-century passenger pigeons. The advent of technologies like railroads and repeating rifles accelerated this process, making extinction a "readily observable phenomenon." Today, extinction rates are hundreds, perhaps thousands, of times higher than natural background rates, affecting all continents, oceans, and taxa, leading to a biodiversity crisis where countless species are "conservation-reliant."

The Devils Hole enigma. The Devils Hole pupfish, a tiny, sapphire-blue fish, lives in a single, isolated cavern in the Mojave Desert, representing the smallest range of any vertebrate. Its survival is a "beautiful enigma," as it has evolved to cope with extreme, constant conditions of high temperature and low oxygen. However, human activities, like groundwater pumping for development, caused water levels to drop, exposing the fish's spawning shelf and pushing it to the brink of extinction.

Assisted survival. To save the pupfish, extensive human intervention became necessary. This included legal battles (Cappaert v. United States, which the fish won 9-0), constructing a "sham shelf" with artificial lighting, and even building an exact, hundred-thousand-gallon replica of Devils Hole ("Devils Hole Jr.") to house a backup population. These efforts, including daily sifting for predatory beetles and supplemental feeding, illustrate the extreme measures required to keep "Stockholm species"—those utterly dependent on their human "persecutors"—alive in a world fundamentally altered by human actions.

5. Reefs on the Brink: Assisted Evolution for Survival

Our project is acknowledging that a future is coming where nature is no longer fully natural.

Coral's silent crisis. Coral reefs, vital ecosystems supporting an estimated one to nine million species, are facing catastrophic decline due to climate change, particularly rising ocean temperatures and acidification. Global bleaching events, like the one from 2014-2017 that killed half of the Great Barrier Reef's corals, highlight the urgency. Marine biologist Ruth Gates, recognizing that simply stopping emissions might not be enough, proposed "assisted evolution" to breed "super corals" capable of surviving future conditions.

Engineering resilience. The "super coral" project involves raising corals under calibrated stress in controlled environments, then crossbreeding the survivors. The goal is to identify and propagate traits that confer greater resilience to heat and acidity. This includes manipulating their algal symbionts or even introducing marine probiotics to enhance bleaching resistance. The approach acknowledges that the planet has already "changed radically" and that active intervention is necessary to "buy time" for reefs.

A new definition of nature. Gates's work, continued by Madeleine van Oppen, represents a shift from traditional conservation to a "futurist" perspective where nature is "no longer fully natural." Experiments at facilities like Australia's National Sea Simulator involve meticulously controlled coral spawning, allowing scientists to select and crossbreed corals from different regions or even different species to create hardier hybrids. This "all-of-reef-scale intervention" aims to reengineer reefs to survive, even if it means accepting a "diminished thing"—a kind of "Okay Barrier Reef"—rather than losing them entirely.

6. Genetic Engineering: Rewriting the Molecules of Life

We now have “a way to rewrite the very molecules of life any way we wish.”

CRISPR's revolution. Genetic engineering, a field that began in the 1970s, has been revolutionized by CRISPR technology. CRISPR, borrowed from bacteria's immune systems, allows scientists to precisely snip and modify DNA sequences, enabling the creation of organisms with desired traits, from drug-resistant bacteria to disease-resistant pigs. This powerful tool offers "a way to rewrite the very molecules of life any way we wish," opening up unprecedented possibilities for biological manipulation.

The cane toad dilemma. Australia faces a severe ecological crisis due to the invasive cane toad, introduced in 1935 to control sugar cane grubs but which instead became a toxic menace to native wildlife. Researchers are now using CRISPR to gene-edit cane toads, aiming to "break" their toxicity by disabling the gene responsible for their potent bufotoxin. The goal is to create "detox toads" that, if eaten by predators, would make them sick but not kill them, thus teaching predators to avoid toads without fatal consequences.

Gene drives: Beyond heredity. The most profound application of CRISPR is the synthetic gene drive, which overrides normal inheritance patterns. By inserting CRISPR-Cas genes into an organism, it can be programmed to genetically reprogram its offspring, ensuring a desired trait spreads rapidly through a population, even if it confers no fitness advantage. This technology could, in principle, be used to spread a broken-toxin gene among cane toads or a heat-tolerance gene in corals, blurring the line between laboratory and wild and giving humans the power to determine evolutionary outcomes.

7. The Carbon Conundrum: Removing Emissions from the Air

I would argue that if technologies to pull CO2 out of the environment fail, then we’re in deep trouble.

The cumulative problem. Despite temporary dips, global CO2 emissions continue to rise, leading to record atmospheric concentrations. Unlike other pollutants, CO2 is cumulative; once in the air, it stays there for centuries. This means that even drastic emissions cuts would only slow the rate of warming, not reverse it. The Intergovernmental Panel on Climate Change (IPCC) models show that achieving climate goals (like staying under 1.5°C warming) is virtually impossible without "negative emissions" technologies.

The promise of removal. Carbon dioxide removal (CDR) technologies aim to extract CO2 directly from the atmosphere. Klaus Lackner, a pioneer in the field, argues that humanity has "unwittingly committed itself" to CDR, viewing CO2 like sewage—something we must manage, not just stop producing. Companies like Climeworks are already turning atmospheric CO2 into rock in Iceland, accelerating a natural process that would otherwise take millennia.

Scaling the challenge. Various CDR methods exist:

• Direct Air Capture (DAC): Machines like Climeworks' units scrub CO2 from the air.
• Enhanced Weathering: Crushing and spreading basalt or olivine to react with CO2.
• BECCS (Bioenergy with Carbon Capture and Storage): Burning biomass for energy, then capturing and storing the CO2.
• Reforestation: Planting trillions of trees to absorb carbon.
  The main challenge for all these is scale and cost. Removing billions of tons of CO2 annually would require a massive, multi-trillion-dollar industry, raising questions of economic feasibility and global equity.

8. Dimming the Sun: The Audacity of Solar Geoengineering

The thing I worry about is that in ten or fifteen years, people could go out in the street and demand from decision-makers, ‘You guys need to take action now!’

Mimicking volcanoes. Solar geoengineering, or "solar radiation management," proposes to cool the Earth by reflecting sunlight back into space, mimicking the effect of large volcanic eruptions like Mount Tambora in 1815, which caused a "year without a summer." Scientists like Frank Keutsch and David Keith are researching injecting reflective particles, such as sulfur dioxide or calcium carbonate, into the stratosphere to reduce global temperatures.

A controversial solution. This technology is highly controversial, described as "dangerous beyond belief" and "unimaginably drastic." Critics worry about unintended consequences like disrupting rainfall patterns, damaging the ozone layer, or creating "whiter skies." However, proponents argue that given the slow pace of emissions cuts, geoengineering might be the only way to "do something fast" to mitigate severe climate impacts, especially during a period of "overshoot" where temperatures temporarily exceed targets.

The "chemotherapy" analogy. Solar geoengineering is seen by some as a last resort, a "chemotherapy" for the planet. It's relatively cheap and fast to deploy, with estimates of tens of billions of dollars per decade to halve warming. However, it treats symptoms, not the cause, creating a "termination shock" if stopped abruptly. The ethical dilemma is profound: do humans have the right to deliberately alter the entire planet's climate, and can such a powerful technology be deployed equitably and responsibly by a world already struggling with climate governance?

9. The Unstable Climate: Humanity's Self-Inflicted Instability

The current Arctic is experiencing rates of warming comparable to abrupt changes, or D–O events, recorded in Greenland ice cores.

A history of wild swings. Ice core data from Greenland, like the Camp Century core, reveal that Earth's climate has not always been stable. During the last ice age, temperatures over Greenland experienced dramatic "Dansgaard–Oeschger events," with average temperatures swinging by as much as 14°F in mere decades. The last 10,000 years, the period of human civilization, has been unusually calm, leading us to mistakenly perceive this stability as the norm.

Greenland's accelerating melt. Humanity, without intending to, has used this period of stability to create Greenland-scale instability. Since 1990, Greenland's temperatures have risen by almost 3°C, and ice loss has increased sevenfold, from 30 billion to over 250 billion tons annually. This melt is now occurring at rates comparable to the abrupt D-O events of the past, raising concerns that the ice sheet may be approaching an irreversible tipping point, with enough ice to raise global sea levels by twenty feet.

The cost of stasis. Rising sea levels and more deadly storm surges threaten coastal cities worldwide. Unlike our nomadic ancestors, modern societies are committed to stasis, with vast infrastructures like subway lines and sewage pipes militating against relocation. This commitment necessitates increasingly elaborate and costly interventions, such as proposed artificial islands and retractable gates for New York Harbor, or even attempts to "refreeze" the poles by blocking glaciers or brightening Arctic clouds, highlighting the immense challenge of maintaining the status quo in a rapidly changing world.

10. The Paradox of Intervention: More Control, More Problems?

We are as gods and have to get good at it.

A cycle of fixes. The book chronicles a recurring pattern: human attempts to solve problems often create new, unforeseen ones, leading to a continuous cycle of further interventions. From reversing rivers to prevent disease, only to introduce invasive species, to building levees that cause land loss, or developing gene drives to combat invasive species, each solution begets another problem, creating a complex, "tangled" reality.

The "gods" dilemma. Stewart Brand's famous dictum, "We are as gods and might as well get good at it," encapsulates the modern human predicament. Given our pervasive impact on the planet, the choice is no longer whether to alter nature, but to what end. Rejecting technologies like genetic rescue or geoengineering as "unnatural" might condemn thousands of species to extinction or lead to catastrophic climate outcomes, forcing a re-evaluation of what "natural" even means in the Anthropocene.

Techno-fatalism. The interventions discussed are often presented not as ideal solutions, but as necessary evils—a form of "techno-fatalism." Scientists acknowledge the risks and unintended consequences, comparing geoengineering to chemotherapy: a dangerous treatment for a dire situation. The ultimate challenge lies not just in developing these technologies, but in the political and ethical decisions surrounding their deployment, raising the specter of an "unprecedented climate for an unprecedented world, where silver carp glisten under a white sky."

Last updated: August 7, 2025