The climate is complex.
And climate change is one of the most pressing challenges of our time, driven by human activity and affecting every corner of the globe. The evidence is undeniable. Understanding its causes and potential solutions requires a deep dive into science and innovation. In this article, we’ll explore the role of carbon emissions on climate and the solutions that could help us reign in its effects on global warming.
In 1961 Edward Lorentz ran weather simulations with a computer when he noticed something strange. He re-ran an old simulation which generated a completely different outcome. It was caused by reducing the number of digits after the decimal point from 6 to 3. Modern chaos theory was born. This sensitivity to input conditions is why weather models can't make long term predictions.
Climate and weather are closely linked. Climate can be thought of as the long-term averages of weather patterns, usually defined as 30 years or more.
The Science of Climate Change and Global Warming
The UN defines climate change as long-term shifts in temperatures and weather patterns. One feature of climate change is global warming which refers to man-made temperature increases. Overwhelming evidence points to recent global warming being driven by human activities, primarily emissions of greenhouse gases (GHG), from burning fossil fuels like coal, oil and gas, and removal of forests since the start of the industrial revolution in the 1800s.
It's getting hot in here... has it ever been hotter?
Not in your lifetime buddy, or even in the last 100,000 years. But as Darrell Kaufman, a paleoclimate scientist who studies temperatures of the past wrote in the Conversation from 2023 clarifies, we can’t know for sure.
This chart maps out the temperature variations relative to a baseline (0) over the last 800,000 years by the 2 Degree Institute. It shows 6 peaks, prior to our current rise, exceeding our current temperature, the most recent 123,000 years ago.
How can we measure temperatures in the past?
For temperatures more than 4000 years ago scientists rely on sediment samples from oceans, lakes, and ice cores but there are limitations. Currents and burrowing organisms can mix sediments and the exact timeline for each record is not precisely known so scientists use averages from samples taken from multiple locations.
The most important factors affecting the earth's temperature in pre-history have been changes in our orbit of the sun impacting the distance and natural fluctuations in the concentrations of greenhouse gasses in the atmosphere.
For temperatures in the last 4,000 years scientists compliment the mentioned techniques with information from stalagmites and tree-rings. In 1880 we started using weather stations at high latitudes and buoys to record global temperatures.
This chart maps out the temperature changes and atmospheric CO2 over the last 360,000 years.
Two things are noteworthy:
CO2 concentrations peaks correlate with temperature peaks
Our current atmospheric CO2, 421ppmv, exceeds all previous levels
Here's a closer look at the meteoric rise of CO2 concentration in the atmosphere over the last 10,000 years from Berkeley Earth.
How has the concentration of atmospheric CO2 increased so quickly?
The growth in atmospheric CO2 is largely the result of our use of fossil fuels to power our machines, transportation, and houses by burning previously trapped organic carbon compounds thus releasing 'extra' greenhouse gasses (GHG) since the start of the industrial revolution.
I call it 'extra' because this carbon was previously trapped either below the surface of the earth in coal or oil or trapped in trees and thus not part of the natural CO2 cycle.
We have also cleared land by cutting down forests, reducing our environment's ability to store and convert CO2 into oxygen.
These images show deforestation of Borneo rainforest 1950 to 2020. According to a research paper it lost 50% of its rainforest between 1973 and 2015. The same has happened in other rainforests around the world.
What is the GHG contribution by souce?
This chart shows a detailed breakdown of the contributing factors for the world's 50BN tonnes of CO2 equivalent emitted in 2016 . You'll notice that this is more than the 35BN tonnes in the previous chart. The difference is due to the addition of other greenhouse gasses beyond CO2, methane being the most significant. Their contributions are added on a CO2 equivalent basis.
As a species we have an insatiable appetite for (electrical) power, material, food, and space. Halting this is at least as hard as it is to collectively ‘stop’ cutting down forests when individuals are economically incentivized to clear land for income generating food production, raw materials and other activities. So how can we reduce it?
Let's look at strategies across 3 major contributors: power generation, transportation, and buildings.
Power Generation
Global demand for power is constantly increasing. However power sources, like solar, wind, hydro and nuclear power, produce electricity with no or little CO2 emissions reducing our dependence on fossil fuels.
However, as Michael Shellenberger explains in his excellent TED talk, even 'green' technologies have disadvantages and harmful environmental effects when we consider their full lifecycle.
Wind and solar power availability depend on season and time-of-day
Wind and solar require significant amounts of land and transmission lines
Hydroelectric dams requires specific geographical features and are expensive
Lack of control forces plants to give away peak power to avoid grid blowout
Wind turbines threaten endangered bird and bat species
Solar, Hydro, Wind and Geothermal require massive amounts of material
Solar panels at end of 20-25 year useful life leave behind toxic substances
These are problems we currently lack solutions for. He concludes nuclear power is the most safe, reliable, and low cost solution.
According to Low Carbon Power site, in 2023 60% of electricity globally was generated from fossil fuel. Is it even possible for a country to generate a significant share of its power from low-carbon sources? It is. Scandinavian countries with small populations and favorable geographic features rely almost solely on low carbon power generation with significant contributions from hydro, geothermal and wind.
France is also able to generate most of its power from low-carbon emitting power sources. As you probably guessed the secret ingredient is nuclear power which makes up 29% of the power in Sweden, 42% in Finland, and 65% in France.
Looking at the world's 5 largest power generating countries shows the challenge in relying on low-carbon power. Here low-carbon peaks at 41% for the US with the rest reaching 36% - 22%. Again, for two countries, the US and Russia, nuclear power comes to the rescue representing 18% of low-carbon generation.
Transportation
The transportation sector generates 16.2% of all GHG emissions with over 2/3 from road transport. Many consumers and innovators have taken heed resulting in the rising popularity of EV vehicles. But how good are they for the environment really?
In another excellent TED talk, Dr Graham Conway, challenges the notion that EVs should be considered ‘Zero Emission’ as measuring the emissions emitted by the car itself is insufficient to account for its environmental impact.
EVs charged from the grid in many countries rely on energy from fossil fuels
EVs generate more CO2 in material extraction and manufacturing due to the battery (12 tonnes) compared to conventional vehicles (6 tonnes) and have a shorter range (125 miles)
He instead promotes hybrids as a better alternative. They have longer range and smaller battery. He does praise EVs for moving pollution out of cities. For city dwellers it is hard to beat public transport, cycling and walking. Given Scandinavian countries high rank on low-carbon power generation it is no surprise that 3 capitals, Copenhagen, Oslo and Helsinki rank in the top 10 cities for bike friendlieness.
Powering Buildings
Buildings, with their temperature control, make up 17.5% of all GHG emissions. Having grown up in Sweden and moved to Shenzhen I can see the need at both ends of the spectrum.
Bryn Davidson in his TED talk challenges the conventional classification of ‘green buildings’ which only consider the net energy demand. He introduces 2 additional factors:
Location: Can you get around by walking or does it need a car?
Replacement: Has it replaced a less environmentally friendly building (good) or was it built on a green field area (bad)?
He advocates reducing energy demand through better insulation, heat pumps, and smart readers which can turn on and off applications to maximize use when electricity is cheaper or greener. This is critical as most of the buildings standing today will still be around by 2050. But he goes beyond by clarifying that by moving from a location where you need a car to somewhere you don't you already generated a positive environmental impact.
He talks about Passivhaus. This is a building that is so well insulated it does not need heating. It is kept hot from residents' body heat.
The passivhaus, in blue, is so well insulated that it does not emit any heat.
Where does the 'extra' CO2 end up?
The earth has 3 main CO2 sinks.
30% is absorbed by our oceans. It turns into an acid which is bad news for shellfish and corals. It causes their shells to dissolve.
30% is absorbed by plants on land. They convert it into energy and oxygen through photosynthesis. Because it's their fuel scientists were hopeful increased concentration of CO2 would stimulate faster plant growth, referred to as the CO2 fertilization effect (CFE). But according to a 2020 study the opposite is true. Increased atmospheric CO2 is making plants less effective at photosynthesis.
The rest, 40%, ends up in the atmosphere where it powers the greenhouse effect.
A short history of the Greenhouse effect
Just like it makes banana farming possible in Sweden, it makes life on earth possible by increasing the temperature at sea level 33°C. The idea was proposed by Joseph Fourier in 1824 and later proved by Eunice Newton Foote in 1856.
In 1896 Svante Arrhenius proposed fossil fuels will warm the planet. His claim was quickly 'disproven' by an experiment and it has been plagued by confusion ever since.
Two common misunderstandings of the theory.
Adding atmospheric CO2 cannot block more radiation.
Abundant water vapor in the atmosphere blocks all Infrared light.
Let's look at each of them in turn.
Adding atmospheric CO2 cannot block more radiation
It was tested experimentally in 1900 using a gas tube with different concentrations of CO2. The CO2 impact on radiation transmission was minimal.
However, this treated the atmosphere as one homogenous layer rather than a series of layers with different concentrations and thicknesses. Additional CO2 works as a blanket on top, with each layer making it harder for light to radiate off the earth. It’s the CO2 concentrations at the top layers, not the bottom near the earth’s surface, that drive global warming.
Water vapor is the main element blocking IR light
Water vapor can make up as much as 3% of the air volume, whereas CO2 at 420 ppmv only makes up a mere 0.04%. Water vapor also absorbs a broad spectrum of light at sea level.
However, military aviation research in the 1940s discovered that water vapor have gaps in its absorption frequencies, which are covered by CO2 and at high layers the atmosphere is very dry.
In contrast CO2 is particularly good at absorbing thermal infrared radiation above 13 micrometers and its concentration is mixed throughout the atmosphere making it more important at higher atmospheric levels where water vapor concentration is low.
How does the Greenhouse effect work
It's all about wavelengths.
The sun hits the earth with shortwave radiation, e.g. visible light, due to its high surface temperature of 5500°C. 29%, bounces off our atmosphere. 23% is absorbed by the atmosphere. The remaining 48% is absorbed by the earth’s surface. Earth has a lower temperature so it emits longwave (IR) radiation. It is cooled by evaporation, 25%, convection, 5% and the infrared radiation 18%. 12% passes through the atmosphere but 6% is captured by greenhouse gasses and is returned to the earth.
This heating effect varies by altitude. At sea level it raises the temperature from 33°C to an average of 15°C. Another way to see it is through heating power. Earth’s surface generates radiation at an average rate of 398W / m2 but only 239 W/ m2 reaches space. The difference of 159 W / m2 is the energy that returns through the greenhouse effect.
So how do we get rid of the extra CO2 in the atmosphere?
Even if we stopped emitting any 'extra' CO2 by halting all burning of fossil fuels today we'd still need to remove the excess CO2 from our carbon sinks: the oceans, land and atmosphere. And while we continue to emit we need to build capacity to slow down the excess emissions.
Again, technology comes to the rescue. McKinsey published an insightful report on 10 carbon dioxide removal (CDR) solutions.
Each solution is judged on:
Permanency: How long will CO2 be removed for.
Cost: How much does it cost per ton of CO2.
Externalities: What additional environmental effects do they have?
I discuss the pros and cons of 4 below.
Let's look at the opportunities and challenges with 4 solutions: reforestation and afforestation, biochar, enhanced weathering, direct air capture and storage.
Reforestation and Afforestation
This involves planting trees in deforested or never-forested land to remove atmospheric CO2. It can benefit biodiversity, increase ecosystem resilience and potentially generate eco-tourism.
Critics point out that trees’ CO2 capture is greatest while they are young and decline over time, this growth also depends on the availability of other soil nutrients, and it's hard to guarantee longevity due to forest fires or decisions to cut down the trees after payment has been made. Monoculture plantations can also negatively affect ecosystems. There is even a study from Scotland where planting and growing trees for 12 years had no positive effect on captured CO2. Instead the soil released CO2 which canceled the benefits of CO2 captured in by the trees.
In New Zealand many sheep farmers seized the opportunity to sell land to prospectors who plant pine trees. So the sheep population dropped from 70MM in the 1980s to 26MM today. Local communities are negatively affected as forestry requires fewer workers causing a domino effect where towns eventually shut down and remaining farms become completely isolated.
Another challenge are legal loopholes and failed regulatory compliance. In Australia benefits from large public spend to plant trees were canceled out from clearing forests to make space for agriculture.
Biochar and Bio-oil
Produced from biomass it can be used to improve soil quality by depositing it underground. Thus it enhances soil fertility and water retention converting waste from agricultural processes.
Given its potential to remove atmospheric CO2 leveraging an agricultural waste product it is not surprising that sales have increased 22x between 2005 and 2021. But some are concerned. A 2021 review raised concerns that the biochar may contain carcinogenic, mutagenic and persistent pollutants. Scientists caution its use as it is near impossible to remove from the soil once introduced. Its dark color may also increase the surface albedo increasing solar absorption.
Enhanced Weathering
Silicate rocks and minerals can store carbon from the atmosphere by reacting with acidic rain, caused by CO2, forming bicarbonate which washes into the oceans where it is stored for a long time. Natural rock weathering already absorbs 0.3% of global fossil fuel emissions. By breaking down rocks into powder and purposefully depositing it you increase its surface area and accelerate the process.
By depositing it on farmland it captures CO2, reduces ocean acidification, and boosts silk nutrient levels improving crop yields and helps to restore degraded soil. It also does not compete for land used to grow food nor increase demand for freshwater. This has been solved logistically from the application of crushed limestone to reverse soil acidification.
However, the energy needed to pulverize rocks will eat up some of the sequestered CO2 benefits, unless done with renewable energy sources.
This technique is particularly valuable in countries with significant crop growth like China, the US, India and Russia which are also the biggest contributors to CO2 emissions. Still the technique is in its infancy and studies are needed to determine the impact on water and soil health.
Direct Air Capture (DAC) and Storage
CO2 is removed from the air, using a solid or liquid chemical filter, and stored underground. The CO2 can also be used to make materials like cement, plastics, or even food driven by research by NASA and entrepreneurs like Lisa Dyson of Kiverdi. It can be deployed in many different places but it needs a lot of energy so it's best employed with low-carbon power generation and it requires little space. One actor focused on this development is Swiss company Climeworks.
In addition to high power requirements it also needs a lot of water and is expensive due to the low CO2 atmospheric concentration. Another risk is by storing it in geological formations there are risk of leakage in transportation and storage. These concerns are explored at depth in a post from 2023 by Mia DiFelice and Oakley Sheldon Thomas from Food & Water watch.
Conclusion
Climate change is a complex issue driven by human deforestation and burning of fossil fuels. And while our weather is unpredictable, global warming is real. Atmospheric CO2 has exceed concentrations in the past 800,000 years causing our planet to warm faster than any time since an asteroid collided with the earth causing the extinction of the dinosaurs.
Renewable energy sources like solar and wind offer hope for a low-carbon future, they come with their own set of challenges, including land use, material demands, and waste management.
Electric vehicles (EV) represent progress, but they are not without environmental costs, especially in manufacturing.
Buildings, too, play a significant role in emissions, and innovative solutions like Passivehaus and smart infrastructure offer potential ways forward.
Finally, innovation and implementation of carbon dioxide removal solutions will require all our support and effort. Each solution comes with trade-offs, but the urgency of action is clear: the future of our climate depends on our collective efforts to reduce emissions and remove the extra carbon that we have put into the atmosphere. Check out my article on Green Collar Jobs if you are unsure how to best join and contribute.
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