Soil & Global Warming

Surface Carbon Water Temperature Biota Climate

Net-Zero fiddles while earth burns

Soil is much more than a lump of carbon; it is a living entity which lives under the surface in water and air.

"Since the birth of soil science, climate has been recognized as a soil-forming factor, along with parent rock, time, topography, and organisms (from which humans were later kept distinct), often prevalent on the other factors on the very long term. But the climate is in turns affected by soils and their management. This paper describes the interrelationships between climate – and its current change – and soil, focusing on each single factor of its formation." (Certini & Scalenghe 2023)

See more of 'GW & CC' here

NASA's Climate Visualization Studio

Look at the global warming over last 125 years as measured by probably most reliable data in the world.

NASA CHART between 1880-1980, shows as many cold years as warm, and over 100 years global temperature rose a mere 0.3C.

Global Warming

The climate spiral shows changes in global temperature since 1880. Between 1880 and 1980, there was little warming, sometimes even slightly cooler. This is despite the dramatic increase in industrialisation. We often here that we have to keep temperatures down in relation to ‘pre-industrial levels’. This gives the impression that it is industrialisation - which has been going on for around 200 years - which is ‘the problem’. Yet all those mines and mills seem to have little effects over that time. Whatever is causing global warming seems to have kicked in about 40 years ago.

So what has caused the dramatic increase in global warming (seen in both air and water) since around 1980? There must be quite a few candidates. Increased transport would be one factor. Can the internet affect global warming? There may be a casual connection, but it is hard to see it being causal. We have also seen dramatic increase on globalisation and free markets capitalism. There must be several phenomenon that coincide with the spiral since 1980. Could it have something to do with soil? .

When dealing with global warming, we need to look at how the air, water and soil interrelate. Now with AI & algorithms we can make a start to looking at how the systems are working, rather than reducing everything to one molecule - carbon.

Last year, 2023 was the hottest year ever. March 2024 was the tenth month in a row to be the hottest respective month. The global average temperature in the twelve months (April 2023 – March 2024) is the highest on record at 0.70°C above the 1991-2020 average. These are air termperatures

Yet from 1980 - 2020 it warmed 1.6C in those 40 years - Each year >10X faster than each of previous 100 years. (0.3/100 = 0.003/yr 1.6/40 = 0-04/yr, ie >10X pre 1980 levels). Each decade since the 1980s has been warmer than the previous one.

Water

Seas are absorbing much more heat, but the temperature is rising only slowly as water has a high capacity to absorb heat without increasing temperature.

Heat Content in the Top 700 Meters of the World's Oceans, 1955–2023

Note again there is a dramatic increase in heat stored since 1980. Between 1980 - 2020, the ocean heat content went from zero to 20-25 all over the world.

Greenhouse Gases

The dominant explanation for the global warming is 'Greenhouse Gases' (GHGs) - the ones that 'trap' heat reflecting it back, like the glass of greenhouses. We know how much warmer they can be in our garden.

The three main groups of GHGs are carbon dioxide (mainly from burning), methane (mainly as natural gas from oil wells) and nitrous oxides (mainly from fertilisers)

Together the potential of these GHGs to warm the earth are measured as ‘carbon equivalents’. So carbon has become a symbol and a commodity to equalise those GHGs emitted to produce ‘net zero’. But do GHGs explain such a rapid rise in global warming?

We have seen throughout soil's evolution its relation with climate conditions, e.g. in Permian, Triassic times and Cenozoic times.

About 80-90% of earth's heat is 'bounced back' by GHGs, about a third of that due to GHG increases in the last 50 years or so.

Agriculture -world

Roughly speaking agriculture contributes about 1/5 of all GHGs and together with food production about ¼ . More exactly agriculture contributes 18.7%, broken down to grassland 0.1% , cropland 1.4% deforestation 2.2%, crop burning 3.5%, rice cultivation 1.3%, agricultural soils (N2O) 4.1% livestock and manure 5.8%

Generally the food sector accounts for higher proportion in the more industrialised world , the farming sector contributes more in less industrialised countries. The Stern report about the ‘economics of climate change’ said farming contribution is caused predominantly by ‘land use change, (ie forest, via grass to arable) and fertiliser use around 33%. (Stern Review Appendix 7g). Roughly speaking the 3 main GHG sources from agriculture - about a third each for nitrates, methane and land use change (ie forest to grass to arable).

Agricuture - UK

UK imports about half of its food by value, but that has disproportionate environmental impact elsewhere. According to the Royal Society “The UK is currently importing over 50% of its food and feed, whereas 70% and 64% of the associated cropland and GHGE impacts, respectively, are located abroad. These results imply that the UK is increasingly reliant on external resources and that the environmental impact of its food supply is increasingly displaced overseas" (De Ruiter et al 2016)

In the UK, following Brexit, it is clear that the dividend is for large landowners re-wilding. Organisations like the National Trust are dedicated to re-wild and plant forests in order to reach Net-Zero. There is nothing to reduce the GHG emitted making UK’ dinner. There will be more dependence on overseas food, and its consequent impacts abroad. While we hear much talk about ‘public money for public goods’, it seems ‘public goods does not include ‘food’. It appears that the UK prefers to ‘beautify the landscape’ as the Prime Minister explained in parliament.

Nitrates

Nitrates in soil have major impacts on global warming. When nitrogen in its active form, such as in fertiliser, is in soil, microbial reactions take place that release nitrous oxide. N2O is generated by the microbial transformation of nitrogen in soils and manures, and is often enhanced where available nitrogen (N) exceeds plant requirements, especially under wet conditions (IPCC 2018). This gas is 300 times more potent at warming the atmosphere than carbon dioxide, and lots more than methane we hear so much about. It also remains active in the atmosphere for more than 100 years.

Nitrates & Global Warming

The contribution of nitrate fertilisers to global warming primarily occurs through two main processes: nitrous oxide (N2O) emissions and the energy-intensive production of nitrogen-based fertilizers. N2O is a potent greenhouse gas, nearly 300X more powerful than CO2 and is produced by bacteria converting synthetic nitrate fertilisers in soil Added to which is the manufacturing of nitrogen-based fertilizers. Thhis requires a substantial amount of energy, often from the combustion of fossil fuels. The famous Haber-Bosch process for ammonia production contributes to carbon dioxide emissions, further adding to the overall carbon footprint associated with nitrate fertilizers.

Researchers, from the University of Cambridge, recently found that two-thirds of emissions from fertilisers take place after they are spread on fields, with one-third of emissions coming from production processes. “Although nitrogen-based fertilisers are already known to be a major source of greenhouse gas emissions, this is the first time that their overall contribution, from production to deployment, has been fully quantified. The analysis found that manure and synthetic fertilisers emit the equivalent of 2.6 gigatonnes of carbon per year –more than global aviation and shipping combined.” Yes, fertilisers and slurry (ie ‘modern manure’) add up to more than aviation and shipping combined!

River Pollution

Then there is the river pollution. “Nitrate is leached much more readily than ammonium from soil, resulting in pollution of ground- and coastal waters, and provides the substrate for denitrification processes, a consequence being increases in emissions of the greenhouse gas nitrous oxide. Recent studies indicate that AOA (ammonium Oxidising Arachaea - remember from 500-1000mya?) may have two distinct ecological and physiological characteristics in comparison to AOB (Ammonium Oxidising Bacteria), which could be considered advantageous in attempts to mitigate nitrification-associated pollution. Firstly, while they can use added inorganic ammonium, AOA in many soils appear to preferentially use ammonium derived from mineralised organic matter, with AOB rapidly oxidising inorganic ammonium fertiliser applied at high concentrations. Secondly, while all ammonia oxidisers generate the greenhouse gas nitrous oxide as a by-product of ammonia oxidation, the yield per ammonia oxidised is approximately half with AOA. Therefore, using fertilisation strategies that favour AOA growth and activity (e.g. use of organic fertiliser) has the potential to dramatically reduce nitrification-associated pollution.”

In agriculture fertilisers contribution to global warming is comparable with aviation and shipping together. Yet we do not talk about ‘green food’ in the same way we talk about ‘green energy’. We should start that conversation, working on ways to reduce fertiliser use, and holding carbon in arable soil

How fertilisers contribute significantly to global warming, an impact comparable to aviation and shipping

Fertilizer Production: The production of synthetic fertilizers, especially nitrogen-based ones, requires large amounts of energy, usually from fossil fuels. This process releases carbon dioxide (CO₂).

The energy to make the fertiliser by the Haber-Bosch process is like a giant pressure cooker and very energy intensive. The energy is used to crack the strong N2 molecular bond. Nitrogen production consumes 1.2% of the world's total energy on an annual basis, with nitrogen fertilisers 90% of that, with approximately 166 million tonnes produced annually.

Nitrous Oxide (N₂O) Emissions: Once applied to fields, nitrogen fertilizers can break down and release nitrous oxide (N₂O), a potent greenhouse gas. Nitrous oxide is around 300 times more powerful than carbon dioxide in trapping heat in the atmosphere. This makes N₂O emissions from agriculture a significant contributor to global warming.
Scale of Impact: The global agricultural sector, particularly due to fertilizer use, contributes a large share of nitrous oxide emissions. According to some estimates, nitrous oxide from fertilizers and agriculture contributes around 6% of global greenhouse gas emissions. Aviation and shipping together also contribute around 5% of global emissions (about 2-3% each for aviation and shipping).

Comparative Impact

Fertilizer-related emissions, especially from nitrous oxide, are on par with the combined emissions from aviation and shipping.
However, while aviation and shipping emissions primarily come from carbon dioxide (CO₂), fertilizer emissions are more damaging on a per-molecule basis because of nitrous oxide’s high global warming potential.

Fertilizers contribute much the same amount to global warming as aviation and shipping combined, with an outsized impact due to the potency of nitrous oxide.

Nitrate fertiliser usage has gone up by 2/3 1between 1980-2020 as a major part of the Green Revolution. Could this begin to explain the NASA reading where global warming really kicks in after 1980? We’ve seen the increase in nitrate fertilisers and we know the GHG potential, so could nitrate fertilisers be a major contributor to global warming? If so, we should hear more about it.

Methane

There could be a new ‘methane burp’. The one we saw 250mya helped with the greatest extinction yet. The soil helped save the planet then. And that took a few million years, which we do not have time for.

Methane could wipe us out, and it was only the soil that saved the planet then. What would a methane burp consist of and what damage could it do? It may contribute to global warming making reversal much harder.

It is only in last 50 years, that levels have increased significantly. There is no question that there is a methane emergency [underway with global methane levels are soaring. (Schiermeier 2020). Is this what is responsible for the dramatic rise in global warming between 1980 - 2020?

In the last 10 million years methane has been 700ppb, The levels have risen in last few years to over 2000ppb. Since 2007, methane—which molecule-for-molecule has 30 times the warming effect of CO2—has risen by more than 3%.

What is this due to?

Various explanations have tried to pin the growth on increased natural gas drilling, rising rice cultivation, and a surge in bovine belches. But none of these explanations has stuck. Methane scientists will need to come together to resolve this debate, as several factors are likely playing a role

Belches We hear a lot that the main contribution of farming to global warming is that animals belch out methane – and that this GHG is 30X more potent than carbon dioxide. Cows do belch methane, this is true. There is all sorts of research to get cows to reduce the methane emissions which look at what they eat and their digestive system. It is an absolutely basic biochemical reaction to produce methane when digesting carbohydrates in anaerobic conditions. Yet there have been massive increase in herbivores, like buffalo & wildebeests, roaming the planet that produced methane, but levels stayed constant at 700ppb. Cows are also unlikely, as their numbers saw their steepest increase between 2000 and 2006, when methane levels were flat. The role of enteric methane is often overstated in measuring terms Global Warming Potential.
The Arctic gets much attention. High methane readings in the Arctic are largely due to the Siberian gas fields. Methane is found next to coal oil and gas. So when these are materials mined, they are bound to release old stores of methane. These stores are often as methane hydrate’, where the methane is enclosed in water lattices. This water can be frozen, so when there is drilling – or increases in temperature, these frozen hydrates cages evaporate and the methane escapes. This is what has been happening across Russia with drilling and Tundra melting.
Wetlands are increasingly seen as responsible, with tropical wetlands featuring more as they warm up. The new concern about methane is coming from the rise in the tropics, due to burning fossil fuels which in turn heat bogs and wetlands. The gas is emanating from tropical wetlands flooded by heavy rains in recent years. Anaerobic microbes may well be helping the emission of methane in these conditions. Expanded rice growing could also play a role. Because global warming is expected to increase tropical rainfall, this methane could be a new signal that "the tropics are changing fast,"

Hydroxl Radicals

Another explanation of the increase in methane is due in part from a drop in hydroxyl, a chemical that acts as an atmospheric detergent.

Hydroxyl radical (OH) is formed in the presence of sunlight by water vapour

Hydroxyl radical (OH) is formed in the presence of sunlight by water vapour with pollutants like ozone and nitrogen oxide, all present just above the soil. It is very reactive as it has a free (unpaired) electron. It persists for just a second in the air before it reacts with other chemicals like methane (CH4 + OH), to produce first carbon monoxide, then carbon dioxide (CO2) and water (H2O). So when cows feed on pasture, the methane levels in the field remain pretty constant as there is more than enough hydroxyl radicals around - 100s times more than is needed. But this does not occur when the cattle are kept indoors.

Isotopes

There is another clue to the puzzle: The carbon atoms in atmospheric methane molecules have shifted toward lighter isotopes. The same gas from fracking has the higher isotopic signature. Because life prefers lighter carbon, this may be due to extra microbial production. But the lighter carbon could also signal that hydroxyl radical levels are falling. OH prefers to react with lighter carbon, so lowered OH levels would allow more of the light, microbial methane to linger in the atmosphere.

The hydroxyl radical is often referred to as the "detergent" it reacts with many pollutants, as first step to their removal.. Apart from methane it also has an important role in eliminating ozone as well as inactivating pathogenic viruses and bacteria and neutralising allergenic pollens and fungal spores.

OH concentrations are pretty stable over time A satellite study over 25 years found: “When OH reacts with methane, it does not necessarily go away, especially in the presence of nitrogen oxides (NO and NO2). The breakdown products from the reaction with methane then react with NO or NO2 to reform OH again. So OH can recycle back into the atmosphere.”

It doesn’t look like there has or will be any great fall in OH radicals doing their job of being an atmospheric detergent. We need to worry about the warming itself increasing methane as a methane burp could do us in.

What else OH does

The more we look at the hydroxyl radical, the more we are finding about what else it does with life around it. Evidence is mounting about how its oxidative power is harnessed to encourage germination, growth, stomatal closure, reproduction, a plant’s immune response, and adaptation to stress (Richards et al 2015). We are going to have to factor in how it features in plant cell death and its key role in microbial degradation of plant matter in the soil.(Richards et al 2015)

The hydroxyl radical is produced at the plasma membrane, helped by a range of peroxidises and catalysts, tightly regulated to target substrates precisely to the site of radical production. Research focuses on the radical's mode of action in wall loosening and in signalling systems, so much so that they are being recognised as a potent regulator in plant cell biology.

BUT BUT BUT!

The Annual Greenhouse Gas Index (AGGI) compares the warming effect of the main human-produced greenhouse gases to conditions in 1990. In 2023, the AGGI was 1.51, indicating a 50% increase in the warming effect of greenhouse gases compared to 1990.

The AGGI predicts about 1C warming in last 40 years. But we saw at the top of the page, according to NASA it has been 1.6C.

Between 1980 - 2020 - 1.46..

Does the increase in AGGI explain all the global warming over the past 40 years?

1. Understanding the AGGI

The AGGI, maintained by NOAA, tracks the combined climate warming effects of key greenhouse gases: carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O), and a set of halogenated gases like CFCs. It's expressed relative to a baseline year, typically 1990 (when AGGI = 1). The AGGI measures the radiative forcing (the warming influence) exerted by greenhouse gases in the atmosphere.

Radiative Forcing (RF): This is the net increase in energy trapped by the Earth's atmosphere due to greenhouse gases, measured in watts per square meter (W/m²).
The AGGI is designed to capture the incremental radiative forcing caused by rising greenhouse gas levels. The more the AGGI rises, the greater the warming potential.

2. Global Warming over the Last 40 Years

The average global temperature has risen by about 0.9°C to 1.0°C over the last 40 years (from the 1980s to 2020s). This increase is primarily due to human activities, particularly the burning of fossil fuels, which release CO₂ and other greenhouse gases into the atmosphere.

To see if the rise in AGGI accounts for this temperature increase, we need to compare:

The increase in radiative forcing due to the rising AGGI.
The corresponding temperature change.

3. Increase in Radiative Forcing

From the early 1980s to now, the AGGI has increased significantly. In 1980, the AGGI was below 0.7 (indicating lower greenhouse gas concentrations compared to the 1990 baseline). By 2023, it has risen to about 1.5 to 1.6, which reflects a significant increase in radiative forcing.

Radiative forcing from CO₂ alone has increased by approximately 1.8 W/m² since pre-industrial times (mid-18th century), and other gases have contributed an additional 1.0 W/m² or so.
Together, the total forcing from long-lived greenhouse gases is around 3 W/m² today, compared to approximately 2 W/m² in the early 1980s.

4. Expected Temperature Response

Climate models estimate that doubling CO₂ concentrations from pre-industrial levels would increase global temperatures by 1.5°C to 4.5°C (the "climate sensitivity" range) over a long period, with 3°C often used as the central estimate.

Given the rise in greenhouse gas concentrations and radiative forcing over the past 40 years, the expected warming can be estimated:

The warming per W/m² of radiative forcing is approximately 0.5°C to 1°C (based on estimates of climate sensitivity).

From 1980 to 2020, radiative forcing from greenhouse gases increased by about 1 W/m². This corresponds to a temperature increase of around 0.5°C to 1°C, which closely matches the observed global warming of around 0.9°C to 1.0°C over this period.

5. Other Factors Influencing Global Warming

While the increase in AGGI (and corresponding radiative forcing) explains much of the global warming over the past 40 years, it's essential to note that other factors play a role as well:

Aerosols (tiny particles in the atmosphere) have a cooling effect by reflecting sunlight back into space. Industrial activities that release aerosols (like sulfur dioxide) can mask some of the warming caused by greenhouse gases.
Land-use changes (such as deforestation) and solar variability (small changes in solar energy) also contribute, though their impacts are much smaller than greenhouse gases.
Natural climate variability (such as El Niño and La Niña cycles) can cause short-term fluctuations in global temperature, but they don't explain the long-term warming trend.

Conclusion: Does the AGGI Increase Explain All Warming?

The increase in the AGGI and its associated radiative forcing is responsible for most of the global warming observed over the past 40 years. The rise in greenhouse gas concentrations and the AGGI corresponds well with the observed temperature increase of about 0.9°C to 1.0°C. While other factors (like aerosols and natural variability) can slightly modify the rate of warming, the dominant cause is the increasing levels of greenhouse gases reflected in the AGGI.

Can this larger (1.6C) observed warming compared to the AGGI-based estimate (1C) be explained? Or is it unaccounted for...

1. Reconciling NASA's 1.6°C Warming with the AGGI-Based Estimate

The AGGI tracks the impact of greenhouse gases in terms of radiative forcing, which leads to global warming. Based on the increase in radiative forcing over the past 40 years (from greenhouse gases alone), usly estimated that this would contribute around 0.9°C to 1°C of warming, depending on the climate sensitivity (how much the Earth warms for each unit of radiative forcing).

If NASA's data suggests that the temperature has increased by 1.6°C over the same period, this leaves a gap of about 0.6°C beyond what the AGGI alone might predict. So, let's explore where this discrepancy comes from and how it might be resolved.

2. Possible Explanations for the Additional 0.6°C Warming

There are several factors that could explain this difference between the warming predicted by AGGI (roughly 1°C) and the observed warming of 1.6°C:

a) Feedback Mechanisms

Amplifying feedbacks such as changes in water vapor (a potent greenhouse gas), melting ice, and changes in cloud cover can intensify the warming caused by greenhouse gases. For example, as temperatures rise, the atmosphere holds more water vapor, which increases the greenhouse effect further.
Ice-Albedo Feedback: The reduction in Arctic sea ice and snow cover decreases the Earth's reflectivity (albedo), causing more sunlight to be absorbed by the darker ocean or land, which amplifies warming.

These feedbacks are not directly captured in the AGGI, but they significantly contribute to the overall temperature response.

b) Ocean Heat Uptake and El Niño/La Niña Cycles

The oceans absorb much of the excess heat generated by increased radiative forcing. However, variations in ocean heat uptake—particularly during strong El Niño events—can lead to additional warming. For example, the strong 2015-2016 El Niño contributed to a noticeable spike in global temperatures.
Over 40 years, periodic fluctuations in the Pacific Decadal Oscillation (PDO) and other oceanic cycles could also add variability to the global temperature trend, contributing to more warming than expected.

c) Underestimated Climate Sensitivity

The AGGI-based estimate uses a central value for climate sensitivity of about 3°C per doubling of CO₂. However, some studies suggest that the Earth’s climate sensitivity could be higher, particularly when considering long-term feedbacks. If the sensitivity is closer to the higher end of estimates (4°C), the amount of warming for a given increase in greenhouse gases would be greater than expected.

d) Reduced Aerosol Cooling

Aerosols (like sulfate particles from industrial pollution) reflect sunlight and cool the planet, partially masking the warming effect of greenhouse gases. If aerosol emissions have declined (for instance, due to cleaner air regulations or a shift in industrial practices), this could reduce their cooling effect, leading to more warming.
There is evidence that aerosol emissions have decreased over the past few decades, particularly in parts of the developed world, reducing their offsetting effect and allowing more of the warming from greenhouse gases to be felt.

e) Other Greenhouse Gases Not Fully Captured by AGGI

While the AGGI focuses on major long-lived greenhouse gases (like CO₂, CH₄, N₂O, and halocarbons), it doesn’t fully account for the warming impact of short-lived climate pollutants, such as ozone and black carbon (soot). These pollutants contribute to warming in ways that aren't directly reflected in the AGGI but have been increasing in some regions.

3. Does the AGGI Explain All the Warming?

While the AGGI explains a significant portion of the warming (around 1°C), the additional 0.6°C observed by NASA over the last 40 years is likely explained by a combination of feedback mechanisms, variations in ocean heat uptake, reductions in aerosol cooling, and perhaps even a slightly higher climate sensitivity than previously thought.

Thus, the AGGI alone doesn't account for all of the 1.6°C warming, but this doesn't mean it's incorrect. Instead, it suggests that:

Amplifying feedbacks (like water vapor and ice melt) are contributing to more warming than the AGGI directly measures.
The warming impact of greenhouse gases may be underestimated when only considering their direct radiative forcing, without accounting for all the complex interactions in the climate system.

In short, the additional 0.6°C is not "unexplained" in the sense that we don't understand where it comes from, but it reflects the broader, more complex reality of the climate system, which involves both greenhouse gases and amplifying feedbacks.

There are several factors at work that influence surface temperatures and the overall climate, beyond GHGs

1. Surface Albedo (Reflection of Sunlight)

High albedo (like snow, ice, and deserts) reflects sunlight, keeping surfaces cooler.
Low albedo (forests, oceans, cities) absorbs more sunlight, increasing surface temperatures.
As ice melts due to warming, less sunlight is reflected, causing more absorption and further warming, called positive feedback.

2. Land Use Changes

Deforestation: Removing forests (which have a cooling effect) increases heat absorption by the ground, raising local temperatures.
Urbanisation: Cities absorb more heat (due to concrete, buildings), creating "heat islands" that make urban areas warmer.
Agriculture: Farming can change land surfaces, impacting evaporation, heat absorption, and albedo.

3. Clouds and Water Vapour

Clouds can either cool or warm the Earth. Thick clouds reflect sunlight (cooling), while thin clouds trap heat (warming).
Water vapour is the most powerful greenhouse gas. More water vapour means more heat trapped, but it also can lead to more cloud formation, complicating things.

4. Ocean Currents and Heat Absorption

The oceans absorb a lot of heat, slowing down the rate of surface warming. But as oceans warm, they can release this heat back into the atmosphere, contributing to global warming.
Ocean currents move warm water around the globe, influencing climate in various regions (like El Niño and La Niña events).

5. Earth’s Energy Balance

The balance between incoming solar energy and outgoing heat energy affects global temperatures. Changes in the Earth’s surface (like desertification, ice melt, or land use) alter how much heat is absorbed or reflected, impacting the climate.

We need to consider all these factors, as you can see how complex global warming is, beyond just GHGs. Surface temperatures depend on the balance between how much energy the Earth absorbs versus how much it radiates back into space - pretty important when we consider global warming.

'Neglected Third'

Rough Summary. GHGs contribute 2/3 to global warming while other factors contribute 1/3. Instead of concentrating exclusively on GHGs, here going to concentrate more on the 'neglected 1/3'. By dealing with the factors producing this 1/3, we may explore many other areas to reduce global warming that help GHG initiatives.

Land Use

What about soil surface and heat exchange. What contributions does this make?

Imagine your greenhouse on different surfaces. Would it be cooler on turf than bare soil? In turn, would it be warmer with concrete base and even warmer with tarmac?

These surface interactions depend on reflection and absorption of heat and the transpiration of plants leading to evaporation of water. These are all to do with how water and warmth interact....

Global warming is also about the soil surface temperature and reactions taking place there. The land surface temperature is generally higher than the air temperature. We should be looking at surface heat exchange, where the sun’s rays hit the earth. This complex equation (based on 3 factors - albedo, capacity and conductivity) happens before any GHG involvement. Any way to reduce heat absorption here, will help the rest of the climate.

For more on surface temperature interactions

It is not a matter of either GHGs or Surface temperatures but both, and we should understand theire interactions much better.

I asked ChatGPt to estimate temepratures under glass with various surface regimes

Given the outside midday temperature of 20°C:

Greenhouse on Grass:
- Likely to reach temperatures of about 24°C to 28°C during the hottest part of the day. The temperature increase is lower due to grass's reflective properties and rapid cooling.
Greenhouse on Bare Soil:
- Temperatures can rise to approximately 26°C to 30°C. The soil's ability to absorb and slowly release heat allows for a more sustained temperature rise.
Greenhouse on Concrete:
- Can reach temperatures of around 28°C to 35°C or higher, especially later in the day. Concrete's high thermal capacity causes significant heat retention and a delayed cooling period.

For more on impacts of concretisation and warming air

Could differences in soils across the world influence global climate patterns?

Yes, differences in soils across the world, particularly in their reflectivity (albedo), water holding capacity, and heat capacity, also play a role in influencing regional and global climate patterns. While their influence is often smaller than the effects of greenhouse gases, soil properties do contribute to local warming or cooling effects and interact with the broader climate system in complex ways.

1. Soil Albedo (Reflectivity)

Albedo is the fraction of solar energy (sunlight) that is reflected back from the Earth’s surface. Lighter surfaces (like snow, ice, or some dry soils) have a higher albedo and reflect more sunlight, contributing to cooling. Darker surfaces (like moist soils, forests, or urban areas) absorb more sunlight and contribute to warming.
Soil types and land cover vary widely across the world. For example, desert soils, which are typically dry and light-colored, have a higher albedo than darker, more vegetated soils. When land use changes, such as deforestation or urbanization, it often reduces the albedo, increasing heat absorption and warming the surface.
Tillage and agriculture practices also influence soil albedo. Bare, tilled fields can have lower albedo than fields with cover crops or natural vegetation, which can exacerbate local warming.

In global terms, changes in soil albedo due to human activities like deforestation, agriculture, and desertification can have a significant impact on regional warming but are less impactful on the global scale compared to greenhouse gases.

2. Soil Moisture and Water Holding Capacity

Soil moisture plays a critical role in regulating temperature through evapotranspiration, the process where water evaporates from soil and plant surfaces, and transpiration from plants. This has a cooling effect because evaporation removes heat from the surface.
Dry soils (like in deserts or during droughts) can exacerbate warming because less moisture is available for evaporation, leading to more direct heat retention at the surface. In contrast, areas with wet soils (such as wetlands or well-irrigated farmland) tend to stay cooler, as the water in the soil helps dissipate heat through evaporation.
Climate feedbacks: As temperatures rise, some regions experience more frequent or severe droughts, which dry out soils. This leads to a positive feedback where the lack of soil moisture reduces evapotranspiration, further increasing local temperatures.

For instance, in semi-arid regions (like parts of the U.S. Midwest or Southern Europe), soil drying has been linked to significant warming during heatwaves because the lack of moisture leads to lower cooling by evaporation.

3. Soil Heat Capacity and Thermal Conductivity

Heat capacity refers to a material’s ability to store heat. Soils with higher heat capacity (like clay-rich soils or wet soils) can store more heat during the day and release it slowly at night, moderating temperature extremes. In contrast, sandy soils or dry soils have lower heat capacity, meaning they heat up and cool down more rapidly.
Thermal conductivity: Some soils transfer heat more efficiently than others. Dry soils (especially sandy soils) have lower thermal conductivity compared to wet soils. As a result, dry soils warm up quickly under the sun but don't retain heat for long, whereas wet soils warm more slowly and retain heat longer.
In permafrost regions, warming temperatures can melt frozen soils, releasing stored carbon dioxide (CO₂) and methane (CH₄), further amplifying global warming. This thawing also changes the heat dynamics of these regions, accelerating the warming trend.

4. Land Use Changes and Soil Degradation

Deforestation: When forests are cleared for agriculture or other uses, not only does the albedo typically decrease, but the water holding capacity of the soil also diminishes, leading to reduced evapotranspiration. Forest soils are generally able to retain more water than bare soils, so deforestation often leads to hotter, drier conditions.
Urbanization: In cities, soils are often replaced with concrete and asphalt, which have very low albedo and minimal water holding capacity. This increases the urban heat island effect, where cities experience higher temperatures than surrounding rural areas. Urban soils that remain tend to be compacted, reducing water retention and increasing runoff, further exacerbating local heat extremes.

5. Carbon Sequestration and Soil Health

Healthy soils with rich organic content act as significant carbon sinks, storing carbon that would otherwise be in the atmosphere as CO₂. Practices that degrade soils, such as overgrazing, deforestation, and poor agricultural management, reduce this carbon storage capacity, releasing more CO₂ into the atmosphere.
Soil carbon loss due to erosion or degradation contributes to global warming, while improving soil health through sustainable agriculture (e.g., cover crops, reduced tillage) can enhance carbon sequestration, mitigating some climate impacts.

Soil’s Role in Global Warming

While the global temperature rise is primarily driven by the increase in greenhouse gases, soil properties play an important role in influencing regional climate variability and feedback loops. The influence of soils on temperature comes through several mechanisms:

Albedo changes: Darker soils absorb more heat, while lighter, drier soils reflect more.
Water holding capacity and evaporation: Wet soils can cool regions through evapotranspiration, whereas dry soils contribute to more warming.
Heat capacity: Wet soils store and release heat differently than dry soils, affecting local temperature extremes.
Land use and management: Human-induced changes in soil properties (like deforestation or urbanization) can intensify local warming.

While soil properties are significant on regional and local scales, they don’t fully account for the additional 0.6°C discrepancy between AGGI-based predictions and observed global warming. Instead, they work in tandem with other processes (like feedback mechanisms and aerosol reductions) to contribute to regional variations in warming. The global-scale temperature increase is still primarily driven by the rise in greenhouse gases, but soil and land use changes play a supporting role in shaping local and regional climate effects.

SAVE

OUR

SOIL!

Instead of trading trillions worth of carbon, why don't we use that money to invest in ways soils can help combat global warming. There are many direct measures, like reducing surface temperatures, desertification and concretisation, which could help in addition to trying to translate a ton of carbon into a temperature. Soils also play a massive role in how 'climate change' manifests itself.

Let's have closer look at soil Carbon
Surface Temperature
Water
Soil biota

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