The Origins of the Earth and the Moon – Why geochemistry doesn’t get the Credit it Deserves

This piece belongs to my blog series at where I discuss the seminars I attended hosted by the University of Edinburgh. The first blog entry can be found at: Why All students, from All years, from All subjects should attend Seminars.

Title of the Talk: The Origins of the Earth and the Moon

Speaker: Miki Nakajima

The Origins of our Moon

Miki Nakajima is a postdoctoral fellow at the Carnegie Institution for Science. In her talk she laid out her work on trying to understand the origins of the Earth-Moon system.

Understanding the chemical makeup of the Moon is important for terrestrial science as the two systems are so interlinked. It would help us to gain a better understanding of tidal interaction between the Earth and the Moon. The data would clean up our chronological understanding of the formation of the Earth.

The original theory was that a small impactor, a Mars size object grazed our planet, kicking out considerable amount of surface mantle material, creating the Moon. There is chemical evidence for this theory from the Moon rocks returned by the Apollo missions.  Both planets have nearly identical isotopic ratios. However several aspects of the Moon’s chemistry are very different to Earth’s. The Moon’s mantle is very Iron poor as well as being low on volatiles and water. The Moon’s overall density is much lower compared to Earth’s. The Moon’s chemistry is partially heterogeneous therefore either a lot of internal changes happened inside the Moon, post collision or the colliding planetoid left more material behind than thought. Clearly the canonical theory on the formation of the Moon does not explain everything.

In order to understand what truly happened in the past Miki and her team ran several simulations in order to answer the questions: Why is the Moon so Iron poor? Where did the volatiles go? Why is the chemistry of the Moon so heterogeneous despite having similar isotopic ratios with Earth?

In her series of simulations she ran the canonical model simulating the heat of individual elements after the collision, tracking how the material mixed and how the volatiles behaved. Different types of collisions have a different effect on planetary material mixing and post formation chemistry. She looked at the other two models proposed for the formation of the Moon: The fast spinning model where the colliding planet completely merges with Earth, the momentum throwing out the debris which formed the Moon. And the the Collision of two half Earths where the two entities collide several times. The two proposed models both show mixing of material. The fast spinning Earth produced partial mixing while the two half-Earths colliding produced complete mixing. The results from the simulations can be seen bellow.

The current canonical Moon-forming impact. The simulation bellow demonstrates the formation of the moon, the possible distribution of material and the cooling of each individual elements:

The possible scenarios were broken down into 3 separate models illustrated bellow:

The 3 main models

Canonical Moon formation:

Moon formation with a fast spinning Earth:

Moon formation with two half-Earths colliding:


While simulations allow us to draw up a working theory, physical evidence is important to confirm it. As the formation of the Moon was a very long time ago and simulations are based on mathematical assumptions, we don’t have much evidence to work with. However there is one key element of Earth that can help us: the magnetic field of our planet. There is evidence that the magnetic field formed very early on. In order to have a magnetic field, a lot of heavy elements need to be molten and in convection inside the core. In order to keep the heavy elements at the core, the right amount pressure and temperature is needed constantly. If the canonical theory is correct, the magnetic field would have formed much later. If the planet would have only grazed Earth, the temperature and pressure balance would have changed, disrupting the iron equilibrium in the core. The only way the collision and the early magnetic field could have happened if the Mars sized planet collided with Earth head-on. This would have caused full core mixing but not much mixing of the mantle. This would explain where the iron went, as the larger core of the Earth would have absorbed much of the original core of the other planet. The missing volatiles could have been burned away by the ionising radiation of the sun when the debris was forming into the Moon.  The large magnetic field of Earth could have come from the extra iron absorbed by the Earth mid-collision (however there is still plenty of debate around the idea).

However after the simulations were run and the volatile loss was checked, the burn-off of the the volatiles was insufficient to account for the missing amount, therefore another past process was at play. The current theories are looking at water absorption by Earth’s mantle to account for the missing material.

The new proposed theory speculates that while the impactor was Mars sized, it didn’t graze the planet but collided head-on with it, allowing the cores of the two planets to mix. Earth absorbed most of the core of the other planet taking the iron with it. The final outstanding question is: Where did all the water and volatiles go from the colliding planet? If there was an insufficient loss from the formation disk in the simulation, was the water absorbed by the mantle of the young Earth?

Planetary Demolition Derby

New information Changes everything

There is one thing that I deeply appreciate about science: everything is not set in stone. If new data comes in challenging the old theory, the old theory goes and the new one gets accepted as standard. This is an amazing system, very unique to the world of Empirical science. In any other fields, the orthodoxy usually stays very dominant, chocking off progress. In science if you have valid data you can change entire fields including the theories on the origins of our planet and our moon. This talk very much connects to that idea. The small impactor theory as the origin of the Moon was very much standard in the past, yet due to the simple inconsistency of geochemical data from the lunar rocks, has been reset to the large impactor theory with further room to understand why the Moon is so depleted in water and Iron. Before going to university I didn’t know about geochemistry (or was very conscious on how important it was). It wasn’t much talked about in school. I haven’t seen it mentioned in public media. Yet after attending several seminars through the years and studying some aspects of it, I can’t stress enough the field’s importance. Modern geological science would be nothing without Geochemistry. The methods within the subject help us pinpoint geological events, understand geological processes and build chronologies.

The department should concentrate more on promoting geochemistry in the media and to the public. It is a science that does a lot of the heavy lifting within geology.

Future Research

Miki in her future research seeks to better understand mantle evolution of the Moon post cooling, planetary accretion of volatiles into mantle, the origins of the Martian moons and other giant past impacts around the Solar System.

Further Reading

Inefficient volatile loss from the Moon-forming disk: Reconciling the giant impact hypothesis and a wet Moon

Hope in an overheated climate

This piece belongs to my blog series at where I discuss the seminars I attended hosted by the University of Edinburgh. The first blog entry can be found at: Why All students, from All years, from All subjects should attend Seminars.

Title of the Talk: Hope in an overheated climate

Speaker: Professor Kevin Anderson

An Inspiring Speaker

Prof. Anderson is the Deputy Director of the Tyndall Centre for Climate Change Research. In his talk he discussed the implications of the recent United Nations IPCC climate report and Scotland’s responsibility in tackling climate change. He revealed how since the 1980s big corporations and various governments knew about Climate Change and its future impact on the world. However due to political expedience they chose to ignore the problem, hoping the next generation with new technology will solve the problem. That did not happen, taking us to the problems of today.

Man made Climate Change

This century’s largest threat to mankind’s existence will be climate change. Our fossil fuels industry on which our economies are extremely reliant on, produce more CO2 than the planet can cope with absorbing. Same is true for our agriculture as our reliance on beef caused astronomical amount of methane being released into the atmosphere. The Oceans are absorbing CO2 at record rates at least in the past 10,000 years. The rising acidity and temperature levels of the oceans are killing off the coral reefs. The overall outlook of the livability of the planet’s climate is not good.

The current projection is putting our worlds path on a 3-4 degrees warming, unless we put our greenhouse gas emissions under control.

The ambitious challenge

Why current measures are a Sham

Despite all the conferences, all the press releases and the promises of new technology, the growth of global CO2 hasn’t stopped. Worse, the general consensus among companies became that we can use future technologies that have not been invented yet or untested to reduce the future CO2 emissions. Worse, a lot of plans see poor countries doing most of work. The same is true for the classes in rich nations. The upper class doesn’t want to change in its lifestyle so they want to introduce extra taxes on the working classes and demand them to give up everything from their cars to their communities.

However the biggest problem globally is the lack of coordination between nations. While the Paris Agreement exists, it is voluntary and full of legal loopholes. Some countries use this as an excuse not to introduce any policies fighting climate change, blaming the lack of action on the other side. As a response to concerns about climate change, governments of the world and the UN have been talking about climate change since the late 80s.  However much action has not been taken as most are expecting some future quick solution (It just became a trend like everything else, to show that people ‘care’).

It was the best of times, it was the worst of times…

What can we really do to fix it?

The current plans on fighting climate change are inadequate as they are designed to kick the can down the road. The Paris agreement aims to have the yearly growth of global temperatures be at about 2 C degrees. Yet the IPCC report clearly states that if we want to avoid most of the damage we should aim bellow 1.5 C degrees. The problem should be tackled the way the United States tackled the Great Depression and post-world war Europe, a Green New Deal and a Green Marshal Plan. There should be a 3 phase strategy: Immediate and near term, where we change behaviour and corporate practices. Near to Medium, where we concentrate on increasing energy efficiency and offer green new jobs. Medium to longer term, Marshal style reconstruction with CO2 storage and major electrification projects. Overall we need a zero CO2 industrial strategy.

What happens if we don’t?

If we can’t reign in our greenhouse gas emissions or we leave the poor countries to pick up the pieces, our global civilisation is in massive trouble. Crop yields will keep on shrinking. The seas won’t yield any life. Summers will be too hot to survive and winters will bring in heavy storms. It would mean total collapse of our current civilisation.

The wide impacts of a rapidly warming world on Europe

What will probably make change happen?

In the current system, nothing much. Wealthy countries will keep avoiding the problem, playing around with numbers. Creative accounting will keep the technical emissions low while real emissions will be sky high. As poor countries are effected first, the populations in wealthier ones will ignore the problem further. The situation might get so drawn out, it wold generate a popular uprising in many countries. Real change will happen when we either radically reform the current Neo-liberal systems or see how can the rich pick up more responsibilities in solving the problems of climate change.

The different points of views on the Problems and Solutions

I find the intersection of politics and science very interesting. A large chunk of Global science is sponsored by the public purse. Therefore research aims and methods are somewhat under the influences of the ones with capital. Public pressure is important as well. If research projects are seen as unethical or purposeless, action groups put a lot of pressures on Government and Business to shut them down. This introduces biases into the research method and interpretation of data. Scientists are human beings with social circles who are reliant on owning and earning capital. Therefore when they present information to the public they try as hard as possible to please the public and the entities that fund them. This phenomena can be observed with Climate Change research. Some profit by denying it, most try to stick to the truth as much as possible and some exaggerate to get attention. When we look at Climate Change data and look through the possible solutions to climate change, we need to keep this in mind.

Further Reading

IPCC special report on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways

What temperature is the surface of the Moon and why should You care?

This piece belongs to my blog series at where I discuss the seminars I attended hosted by the University of Edinburgh. The first blog entry can be found at: Why All students, from All years, from All subjects should attend Seminars.

Title of the Talk: What temperature is the surface of the Moon and why should I care?

Speaker: Neil Bowles

Our weird Neighbour

If you would be an alien browsing across our Solar System you would find certain oddities. No it wouldn’t be our gas giants. Or the giant rings of Saturn. Your focus would shift on the planet third in line. A blue dot in the sky that is not like the other planets in our system. This bright ball in the sky is mostly blue with green and brown blotches running across her surface. After taking a closer look, you the alien would realise that warm water runs across this planet. You would see, it is teaming with Life, great and small. You would quickly realise that an oxygen rich atmosphere reaches across this planet, like a great space suit, keeping everything alive. Your instruments would detect a giant magnetic field, like a shield, defending the planet from the fiery dragon breath of the sun. This sphere would certainly be a great interest to you. But you would notice, this odd fella is not a lone traveller. It has a partner, a moon. However this companion couldn’t be a greater contrast to the blue ball of life. It is barren. Craters spawn its surface. No life whatsoever. No flowing water. The temperatures are hellish. On the sunny side you fry. In the dark, you freeze stone solid. No air to breathe. No magnetic field to shield you from the ionising radiation ripping up your DNA. The place is Death. Sitting opposite to the space ship of Life. An odd couple indeed. However, if you are an alien of a scientific mind, you would notice that the two are deeply interconnected. This moon is relatively close to the big blue ball. Their orbital paths are so synchronised that it only shows one face towards the planet of life. This moon is very large compared to other similar systems. If you would take rock samples from both planets you would learn that this moon formed hot and has a lot of chemical similarities to the planet of life. Taking your knowledge of the formation of other systems you would guess that this system formed when a past large impactor collided with the blue planet forming the moon. A violent beginning to such a peaceful dancing formation today. You as alien would certainly be hungry to find out more.

Neil’s research focuses on trying to understand this strange big rock, our heavenly neighbour. More precisely the origins of the Moon, the reasons for the wide temperature contrasts on the surface and how the craters play a key role in preserving potential water ice on the surface. He argues that we should send more probes to the Moon especially to the polar regions to understand the weird temperature fluctuations there. He is curious to see how good the shady craters are to preserve water ice. He thinks if we find plenty of water ice in the polar regions, future generations could set up Moon bases there and use it as a jumping platform for our journey into the cosmos.

Lunar Reconnaissance Orbiter – Measuring the surface temperatures of the Moon

Historical Context

The Moon was a focal point of the Space Race of the 1960s. It represented the prize for both the Americans and the Soviets. Both sides visited it extensively with manned missions and robotic probes bringing back plenty of rock samples. Plenty of studies were done on the Moon using the samples in the 60s and 70s. However the aims of most Moon missions were not scientific but political. The United States and the Soviet Union were locked in a deadly Cold War. They saw getting to the Moon as a political victory over the other. Therefore the geologically interesting areas of the Moon were not visited, only the flat relatively mountain free areas to make the landings as risk free as possible. Scientific data is limited about the Moon despite us visiting for such a long time. Newer probes such as the Lunar Reconnaissance Orbiter or the SELENE probe while did make some broad observations and yielded good surface temperature data, did not provide the complete picture. The current aim of Prof. Neil is to convince ESA and NASA to send a lander, similar to the Martian InSight probe to directly study the surface of the lunar poles. Therefore despite popular belief our work on the Moon is far from over.

Surface Temperatures and Hidden Ice

The temperature of the Moon greatly fluctuates much more than a normal interplanetary body. It has no atmosphere so there is no gas absorbing or releasing heat. The top surface has poor heat conduction, as it underwent heavy asteroid bombardment. On the sunny side the average temperature can be as high as 60 C degrees while on the shaded side it reaches -180 C degrees. These heavy temperature fluctuations suggest poor hydration of the rocks therefore a water depleted lunar mantle. The surface temperatures are measured by satellite looking at the amount of heat radiated back into space. The rate of cooling and heating was calculated based on thermal inertia.

One of the most interesting locations on the Moon are the Polar regions. They are covered in wide and deep craters and due to the sun’s low angle they are in darkness all the time. This maintains the low, bellow freezing temperatures through the lunar year, allowing the preservation of water ice. The stability of ice on the moon is influenced by several factors. Erosion of the lunar surface driven by impact of micro-meteorites and irradiation of heat by crater walls.

The areas with the highest potential for water have been mapped by the Lunar Crater Observation and Sensing Satellite (LCROSS) based on hydrogen emissions of the area. While evidence for water was poor, the South Pole yielded the best evidence for a good stability field for subsurface water. With a new satellite solely focusing on the area, we could learn more about the location of the water ice.

Maps of measured and model-calculated surface and subsurface temperatures in the lunar south polar region – Ideal place for a Human colony?

Why should we go back?

We still have a limited understanding of our own neighbour. Going back would enable us to expand our scientific knowledge. If we find water ice in the poles, it would provide us raw materials for oxygen generation, rocket fuel and drinking water. The rocky body of the Moon is rich in minerals and Helium3 (a source of fuel for safe nuclear fission reactors) which would enable us to build a civilisation and increase the reach of mankind. The Moon is safer to navigate than asteroids therefore it would make a better platform for Mars missions and planetary exploration. The gravity of the Moon is low, while predictable (unlike an asteroid’s) allowing the launches of rockets at a much cheaper cost than from Earth. The Moon would be a great stepping stone for mankind to further reach into the heavens. Understanding the surface temperature fluctuations and explaining them would go a long way in preparing us for a journey to Mars and beyond.

The best way to summarise why should mankind return to the Moon and beyond is summed up perfectly by astronaut and commander of the Apollo 15 mission, David Scott:

“As I stand out here in the wonders of the unknown at Hadley, I sort of realize there’s a fundamental truth to our nature, Man must explore . . . and this is exploration at its greatest.

For when I look at the Moon I do not see a hostile, empty world. I see the radiant body where man has taken his first steps into a frontier that will never end.”

The plaque left behind by Apollo 17 – “May the spirit of peace in which we came be reflected in the lives of all mankind”

Further Reading

Diviner Lunar Radiometer Observations of Cold Traps in the Moon’s South Polar Region

An Origin Story – Brain Evolution in Rodents: What did our ancestor’s brain look like?

This piece belongs to my blog series at where I discuss the seminars I attended hosted by the University of Edinburgh. The first blog entry can be found at: Why All students, from All years, from All subjects should attend Seminars.

Title of the Talk: Brain Evolution in rodents: What did our ancestor’s brain look like?

Speaker: Dr Ornella Bertrand

Humans and Squirrels are related

Dr. Bertrand’s talk and research aims to understand the evolution of rodent brains from the Euarchontoglires family as they share a common ancestor with us, mankind. If we can understand how brains changed in other species genetically close to us, we can gain a greater insight about our own brain’s evolution. This would permit us to gain a greater insight into the inner workings of our own brains.

The main question about the past of our brain is: How did brain diversity emerge? And Why did it emerge?

In order to understand the processes bringing our brain to life, Dr. Bertrand took fossils from the Euarchontoglires family and attempted to recreate their brain in order to measure their overall size and the sizes of specific areas. Than she compared brain sizes and specifically the size difference between the different neocortexes with the past lifestyles of the creatures (based on fossil evidence and modern ancestors). She gained the measurements by using a micro-CT scanner, latex and plaster, getting the endocast of the brain of each animal, revealing their past shapes and sizes.  She fed the data into a computer program allowing an understanding of how the skulls changed over time to accommodate different brains and how certain elements of the brain changed due to environmental pressures.

CT scan of a young Prosciurus relictus

Her findings were very interesting and revealed a lot about long term brain plasticity. As intelligence goes up in an animal, the brain size increases compared to the body mass, however it can decrease if the animal does not require intelligence for survival.

The living environment is one of the largest factors influencing brain development. The ancestors of squirrels and moles both belong to the Euarchontoglires family, yet they turned out to be completely different. The squirrel lives up in the trees and is more intelligent compared to the mole which spends most of its life underground. This can be observed of their diet too. The diet of the squirrel is much more diverse compared to the mole’s. The two creatures in their group changed completely (including their brains) when they happened to live in two different environments.  This effect was the most visible on their neocortex (the section of the brain responsible for sight and hearing in mammals). The neocortex of the ancestors of the modern squirrel grew as they moved up into the trees. In order to survive the ancestor needed extra brain power for complex locomotion and navigation between the trees. The exact opposite happened for the ancestor of the mole. It had no reason to develop a good eyesight so along with its eyes the overall brain and the neocortex shrunk.

The changing size of the neocortex

The squirrels with their larger brains became good generalists, while the moles only adapted to a certain set of conditions and lifestyle.

Dr. Bertrand looked at other reasons for a decrease in brain size. The two other major factors were lack of predators and human domestication.

Her continuing research will aim to document the further members of Euarchontoglires from the fossil record in more detail. She wants to learn more about mammal evolution after the extinction of the dinosaurs. The aim would be to see how placental diversification happened. Did the diversification of mammals explode in rate or did it steadily increase after the K-T extinction? She aims to apply her current research techniques on later mammals to mammals right after the K-T extinction event. How did the post-dinosaur environment effect their brain growth? Did it cause an acceleration in their intelligence?

Why this is a Philosophical matter not just a Palaeontological one

In the pre-Darwin era the origin of mankind was simple. Man created by God, ever perfect, only corrupted by original sin. Evolution threw that idea back into chaos. The pedestal on which man stood as infinitely above raw nature, a creature that is wise and not subject to the whims of natural forces, crumbled. Morality itself was questioned. Were we creatures capable of free choice? Did our actions follow our knowledge of Good and Evil? Or were they a consequence of the impulses of natural selection, where the weak had to die and the strong strive to dominate all? Were we just another entry on the long line of the evolutionary story where we were destined to be swept away by the sandstorm of time?

These are questions that since the 19th century have bothered peasant and king. Some rejected the ideas of Darwin as fanciful and nothing else. Others while deeply agreeing with Darwin chose to separate the two, treating mankind as the next step. As a civilisation builder, who while originated from apes, have moved beyond carnal desires, using science and philosophy to light a candle in the dark. A being that managed to be that conscious point of the universe, casting the rules of evolution aside.

Others took the idea of evolution to their very heart: Nature is a dangerous game and everybody is a player, subject to the same harsh rules. If you loose (which you must not) you die. This mentality was taken up by the highest echelons of power and applied on a scale of civilisations. Ultimately this lead to the rise of social Darwinism internally of civilisation and externally. A lot of European Empires based their conquests on those ideas. The world was a free for all and if you didn’t dominate, you were crushed by some other Empire joining the ranks of Ancient Egypt, Rome or the Aztecs. This view of the world ultimately ended in the horrors of the World Wars.

However after the levelled cities of Europe and the burnt out islands of the Pacific, the pendulum swung the other way. Mankind invented and discovered so much in the past 400-500 years. No way we were just machines of nature acting out impulses to propagate the species. We were (and are) thinkers that are capable to dream up and create abstract systems. We built civilisations and when they burnt down, we rebuilt them. Therefore despite a divided world of East and West both parties came to the same conclusions: Evolution while interesting to study is not a determiner of the future. The force that created mankind must be shunned and controlled in order for mankind to have a hope at a future. This was to be seen in Global Politics. The West had embraced Capitalism and Liberalism, ideas that while fed into evolution, stand contrary to the basic rules of natural selection. The East embraced Socialism and Communism, another set of ideas that emphasised mind and human will over Nature. The idea of Evolution completely changed the way we look at the world and the way we look at ourselves. We stare back at the depth of time with fear but with a touch of slight amusement and hope, but mostly fear. It is really hard to take ones existence as being from microbes and muck (the legacy being carried on by us).

Same questions apply to this talk.

Were we lucky that our rodent ancestors chose the trees instead of the bowels of the Earth? Did they chose at all? Were they simply subject to the tools of evolution? If you climb, you brain goes high but if you stay, your brain wastes away? Was it ambition that drove our ancestors up the trees or was it simple survival? Or was it just simple coincidence that as you needed more processing power to move around the trees, your brain size naturally grows, enabling the spare neurons to crack on with some other task. (It was also a nice piece of luck for that plucky asteroid that managed to hit Earth an odd 66 million years ago.)

These are hard questions, however at least they teach humility. When you go out in the park and look at a grey squirrel munching on a pizza, you can see some kinship with the creature and have some understanding how it all came to be.

Evolution? – Soviet poster against the Nuclear Arms race

Further Reading

Virtual endocasts of fossil Sciuroidea: brain size reduction in the evolution of fossoriality

Virtual endocasts of Eocene Paramys (Paramyinae): oldest endocranial record for Rodentia and early brain evolution in Euarchontoglires

Soil Erosion Rates at a Global Scale – A Story about Sense and Nonsense of Modelled Data

We all agree that numbers and models are an important service of science for a various set of reasons. For instance, they help decision-makers in our society understand current and future trends and therefore contribute to a differentiated planning of development regarding numerous issues in the environmental, societal and economic sphere. One of the most pressing environmental issues, that was recognized by the United Nation’s food and agriculture organisation (FAO), is “soil degradation”. This process is a global phenomenon and is caused by non-sustainable land management and land use as well as natural processes, such as droughts. Soil is a «non-renewable natural resource»: The time it takes to develop new soil exceeds the time of many human generations and land degradation obviously contributes to an increase in development time. Thus,  the natural base for sustaining human and other life decreases faster than it can be recovered therefore threatening important ecosystem functions of soils such as providing food and fuel as well as other ecological services. According to the FAO, the «current state of soil degradation threatens the capacity of future generation[s] to meet their needs». But how can we know about the «current» state of soil degradation? This article aims to address this question by looking at how global soil degradation can be studied, show uncertainties in the resulting models and briefly address what kind of information on different spatial scales the models can actually provide.

In 2003 for example, a group of researchers around Dawen Yang from the University of Tokyo modelled the global soil erosion potential with the so-called RUSLE approach (Revised universal soil loss equation). Soil erosion is a process where soil gets allocated from its initial location, most often leaving the place without fertile topsoil. Drivers of this process are mostly water and wind that hit unprotected soils (with little to now vegetation cover) under certain natural- or land management conditions.

An approach to modelling the global soil erosion potential

The RUSLE-approach as used in the study of Dawen Yang and others can be summarized as follows: it is assumed that the soil erosion potential (A) has different contributing factors. The rainfall erosivity (R-factor) describes to what degree soil is eroded by being directly hit with rain drops. The topography (LS-factor) describes the influence of length and steepness of slopes in an area on the potential soil erosion as soil is assumed to be more vulnerable to erosion with increasing length and steepness of a slope. Additionally, the soil erodibility (K-factor) is determined by looking at the soil properties (for example soil texture and water permeability). More focused on the human impact on soil erosion are the land cover and management (C-factor) and the soil conservation practices (P-factor). The importance of land cover and management relates to the linkage between vegetation cover and soil erosion. For instance, soils under intensive agriculture have a higher soil erosion potential than soils under grassland or forest. Land conversion processes, as for example deforestation with the aim to transform an area into arable land, are known to increase the soil erosion potential. However, there are also soil conservation practices of land users that can decrease soil erosion (for example agro-forestry). Altogether, the soil erosion potential can be expressed with the following simple equation:


The “sense” of modelled soil erosion

The research group around Dawen Yang used this RUSLE-approach and calculated the soil erosion potential on a 55 km2 grid globally. They estimate the accumulated annual soil erosion potential to be 133 billion tons, or an annual average of 10.2 tons per hectare globally. However, the soil erosion potential is not equally distributed over the globe. They identified two zones where soil erosion is most pronounced. Zone one is located on the west coast from North- to South America. The second zone goes from South Europe via the Middle East to Southeast Asia. The authors outline that the modelled soil erosion is most pronounced for mountainous areas, intensive croplands and highly populated regions therefore indicating natural and anthropogenic drivers. However, it is questionable if mountainous areas in high altitudes even feature developed soils, leave let alone the question about if whether they are used. Whereas it is obvious that the results of the presented study show tremendously high values of soil erosion, they also have to be looked at in the context of other current research. A study from Gerard Govers and others from Belgium in 2014 compared different studies from 1991 to 2007 that, like the study by the researchers from Tokyo University, estimated global soil erosion rates. They showed that the modelled global soil erosion rates differ greatly in a range between 50 billion up to 172 billion tons per year. This sheds a different light on the Yang’s study using the RUSLE-approach in 2003. It has severe consequences on the planning of international efforts to combat soil degradation if soil erosion rate estimates are at 50 billion tones per year or versus a rate three times higher are assumed as a baseline quantity of the environmental problem. This leaves us with the question of if and how this wide range of estimations can be explained.

The “non-sense” of modelled soil erosion

As outlined, estimates of global soil erosion differ widely. A reason for that can be located for example in the RUSLE-approach itself. In order to estimate a factor globally, researchers often have to extrapolate data from one or more places over the globe because there is no global data set available. In other words, it is assumed that a relationship between, say, rainfall amount/intensity and the rainfall erosivity (R-factor) that is measured in North America, holds true for every region of the world. Obviously, this assumption is problematic since rainfall amounts and intensities differ greatly between places on the global scale. Additionally, many of the RUSLE-factors are calculated based on global datasets that are incomplete or widely averaged. For example, a data set about soil conservation practices will never contain every single location where those practices were implemented by the land users, let alone that the practices may differ a lot. In other words, some RUSLE-factors are estimated based on global estimates of sub-factors which therefore show a very distorted picture of reality. Another issue is the selection of the spatial resolution of a model: researchers must deal with the trade-off between accurate information and global coverage. With a lower spatial resolution (e.g. 100 km2 grid cells), different functional landscapes are averaged to one potential soil erosion value. This can be misleading because for instance mountainous areas react differently to soil erosion triggers than agricultural areas, yet they are averaged in the model. With higher resolutions (e.g. 10 km2 grid cells) the researchers can use more precise datasets of the regions (where available!) with specific calculations. However, this leads to a decrease of comparability between locations and thus pronounces difficulties in interpreting global models. Using a global modelling approach to answer a research question thus has intrinsic shortcomings. The outcome of the model is determined by how a variable is calculated and estimated, what reference data was used, etc. Also, different modelling-approaches use different variables or calculations. This partly explains the large differences of global soil erosion rates modelled by different studies which was summarized by Govers and others in 2014. Their study also outlined that most soil erosion estimates don’t investigate what happens with eroded soil. Soil can get transported multiple times in a series of erosion events before being deposited at the «final» location. So, most models estimate the loss of soil but not where it ends up. In terms of land management this appears problematic since for instance terraces on hillslopes can be used to catch the eroded topsoil and re-use it at the deposition site. This shows that there are impacts of land management practices which current global soil erosion models cannot claim to cover.

Are global models enough to support combating soil erosion?

Using models offers a way to estimate the global soil erosion potential which can be identified as a global environmental issue with multiple drivers. Thus, this approach provides information about spatial patterns of severity of soil erosion. Hence, models are surely important tools to concentrate international efforts to combat soil degradation in a meaningful way. However, models cannot capture the whole reality of current soil erosion processes and extents and that the numerical results heavily depend on the dataset, calculation methods and spatial resolution that is selected for the model. Additionally, one has to ask how the people actually managing the world’s soils (foremost farmers and pastoralists) benefit from information about global erosion. Small-scale land management surely requires more detailed information about processes and leading to – or conservation practices preventing – soil erosion, other than can be provided by a 55 km2 resolution model. Also, the question about practices that are meaningful to combat soil erosion in individual socio-ecological contexts cannot be addressed by such methods of research, thus leaving local (and relevant!) actors of land management out of the focus. In conclusion, models provide soil erosion estimates on a large spatial scale, but they include uncertainties and cannot provide context-driven information on soil conservation practices that is needed by local actors to combat soil erosion.

  •  General information about soil and soil degradation are provided by the FAO.
  • The study from Dawen Yang and others (2003) was published in Hydrological Processes.
  • The findings of Gerard Govers and others (2014) were published in Procedia Earth and Planetary Science.

*The heading picture of this post was found on GeoLog (EGU). Credits go to Matthias Vanmaercke.

*The original version of this essay was written by the author in “Challenges in Geography II” at the University of Berne in the spring semester 2018.


Is Urban Gardening a Social Innovation?

Over the last decade, “urban gardening” and “urban agriculture” became increasingly popular among public policy makers and civil individuals (Ernwein, 2014: 77). Those community-based initiatives are acknowledged for a wide set of reasons. For instance, they seem to promise a response to urban degradation (Kurtz, 2001: 656) and are believed to offer a potential for contributing to sustainable food systems (CoDyre et. al., 2015: 71). Moreover, urban gardening is perceived as a way to deal with social fragmentation by promoting social inclusion in a shared open space (Ernwein, 2014: 77). Thus, urban gardening projects appear to be civic bottom-up initiatives that meet different social needs. An increasing number of political administrations in Western countries are developing urban agriculture policies that include all practices of growing food in and near cities (e.g. community gardens). Those public policies can be understood as a part of a policy-making trend that focuses on enabling civic initiatives “to empower and to promote the renaissance of the cooperative movement” (Bock, 2016: 553). Those initiatives can be subsumed under the term “Social innovations”. They can be distinguished from economic innovations along several key factors. For instance, social innovations include social entrepreneurs, initiatives, and movements as contributing actors whereas economic innovations rather rely on companies and research institutes (Rehfeld et. al., 2017: 7). Most important, the objective of social innovation is of social character which stands in contrast to the economic objective of economic innovations (Rehfeld et. al., 2017: 7). There exist numerous definitions of social innovation and no explicit scientific or public consensus on the exact meaning has been reached yet (Bock, 2016: 553; Bornstein et. al., 2014: 4). Following Bock (2016), this essay will go with the definition of the European Comission (2011):

“Social innovations are innovations that are social in both their ends and their means. Specifically, we define social innovations as new ideas (products, services and models) that simultaneously meet social needs (more effectively than alternatives) and create new social relationships or collaborations. They are innovations that are not only good for society but also enhance society’s capacity to act.” (European commission, 2011: 9).

On different administrative levels, it is widely accepted  that urban gardening can be considered as an example for a social innovation. The question at hand is if, or to what extent, this holds true when social innovation is viewed according to the definition introduced above. This essay aims to address this question by looking at the urban gardening project at the “altes Tramdepot” in the city of Berne and by discussing how urban gardening may or may not contribute to social inclusion.
In the city of Berne, various urban gardening projects are in place at different locations (Stadt Bern, 2017). One of them is the project at the “altes Tramdepot” which is an urban gardening project that was initiated by the city’s administration and the neighborhood-association “Quavier” to allow the intermediary use of the area before it gets converted into a new housing- and business complex (Hämmerle, 2013). According to the responsible policy-makers, the goal of this project is of social character: The urban garden offers the possibility for individuals to meet without obligations which meets a need of the local neighborhood (Hämmerle, 2013). Thus, this project meets a social need (social inclusion- and networking). However, it is not designed in form of a bottom-up civic initiative but in a form of a partnership between the public policy sector and a group that represents the interests of a local community. Therefore, in this example, the idea of urban gardening was formally institutionalized. This corresponds to the findings of Ernwein (2014) who mentioned that urban gardening projects are often embedded in the local politics of their respective administrative space (Ernwein, 2014: 77). Also, the goal of social inclusion- and networking needs to be critically assessed. Community garden projects differ greatly from each other. Their degree of social inclusiveness varies and depends on each project’s accessibility and their membership (i.e. the social and spatial framing of the project). Thus, not all community gardens act as „community catalysts“ (Ernwein, 2014: 77-79). Referring to the project introduced above, I hypothesize that the project might very well possess a certain degree of social exclusion because it was partly initiated by community-representatives of the neighborhood where the project takes place. It might be spatially accessible to a broader public but is designed for the specific needs of a specific community. Thus, social inclusion of community outsiders (e.g. individuals of near neighborhoods or groups with other needs) is not addressed by the project. Looking at the definition of social innovation of the European Comission (2011), I argue that the presented urban gardening project can be partially regarded a social innovation: It addresses a social need of a community, but it is questionable to what extent it promotes inter-communal relationships or collaborations. Nevertheless, the project stands for a joint effort of a community and the public policy sector which showcases that bottom-up initiatives can be recognized and supported by public administrations. However, the social and spatial framing of such projects are embedded in different interests and power-relations of different contributing actors. Thus, the social means and ends of similar projects will only be achievable as long as the interests are aligned.

Broader speaking, I question the potential of urban gardening for social inclusion since it meets the interests of specific communities and therefore also contributes to some sort of social exclusivity, based on where the project takes place and who can contribute to it.
Finally, it must be mentioned that urban gardening projects differ among each other. Also, as mentioned, there are many different definitions of “Social Innovation”. Thus, there might very well exist a project that can be considered as a social innovation when contemplating more than one definition. This circumstance displays the present challenge of working with the terms “urban gardening” and “social innovation”: With that many definitions and perspectives in use, it is becoming increasingly difficult to analyze project-based case studies because the applicability of both concepts can be argued in various ways with different outcomes. Consequently, also public administrators need to settle on well-defined approaches of social innovation and urban gardening (and how they meet each other) in order to lower the risk of policy-misalignments.

*The original version of this essay was written by the author in the lecture “urban and rural development theories” in Automn 2018 at the institute of Geography, University of Bern.


Bock, B. (2016): Rural marginalisaion and the role of social innovation: A turn towards nexogenous development and rural reconnection. Sociologica Ruralis, (56) IV, pp. 552-573.

Birnstein, N., Pabst, S., Sigrist, S. (2014): Zur Bedeutung von sozialer Innvoation in Wissenschaft und Praxis. Im Auftrag des Schweizerischen Nationalfonds SNF. W.I.R.E, pp. 1-78.

CoDyre, M., Fraser, E., Landman, K. (2015): How does your garden grow? An empirican evaluation of the costs and potential of urban gardening. Urban forestry & urban gardening, (14), pp. 72-79.

Ernwein, M. (2014): Farming urban gardening and agriculture. On space, scale and the public. Geoforum, (56), pp. 77-86.

European Comission (2011): Empowering people driving change: Social innovation in the European Union. Bureau of European policy advicers (bepa). pp. 1-176.

Kurtz, H. (2001): Differentiating multiple measnings of garden and the community. Urban Geography, (22) VII, pp. 656-670.

Rehfeld, D., Terstriep, J. (2017): A theoretical framework for the economic underpinnings of social innovation. SIMPACT working paper, (1), pp. 1-23.



Hämmerle, B.(2013): Jedem Berner sein Garten. DerBund. In <>. Access: <03.12.2013>.

Stadt Bern (2017): Urban Gardening. In: <>. Access: <03.12.2017>.


Picture of blog-post: A guide to urban guardaning. In: <>. Access: <13.05.2018>

London Underground – The Journey of Life

This interactive web map explores life expectancy discrepancies between London Underground Stations. The output is a startling reminder of the importance of ‘place’ to people’s lives. It displays sharp contrasts between life expectancy on a small spatial scale. For example, Ladbroke Grove and Latimer Road on the Hammersmith and City line are separated by one stop (800 metres) but the average life expectancy is seven years higher in Ladbroke Grove.

My intention in designing this map was to create a memorable impression of the spatial inequalities along the routes travelled by Londoners each day. Within ArcGIS online, I uploaded a dataset which contained the average life expectancy from health clinics in London (total of 1436 health clinics) and created a spatial join to connect them to their closest underground station (total of 312 stations). The station then displays the average life expectancy (male and female combined).

Webmap URL: Click here

Distributed GIS

What are Distributed Geographical Information Systems (GIS)? Distributed GIS are systems that do not have all the components in the same physical location. – Here a diagram complying with the old saying, “A picture is worth a thousand words”.




Peng, Z. and Tsou M. (2003). Internet GIS: Distributed Geographic Information Services for the Internet and Wireless Network. London: Wiley.

Young C. (2017). Distributed Geospatial Computing (DGC). In: Encyclopedia of GIS. 2nd ed. New York: Springer.

Icon Sources within the Diagram

Clip art images: Available at: [Accessed 23. Sept. 2017].

Globe image: Available at: [Accessed 23. Sept. 2017].



Welcome to Geo-Blog


We are very excited to start the new project Geo-Blog!

Geo-Blog is a platform serving as an opportunity for young geoscientists and students to share and publish their ideas, experiences and projects. Find other people with shared interests to discuss current topics and get valuable inputs from fellow young scientists. Every specialization is welcome to be a part of Geo-Blog! You are also invited to share your experiences in the field and find others to join your next trip.

We believe that the different Geosciences are working too seperately on topics of shared interest. The potential of synergies is large but often not used or appreciated. Our platform marks a step in the opposite direction by providing you the opportunity to share your own ideas and experiences as well as give feedback to others. We believe that a community that offers a membership to all geoscientists and students can bring together different perspectives on the same topic. This allows scientific discourses to open up and to think outside the box.

Feel free to join and write one of the first posts.


We are looking forward to welcoming you,

Tobias and Livia