Feeding a growing world population has been a serious concern for decades, but today there are new causes for alarm. Floods, heat waves and other weather extremes are making agriculture increasingly precarious, especially in the Global South.

The war in Ukraine is also a factor. Russia is blockading Ukrainian grain exports, and fertilizer prices have surged because of trade sanctions on Russia, the world’s leading fertilizer exporter.

Amid these challenges, some organizations are renewing calls for a second Green Revolution, echoing the introduction in the 1960s and 1970s of supposedly high-yielding varieties of wheat and rice into developing countries, along with synthetic fertilizers and pesticides. Those efforts centered on India and other Asian countries; today, advocates focus on sub-Saharan Africa, where the original Green Revolution regime never took hold.

But anyone concerned with food production should be careful what they wish for. In recent years, a wave of new analysis has spurred a critical rethinking of what Green Revolution-style farming really means for food supplies and self-sufficiency.

As I explain in my book, “The Agricultural Dilemma: How Not to Feed the World,” the Green Revolution does hold lessons for food production today – but not the ones that are commonly heard. Events in India show why.

A triumphal narrative

There was a consensus in the 1960s among development officials and the public that an overpopulated Earth was heading toward catastrophe. Paul Ehrlich’s 1968 bestseller, “The Population Bomb,” famously predicted that nothing could stop “hundreds of millions” from starving in the 1970s.

India was the global poster child for this looming Malthusian disaster: Its population was booming, drought was ravaging its countryside and its imports of American wheat were climbing to levels that alarmed government officials in India and the U.S.

Then, in 1967, India began distributing new wheat varieties bred by Rockefeller Foundation plant biologist Norman Borlaug, along with high doses of chemical fertilizer. After famine failed to materialize, observers credited the new farming strategy with enabling India to feed itself.

Borlaug received the 1970 Nobel Peace Prize and is still widely credited with “saving a billion lives.” Indian agricultural scientist M.S. Swaminathan, who worked with Borlaug to promote the Green Revolution, received the inaugural World Food Prize in 1987. Tributes to Swaminathan, who died on Sept. 28, 2023, at age 98, have reiterated the claim that his efforts brought India “self-sufficiency in food production” and independence from Western powers.

Debunking the legend

The standard legend of India’s Green Revolution centers on two propositions. First, India faced a food crisis, with farms mired in tradition and unable to feed an exploding population; and second, Borlaug’s wheat seeds led to record harvests from 1968 on, replacing import dependence with food self-sufficiency.

Recent research shows that both claims are false.

India was importing wheat in the 1960s because of policy decisions, not overpopulation. After the nation achieved independence in 1947, Prime Minister Jawaharlal Nehru prioritized developing heavy industry. U.S. advisers encouraged this strategy and offered to provide India with surplus grain, which India accepted as cheap food for urban workers.

Meanwhile, the government urged Indian farmers to grow nonfood export crops to earn foreign currency. They switched millions of acres from rice to jute production, and by the mid-1960s India was exporting agricultural products.

Borlaug’s miracle seeds were not inherently more productive than many Indian wheat varieties. Rather, they just responded more effectively to high doses of chemical fertilizer. But while India had abundant manure from its cows, it produced almost no chemical fertilizer. It had to start spending heavily to import and subsidize fertilizer.

India did see a wheat boom after 1967, but there is evidence that this expensive new input-intensive approach was not the main cause. Rather, the Indian government established a new policy of paying higher prices for wheat. Unsurprisingly, Indian farmers planted more wheat and less of other crops.

Once India’s 1965-67 drought ended and the Green Revolution began, wheat production sped up, while production trends in other crops like rice, maize and pulses slowed down. Net food grain production, which was much more crucial than wheat production alone, actually resumed at the same growth rate as before.

But grain production became more erratic, forcing India to resume importing food by the mid-1970s. India also became dramatically more dependent on chemical fertilizer.

According to data from Indian economic and agricultural organizations, on the eve of the Green Revolution in 1965, Indian farmers needed 17 pounds (8 kilograms) of fertilizer to grow an average ton of food. By 1980, it took 96 pounds (44 kilograms). So, India replaced imports of wheat, which were virtually free food aid, with imports of fossil fuel-based fertilizer, paid for with precious international currency.

Today, India remains the world’s second-highest fertilizer importer, spending US$17.3 billion in 2022. Perversely, Green Revolution boosters call this extreme and expensive dependence “self-sufficiency.”

The toll of ‘green’ pollution

Recent research shows that the environmental costs of the Green Revolution are as severe as its economic impacts. One reason is that fertilizer use is astonishingly wasteful. Globally, only 17% of what is applied is taken up by plants and ultimately consumed as food. Most of the rest washes into waterways, where it creates algae blooms and dead zones that smother aquatic life. Producing and using fertilizer also generates copious greenhouse gases that contribute to climate change.

In Punjab, India’s top Green Revolution state, heavy use of fertilizers and pesticides has contaminated water, soil and food and endangered human health.

In my view, African countries where the Green Revolution has not made inroads should consider themselves lucky. Ethiopia offers a cautionary case. In recent years, the Ethiopian government has forced farmers to plant increasing amounts of fertilizer-intensive wheat, claiming this will achieve “self-sufficiency” and even allow it to export wheat worth $105 million this year. Some African officials hail this strategy as an example for the continent.

But Ethiopia has no fertilizer factories, so it has to import it – at a cost of $1 billion just in the past year. Even so, many farmers face severe fertilizer shortages.

The Green Revolution still has many boosters today, especially among biotech companies that are eager to draw parallels between genetically engineered crops and Borlaug’s seeds. I agree that it offers important lessons about how to move forward with food production, but actual data tells a distinctly different story from the standard narrative. In my view, there are many ways to pursue less input-intensive agriculture that will be more sustainable in a world with an increasingly erratic climate.

Glenn Davis Stone receives funding from the National Science Foundation and the John Simon Guggenheim Memorial Foundation.

Each year, the federal government purchases about 50,000 new vehicles. Until recently, almost all of them ran on diesel or gasoline, contributing to U.S. demand for fossil fuels and encouraging automakers to continue focusing on fossil-fueled vehicles.

That’s starting to change, and a new directive that the Biden Administration quietly issued in September 2023 will accelerate the shift.

The administration directed U.S. agencies to begin considering the social cost of greenhouse gases when making purchase decisions and implementing their budgets.

That one move has vast implications that go far beyond vehicles. It could affect decisions across the government on everything from agriculture grants to fossil fuel drilling on public lands to construction projects. Ultimately, it could shift demand enough to change what industries produce, not just for the government but for the entire country.

What’s the social cost of greenhouse gas?

The social cost of greenhouse gases represents the damage created by emitting 1 metric ton of carbon dioxide, methane and other greenhouse gases into the atmosphere.

These greenhouse gases, largely from fossil fuels, trap heat in the atmosphere, warming the planet and fueling climate change. The result is worsening storms, heat waves, droughts and other disasters that harm humans, infrastructure and economies around the world. The estimate is intended to include changes in agricultural productivity, human health, property damage from increased flood risk, and the value of ecosystem services.

By directing agencies to consider those costs when making purchases and implementing budgets, the administration is making it more likely that agencies will purchase products and make investments that are more energy efficient and less likely to fuel climate change.

While only a fraction of the roughly $6 trillion that the U.S. government spends each year would likely be considered under the new directive, that fraction could have far-reaching impacts on the U.S. economy by reducing demand for fossil fuels and lowering emissions across sectors.

Estimating the cost

The Obama administration introduced the first federal social cost of carbon to incorporate climate risk in regulatory decisions. It’s calculated using models of the global economy and climate and weighs the value of spending money today for future benefits.

When the Trump administration arrived, it cut the estimated cost from around $50 per metric ton to less than $5, which justified rolling back several environmental regulations, including on power plant emissions and fuel efficiency. The Biden administration restored an interim price to about $51, with plans to raise it.

Recent research suggests that the actual social cost of carbon is closer to $185 per metric ton. But carbon dioxide is just one greenhouse gas. The new directive takes other greenhouse gases into consideration, too – in particular, methane, which has about 80 times the warming power of carbon dioxide over 20 years.

Estimates of the social cost of methane, which comes from livestock and leaks from pipelines and other natural gas equipment, range from $933 per metric ton to $4,000 per metric ton.

Without directives like these, decision-makers implicitly set the cost of greenhouse gas emissions to zero in their benefit-cost analyses. The new directives allow agencies to instead compare the expected climate damages, in dollars, when making decisions about vehicle purchases, building infrastructure and permitting, among other choices.

The vehicle fleet as an example

The federal vehicle fleet is a good example of how the social costs of greenhouse gases add up.

Let’s compare the costs of driving an electric Ford Focus and an equivalent conventional-fuel Ford Focus.

Assume each vehicle drives an average of 10,000 miles (about 16,000 kilometers) per year – that’s less than the U.S. average per driver, but it’s a simple number to work with. The damages from emissions in dollars from driving a conventional Ford Focus 10,000 miles are between $133 and $484, depending on whether you use a social cost of carbon of $51 per metric ton or $185 per metric ton.

The climate harm from driving an equivalent electric Ford Focus 10,000 miles, based on the average carbon dioxide emissions intensity from the U.S. electricity grid, would be between $59 and $212, using the same social costs.

Scale that to 50,000 new vehicle purchases, and that’s a cost difference of about $4 million to $13.5 million per year for emissions from operating the vehicles. While producing an EV’s battery adds to the vehicle’s emissions up front, that’s soon outweighed by operational savings. These are real savings to society.

The U.S. government is also a major consumer of energy. If agencies begin to consider the climate damages associated with fossil energy consumption, they will likely trend toward renewable energy, further lowering their own emissions while boosting the burgeoning industry.

How the government can shift demand

These types of comparisons under the new directive could help shift purchases toward a wide range of less carbon-intensive products.

Much of the U.S. government’s spending goes toward carbon-intensive goods and services, such as transportation and infrastructure development. Directing agencies to consider and compare the social cost of purchases in each of these sectors will send similar signals to different segments of the market: The demand for less carbon-intensive goods is rising.

Because this new directive expands to other greenhouse gases, it could have broad implications for new permitting for oil and gas development and agricultural production, as these are the two largest sources of methane in the U.S.

While this decision is not a tax on carbon or a subsidy for less carbon-intensive goods, it will likely send similar market signals. With respect to purchases, this policy is akin to tax rebates for energy efficient products, like electric vehicle incentives in the Inflation Reduction Act, which boost demand for EVs.

Ultimately, if one of the largest segments of demand, the U.S. government, transitions to less carbon-intensive products, supply will follow.

Jesse Burkhardt receives funding from the USDA and Department of the Interior.

Lauren Gifford does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Hatchling turtles are cute, small and inexpensive. Handled improperly, they also can make you sick.

Turtles are well-known carriers of salmonella, a common bacterial disease that causes fever, stomach cramps and dehydration and can lead to severe illness, especially in young children and elderly people. In August 2023, the Centers for Disease Control and Prevention released an advisory about an 11-state outbreak of salmonella bacteria linked to pet turtles.

“Don’t kiss or snuggle your turtle, and don’t eat or drink around it. This can spread Salmonella germs to your mouth and make you sick,” the agency warned.

Global trade in turtles is big business, and the U.S. is a leading source, destination and transit country. Some of this commerce is legal, some is not. For example, it has been illegal in the U.S. since 1975 to sell turtles with shells less than 4 inches (10 centimeters) in diameter because young children often contract salmonella from them. But it’s easy to find them for sale nonetheless.

However, humans are a much bigger threat to turtles than vice versa. Over half of the world’s turtle species are classified as threatened or endangered, and overharvesting of wild turtles is a major cause. Turtles also face other threats, including habitat loss, climate change, pollution, diseases, invasive species and death or injury while trying to cross roads.

As a conservation biologist, I work with colleagues from academia, nonprofit organizations and state and federal agencies to protect threatened species and combat wildlife trafficking. I also use the global wildlife trade to teach important ecological concepts and research skills. Here’s what we know about trade in turtles and how it threatens their survival.

Life in the slow lane

It’s hard to harvest turtles sustainably because they are so long-lived. Individual turtles of some species can survive for more than 100 years. Most turtles reach reproductive maturity late in life and have relatively few eggs, not all of which produce successful offspring.

To put this in context, compare a common female snapping turtle from the northern U.S. with a female white-tailed deer. Begin at the start of their lives and fast-forward 17 years. At this point, the snapping turtle will just be ready to reproduce for the first time; the deer will already be dead, but it may have produced over 600 descendants. It can take a female turtle her entire life to generate one or two offspring that in turn reach adulthood and replace her in the population.

Turtles are valuable because they play diverse roles in land, freshwater and ocean ecosystems. For example, tortoise burrows provide refuge for hundreds of other species, including birds, mice, snakes and rabbits. Box turtles – the type you may encounter in your garden – consume practically any kind of plant material and excrete the seeds as they move around, helping plants spread. Some seeds even germinate more readily after passing through a box turtle’s gut.

In lakes and ponds, freshwater turtles serve as both predator and prey, and they help maintain good water quality by consuming decaying organisms. Terrapins reside in brackish water zones, where rivers flow into oceans and bays, and feed heavily on snails. Without terrapins present, the snails would quickly consume all underwater seagrasses, which would harm fish, shellfish, sea urchins and other organisms that rely on seagrasses for their survival.

In global demand

Humans have long been fascinated with turtles. Revered in many cultures, turtles have symbolized strength and longevity for centuries. Today, people use turtles as pets; sources of food, jewelry and other curios; and in traditional medicines and religious and cultural practices.

International trade in turtles takes place on a massive scale. According to the U.S. Fish and Wildlife Service, nearly 127 million turtles were exported just from the U.S. between 2002 and 2012. About one-fifth (24 million) came from the wild.

More recent data indicates that exports declined between 2013 and 2018, but trade in particular species increased. Commercial freshwater turtle farming is still a multimillion-dollar industry in the southeastern U.S.; a small number of native turtle species, largely bred on turtle farms, now make up the bulk of legal U.S. exports, for use as both pets and food.

There’s no good way to quantify how many native turtles are harvested from the wild. But history shows what happens when they are hunted without limits. Historic demand for sea turtles, diamondback terrapins and snapping turtles as food led to such crashes in populations that management agencies had to regulate their harvesting.

Turtles also are gaining popularity as pets, particularly for younger adults. Surveys indicate that more than 2 million Americans own turtles. To curb pressure on wild populations, state agencies are prohibiting or limiting personal collection and possession of native turtles.

Black market turtles

Despite existing regulations, demand for some native North American turtle species is so strong that people collect, smuggle and sell the animals illegally. For example, in 2019 a Pennsylvania man was sentenced to six months in prison and fined $250,000 for trafficking thousands of protected diamondback terrapins.

Rare species such as wood turtles and Blanding’s turtles, as well as uniquely patterned individual turtles, command top value on the black market. Internet commerce, social media apps and online payment mechanisms make it easy for illegal buyers and sellers to connect.

Between 1998 and 2021, U.S. enforcement agencies intercepted at least 24,000 protected freshwater turtles and tortoises from 34 native species that were being illegally traded across the U.S. These animals may be held without food and water and in crowded spaces, sometimes wrapped in tape and stuffed in socks.

How to help

To curtail the illegal turtle trade, regulators are working to strengthen regulations and increase enforcement. Private citizens can also help reduce the demand and protect wild turtles. Here are some simple steps:

• Before you purchase any live animal or wildlife-related product, review relevant local, state, national and international regulations. Just because something is for sale doesn’t mean it’s legal.

• Make an informed decision about owning a turtle. Consider the size it will reach as an adult, its care requirements and its life span. Prioritize adopting one from a reputable rescue organization, and seek out a captive-bred turtle instead of a wild one.

• Don’t release an animal that you no longer want or can’t care for into the wild. This is illegal and can have serious ecological impacts. The red-eared slider (Trachemys scripta elegans), a freshwater turtle that’s native to the Mississippi River basin, was sold by the millions in recent decades and released by many pet owners. Now it is considered one of the world’s most invasive species because it outcompetes native turtles for food and space.

• If you encounter illegal wildlife collection, smuggling or sales, report them to your state fish and wildlife agency or the U.S. Fish and Wildlife Service for investigation.

• Support efforts to conserve and restore turtle habitat and minimize other threats, such as pollution and road traffic.

Jennifer Sevin is a co-founder and serves on the steering committee of the Collaborative to Combat the Illegal Trade in Turtles.