The goal of this blog is to create a long list of facts that are important, not trivia, and that are known to be true yet are either disputed by large segments of the public or highly surprising or misunderstood by many.
Super fact 43 : The United States has emitted more CO2 than any other country to date, around 400 billion tons since 1751. It is responsible for 25% of historical emissions. Click here.
But what about China? That is 12.7%, or around half. This is surprising information to many Americans, yet it is true, and therefore a super fact. In the US it is very common to blame China for our carbon emissions. In China they blame the US. In Europe they blame the US and China. Who is right? It turns out that the blame game is complicated and futile.
Carbon Emissions Around the World
Who should we blame the most for our carbon emissions?
On the other hand, the US carbon emissions per capita (14.3 ton) is considerably larger than that of China (8.4 ton). China has 1.4 billion people after all and the US only 340 million people.
On the other hand, China used to be very poor and is quickly catching up to our standard of living with the help of fossil fuels, just like the western world once did.
It should also be noted that the countries that are emitting the most carbon emissions per capita are several smaller developing (third world) countries including Palau, Qatar, Kuwait, Brunei, New Caledonia, Bahrain, United Arab Emirates, Trinidad and Tobago, Gibraltar, Saudi Arabia, Oman, etc.
On the other hand, according to this analysis presented in the Guardian, the Netherlands has the highest per capita historical emissions, followed by the UK in second place. The analysis calculates the national cumulative emissions from 1850 per person, based on today’s population, among countries with populations of at least 1 million.
In other words, if you want to blame another country for the carbon emissions, take your pick, well your cherry pick. Why should we do something about our carbon emissions when X is worse? Those who want no action on the global warming / climate change problem love the blame game. Like denial or despair, which are both irrational positions, the blame game hinders action. The blame game can also get very complicated and contentious.
The graph shows the fossil fuel emissions (in carbon dioxide equivalents) per capita from 1750 to 2023 for the World, the United States, Canada, China, European Union, India, South Africa, United Kingdom, and Kenya. Notice that the United Kingdom dominated the emissions in the 1700’s and 1800’s. Data source: Global Carbon Budget (2024); Population based on various sources (2024). The graph is from Our World in Data .
Note regarding the graph above: By clicking here you can find this graph and then select to display any set of countries or regions. Have fun experimenting.
Note regarding Fossil emissions: Fossil emissions measure the quantity of carbon emissions (CO2) emitted from the burning of fossil fuels, and directly from industrial processes such as cement and steel production. Fossil CO2 includes emissions from coal, oil, gas, flaring, cement, steel, and other industrial processes. Fossil emissions do not include land use change, deforestation, soils, or vegetation.
Overview of Cumulative Carbon Emissions
As you can see in the graph below the cumulative carbon emissions from 1751 to 2017 are 25% for the United States, 22% for the EU (28 countries), 12.7% for China, 6% for Russia, 4% for Japan, and 3% for India. If you count the entire continent of Europe, you get 33% for Europe.
Figures for the 28 countries in the European Union have been grouped as the EU-28 since international targets and negotiations are typically set as a collaborative target between EU countries. Values may not sum up to 100% due to rounding. Data Source: Calculated by Our World in Data from the Global Carbon Project (GCP) and Carbon Dioxide Analysis Center (CDIAC). This is a visualization from Our World in Data, where you can find data and research on how the world is changing.
Super fact 42 : The developed nations (rich countries) have reduced their carbon emissions since the 1990’s despite continued GDP growth, even if we take offshore production into account. In addition, many developing countries have succeeded in reducing their emissions as well. Other fast-growing developing countries have flattened or at least slowed their increase in carbon emissions. Many countries have decoupled economic growth from CO2 emissions. In other words, we do not need to increase carbon emissions or burn more fossil fuels to grow the economy.
This is good news as well as a surprise to many people who falsely believe that to grow the economy (grow GDP) you need to burn more fossil fuels and an increase in carbon emissions is inevitable if you want to grow the economy. The data shows otherwise. This is important news that is difficult to believe in for many people. It is a super fact.
Carbon Emissions and GDP
In the past carbon emissions were strongly correlated with national wealth. The wealthier a nation was the higher its carbon emissions were and as the economy grew so did the carbon emissions. This has not been true since the 1990’s. The developed nations of the world have continued growing their GDP whilst reducing their carbon emissions.
You may think that the reason is that we shipped much of our manufacturing overseas and that if you consider the consumers in the importing country responsible for the overseas emissions this decoupling of GDP and emissions would disappear. But you would be wrong. Even if you make the consumers in the importing country responsible for the emissions during production in the exporting country the emissions have gone down. One example taken from this article in Our World in Data is the United Kingdom.
In the graph below for the UK the GDP (adjusted for inflation) grew by 53.26% between 1990 and 2023 and the emissions were reduced by 57.66%. If make UK consumers 100% responsible for the emissions in China and India, etc., caused by the production of goods imported to the UK the reduction until 2022 was 38.59%. That is not as much but it is still impressive and demonstrates the decoupling between GDP growth and carbon emissions.
Data source: Data compiled from multiple sources by World Bank (2025); Global Carbon Budget (2024); Population based on various sources (2024). Note: GDP per capita is expressed in international dollars at 2021 prices. Graph taken from Our World in Data.
The text in the graph above is difficult to read so I’ve copied it below in larger text:
Consumption-based emissions: Consumption-based emissions are national or regional emissions that have been adjusted for trade. They are calculated as domestic (or ‘production-based’ emissions) emissions minus the emissions generated in the production of goods and services that are exported to other countries or regions, plus emissions from the production of goods and services that are imported. Consumption-based emissions = Production-based – Exported + Imported emissions.
Fossil emissions: Fossil emissions measure the quantity of carbon dioxide (CO2) emitted from the burning of fossil fuels, and directly from industrial processes such as cement and steel production. Fossil CO2 includes emissions from coal, oil, gas, flaring, cement, steel, and other industrial processes. Fossil emissions do not include land use change, deforestation, soils, or vegetation.
International dollars: International dollars are a hypothetical currency that is used to make meaningful comparisons of monetary indicators of living standards. Figures expressed in constant international dollars are adjusted for inflation within countries over time, and for differences in the cost of living between countries. The goal of such adjustments is to provide a unit whose purchasing power is held fixed over time and across countries, such that one international dollar can buy the same quantity and quality of goods and service no matter where or when it is spent. Read more in our article: What are Purchasing Power Parity adjustments and why do we need them?
Below is the same type of graphs for the United Kingdom as well as France, Germany, Sweden, United States and Finland. The numbers for these countries are as follows:
United Kingdom: GDP growth 53.26%, CO2 emissions reduction 57.66%, trade adjusted CO2 emissions reduction 38.59%.
France: GDP growth 39.74%, CO2 emissions reduction 40.64%, trade adjusted CO2 emissions reduction 28.82%.
Germany: GDP growth 49.04%, CO2 emissions reduction 46.72%, trade adjusted CO2 emissions reduction 33.95%.
Sweden: GDP growth 56.00%, CO2 emissions reduction 48.45%, trade adjusted CO2 emissions reduction 34.75%.
United States: GDP growth 68.05%, CO2 emissions reduction 29.25%, trade adjusted CO2 emissions reduction 17.04%.
Finland: GDP growth 45.69%, CO2 emissions reduction 50.54%, trade adjusted CO2 emissions reduction 42.79%.
Note these are emissions reduction numbers per capita (growth for GDP) not carbon emissions per capita. For example, the United States has three to four times larger carbon emissions per capita as, for example, Sweden or France.
Data source: Data compiled from multiple sources by World Bank (2025); Global Carbon Budget (2024); Population based on various sources (2024). Note: GDP per capita is expressed in international dollars at 2021 prices. Graph taken from Our World in Data.
Many Countries Have Reduced Their Carbon Emissions
However, the story does not end with these six countries or even with the developed world. The 30 graphs below all demonstrate significant reductions in carbon emissions as GDP is growing, demonstrating a decoupling between GDP growth and carbon emissions. Note that Azerbaijan’s GDP grew by 93% as its carbon emissions was reduced by 7% (all carbon emissions below are adjusted for trade).
Data sources: Global Carbon Project & World Bank. There are more countries that achieved the same, but only those countries for which data is available and for which each exceeded 5% are shown. The graphs are from Our World in Data <<Link-1>>. All carbon emissions in the graphs above are adjusted for trade.
The World’s Carbon Emissions Per Capita Has Flattened
World GDP per capita has increased by 83.54% since 1990 while carbon emissions per capita have grown by 9.48%. That may not be as impressive but note two things. That is still a decoupling between economic growth and if you look in the graph, you’ll see that carbon emissions were higher in 2008 to 2019. The curve has flattened and gone down a bit. Global Warming caused by our burning of fossil fuels may be the greatest environmental challenge in recorded history, but we are slowly and steadily turning things around. We are not doing it fast enough to avoid major damage to our eco systems and perhaps civilization, but we are still turning things around. If you have any doubts about global warming / climate change or that we are causing it click here for a summary of the evidence.
Data source: Data compiled from multiple sources by World Bank (2025); Global Carbon Budget (2024); Population based on various sources (2024). The graph is taken from Our World in Data <<Link-1>>.
China’s Carbon Emissions
One reason the world’s carbon emissions per capita have not been reduced much despite the fact that so many countries have reduced their emissions is that the world’s largest emitter China, has grown their carbon emissions steadily since 1990. Between 1990 and 2023 China’s GDP per capita (and adjusted for inflation) grew by 1,245.28% and their emissions grew by 288.43% per capita. Remember that China has 1.4 billion people so that is a big carbon blast for the world.
However, before you blame China too much remember that China’s carbon emissions per capita is less than that of the United States and that of many other developed countries, and the country with the largest cumulative carbon emissions is the United States. China’s economic growth has been immense, and its immense population of 1.4 billion people explains its huge impact on the world’s carbon emissions.
Super fact 41 : Largely thanks to the Montreal Protocol in 1987 the emissions of ozone-depleting gases have fallen by more than 99%, 99.7% to be exact, according to Our World in Data. This has resulted in halting the expansion of the ozone holes and the reduction in emissions of ozone-depleting gases is saving millions of lives every year.
This is my good news for Earth Day, and it is a super fact. It is a super fact because a lot of people believe that the issue with ozone depleting gases and Montreal protocol is bunk. They take the fact that we are not talking about it much nowadays as evidence that there was nothing to it in the first place. However, they are wrong. We typically don’t talk much about environmental problems that have been addressed successfully. The Antarctic ozone hole that we used to worry about is still there, but its worrisome expansion has been halted.
The Reduction of Ozone-Depleting Gases
The ozone layer, located in the stratosphere, protects Earth from harmful UV radiation. Ozone (O3) is naturally created and destroyed in a balance, but ozone-depleting substances damage the ozone layer by releasing chlorine atoms that catalyze the destruction of ozone molecules.
This problem was discovered by Mario Molina and F. Sherwood Rowland in 1974. They were awarded the 1995 Nobel Prize in Chemistry, along with Paul Crutzen, for their work in atmospheric chemistry. Examples of ozone depleting gases are chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), halons, methyl chloroform ,methyl bromide, carbon tetrachloride, hydrobromofluorocarbons, and chlorobromomethane.
Ozone layer depletion diagram. Earth’s sunscreen, shielding us from the sun’s harmful ultraviolet rays. UV A, B, C. UVA, UVB, UVC.
Ozone depletion causes a breakdown of the ozone layer around the world, including the famous Arctic and Antarctic ozone holes. This allows more UV radiation to reach Earth surface, increasing the exposure to harmful ultraviolet (UV) radiation, which can cause skin cancer, cataracts, and immune system damage.
It also harms plants and marine life, as well as climate. It should be noted that this is a different problem from climate change or if you call it global warming, even though ozone depletion to some degree influence climate change. You can read about climate change related super facts here, here and here.
The Reduction of Ozone-Depleting Gases
The good news is that we have been very successful in reducing ozone depleting gases. The Montreal protocol, a landmark international agreement signed in 1987 to protect the Earth’s ozone layer by phasing out ozone depleting gases, has been very successful.
As you can see in the diagram below from Our World in Data. We have had at least a 99% reduction in ozone depleting gases according to the NASA, the World Economic Forum and the UN Environment Program. More specifically, the reduction is 99.7% by 2018 according to Our World in Data.
The phase out of six ozone depleting gases. Data source UN Environment Program (2023).
443 million Cases of Skin Cancer Prevented
The NIH estimate that the Montreal Protocol has prevented 443 million cases of skin cancer, 2.3 million skin cancer deaths, and 63 million cases of cataracts in the United States alone. Globally, it is estimated that the Protocol has saved an estimated 2 million people from dying from skin cancer each year.
Yes, you can read that again :
Worldwide the Montreal Protocol has saved an estimated 2 million people from dying from skin cancer each year.
To read more about the Montreal Protocol and the ultimate repair job click here.
The Antarctic Ozone Hole
What about the Arctic and Antarctic ozone holes? Well, they are not gone but they are retreating. When there is an environmental problem, it does not entirely disappear right away even if you remove the root cause. The same is true for global warming. If we succeeded to stop all carbon emissions tomorrow it would take decades for average temperatures to stop rising and hundreds of years for them to come down to “normal”. But remember it would have been much worse without the Montreal Protocol.
The graph is from Our World in Data and data comes from NASA Ozone watch 2024.
Super fact 39 : Relativistic length contraction goes both ways. If two observers are moving compared to each other both will observe the length of the objects in the other’s system to be shorter in the direction of motion. The first observer will think that a yard stick in the second observer’s frame will be shorter whilst the second observer will think that the yard stick in the first observer’s frame is the shorter one.
Assume a pole and a barn are of equal length when both objects are stationary. If the pole is moving (at a high speed) compared to the barn, then the pole will be shorter than the barn from the barn’s perspective but longer than the barn from the pole’s perspective. Does the pole fit inside the barn or not? This is referred to as the pole-barn paradox, or the barn-door paradox, or the ladder paradox (if a ladder is used instead of a pole).
I call this conundrum a super fact because whilst most people have heard of relativistic time dilation and perhaps length contraction, the fact that it goes both ways comes as a surprising head scratcher. The situation is analogous to my super fact post “Time Dilation Goes Both Ways” where I state:
Super fact 38 : If two observers are moving compared to each other both will observe the other’s time as being slower. In other words, both observers will observe the other’s clocks as ticking slower. Time slowing down is referred to as Time Dilation. And this post is about how time dilation goes both ways.
Both the time dilation paradox and the pole-barn paradox are solved by the non-simultaneity in relativity. However, the pole-barn paradox is more concrete and perhaps more in your face. You can easily imagine the problematic paradox.
Amy is speeding past Alan and his barn at a high speed. Amy has a pole. Because of the high-speed Amy’s pole appears shortened and will easily fit in Alan’s barn. However, to Amy it is Alan’s barn that is contracted, and her pole has the normal length and will therefore not fit in Alan’s barn.
The laws of physics are the same in all inertial frames of reference. An inertial frame is a system that moves at a constant velocity.
The speed of light in a vacuum is constant for all observers, regardless of the motion of the light source.
The first postulate is called the principle of relativity and goes all the way back to Galileo Galilei. It means that no experiment can determine whether you are at rest or moving at a constant velocity. The reciprocity of length contraction follows from this postulate. If the length of the pole in the example above is half as long as the barn in both the barn frame and the pole frame then you could tell who was standing still and who was moving from that fact, and that violates the first postulate. The first postulate demands that if the pole is half as long in the barn frame and that the barn is half as long in the pole frame.
The second postulate is the more shocking one and is special to relativity. It was discovered experimentally at the end of the 19th century but was too difficult for scientists to accept at first so various ad hoc explanations were put forth to explain it away, until the theories of relativity were created. I designated this postulate as my super fact #4 and you can read about it here.
Length Contraction
Time dilation means that a time interval between two events in a certain frame is longer by a factor B in a frame moving relative to the first frame (see picture below). Let’s imagine Amy moving at the speed v compared to Alan and his barn. Amy passes the left side of the barn at a certain time and soon after the right side. The time difference from Alan’s perspective is T and the width of the barn is L, so L = vT. From Amy’s perspective the time difference is T’ and width of the barn L’ and L’ = vT’. We denote Amy’s measurements with a prime. Note the velocity must be the same in both systems. However, Amy’s clock ticks slower (from Alan’s perspective) so T’ = BT or T = T’/B (time dilation). So, L’ = vT’ = vT/B = L/B.
If the derivation of the formulas above is confusing to you, ignore the math, and just remember that Alan measures a shorter time for the passing of the pole (because Amy’s clock is slower) from his perspective and therefore the pole must be shorter as measured from his system. If Alan measures two seconds for the passing of the pole than Amy measures maybe four seconds. It is Amy’s pole, so her longer measurement corresponds to the proper length of the pole whilst Alan’s measurement is the contracted length. Note the length contraction can only happen along the direction of motion, not perpendicular to it. To read more about length contraction click here.
The beta factor used in the formula for time dilation as well as length contraction.
Solution to the Pole-Barn Paradox
So, Amy’s pole cannot fit in Alan’s barn. The pole is moving fast so it must move in and out of the barn. Now let’s create the paradox. Imagine the barn having doors on each side that open for the moving pole and then close for a moment to entrap the pole and then they open as the pole leaves the barn. Here is the paradox, if they open and close at the same time, than the pole can be inside the barn (entrapped) from Alan’s perspective but not from Amy’s perspective. From Amy’s perspective the pole does not fit.
However, the solution to the paradox lies in “open and close at the same time”. If the doors open and close at the same time from Alan’s perspective, then they don’t open and close at the same time from Amy’s perspective.
From Amy’s perspective the door on the left side will open first and let the pole in and then after that the right door will open. After the pole has fully entered the barn and some of it is sticking out on the right-hand side then the left door will close but the door on the right will remain open until the pole is entirely outside. Relativistic non-simultaneity solves the paradox.
In Alan’s frame the doors can be closed at the same time and enclose Amy’s pole. In Amy’s frame the doors open and close to let the pole through but they don’t open and close at the same time.
Finally, below is a YouTube video that explains and solves the pole-barn / barn-door / ladder paradox simply and efficiently in a little over two minutes.
Einstein’s Miraculous Year. This book features the translations of the five famous papers that Albert Einstein wrote in 1905 including “On the Electrodynamics of Moving Bodies”, which was his paper on Special Relativity. Not for the faint of heart but very interesting.
Super fact 38 : If two observers are moving compared to each other both will observe the other’s time as being slower. In other words, both observers will observe the other’s clocks as ticking slower. Time slowing down is referred to as Time Dilation. And this post is about how time dilation goes both ways.
A lot of people know that if someone moves very fast his clocks will run slower. That’s relativity. If someone speeds through space in a rocket ship, close to the speed of light his time will slow down. When one hour passes on earth only half an hour may pass in the rocket. What comes as a shock to many people is when they find out that the converse is also true. When one hour passes in the rocket only half an hour will pass on earth.
Clearly that looks like a contradiction, but there is an explanation. I consider this a super fact because it is so strange and almost impossible for people to believe, and yet it is true.
The guy on earth says my clock (left) is ticking double as fast as the rocket man’s clock (right). The rocket man say’s my clock (right) is ticking double as fast as the clock on earth (left). Who is right? Surprisingly both of them.
The laws of physics are the same in all inertial frames of reference. An inertial frame is a system that moves at a constant velocity.
The speed of light in a vacuum is constant for all observers, regardless of the motion of the light source.
The first postulate is called the principle of relativity and goes all the way back to Galileo Galilei. It means that no experiment can determine whether you are at rest or moving at a constant velocity. The reciprocity of time dilation follows from this postulate. If the time for the rocket man in the example above was ticking at half the speed compared to the time for the guy on earth and they both agreed, then you could tell who was standing still and who was moving from that fact.
The first postulate demands that they disagree. The guy on earth thinks the rocket man’s clock is ticking at half the speed of his own clock, whilst the rocket man think it is earth man’s clock that is going slow. Therefore, you can’t tell who is standing still, which is what the first postulate requires.
The second postulate is the more shocking one and is special to relativity. It was discovered experimentally at the end of the 19th century but was too difficult for scientists to accept at first so various ad hoc explanations were put forth to explain it away, until the theories of relativity were created. I designated this postulate as my super fact #4 and you can read about it here.
In this picture Amy is traveling past Alan in a rocket. Both have a laser. Both measure the speed of both laser beams to be c = 299,792,458 meters per second. The speed of light is a universal constant.
Time Dilation
In the pictures below I am showing two rocket systems in space, Amy’s rocket and Alan’s rocket. They are travelling at a high speed compared to each other. Each rocket has a light clock that consists of a light beam bouncing up and down between a mirror in the ceiling and a mirror on the floor. The two light clocks are identical, and each bounce corresponds to a microsecond.
Amy is passing Alan at a high speed, and therefore Alan will see Amy’s light clock running slower than his because Amy’s light beam must travel further. Remember, the speed of light is identical for both light clocks (light speed is a universal constant). For those interested I am also deriving the formula for time dilation.
Alan and Amy have identical light clocks. We call the time it takes for the light beam to go from the floor to the ceiling (one clock tick) Dt in Amy’s case and Dt’ (reference frame) for Alan. Amy is speeding past Alan towards the left. From Alan’s perspective Amy’s clock is running slower. Using Pythagoras theorem, it is possible to derive the formula for time dilation shown in the lower left corner.
Since Amy moving left is the same as Amy standing still and Alan moving right you can say that Alan is the one moving fast. In this case it is Alan’s light clock that is ticking slower because from this viewpoint it is his light beam that has to travel further. From Amy’s perspective it is Alan’s clock that is going slower.
It is equally correct to say that Amy is standing still and that it is Alan that is moving fast to the right. This time (pun not intended) it is Alan’s clock that is ticking slower. Dt corresponds to Alan’s clock ticks and Amy’s clock ticks are Dt’.
This seemingly contradictory situation is resolved by the fact that Amy’s and Alan’s perspectives will drift apart as they continue their journey. They will increasingly disagree on whether events are simultaneous or not, and they will disagree in which order events occur. This is another shocking fact, or as I refer to it, super fact. It is strange but it resolves the apparent contradiction of reciprocal time dilation. I am explaining this in greater detail in this post.
The Twin Paradox
But what happens if one of Amy or Alan decides to turn around so that they meet up again. If Amy’s clock runs slower from Alan’s perspective and Alan’s clock runs slower from Amy’s perspective, how can you reconcile that when they meet up again? It turns out that whoever is turning around or accelerating or decelerating to turn back is the one who will have the least time pass. If Amy is the one turning back, then she will age less than Alan. During her acceleration she will see Alan’s clock starting to run faster and faster until he is older her.
Let say Alan’s clock is running half the speed of Amy’s clock from Amy’s perspective and Amy’s clock is running half the speed of Alan’s clock from Alan’s perspective. Let’s also say that Amy traveled to the left for 10 years before turning around.
From Alan’s perspective she would have traveled 20 years before turning around. However, from Amy’s perspective 5 years would have passed on Alan’s clock. As she turns around Alan’s clock will run faster and catch up so that when they meet up again Amy will be aged 20 years, while Alan will be aged 40 years. That is 35 years of catching up for Alan’s clock from Amy’s perspective. Alan’s clock advanced 35 years from Amy’s perspective after Amy turned around. In the end Amy will be the younger one.
Observe that the fast-forward advancement of Alan’s clock from Amy’s perspective happens only while Amy is in the process of turning around (accelerating / decelerating). Further, how fast the fast forward happens depends on the distance as well. Once Amy is traveling at a constant speed again (inertial frame) Alan’s clock will run slower again from Amy’s perspective.
A somewhat halting but OK analogy for the 35 years of catching up that happens on Alan’s clock from Amy’s perspective is when you turn a boat around on a wavy sea. As you are moving in the direction of the waves the waves will hit you much less often (if at all) but after you turn around and move against them the waves will hit your boat very frequently. Alan’s clock will run faster for Amy whilst she is turning around.
Einstein’s Miraculous Year. This book features the translations of the five famous papers that Albert Einstein wrote in 1905 including “On the Electrodynamics of Moving Bodies”, which was his paper on Special Relativity. Not for the faint of heart but very interesting.
Super Facts 