Climate change is a very hot topic these days. Many startups attempt to come up with innovative solutions to prevent CO2 emissions, pension funds offer “green” investment profiles and countries around the world are uniting to fight global CO2 emissions.
There is also a lot of talk about the weight of personal responsibility and what each of us can do to contribute to reduce our carbon footprint. As a scientist, I wanted to get my own idea of what the situation is and what is needed to fight the climate crisis on a global level.
My starting point was the latest book 📕 from Bill Gates, “How to avoid a climate disaster”. It is definitely a good read providing a simple and efficient helicopter view on the topic. After browsing around and collecting some figures on climate change, I thought it would be a good idea to write a small review to cover the following points:
- ☁️ How much greenhouse gases are we talking about ?
- 🦹🏻♂️ Who is responsible ?
- 💡 What are the current technological solutions?
- 🧑🏼 What can be done at an individual level?
If you are completely new to the topic, you can start by watching this short introduction video to climate change from Breakthrough Energy (coalition funded by Bill Gates to fight climate change). Many of the figures mentioned in this post come from Bill Gates’ book and can be found on breakthroughenergy.org.
0. How fast does climate change need to be addressed 🌎 🏃?
Human industrial activities have already increased the global temperature by +1 degree Celsius compared to pre-industrial times (ca. before 1750). It looks like with the current policies in place the world is heading towards +3 degrees by the end of the century (see graph below). Maybe it doesn’t sound like much, but it unfortunately is.
Achieving +3 degrees would already require to more or less immediately stop producing more greenhouse gases (i.e. CO2, Methane, Nitrous Oxide, F-gases) than we currently do and slowly decrease the emissions even though the global population is increasing as well as the demand on natural resources. Limiting the temperature increase to only +1.5 degrees would require to globally get to almost zero emissions by 2050 and actually starting removing CO2 by 2100.
What would be the consequences by 2100 if we live in a +1.5 degrees warmer world?
According to the IPCC (Intergovernmental Panel on Climate Change — the United Nations body for assessing the science related to climate change), a +1.5 degree warmer world would already face major challenges:
- More frequent, more intense and longer-lasting heatwaves
- More frequent destructive weather events, including storms, winds, flooding and fires
- Changing disease patterns
- Shifting agricultural patterns
- Pressure on the availability and quality of water
- Rising sea levels
1. Which countries produce the most greenhouse gases?
Public reports on C02 emissions show that nearly 70% of global C02 equivalent emissions are made by a relatively few number of actors where China 🇨🇳 and USA 🇺🇸 alone represent more than 40%.
It is worth noting that fossil fuels emissions are increasing year over year for all countries - except for USA and the EU who have started to slightly decreasing their emissions.
2. Which activities generate greenhouse gases ?
A full breakdown of CO2e emissions per sector can be found on ourworldindata.org, but for the sake of simplicity I prefer to reuse the simpler categorization introduced in Bill Gates’ book to distinguish between the different activities responsible for CO2e emissions:
- Plugging in 🔌: production of electricity
- Getting around 🚗✈️🛳: transportation of people and goods, i.e. cars, trucks, ships, planes etc.
- Growing things 🌾🐮: plants and animals
- Making things 🏭: manufacturing, cement, steel, plastic etc.
- Keeping warm and cool 🔥❄️: heating, cooling and refrigeration
The graph below shows how much CO2e emissions each category is responsible for:
The main message conveyed in Bill Gates’ book is that the world needs to go from 51 Gigatons (Gt)/year of global emissions of CO2e (CO2 equivalent) to zero by 2050 (cf. IPCC report).
Stating that this is a challenging target is quite an understatement considering that:
- 30 years is a very short span of time if you look at how slow things evolve. Ex: most energy sources took more than 60 years to be widely adopted and we have barely started on renewables. Btw, most of Asia’s fossil fuel based power plants are only on average a decade old whereas their lifetime is above 40 years.
- World population expected to grow from 7.8 billion in 2021 to 9.9 billion in 2050 thus putting dramatic pressure on the Earth finite resources.
- There isn’t a massive public mobilization for climate change. The world’s leading countries governments should enact much more drastic measures that the ones detailed in the Paris agreement.
Now, let’s have a deeper look at each category to understand where the CO2 emissions come from and what can be done to prevent them.
2.1 Plugging in 🔌 — 27%
Producing carbon free electricity is one of the key factors to operate a green transition. As you can see from the graph below, more than 50% of all electricity is produced from burning fossil fuel:
Producing clean (and cheap) electricity in large amount would offer the possibility to decarbonize other sectors of activities by electrifying them, meaning replacing whatever “C02e emitting” source of energy by electricity (think electric cars 🚗 🔋 ).
Paradoxically, electricity may also be fairly easy to produce in a C02 neutral way since the technologies already exists: solar ☀️, wind 🌪, hydropower 💦, and more importantly nuclear power ⚛.
As the nuclear physicist and MIT professor, Ian Hutchinson, puts it:
[…] it’s a grave mistake to think that science of any sort is suddenly going to find a magic bullet for meeting all the energy needs of society and any of the other needs of society by the way […] I think that nuclear power is obviously important to meet the energy challenges of our age, it is completely and intrinsically CO2 emission free and in fact the wastes that come from nuclear power […] are so moderate in quantity that we shouldn’t be worried about them […] there is so little of them that keeping them away from people is not particularly difficult. And so while people complain a lot about the drawbacks of fission energy, I think that most of those complaints are ill-informed […] I think that fission in the near term offers a terrific opportunity for environmentally friendly energy, which in the world as a whole is rapidly being taken advantage off in China, in India, in places like that are rapidly building fission plants. We are not rapidly building fission plants in the US, although we are actually building two at the moment, but we do still get 20% of our electricity from fission energy and we could get a lot more. — Artificial Intelligence with Lex Fridman Podcast — Episode #112 with Ian Hutchinson
Renewable energies such as solar and wind are great but they require a LOT of power units and space to install them since each unit doesn’t produce that much electricity. Besides, they produce power intermittently so they need to be coupled with large scale batteries in order to achieve proper reliability. Considering that we need a solution on the short term, nuclear fission seems very much needed.
Why is nuclear power not more prominent?
- nuclear waste: highly radioactive waste requires advanced post-treatment and storage capabilities to put it away. At the moment, nuclear waste is placed in sealed containers and buried in stable geological grounds.
- risk of nuclear weapons proliferation: nuclear weapons should of course not proliferate. This implies that nuclear power is not a universal solution for all countries. However, big polluters (ex: US & China) already leveraging nuclear power to produce electricity could replace their coal and gas power plants by nuclear ones to fast track decarbonization.
- nuclear fuel: uranium is the primary fuel for fission energy and will eventually run out. That being said, there is enough to power the whole world for at least thousand years.
- safety concerns: accidents such as Tchernobyl and Fukushima have sparked much fear against nuclear power. Paradoxically, nuclear kills approximately as much as solar and wind power! There have been very few deaths related to nuclear accidents and the technology has become very safe and mature. Deaths from renewable energies incl. nuclear are negligible compared to the ones caused by fossil fuels.
What is the potential for using more nuclear power among the world’s biggest polluters ?
As can be seen from the graph below, around 2/3 of electricity produced by the top polluter comes from fossil fuels ⛽️… The share of nuclear has either remained constant for the past 10 years or has decreased like in Japan. However, the share of renewables has doubled in the USA 🇺🇸 going from 10% to 20% between 2010 and 2020 and gone from 18% to 29% in China 🇨🇳 during the same period. That’s a positive development, BUT, if these trends keeps on linearly increasing by 10% per decade, it will take over 60 years for the USA and China to rely only on renewable energies assuming that: 1. enough electricity can actually be produced by renewables. Eventually, they will run out of space to put all the wind turbines and solar panels, 2. large scale batteries can be produced at industry-scale and enable reliability, i.e. enough electricity for all at all time.
Looking at the velocity at which the top emitters are reducing the share of fossil fuels used to produce electricity, there is simply NO WAY the world will get to 0 emissions by 2050 without immediate drastic measures and the use of nuclear power.
Bill Gates rightfully mentions the importance of focusing on renewables energy such as solar, wind and hydropower but also on battery technology which are not only important to store the excess of energy produced to be used at a later point but also to decarbonize other sectors such as transportation for instance (think electric cars, buses, and trucks).
Just like Bill Gates, OurWorldInData.org also advises to switch towards low-carbon electricity power sources such as renewables and nuclear power.
2.2 Getting Around 🚗✈️🛳 — 16%
This sections deals with transportation of people and goods. It was surprising to me to discover that 80% of transport-related emissions were caused by cars, trucks and buses, as international shipping operated by planes and cargo ships “only” represents 2% of global emissions.
Technologically speaking, transportation doesn’t constitute much a of a challenge:
- Electric cars 🚗 🔌 are booming and solid-state batteries 🔋 are on their way — solid state batteries would be revolutionary as they have a much higher energy density, hear much wider driving range, and recharge super fast, i.e. 5 min vs 1 hour. What is needed are strong incentives from governments to force the renewal of the car park from fossil to electrical. Note: electric cars are only good if they are powered with clean electricity ⚡️☘️ (yes, I’m talking to you nuclear fission ⚛).
- Garbage trucks 🚛 and buses 🚌 can also be electric as it is already implemented in many cities. Again, it boils down to government taking action and choosing green investments.
- As for heavy means of transportation such as 18-wheelers, cargo & cruise ships and airplanes, electricity is not an option because of unsolvable energy density problems. They will have to use cleaner fuels such as biofuels or electrofuels. Actually as per 2021, all cargo ships have to switch from high-sulfur bunker fuel to low-sulfur fuel which will further reduce global emissions, but yet again it’s “only” 2% of the bill we’re talking about here.
2.3 Growing things 🌾🐮 — 19%
With Agriculture, the main culprit isn’t CO2 but methane — which causes 28 times more warming per molecule than carbon dioxide over the course of a century — and nitrous oxide, which causes 265 times more warming. “How to avoid a climate disaster”, Bill Gates.
Ok so where does methane and nitrous oxide come from ?
- Methane comes from ruminants 🐮 burping 💨, farting ☁️ and pooping 💩. That’s 2 billions tons CO2e globally, i.e. methane is responsible for 4% of global greenhouse gases emissions.
- Nitrous oxide comes from the wasted fertilizers, i.e. nitrogen not absorbed by plants and represents 1.3 billions of CO2e globally, i.e. nitrous oxide is responsible for 2.5% of global greenhouse gases emissions.
What are the proposed solutions? Well, you are not gonna like the answer…
Eat less meat 🍖! Or you know, prevent animals from burping, farting or pooping ... Alternatively, we can eat meat grown in laboratory 🧪 and/or plant-based 🌿 “meat” — yeay! tofu-based bacon 🥓, I was so much look forward to that one… I used to eat one burger per day every time I would find myself in New-York but after I witnessed the reality of large scale cattle farms in the US, I re-thought my own policy a little bit.
Fun fact 🤡: if everyone would adopt a vegan diet by 2050, we would sequester 15 years of worldwide global CO2 emissions (547 Gt CO2) !!!
As for the nitrous oxide problem (i.e. fertilizers), there doesn’t seen to be an immediate fix. We can probably decarbonize how nitrogen is produced (using clean electricity ⚡️☘️) and optimize the use of fertilizers on plants to maximize absorption and minimize waste, but that’s about as good as it gets on the short to mid-term perspective — though it would already be huge.
2.4 Making things 🏭 — 31%
According to Bill Gates, the main emitters of CO2 in manufacturing, including the construction of buildings and infrastructures are mostly due to the production and use of concrete 🧱, steel ⛓ and plastic 🧩. Together they currently account for ca. 12% of global emissions and their share will keep on drastically increasing over the next decades.
Why are these three so problematic? Well, because their production releases a lot of CO2 including the dirty electricity ⚡️💩 used to power the production factories.
- Concrete 🧱: to make concrete you need gravel, sand, water and cement. The latter is the culprit responsible for CO2 production. Simply put, throw limestone, carbon and oxygen in a furnace and you get calcium oxide (key ingredient of cement) and CO2. Producing 1 ton of cement releases 0,54 ton of CO2 (as of 2018). To this day, we don’t know how to do it otherwise. Concrete is responsible for 4,1 Gt of CO2 a year, i.e. nearly 4,3% of global emissions. It is worth mentioning that China is responsible for producing 55% of cement worldwide, so China has a major role to play in decarbonizing cement production.
- Steel ⛓: to make steel, you need to separate the oxygen from iron and add a little bit of carbon. If you throw iron ore, oxygen and coke, in a furnace that will give you steel and… CO2. Actually producing 1 ton of steel, releases 1.8 tons of CO2. Since we produce 1.8 billion tons of steel yearly that’s 3.3 Gtons of CO2, i.e. nearly 6,4% of global emissions. Again, China is responsible for about 50% of global steel production.
- Plastic 🧩: plastic is not that bad in terms of CO2 production as 50% of the plastic is actually made of carbon, so it could be considered as a sink for CO2. However, they pose other major environmental and health issues. Plastic production represents around 2% of global emissions.
So how can we decarbonize the production of concrete, steel and plastic?
- greenify the heat production ⚡️🔥 required for the chemical reactions. However, producing high temperature heat is actually quite hard with electricity so a more realistic option is to use some other fuels incl. clean hydrogen.
- get the electricity from a clean source ⚡️☘️.
- capturing the CO2 emissions to produce heat and CO2 emissions from the chemical reactions to produce concrete, steel and plastic. It is an expensive solution 💵 but it’s technically doable.
2.5 Keeping warm and cool 🔥❄️ — 7%
Finally, this section is about how we regulate temperature inside buildings, i.e. both cooling and heating, including industrial heating and refrigeration. In a world becoming increasingly warmer, the demand for air conditioning devices has truly exploded in the recent years and the trend is only increasing. On the heating side, more than half of the heating systems currently in use still rely on fossil fuels.
Technologically speaking, this problem has been solved a long time ago with heat pumps. Heat pumps are powered by electricity, have the best efficiency in terms of energy conversion, and are cheaper to run. What’s not to like? So let’s get rid of all these old gas and oil stoves and replace them with heat pumps powered with clean electricity ⚡️☘️.
3. Summary 🎯
In the table below, I have summarized the share of global CO2 emissions for each activity discussed in the post along with the short-term and long-term technological solutions to decarbonize these activities. Taken together they account for about 75% of all yearly global CO2e emissions!
Some short-term solutions turn out to be either unpopular (ex: nuclear) or expensive (ex: carbon capture) which explains why they haven’t been more widely adopted. Nevertheless they have the merit of existing, unlike hypothetical long-term solutions which may be more efficient and cheaper but which may or may never come to pass.
So what can we do on a personal level? These are examples of simple things one can do to adopt a more climate-friendly lifestyle:
- meat 🍖 consumption. Can you at reduce your consumption of red meat? Check the environmental impact of your food with apps such as Open Food Facts. More generally, paying attention to the environmental cost of our diet. Ex: palm oil 🌴 🛢 is a saturated fat oil not only used in the food industry but in many other type of products. Unfortunately, it is also responsible for significant deforestation, so until we find a better replacement for palm oil, we could reduce our consumption of palm oil-based products.
- electric cars 🚗 ⚡️. Electric cars now cost about the same as their gas equivalent and they are cheaper to operate.
- circular economy ♻️. Decrease the overall production of goods by optimizing your own consumption for example by buying second hand goods.
- improving you home energy consumption 🏠⚡️. Do you have the possibility to upgrade your old oil furnace for a heat pump? Can you run your appliances when the electricity on the grid is green ⚡️☘️?
Although hundreds of millions of people would have to do the same in order to have an actual impact on the market… See more high-level recommendations from ourworldindata.org.
However, in order to have a chance at really changing things on a much larger scale, I very much agree with Bill Gates when he posits that:
[…] engaging in the political process is the most important single step that people from every walk of life can take to help avoid a climate disaster. “How to avoid a climate disaster”, Bill Gates.
A word on the importance of a global carbon tax
The Paris Agreement aims at uniting the countries worldwide to reduce global emissions. It constitutes a first step to create global awareness and consensus on the problem and start acting on it. The biggest criticism is the lack of binding enforcement mechanism. The agreement is purely based on the good will of the countries to reach their emission reduction targets and there is no economical sanction if they fail to do so.
Bill Gates introduced the concept of Green Premiums which represent how much more expensive it is to switch from CO2 emitting technologies to clean(er) alternatives. He advocates that we need to develop new technologies to make the green premiums negative, i.e. saving money by choosing the green alternatives. As a result, companies would naturally operate the switch driven by the economic incentive. Governments could be more proactive and choose to apply either fiscal pressure under the form of a carbon tax or to make legislation to force companies to abandon polluting technologies and offer financial support to operate the switch. However, such crucial initiatives would have to be established at a global level to avoid hurting competitiveness and force the CO2 emissions down fast enough to avoid the worst effects of global warming.