PDF Summary:Numbers Don't Lie, by Vaclav Smil

Have you ever wondered how we calculate happiness levels among different countries or the amount of fossil fuels it would take to switch to renewable energy? Have you considered what unemployment numbers and infant mortality rates say about a population? In Numbers Don’t Lie, scientist and economist Vaclav Smil wants to help you understand the world by understanding numbers and statistics. Numbers can help you see the world more clearly, but only if you know what they’re actually saying.

Smil examines commonly used metrics like GDP, vaccination rates, and fertility rates and asks what they say about countries like the US, China, and Japan. He also reviews humanity’s impact on the planet through the energy, transportation, and food sectors. In our guide, we’ll go over these numbers, metrics, and statistics and provide additional scientific and historical context to help you understand the world around you even better.

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Significantly Curbing Carbon Emissions Will Be Nearly Impossible

To help understand our environmental challenges, Smil provides the numbers for the amount of carbon we emit through the use of fossil fuels. At the beginning of the 19th century, global carbon emissions were relatively low at around 10 million tons a year. By the end of the century, that number was over half a billion tons. And by 2000, global carbon emissions were over seven billion tons a year. To put it another way, from 1800 to 2000 carbon emissions grew 650-fold while the global population only grew sixfold.

(Shortform note: In Thank You For Being Late, Thomas Friedman provides historical context on the climate change crisis. He argues that global emissions have increased so dramatically, that we’re creating a new epoch: the Anthropocene, a period in which the Earth can’t keep up with the changes humans are causing to the planet. Starting with the Industrial Revolution, the Earth began heating up rapidly due to increased greenhouse gas emissions. In the 1960s and 1970s, as more people gained access to cars, planes, and single-family homes, this heating sped up even further.)

Even as governments and other organizations have started to implement large-scale efforts to curb carbon emissions, global emissions continue to grow, writes Smil. By 2017, emissions had declined in Europe and the United States, but those declines were offset by China, which contributed three billion tons of carbon emissions.

More recently, China’s increase in carbon emissions has slowed, but emissions in India and Africa are expected to continue growing, making any substantial decreases in overall global emissions unlikely. Even if we meet the targets set forth by the Paris Agreement of 2015, an international committee dedicated to reducing carbon emissions, carbon emissions would still be about 50% greater than their 2017 levels.

If we are to avoid environmental disaster, scientists estimate we need to keep global temperatures from increasing more than 1.5 degrees Celsius. According to a 2018 study, the only way to do this is to get to zero net emissions by 2050. Smil claims reaching zero emissions by 2050 will take an unprecedented global effort on a massive scale.

Additional Temperature Forecasts

Many climate scientists believe that meeting the goal of the Paris Climate Agreement is unlikely and provide additional evidence to prove that: The main target of the Paris Agreement is to keep the global temperature rise under two degrees Celsius, preferably under 1.5. A 2017 study found that the chances that global temperatures will rise more than two degrees Celsius this century are around 95%, with a less than 1% chance they rise less than 1.5 degrees. The most likely scenario is that global temperatures will rise between two and 4.9 degrees Celsius by 2100.

The main factors contributing to this increase are population growth and carbon intensity, or the measure of carbon dioxide emitted per unit of gross domestic product. If we wish to keep global temperatures down, we must drastically reduce carbon intensity.

The same research team released another study in 2021, this time looking to determine exactly by how much we need to reduce carbon emissions to keep global temperatures steady. They found that we need emission reductions about 80% greater than the Paris Climate Agreement proposed: Instead of 1% annual reductions in carbon emissions, we’ll need about 1.8%.

We Rely Too Much on Technology to Save Us From Environmental Destruction

Smil argues that many people wrongly believe technology can save us from environmental disaster. This is because they often have unrealistic expectations about the speed at which technology will advance.

These unrealistic expectations are often because people are influenced by the numbers underpinning Moore’s law, which states that the speed and capabilities of computer chips double every two years. This law has largely held true since its inception in 1965, and it has allowed for a great deal of innovation in computers and electronics.

People often assume the same rate of progress applies to other fields—for instance, in environment-related industries—but technological progress happens much more slowly outside of computer-based technologies. For example, corn yields have risen by an average of only about 2% per year since 1950, and fuel efficiency has increased by about 2.5% a year.

Instead of relying on future technologies to save us, we should be searching for realistic and practical solutions, and if a problem can’t be completely and immediately solved, incremental progress is still better than no progress at all, contends Smil.

Can Technology Save Us at All?

A 2017 MIT study found that even in the fields of computers and electronics, where Moore’s law applies, technological advancements still aren’t enough to create a sustainable world. Some scientists believe that as we become more technologically advanced, we’ll use fewer materials and be a more sustainable society. But researchers found that no matter how much more efficiently a product is made, consumers will only demand more of that product and thus produce more material waste.

For example, the amount of material to make a transistor has greatly decreased over the last few decades. This has made computers and smartphones much more powerful and compact, but the increase in demand for these superior products has outpaced further technological improvements to their sustainability.

When researchers looked at materials, goods, and services outside of the electronic and computer industries, they found a similar trend: As products become smaller, better, and cheaper, demand increases, and there is no overall reduction in the amount of material used to make them. The only cases in which significant dematerialization occurs are when a product is replaced by something else (wool with nylon and polyester, for example), or the government intervenes (for instance, by passing laws against asbestos and thallium).

The latter case exemplifies how practical solutions are more effective than reliance on not-yet-discovered technologies: Asbestos was discovered to be hazardous, so the US government passed a law limiting the production and use of asbestos.

The Numbers on Sustainable Energy

A key environmental challenge of the 21st century is transitioning our energy sources away from fossil fuel consumption. Smil argues that we must be realistic about this transition, and understand the numbers behind it if we wish to make meaningful progress.

Energy transitions take time. The transition from wood and charcoal to coal, oil, and gas as the world’s main source of energy took a century. Transitioning away from fuels that currently produce 10 billion tons of annual carbon emissions will be a much more difficult task. While alternative energies like solar, wind, and nuclear are being adopted, they won’t be able to replace fossil fuel consumption any time soon. In this section, we’ll go over each of these energy alternatives and provide further insight into our reliance on fossil fuels.

Nuclear Energy Isn’t Strong Enough to Reduce Our Dependence on Fossil Fuels

Many point to nuclear energy as the best possible replacement for fossil fuel energy; when it began to take off in the 1970s, some predicted it would provide virtually all of the world's electricity by 2000. However, Smil argues that it has failed to do so for several reasons.

Catastrophic failures of nuclear power plants occurred at Three Mile Island, Pennsylvania, at Chernobyl, Ukraine, and at Fukushima, Japan, which has made the public and governments more skeptical of nuclear energy. Also, the constructions of many nuclear plants have gone over budget, there is still not a viable option for permanent storage of nuclear waste, and we still haven’t come up with a safer, less expensive design for new reactors.

For these reasons, the prominence of nuclear energy has receded, especially in the Western world, writes Smil. Germany and Sweden are removing nuclear energy entirely, and France, the leading adopter of nuclear energy, is also cutting back. As a result, the percentage of global electricity powered by nuclear energy has gone from 18% in 1996 to 10% in 2018. Though nuclear power still has the potential to drastically reduce carbon emissions, it isn’t on track to do so, as it is estimated to provide only about 12% of electricity by 2040.

Nuclear Energy Continues to Decline

Beyond the publicized failures of nuclear energy Smil mentions, there are other reasons nuclear energy failed to take off, including the low cost of natural gas, the falling cost of renewables, and the fallout and heightened safety requirements caused by the 2011 Fukushima accident. Though scientists believe nuclear energy will play a big role in reducing carbon emissions, 2021 estimates from IAEA project nuclear energy to account for only 6 to 12% of global electricity in 2050.

What’s more, when looking back at previous projections, we see that the estimates for future nuclear energy usage are becoming smaller and smaller: In 2007, the low-end projection for 2030 nuclear energy production was 447 gigawatts. By 2016, the low-end projection was significantly lower at 390 gigawatts. These projections indicate that nuclear energy may not play such a significant role in the reduction of carbon emissions.

Wind Energy Requires Fossil Fuel Inputs

According to Smil, numbers don’t suggest that wind turbines will provide an efficient solution to environmental problems, either. The main issue with wind-generated electricity is the amount of fossil fuel required to build wind turbines. Though a wind turbine can generate the energy it took to produce it in less than a year, these turbines only produce energy intermittently, and we need large amounts of steel, oil, and cement to make them. For wind to provide just a quarter of the world’s electricity by 2030, we’d need around 450 million tons of steel, which as of now can only be made using coal and natural gas. Until we can make wind turbines using only renewable resources, we will continue to depend on fossil fuels.

(Shortform note: Though it will indeed be difficult to replace carbon-powered electricity with renewable energy, it is theoretically possible. A 2012 study found that there is enough wind energy to meet global demand. As of 2012, humans used about 18 terawatts of power a year, while more than 400 terawatts of power could be extracted from surface winds every year. Furthermore, wind turbines make up for the carbon emissions of their production in as little as three months.)

Solar Energy Is Growing Slowly

Solar energy, though efficient, provides more evidence to Smil’s argument that energy transitions take time: The photovoltaic effect, the generation of electricity when a material is exposed to light, was first discovered in 1876. Yet it wasn’t until the 21st century that solar electricity generation became efficient enough for large-scale usage. In 2000, solar power provided 0.01% of global electricity. In 2010, that number went up to 0.16%. By 2018, it was at 2.2%. This is a sharp rise, and with solar energy becoming more efficient, it could certainly make a dent in global carbon emissions. But it isn’t likely to replace fossil fuels entirely.

(Shortform note: Though it will take significant investment, scientists believe it is possible to shift to 100% renewable energy by 2050 with the help of solar energy. A 2020 study predicted what it would take for the solar energy industry to meet the Paris Agreement targets: Along with other renewable energy sources, we would need a capacity of 70 to 80 terawatts from photovoltaic systems, more than 100 times what we currently have. While this is a drastic increase, it isn’t impossible, as solar energy is expected to become much more cheap and efficient in the coming decades.)

Battery Improvements Will Be Necessary to Store Renewable Energy

If we hope to provide year-round renewable electricity to big cities through wind and solar power, we’ll need better batteries to store saved-up energy more efficiently, claims Smil. This is because there are gaps in the flow of wind and solar energy: For instance, an unusually cloudy or windless month could render a city’s solar panels or windmills inadequate.

As of now, lithium-ion batteries are the best thing we have, but they are still too inefficient to hold enough power for a city of millions. We’ll probably need something more efficient, like hydrogen-based or compressed air batteries, but the technology for those is still in early development.

(Shortform note: A 2013 study examined how efficient it would be to store surplus solar and wind energy using current battery technologies. It found that when factoring in the energy costs of storing it, this could work for solar energy but not for wind energy. This is because it is more energy-efficient to temporarily shut down a wind turbine than it is to store its surplus energy in batteries. In other words, building the batteries to store the surplus electricity would require too much energy for it to be worth it.)

The Environmental Footprint of Transportation and Shipping

Statistics show that another significant contributor to carbon emissions is transportation and shipping. Smil argues that it will take a radical change to go carbon-neutral in these industries. From cargo ships to airplanes to cars, the entire world now runs on fossil fuel-powered vehicles. Let’s look at the numbers behind the transportation and shipping industries.

Diesel Engines Will Continue to Dominate

According to Smil, diesel engines are an integral part of the globalized economy. Diesel engines are much more efficient (15 to 20%) than their gasoline-powered counterparts, and they are reliable, durable, and have relatively low operating costs. Because of this, they power virtually every container ship, truck, and freight train, moving our most important commodities (oil, cement, grain) around the world. There is simply no better way to transport the massive amount of materials than diesel engines, and this will remain true for the foreseeable future.

(Shortform note: While we aren’t getting rid of diesel engines any time soon, there are some new technologies that may drastically reduce emissions from the transport sector. A Swedish transport company is using over 50 vehicles that run on HVO 100, a synthetic biodiesel, and they hope to further reduce energy consumption by designing more aerodynamic trucks. Additionally, researchers at MIT have devised a new way of powering trucks using a hybrid engine system that could also sharply reduce pollution.)

Electric Container Ships Won’t Be Efficient Enough in the Short Term

Though we’ve successfully built electric trains and cars, Smil points out that building efficient electric container ships will be a monumental task. The first electric container ship, built in the late 2010s, can only carry 120 containers, will travel at a slow speed of six knots, and will only be used for trips of up to 30 nautical miles. In contrast, diesel-powered container ships can carry over 20,000 standard-sized containers, travel at a speed of 16 knots and commonly make trips of over 20,000 kilometers.

To match the production of diesel, container ships would require lithium-ion batteries over 10 times more efficient than what we have today. To put this in perspective, in the last 70 years the efficiency of commercial batteries hasn’t even quadrupled.

(Shortform note: Besides electric container ships, there are other more environmentally friendly ships in the works, but they, too, are a long way from replacing diesel-powered cargo ships. One ship design, Vindskip, is partially powered by wind, and early tests have seen a 63% reduction in carbon emissions. But the earliest these ships could hit the waters is 2025. Another Norwegian ship design is meant to use hybrid propulsion systems to save energy and fuel, but again, these are hardly going to make a dent in near-term carbon emissions.)

Both Carbon-Producing Cars and Electric Vehicles Produce Significant Emissions

Smil argues that the age of the car began on August 12, 1908. This was the day the first Model T was assembled, making cars a much more affordable commodity. The automobile has had an enormous impact on the world but is also a major contributor of carbon emissions. We’ll look at the numbers behind vehicles to explain why they are so inefficient as a means of transportation and why electric cars won’t save us.

Cars Use Energy Inefficiently

According to Smil, the main reason cars are energy-inefficient is their large weight-to-payload ratio—in other words, the weight of the car versus the weight of the people it’s carrying. This means it takes a huge amount of energy simply to move the car itself, not the passengers in it. For comparison, a Ford F-150, the most popular American car, has a ratio of 32, a bike has a weight ratio of 0.1, and a Vespa scooter 1.6 (for an average-sized human).

To make matters worse, in the US, almost three-quarters of Americans commute to work without other passengers, so the weight-to-payload ratio is especially bad. What’s more, the average car size is only increasing, especially with the heavy batteries required for electric cars. And while lighter cars would help, having fewer people drive alone would be the best thing to do to reduce the weight ratio of cars.

(Shortform note: Another factor that adds to the US weight-to-payload problem is the number of US citizens who are overweight. A 2006 study found that the average weight of a US citizen rose 24 pounds from 1960 to 2002. This meant cars were using almost a billion more gallons of gasoline a year due to overweight passengers, or about $2.8 billion annually at $3 a gallon. Interestingly, it seems the amount of driving Americans do could partially cause their overweight problem: A 2012 study found a positive correlation between daily automobile travel and body mass index.)

Electric Vehicles Also Produce Significant Carbon Emissions

While electric vehicles (EVs) can help with carbon emissions, Smil argues that they aren’t an effective means of displacing carbon just yet. First, since global electricity still mostly comes from fossil fuels, simply powering EVs will continue to be a source of carbon emissions. Further, as we’ve discussed, building the infrastructure for renewable energy takes fossil fuels, so even getting to the point where many people drive sustainably powered EVs will require a lot of carbon, as will producing the EVs.

To add to this, EV production also creates about three times as much toxicity as a gas-powered car. This is due to the use of more heavy metals, which are more toxic to both humans and our freshwater sources.

(Shortform note: Studies support Smil’s claim that electric vehicles aren’t as environmentally friendly as advertised. A German study compared the carbon footprints of a Tesla Model 3, a Mercedes that runs on diesel, and a Mercedes that runs on natural gas. They found that the Tesla has the highest carbon footprint per kilometer of driving when taking the cars’ entire life cycle into account. The main reason for this is the carbon cost of the EV’s battery production and recycling.)

Airplanes Would Need to Run on Biofuel to Reduce Their Carbon Footprint

According to Smil, the numbers show that eliminating the carbon footprint of air traffic will be another great challenge of a transition to a carbon-free world. Airplanes use kerosene-based jet fuel, and there is currently no viable alternative to that. The best alternative may be fuel from organic matter, but to meet the increasing demand for air travel with biofuel, we’d need to cultivate oil-rich crops, which have their own environmental issues (more on this later).

Further, like container ships, making electric airplanes will be difficult, as batteries are heavy and a plane needs to be as light as possible to function properly. Of course, the most practical and effective way to limit airplane emissions would be to limit air traffic, but airplane use is expected to continue growing in the coming years.

(Shortform note: Like Smil, scientists seem to think one of the best ways to curb the carbon emissions of airplanes is to use biofuel. The most promising biofuel for this purpose comes from the camelina plant. In 2009, researchers found that oil from camelina can be converted to a green jet fuel that meets the standards of current petroleum jet fuels. The widespread use of camelina jet fuel could reduce carbon emissions of air traffic by up to 84%. The biggest roadblock to this currently is the cost and availability of growing the camelina crop at the required scale.)

Trains Are an Excellent Medium-Distance Mode of Transportation

As Smil points out, no mode of transportation is as efficient for medium distances as a high-speed electric train. While high-speed trains can’t replace the intercontinental capacity of planes or the local capacity of cars, they’re the best option for travel between these extremes.

For inter-city travel, trains offer high speeds, convenience, and relatively low energy usage and carbon emissions. A high-speed train can cover 300 kilometers in just under two hours. This is just a little bit longer than an airplane takes at a fraction of the energy usage. While Europe and China have adopted the use of electric trains, the United States is lagging behind: There’s not a single high-speed train connecting major cities in the US.

(Shortform note: A 2021 study on the high-speed rail system in China highlights how much more efficient and environmentally friendly high-speed trains are than airplanes. The study estimates that air travel emits seven times more carbon per passenger than high-speed rail (HSR) travel. The extensive HSR system in China is reducing carbon emissions drastically, as people are switching from plane to HSR travel within China. This switch to HSR has reduced China’s air carbon emissions by approximately 18%, or 12 million metric tons, over the last few years.)

Food Production’s Contribution to Carbon Emissions

Our food production also plays a big role in climate change, and as the global population continues to rise, Smil argues we must make changes in the way we produce and consume food. We’ll look at the numbers of three key aspects of food production: the use of nitrogen fertilizer, food waste, and meat consumption.

Nitrogen Fertilizers Are Harmful

Smil argues that the use of synthetic nitrogen fertilizers impacts the environment in two major ways: It adds to greenhouse gas emissions, and it causes nitrogen to be removed from the soil. Crops need nitrogen, and the traditional ways farmers supplied nitrogen to crops (recycling organic materials and rotating crops) are no longer adequate as the population now reaches close to 8 billion people. To provide nitrogen to crops, we synthesize almost 150 million tons of ammonium a year to make fertilizers, a process that’s environmentally harmful. Let’s look in more detail at fertilizers’ impact on greenhouse gas emissions and soil nitrogen.

(Shortform note: In The Omnivore’s Dilemma, Michael Pollan provides historical context for the proliferation of nitrogen fertilizers in the 20th century and how they paved the way for our damaging agricultural practices. The process that synthesizes nitrogen to make fertilizers can also be used to make explosives. After World War II, the manufacturing plants that made explosives for the war began making nitrogen fertilizers instead. This resulted in massive amounts of nitrogen fertilizer being made and used, which increased crop yields around the world but significantly damaged the environment as we grew more and more crops.)

Nitrogen Fertilizers Emit Greenhouse Gases

Though carbon dioxide contributes the most to the heating of the Earth, Smil points out that the next largest contributors are methane and nitrous oxide. The production and use of nitrogenous fertilizers add all three of these gases to the atmosphere. The synthesis of ammonia requires a lot of energy, usually provided by the burning of coal, which emits carbon dioxide, or natural gas, which in turn emits methane. The use of fertilizers also adds nitrous oxide to the atmosphere. Altogether, synthetic nitrogen fertilizers are estimated to account for about 1% of global greenhouse gas emissions.

(Shortform note: A 2014 study examined the effect nitrogen fertilizers have on carbon emissions and found that nitrous oxide emissions could be significantly reduced by simply using the correct amount of fertilizer. According to the study, agriculture accounts for 8 to 14% of global greenhouse gas emissions, and around 80% of nitrous oxide emissions. These numbers could be drastically reduced by limiting the over-fertilization of crops, as using the exact right amount of fertilizer has shown a sharp decrease in nitrous oxide emission.)

Nitrogen Fertilizers Lead to Nitrogen Loss

According to Smil, nitrogen fertilizers also contribute greatly to nitrogen loss, which affects crop yields and makes us more dependent on synthetic nitrogen. Nitrogen loss happens when the nitrogen naturally found within the soil decreases. As more and more nitrogen is removed from the soil, crop yields become smaller, which could lead to widespread hunger and famine. Because of this, farmers will have to increase their use of synthetic nitrogen fertilizers, further adding to the problem.

To avoid this vicious cycle, we must find a way to reduce the use of nitrogen fertilizers, whether through increased fertilizer efficiency or a more sustainable, natural supply of nitrogen.

(Shortform note: One of the main ways nitrogen leaves soil is through leaching: when nitrogen leaves the soil through drainage water, usually rainwater or irrigation. A 2022 study provided three ways to prevent nitrogen loss caused by leaching. First, farmers can mitigate drainage by carefully managing the amount of irrigation when there is heavy rain. Second, farmers should avoid overfertilizing so that more nitrate isn’t lost to drainage. Third, farmers can plant “cover crops” during times when no cash crop is growing. Rye, for example, can be grown in the winter and helps soak up some of the nitrogen that’s normally washed away during this time.)

Food Waste Exhausts Labor and Energy and Harms the Environment

Smil argues that reducing global food waste would greatly benefit the environment. The amount of food humans waste is massive. According to the UN, at least a third of all harvested food is wasted. The biggest contributor is the United States, with over 40% of food going to waste—an amount that would be enough to feed about 230 million people annually.

Further, when we waste food, we also waste a great deal of labor and energy while furthering the damage to the environment. If we wasted less food, we’d have less soil erosion, nitrogen loss, and greenhouse gas emissions.

(Shortform note: A Finnish study from 2012 evaluated the impact of food waste on a global scale. Globally, an estimated 614 calories per person are wasted every day. For every person on the planet, we waste around 27 cubic meters of water, 300 square meters of land, and 4 kilograms of fertilizer each year. If we just halved the amount of food waste, we could feed up to a billion more people each year and drastically reduce our use of the planet’s natural resources.)

Meat Production Requires a Huge Amount of Crops to Feed Livestock

Another change Smil advocates that could have a great environmental impact is limiting the consumption of meat, especially beef. Reducing all meat consumption would be helpful, but we could make a substantial impact just by eating more chicken and less beef.

One of the main reasons meat is bad for the environment is because of the amount of crops required to feed animals. In North America and Europe, approximately 60% of the total crop harvest is used for feeding livestock. Cows, in particular, require a lot of feed for the amount of meat they provide. Chickens require less than a third of the amount of feed to provide the same amount of edible meat.

(Shortform note: In 2014, a team from the Weizmann Institute of Science compared the environmental costs of the most popular livestock-based foods (beef, pork, poultry, dairy, and eggs). The main takeaway from the study confirms Smil’s argument: that beef has by far the largest environmental impact. Compared with poultry, beef requires about 28 times more land, 11 times more water, 6 times more nitrogen, and releases 5 times the amount of greenhouse gases. The study also found that pork, poultry, eggs, and dairy have relatively similar environmental impacts.)