Climate Change – Super Facts

Scientists Agree that Global Warming is happening and that we are the Cause

Super fact 34: Climate Scientists agree that Global Warming or if you call it Climate Change is happening, and that it is caused by us primarily because of our burning of fossil fuels. There is a long-standing scientific consensus on these two facts because the evidence is conclusive. Typically, studies show an agreement of at least 97% or 98% among climate scientists.

This is a super fact because surveys show that this is not what the public believes and yet it is true. The public incorrectly believes that there is a large disagreement among scientists on this topic. A note, to understand why the evidence is conclusive as to why global warming is happening and is caused by us click here.

Note : I will use the term “global warming” in this review. Whether you call the phenomenon climate change, climate disruption, or global heating, is not important.

The Scientific Consensus

This extensive survey from 2013 of 12,000 climate papers (papers published over two decades) by Dana Nuccitelli and Cook, etc., concluded that 97.1% of climate scientists endorsed the consensus position that humans are causing global warming.

They also did a science author self-rating which concluded that 97.2% of climate scientists endorsed the consensus position that humans are causing global warming. Another conclusion from the survey was that the consensus had increased from around 90%, perhaps less, in the early 1990’s.

A later review of six independent, peer-reviewed studies examining the scientific consensus about global warming have concluded that between 90% and 100% of climate scientists are convinced human-caused global warming is happening. A more recent study (2021) found that as many as 98% of climate scientists are convinced global warming is happening and is human-caused. Numerous other surveys have concluded the same thing.

People’s Beliefs About Global Warming

This 2024 survey from Yale University show that most Americans (61%) understand that global warming is mostly human caused. By contrast, 28% think it is caused mostly by natural changes in the environment. Most Americans (58%) <<Link-6>> understand that most scientists think global warming is happening. This percentage has trended generally upward since this survey began in 2008. By contrast, about one in five (22%) think there is a lot of disagreement among scientists about whether global warming is happening.

The green graph corresponds to “most scientists think global warming is happening (%).” The black graph corresponds to “there is a lot of disagreement among scientists (%)”. The yellow graph corresponds to “Most scientists think global warming is NOT happening (%)”. Graph taken from the Yale Program on Climate Change Communication.

However, only one in five Americans (20%) understand that nearly all climate scientists (more than 90%) think that human-caused global warming is happening. The aforementioned Dana Nuccitelli refers to this in his book Climatology versus Pseudoscience as the consensus gap. Again, this large discrepancy between public perception and reality makes the consensus gap a super fact. Research has shown that this discrepancy has a large impact on people’s other beliefs regarding global warming.

The question was, To the best of your knowledge what percentage of climate scientists think that human-caused global warming is happening? Graph taken from the Yale Program on Climate Change Communication.

Why is there a Consensus Gap?

In his book Climatology versus Pseudoscience Dana Nuccitelli explains that a relatively small group of so-called climate skeptics, or more accurately called climate contrarians have received a lot of attention from media. Even though their science is bad, and they’ve published their error ridden papers in obscure or discredited journals, and the fact that their predictions have failed repeatedly many times over, they have had an enormous influence on public discourse. Conservative politicians, and many talk show hosts are blindly devoted to their falsehoods, whilst real scientists are being attacked.

It is not just rightwing media who are using them for their purposes, but mainstream media are giving the contrarians undue attention as well. Sensationalism is one issue. A science contrarian claiming that all the climate scientists are wrong, and that he is the only one who finally got it right is a lot more interesting of a story than a repeat of the consensus. Another issue is false balance. Journalist should not feel that they must give equal time to evidence-based science and nonsense, but that is often the case. To read my review of this book click here.

The Oregon Petition

I am mentioning the Oregon petition because I fell for it myself. The Oregon petition was an official looking petition circulated by climate contrarians, claiming that there is no evidence that human-caused global warming will cause catastrophic heating of earth’s atmosphere and disruption of earth’s climate, and that adding more carbon dioxide to the atmosphere would even be beneficial for plants and animals. It got an impressive number of signatures, 32,000 after some years.

However, it turned out that the signatories rarely had climate expertise, and were not scientists, and the survey listed many falsified names such as the names of the Spice Girls and several fictional characters. Less than 200 of the signatories were climate researchers.

It was a con, but it was touted in a lot of media as the truth. I saw it over and over and I believed it. I was later surprised to learn that it was a con and that a scientific consensus existed on global warming / climate change. Learning that I had been bamboozled on this matter was one of the red flags that prompted me to start doing some fact checking on the issue global warming.

To see the other Super Facts click here

Many Popular Environmental Actions Are Ineffective

Super fact 33: Actions such as eating locally, buying organic produce, using paper straws, and recycling can be good for the environment but can also be worse for the environment and these actions often have a much smaller positive impact than alternative rarely considered actions. What are popular actions for the environment is often different from what is effective.

I consider this a super fact because the beliefs regarding what is good for the environment and what is bad for the environment and what has a significant impact and what has not, are often based on popular trends and culture rather than knowledge. We need to educate ourselves. Following trends is not the answer to good stewardship of the planet.

This content was generated by an Artificial Intelligence (AI) system. Asset id: 2531547331

Is Locally Grown Food Really Better for the Environment?

As I explained in this post eating locally is not necessarily ecological. Agricultural products that are grown off season or in non-native environments are often grown in greenhouses, which require a lot of energy and generate significantly more emissions than shipping the produce across oceans would. This is especially true for crops like tomatoes, cucumbers, mangoes and bananas, that require warmer climates to be grown in open fields.

In some cases, the crop requires significant water resources or chemical inputs to thrive and may not be suitable for warmer climates, for example, apples. Some crops, like avocados or almonds require a lot of water but despite that they are grown in dry places like California (80% of California’s freshwater is used for agriculture). From an environmental perspective it would be better to grow these crops in a suitable environment and then transport them.

Is Eating Organic Really Good for the Environment?

As explained in this post eating organic is not necessarily ecological. Despite strong public perception of organic agriculture producing better environmental outcomes, conventional agriculture often performs better on environmental measures including land use, greenhouse gas emissions, and pollution of water bodies. There are, however, some contexts where organic agriculture may be better for the environment.

The graph below gives an overview of the environmental impact of various types of crops grown organically and conventionally. As you can see organic crop often require double as much land compared to conventionally grown crops. It is complicated.

Shown is the relative environmental impact of organic and conventional agriculture across various ecological and resource indicators based on a meta-analysis of 164 published life-cycle analyses (LCAs) across 742 agricultural systems. Roughly, lower in the graph means organic is better and higher up in the graph means conventional farming is better. Data source: Clark & Tilman (2017) – Comparative analysis of environmental impacts of agricultural production systems, agricultural input efficiency, and food choice. In Environmental Research Letters. The data visualization is available at OurWorldinData.org<<Link-10>>. There you can find research and more visualizations on this topic. Licensed under CC BY-SA by the authors Hannah Ritchie and Max Roser.

What really matters though is the type of food you eat, not whether it is organic or not. For example, beef (from beef herd) causes emissions 188 times larger than nuts do for the same amount of protein provided. Another thing to note is that if you eat 300 steaks per year you will have a 100 times larger environmental impact from your meat eating compared to someone who eats 3 steaks per year. You don’t have to become a vegetarian to have a smaller environmental impact but quantity matters.

Is Recycling Important?

The common perception that recycling is one of the best things you can do for the environment is not correct. Its impact is often not very large and if not done properly it can be counterproductive. If you throw a greasy pizza box in the recycling, you can ruin the entire batch.

Surveys across 21,000 adults in 30 countries showed that the two actions among twelve that people believed saved the most greenhouse gases were recycling (59%) and upgrading lightbulbs (36%). As it turns out, those two saved the least greenhouse gases among the twelve options. The option saving the most greenhouse gases among the 12 was giving up an SUV, which saved 18 times as much greenhouse gases as recycling. 17% of respondents picked that one.

According to Our World in Data (and the book Not the End of the World page 114<<Link-6>>), which is based on this research, giving up an average SUV for a sedan would save 3.6 metric ton, or 22.5% of the carbon emissions for the average American. Switching to a plant-based diet would save 2.2 metric ton per person, or 13.8%. Recycling comes in at a savings of 0.2 metric tons according to the same data. EPAs estimates are slightly higher but still low in comparison.

Plastic straws versus paper straws

Producing a plastic straw requires 39 kilojoules of energy and produces 1.5 grams of carbon dioxide emissions. However, producing a paper straw requires 96 kilojoules of energy and produces 4.1 grams of carbon dioxide emissions. So, plastic straws are better for the environment from that perspective. However, this could be compared to a typical passenger vehicle, which emits about 4.6 metric tons of CO2 per year according to EPA. That corresponds to more than 3 million plastic straws and more than one million paper straws.

According to the same article the average passenger vehicle emits about 400 grams of CO2 per mile. So, driving just one mile corresponds to hundreds of plastic straws and paper straws.

One advantage of paper straws is that they are easier to recycle, at least under ideal circumstances. Unfortunately, they often get soggy, and recycling plants don’t want that so they often throw them out. Another advantage is that paper straws decompose and don’t end up in our ocean.

However, not only are straws very small items, most of the plastic pollution in the ocean does not come from north America(1%) or Europe (1%). Paper straws versus plastic straws seem like a complex riddle but it may not be an important one. Whether you drive more or drive less is probably a lot more important.

Plastic bags versus paper bags

As with plastic straws versus paper straws plastic bags versus paper bags is a complicated question. From an environmental perspective they both have advantages and disadvantages. Plastic bags are less carbon intensive to produce, are easier to reuse several times, and the production of plastic bags require on average four times less energy than the production of paper bags.

On the other hand, paper bags are decomposable and easier to recycle. However, the chemicals and fertilizers used in producing paper bags create additional harm to the environment. It is a complicated question.

Plastic Ocean pollution. Whale Shark filter feeds in polluted ocean, ingesting plastic. Asset id: 1120768061 by Rich Carey

Having a Significant and Positive Impact on the Environment

Some of the allegedly sustainable practices and actions mentioned above are counter productive and others have a very small effect, for example, carbon emissions savings that are a few grams. According to the “Our World Data” and the book “Not the End of the World” page 114, a compilation of data research, some actions that you can take that will significantly reduce carbon emissions are (savings in metric tons per year, for flight it is per trip):

Giving up an SUV 3.6 tons
Go car free (average car) 2.4 tons
Switch to plant-based diet 2.2 tons
Avoid transatlantic flights 1.6 tons
Buy green energy 1.5 tons
Switch to electric car (from average sedan) 1.2 tons
Switch from electric car to none 1.2 tons
Avoid medium flight 0.6 tons (1,700 miles each way going and returning)
Laundry in cold water 0.25 tons
Hand-dry clothing 0.2 tons
Recycle 0.2 tons
Upgrade light bulbs 0.1 tons

As you can see in the graphs below, the largest contributor of greenhouse gas emissions in the World and in the United States is electricity and heat. Unfortunately, the composition of the electric grid is something we as consumers have very little control over. We can save energy, get solar panels for our roof, or buy our electricity from green energy companies, but we cannot easily change the composition of the grid. Energy companies and politicians must do that.

However, we can make our voices heard by calling and writing to our representatives. This might be the single most impactful action that you as an individual can take. Your congressman, senator, or state legislator will probably not read your letter. They have hundreds of thousands or millions of constituents and get lots of letters every day. What is likely to happen is that a staff member will skim the letter and note the concern in a database.

Just make sure that your letter is politely written so it does not go in the wastebasket. Also make sure that you are a constituent. Writing to Ted Cruz when you live in Florida is not going to have an impact. They are interested in finding out what the concerns of their constituents are and according to staff members and other information I have come across, this really has an impact.

Data source : Climate Watch (2024). Note : Land use emissions can be negative. OurWorldinData.org/co2-and-greenhouse-gas-emissions| CC BY

Conclusion

The survey mentioned above showed that among the twelve environmental actions an individual could take, the one with the second to smallest positive impact was the one that the majority thought had the biggest positive impact, despite it having a relatively tiny impact. The actions that could really make a huge difference were hardly considered.

We, the public, are very bad at determining what is good or bad for the environment and what has a significant and positive impact or not, even though the data is out there and we easily can look it up. Maybe the biggest positive impact one could have on the environment is to look up the facts and get better educated.

To see the other Super Facts click here

Climate Science versus Pseudo Science

The goal of this blog is to create a list of what I call super facts. Important facts that we know to be true and yet they are surprising, shocking or disputed among non-experts. It is a type of myth busting. However, I also create posts that are not super facts but other interesting information, such as this book review and book recommendation.

Climatology versus Pseudoscience: Exposing the Failed Predictions of Global Warming Skeptics by Dana Nuccitelli

Climatology versus Pseudoscience by Dana Nuccitelli is a book about human-caused Climate Change, or global warming, and how we know that is happening and how we know that we are the cause of it. If you want to see more about why we know this click here.

The book pays a lot of attention to so called climate skeptics; more accurately called climate contrarians. They are not true skeptics but agenda driven contrarians. Even though their science is bad, and their predictions have failed repeatedly many times over, they have had an enormous influence on public discourse. Conservative politicians, and many talk show hosts are blindly devoted to their falsehoods, whilst real scientists are being attacked. Large segments of the population in the United States, and to some extents elsewhere, have been bamboozled by the pseudo-science.

The good news is that people are waking up to the reality that they have been bamboozled. We know that global warming, or if you call it climate change, is not only real, but we also know that the current rapid warming is caused by us, primarily via our carbon emissions. I was bamboozled by the pseudo scientists myself, but then I took a serious look at the science, and I realized that that I had been bamboozled. This book will walk you through the faulty arguments of the climate contrarians, and it does so in a logical and convincing manner. It features hundreds of references. I bought the hardback version of this book.

Hardcover – Publisher – Praeger; Illustrated edition (March 3, 2015), ISBN-10 : 1440832013, ISBN-13 : 978-1440832017, 232 pages, item weight : 1.3 pounds, dimensions : ‎ 6.14 x 0.56 x 9.21 inches, it costs $11.96 – $53.00 on US Amazon. A new copy is $53.00. Click here to order it from Amazon.com.
Kindle – Publisher – Praeger; Illustrated edition (March 3, 2015), ASIN : B0C71FFTQT, 230 pages, it costs $50.35on US Amazon. Click here to order it from Amazon.com.

Front cover of Climatology versus Pseudoscience. Click on the image to go to the Amazon page for the hardcover version of the book.

Amazon’s Description of Climatology versus Pseudoscience

This book explains the science of climate change in plain language and shows that the 2 to 4 percent of climate scientists who are skeptical that humans are the main cause of global warming are a fringe minority—and have a well-established history of being wrong.

Although some politicians, pundits, and members of the public do not believe it, global warming predictions by mainstream climate scientists have been remarkably accurate while those made by climate deniers have not. And if mainstream global warming predictions continue to prove correct, the window of opportunity to prevent a climate catastrophe is quickly closing. This book is the first to illustrate the accuracy—and inaccuracy—of global warming predictions made by mainstream climate scientists and by climate contrarians from the 1970s to the present day. Written in simple, non-technical language that provides an accessible explanation of key climate science concepts, the book will appeal to general audiences without previous knowledge about climate science.

This is my five-star review for Climatology versus Pseudoscience

A Journey into Climate Science and a Debunking of Climate Contrarianism

The author starts out by giving us an overview of climate science starting with the discovery of the greenhouse effect by Jean Baptiste Joseph Fourier in 1820’s. He explains that the planet would be much colder than it is if it wasn’t for the greenhouse effect. The greenhouse effect acts like a blanket. He also explains why we know that the global warming that we have seen in recent decades is a greenhouse effect chiefly caused by our burning of fossil fuels, and not natural causes.

The warming is leaving behind various fingerprints, such as the upper atmosphere cooling while the lower atmosphere is warming (like a blanket would), which wouldn’t happen if it was the sun or an orbital cycle causing the warming. The conclusion is that we know that global warming is real, and we know that we are the ones causing it.

Note : I will use the term “global warming” in this review. Whether you call the phenomenon climate change, climate disruption, or global heating, is not important.

The author also discusses climate models, and he notes the astounding accuracy of the early climate models. He takes us on a journey through the development of modern climate science into the 1950’s, and the rapid growth of climate science in the 1960’s and 1970’s and then into the 1980’s, 1990’s and the 2000’s. He describes the increasingly advanced and increasingly accurate climate models. In addition, he discusses sulfate aerosols and global warmings forgotten evil twin ocean acidification.

This is all very interesting to any science nerd and it makes you understand why we know that we are causing the global warming we are seeing. It also makes it obvious why there is a consensus on the topic. Several studies have shown that at least 97% of climate scientists believe that global warming is real and that we are the cause of it.

However, despite the scientific rigor of peer reviewed mainstream climate science, despite the impressive success of climate models, and despite the scientific consensus, the public is very confused about the topic. Enter a small group of so-called global warming skeptics, or more accurately, global warming contrarians. They are not true skeptics but agenda driven contrarians. Even though their science is bad (pseudoscience) and the fact that their predictions have failed repeatedly many times over, they have an outsized presence in the media and often a large enthusiastic following.

It is not just rightwing media who are using them for their purposes, but mainstream media are giving the contrarians undue attention as well. Sensationalism is one issue. A science contrarian claiming that all the climate scientists are wrong, and he is the only one who finally got it right is a lot more interesting of a story than a repeat of the consensus. Another issue is false balance. As a journalist you should not feel that you must give equal time to evidence based science and nonsense.

The author also discusses various myths and false claims spread by climate science contrarians. He mentions that unfortunately most Republican congressmen stand with the contrarian pseudoscientists rather than with the science. Well, with the exception for a few brave souls. On average the American public believe that 55% of scientists agree that we are the cause behind the global warming while the consensus is more than 97% and growing stronger. The author refers to this as the consensus gap.

It is easy to be confused. I have a degree in physics and a PhD in electrical engineering / robotics and yet I was bamboozled by the climate science contrarians. I read books by the contrarians including some of the ones the author discusses, and I believed them. I also followed pretty much only rightwing media at the time and as a result I became misinformed. It was not until I took a deep dive into the subject and read what the actual science said that I realized that I had been bamboozled. Some of the science articles that initiated my change of heart were written by the author. That was back in 2012 and 2013.

This book is a great start if you want to take a serious look at climate science. The book is well organized, and the author is an expert on the subject, as well as a great communicator. Even though many of the things he discussed in the book were not new to me, I very much enjoyed reading the book and I learned some new things. If you don’t know much about climate science but are interested in science, then this book is a must read.

Back cover of Climatology versus Pseudoscience. Click on the image to go to the Amazon page for the Kindle version of the book.

About the Author of Climatology versus Pseudoscience

Dana Nuccitelli is an environmental scientist and climate blogger for The Guardian and SkepticalScience.com. He’s been researching and writing about climate science since 2006. He has a bachelor’s degree from UC Berkeley in astrophysics, and a master’s degree from UC Davis in physics.

To see the Super Facts click here

Environmental Benefits of Recycling Are Overestimated

Super fact 32: The common perception that recycling is one of the best things you can do for the environment is an exaggeration. Its impact is often not very large and if not done properly it can be counterproductive.

In general recycling is beneficial, because you conserve natural resources, reduce climate change, save energy and reduce waste and pollution. Battery recycling is particularly important since it reduces toxic waste and reduces the risk of a future shortage of certain minerals. Recycling is often viewed as a very important activity that everyone should participate in, and neighbors often shame those who fail to comply.

The shocking news is that even though recycling in general is good for the environment it may not be as beneficial as it is assumed. It turns out to be complicated. As you will see later, most people think that recycling is the most impactful action you can take as an individual to reduce carbon emissions, when in fact it is of very marginal importance. This is what made me consider this a super fact.

Recycling and Greenhouse Gases

According to EPA recycling saves 193 million metric tons of carbon emissions, which sounds a lot until you consider that the US emit 6,343 million metric tons per year according to EPA making it 3%. According to this website consumers can save 732 kilograms of CO2 assuming they do the recycling correctly. This should be compared to the average carbon footprint for an American (US), which is 16 metric tons, making the savings for good recyclers 4.6%.

According to our World in Data (Not the End of the World page 114), based on this research, giving up an average SUV for a sedan would save 3.6 metric ton, or 22.5%. Switching to a plant-based diet would save 2.2 metric ton per person, or 13.8%. Actions saving more greenhouse gases than recycling that we as consumers can take, are for example: give up SUV, go car free, have a plant-based diet, avoid transatlantic flights, buy green energy, switch to electric car, switch from electric car to no car, avoid medium flights, laundry in cold water, and hand dry clothing.

Surveys across 21,000 adults in 30 countries showed that the two actions that people believed saved the most greenhouse gases were recycling (59%) and upgrading lightbulbs (36%). Upgrading lightbulbs have an even smaller effect than recycling. It is of course still a good action to take.

However, what this data demonstrates is that we are bad at guessing which actions are impactful. We need to get better informed and not make assumptions. It should be noted that the efficiency of the recycling efforts varies from country to country. Among the 32 developed countries for which there is data the United States ranks 25.

Recycling and Plastic Waste

Greenhouse gas emissions is certainly not the only issue to consider. What about plastic waste? As it turns out plastic is very difficult to recycle (depending on the kind of plastic) and according to the EPA less than 9% of plastic is recycled. According to Our World in Data and the book “Not the End of the World” by Hannah Ritchie the US and Europe have well managed landfills and good waste management systems that make our plastic problem less of an issue. That’s good news.

But what about the awful problem with plastic in the ocean? Plastic ending up in the ocean is indeed a bad problem. However, 81% of all plastic in the ocean come from Asia, and the rest mostly comes from Latin America. Only 1% come from the United States and 1% from Europe and Oceania. According to Scientific American 93% of plastic in ocean come from just 10 rivers. Eight of them are in Asia: the Yangtze; Indus; Yellow; Hai He; Ganges; Pearl; Amur; Mekong. Two are in Africa – the Nile and the Niger.

None of them are in North America or Europe. Therefore, if we in the developed world greatly improve our recycling of plastic, it would not make much of a difference with respect to the problem of plastic in the ocean. What we need to do is assist China, India and southeast Asia with improving their waste management systems.

Another issue to keep in mind is that uneducated consumers can do a lot of damage to the recycling process. For example, throwing a greasy pizza box into the recycling bin can ruin the entire batch. You are not just recycling incorrectly you are ruining the recycling efforts of your neighbors too. There are many ways to ruin the recycling process, by throwing items in the recycling that don’t belong there. Recycling requires consumers to pay attention to the instructions. It should also be noted that some companies have been found to ignore the recycling process and throw all recycled items in with the trash. There are also neighborhoods that don’t have recycling.

Conclusion

In summary, recycling may not be as great as it is often made out to be. You should still do it if you care about the environment. Just be aware that there are actions that you can take and that your government can take that are much more impactful.

One of the conclusions you can draw from this discussion is that if you are driving a big SUV or eating red meat every day you should probably abstain from shaming your neighbor for not recycling.

To see the other Super Facts click here

Eating Organic is not Necessarily Ecological

Super fact 31: The common perception that organic food is by default better for the environment or is an ideal way to reduce environmental impact is a misconception. Across several metrics, organic agriculture proves to be more harmful for the world’s environment than conventional agriculture.

There are things you can do as an individual to reduce your carbon footprint, use public transportation instead of driving, fly less, eat less read meat, don’t waste food, reduce your energy usage. There are straightforward actions you can take to reduce your use of water and avoid adding harmful pollution to the environment. However, as with eating locally grown food, eating organic food is often viewed as an environmentally friendly choice even though it often is not.

Organic farming is a method of growing food without using synthetic chemicals or genetically modified organisms (GMOs). Organic farming practices are intended to protect soil fertility, promote ecological balance, and reduce environmental impact. That’s all good. On the other hand, it should be noted that modern farming techniques, for example, using synthetic pesticides, have greatly increased cereal yield per acre and GMOs can reduce the use of toxic pesticides. It is complicated.

I consider this a super fact because it is often incorrectly assumed that eating organic food is the best choice for the environment.

Global Land Use

Before looking at the details of conventional farming versus organic farming lets look at global land use. In the figure below from Our World in Data you can see that agriculture already uses nearly half of all habitable land in the world. We cannot easily enlarge this percentage and therefore crop yield per acre is a very important factor to consider, and this is a great weakness for organic farming.

Also notice that 80% of agricultural land is used for livestock, meat, dairy and textile, but it only provides 17% global calorie supply. This second observation indicates that the type of food you eat may matter a lot more than whether it is produced via organic or conventional farming.

Global land-use graphics. Licensed under CC-BY by authors Hannah Ritchie and Max Roser (September 2023).

As you can see in the graph below, again from Our World in Data, the land used for producing 100 grams of protein varies enormously between different food groups. 100 grams of protein from lamb and mutton require on average 52.8 times as much land as 100 grams of protein from groundnuts. This graph does not make a distinction between organic farming and conventional farming, but it highlights the huge difference between different food sources. I’ll get to the difference between organic farming and conventional farming with respect to land use later in the post.

Additional calculations by Our World in Data. OurWorldinData.org/environmental-impacts-of-food | CC BY

Agriculture and Greenhouse Gas Emissions

The next two graphs focus on the greenhouse gas emissions including those from agriculture. Electricity and Transport dominate both globally and in the United States, but globally agriculture comes in at 6 billion of the 40 billion tons of greenhouse gas emissions for 2021, which is 15%. For the United States agriculture comes in at 10.6% of greenhouse gas emissions for 2021. In other words, agriculture was not the largest contributor of greenhouse gas emissions but still an important factor.

Finally, the contribution for different types of food. Notice that beef (beef herd) at 49.89kg is 188 times larger than the 0.26kg for nuts. 188 people eating nuts contribute as much to carbon emissions as one person eating beef.

Greenhouse gas emissions per 100 grams of protein. Greenhouse gas emissions are measured in kilograms of carbon dioxide equivalents (see below). Data source: Poore and Nemecek (2018). OurWorldinData.org/co2-and-greenhouse-gas-emissions| CC BY

Carbon dioxide equivalents (CO2eq)

Carbon dioxide is the most important greenhouse gas, but not the only one. To capture all greenhouse gas emissions, researchers express them in “carbon dioxide equivalents” (CO2eq). This takes all greenhouse gases into account, not just CO2. To express all greenhouse gases in carbon dioxide equivalents (CO2eq), each one is weighed by its global warming potential (GWP) value. GWP measures the amount of warming a gas creates compared to CO2. CO2 is given a GWP value of one.

If a gas had a GWP of 10 then one kilogram of that gas would generate ten times the warming effect as one kilogram of CO2. Carbon dioxide equivalents are calculated for each gas by multiplying the mass of emissions of a specific gas by its GWP factor. This warming can be stated over different timescales. To calculate CO2eq over 100 years, we’d multiply each gas by its GWP over a 100-year timescale (GWP100). Total greenhouse gas emissions – measured in CO2eq – are then calculated by summing each gas’ CO2eq value.

Environmental Impact of Organic Versus Conventional Agriculture

At this point it should be clear that eating different types of food, nuts and vegetables versus red meat makes huge difference regarding the environment. How about organic versus conventional farming? Well, it is complicated. You have to take into account land use, greenhouse gas emissions, biodiversity, pesticide application, energy use and more.

Clark and Tilman (2017) published a meta-analysis of results of published organic-conventional comparisons across 742 agricultural systems over 90 unique foods. The food groups consisted of cereals, pulses and oil crops, fruits, vegetables, dairy and eggs, and meats. As you can see in the resulting graph below organic agriculture is worse for the environment for most food groups with regards to land use, eutrophication potential, and acidification potential. The result is mixed with respect to greenhouse gas emissions and energy use.

It appears that it is best to choose organic pulses and fruits and choose non-organic for all other food products (cereals, vegetables, dairy and eggs, and meat). However, if your primary concern is whether the potato accompanying your steak is conventionally or organically produced, then your focus is arguably misplaced. Whether you go organic or non-organic the steak is much worse for the environment.

Conclusion

In this post I present empirical evidence from reliable sources comparing organic to conventional agriculture in terms of environmental impact. Despite strong public perception of organic agriculture producing better environmental outcomes, conventional agriculture often performs better on environmental measures including land use, greenhouse gas emissions, and pollution of water bodies. There are, however, some contexts where organic agriculture may be better for the environment. In short it is complicated.

What really matters though is the type of food you eat, not whether it is organic or not. Another thing to note is that if you eat 300 steaks per year you will have a 100 times larger environmental impact compared to someone who eats 3 steaks per year. Quantity matters. This post was about environmental impacts. There are other considerations such as health, what you like, whom you want to support, etc.