small and significant

You may be a small part of this world, but you are not insignificant!

Month: August 2019

Climate Change: The Science (week 4)

I have just finished the fourth and final week of learning with this online course by the University of Exeter, which I found on During the past month, I have learnt a lot of new, interesting things about why climate change is happening and what effects it is already having on ecosystems and communities. This post is supposed to help me summarise and reflect on what I have learned and I hope that it will also be interesting and helpful to you (my comments are in bold). Thank you for visiting my blog! 🙂

What was covered?

This week, the course was wrapped up with information on making climate predictions, on the tipping points we should be careful not to reach, on the Anthropocene and the ‘Great Acceleration’, as well as on mitigation and adaption to climate change.

Climate models

Making a climate model

At the beginning of the week, it was explained that whether you are making predictions about short-term weather changes or about long-term climate changes, the processes which have to be modelled are quite similar. However, when making climate projections, additional processes are required, as you also have to take into account the slower components of the climate system, like ocean currents or carbon being stored in vegetation.

Supercomputer used to produce climate model (source: online course)

With all of these additional factors added, a climate model aims to simulate how the temperature, humidity and wind in the atmosphere and the temperature, salinity and currents in the ocean will vary over time. As one can imagine, making one of these models requires a large supercomputer, as about two million calculations are required for every time step of the model (about 20 minutes) and as more than 100 years have to be simulated. As a result, even a large supercomputer will take three months for a typical climate simulation, which is why people are very careful not to make any mistakes on them.

Another challenge is that some of the underlying equations which control the system are not known to us, for example equations about how vegetation and soil will respond to climate change and how much carbon they will absorb. It is very difficult to determine what these equations should look like, so scientists have to make predicitons by looking at lots of data from the past. However, in many cases, we have known the underlying equations for quite a long time, with one example being the Navier-Stokes equations, which help to determine how the atmosphere and oceans move.

Testing whether a model is realistic

Testing model only with natural factors: green – simulation, red – observed (source: online course)

Once a climate model has been finished, it has to be tested whether it is realistic or not. To do this, you check if it can reproduce aspects of the past that have been observed, most importantly the 0.8 degrees Celsius of warming since the mid-19th century. What is interesting is that, if you only put natural factors into the models (e.g. varied output from the sun, volcanism), they reproduce the observed aspects of the climate only until about 1970. From then onwards, actual warming and the simulation diverge and the models tend to have the climate cooling instead of warming.

Testing model with human factors: green – simulation, red – observed (source: online course)

However, when you add human factors, particularly the increase in the release of carbon dioxide, the models reproduce the observed warming extremely well. Thus, the climate models help us to work out how much of contemporary climate change is due to human activity. They allowed the IPCC to make a quite definitive statement about the causes of climate change, in which it said that there is a chance of at least 90% that global warming is due to man-made greenhouse gases. I learned that this method of attributing observed global warming to different factors is sometimes called fingerprinting, which I think is quite fitting.

I think it is really interesting that the models tend to show that the climate should be cooling right now if it were not for human influence. The main argument I have been hearing from people who do not believe in climate change is that the climate has been changing since long before humans existed and that contemporary climate change is just another example of such natural change. To be able to show that the climate would be doing the opposite to what it is doing now if only natural factors were influencing it could be helpful in starting to convince others of caring more about the issue.

Challenges of projecting future climate

After having checked how realistic the models are, the next stage would be to try and project how the climate might be changing over the next 100 years. The online course underlined how challenging this is by mentioning the fact that we cannot really be sure how atmospheric carbon dioxide levels will change in the future, as we do not know how human activities (population growth & energy generation) and the natural world (absorption of carbon dioxide by ocean and vegetation) will develop.

When I tried out the ‘My2050 Calculator‘, I was happy to see what changes in the behaviour of individuals, were they to spread and become mainstream, could do in terms of reducing emissions and combatting climate change. I am still optimistic that many people will be inspired in the coming years to live more sustainably and that the decisions of governments and companies will be influenced by this. However, the future lifestyle choices of people (including how many children they want to have) and the decisions of companies and governments are very difficult to predict and even if they became ever more supporting of the environment, there is still a range of unpredictable environmental events that could take place. One disaster we are not able to control in time could trigger an irreversible feedback.

Because of these challenges, scenarios produced by the IPCC are based on different storylines of how the world will evolve over the next 100 years. They range from a world in which we work very hard to cut emissions and avoid two degrees of warming, to a world where we go on with ‘business as usual’ and get as much as 6 degrees Celsius of warming over the next 100 years.

The IPCC climate models

The IPCC climate scenarios (source: online course)

The IPCC’s four climate models project global warming based on potential ‘Representative concentration pathways’ (RCPs). The most optimistic scenario of the four would be RCP2.6, which requires immediate and drastic action before 2020 and which would result in a temperature rise of 0.9 to 2.3 degrees Celsius (relative to pre-industrial) by 2100. The worst case scenario would be RCP8.5, which would effectively mean ‘business as usual’ and lead to an increase in global temperatures of 3.2 to 5.4 degrees Celsius by 2100.

There is already evidence that global warming is associated with increasing heat waves, droughts and more intense hurricanes and it is expected that we will see even more of that at ‘only’ 2 degrees Celsius of warming. If RCP8.5 becomes a reality and we eventually reach 6 degrees of warming, that would mean that the climate would have changed more than between the Ice Age and now, only 100 times faster. The result would be an extreme danger of crossing tipping points. For example, the gulf stream, which actually keeps the UK warmer than it should be at its latitude, could be weakened, leading to the area getting cooler. Even worse, the Greenland and West Antarctic ice sheets, which have the potential of raising the global sea level by ten metres, could collapse.

All of this is extremely scary. The graph at the beginning and all the information from the past weeks on the effects of ‘only’ 1.5 or 2 degrees Celsius of warming make you realise how important it is that the RCP2.6 becomes a reality. But how likely is it that world leaders and corporations will take drastic and immediate action before 2020? I so want to be omptimistic and I do think that it is important to find out about all of these scenarios, but it is starting to make me feel a little hopeless and powerless.

Tipping points

The warming predicted by the IPCC only relates to carbon emissions, however, there are many more feedbacks in the climate system that may be important in determining future global warming potential and that may lead to tipping points:

Tipping points in the climate system identified by Professor Tim Lenton
(source: online course)
  1. Release of methane: Methane has a global warming potential 25 times greater than carbon dioxide. The Permafrost regions of Alaska, Siberia and Canada may become net releasers of methane if they thaw as a result of global warming. This would mean that old organic matter would be exposed, which would lead to it releasing significant methane stocks as it decomposes.
  2. Instability of the West Antarctic ice sheet: Much of the West Antarctic ice sheet is grounded below sea level, which means that warming ocean waters can melt the ice. Additionally, the floating ice shelves which normally buttress the glaciers are breaking up. Examples of concerning events in the Antarctic are the collapse of the Larsen ice shelves, which led to glacier acceleration, and the apparent irreversible retreat of glaciers entering the Amundsen Sea Embayment. The loss of this area would contribute more than one metre to sea level rise and destabilise the rest of the ice sheet, which could lead to the collapse of the West Antractic ice sheet.
  3. Atlantic Thermohaline Circulation: The Atlantic Thermohaline Circulation brings warm waters northwards before they cool and sink to the bottom of the ocean on either side of Greenland, propelling a southward flow of cold water at depth. An influx of fresh water or heat energy could disupt this circulation or even lead to its collapse, which would have effects all around the planet, like disrupting the summer monsoons in India and West Africa.
  4. Amazon rainforest dieback: As a result of the 2005 and 2010 droughts across the Amazon, the rainforest switched from being a net sink to being a net source of carbon and droughts are still increasing tree mortality. Moreover, further changes in precipitation may lead to a dieback of the rainforest, which would lead to a very significant amount of carbon dioxide being released and triggering a positive feedback. Lastly, 20% of the Amazon have already been deforested, which puts increasing stress on an already fragile ecosystem.
Amazon rainforest fire (Photo by Stock Connection/Shutterstock (2390417a) Amazon rain forest afire. VARIOUS)

Just this morning, I read this Aljazeera article on fires in the Amazon rainforest and I was shocked once again by the extent of the negative impact we are having on this beautiful ecosystem and by the unbelievable reaction of denial and hatred from the Brazilian president. He baselessly claims that NGOs are starting the fires to make him look bad and denies that man-made climate change is happening.

The Anthropocene

Next, the online course introduced us to the idea that we are standing at the dawn of a new geological epoch, the Anthropocene, in which climate change will alter the face of the planet. It was explained that we have recently reached a milestone in the levels of carbon dioxide in the atmosphere: 400 parts per million in May 2013, and that these levels are expected to rise to 1,500 parts per million around the year 2,300 if we continue to burn the known 4,000 billion tonnes of fossil fuels.

Moreover, in the coming centuries, and if that scenario becomes a reality, the planet could see the global average temperature peak at 8 degrees centigrade above pre-industrial levels, the interruption of the natural cycle of ice ages for hundreds of thousands of years, and sea-level rise of tens of metres. Additionally, it would take about one million years to return all the released carbon dioxide to the lithosphere, as it is a very long-lived pollutant and more persistent in the atmosphere than radioactive waste.

Recovery to pre-industrial temperatures & carbon dioxide levels after man-made climate change (source: online course)

It is unbelievable how profound and long-lasting our effect on the planet might be if we do ‘business as usual’ (even if people might have a point when they say it is a little arrogant to claim that we will be the main thing shaping an entire epoch). It seems to me that humans do not usually think enough about the implications their actions have long-term. Maybe it’s because we are quite selfish animals and primarily care about our individual well-being. Even when we hear the most devestating things about how our behaviour might mess up the Earth’s systems for hundreds of thousands of years, many people refuse to cut back on their luxuries in order to reduce their negative impact.

We want a globalised world where we are connected to everything and everyone, but we refuse to acknowledge the disadvantages of this. I think all of us feel that urge to go on with bussiness as usual to some extent, because we’re just scared of change, especially when it is for a global cause of which we can’t even fully grasp the complexity. In addition to that, we imitate the people around us and do not want to stand out and do something ‘weird’. It actually reminds me of the bystander effect, only that the person who needs help is our planet. That’s why it is so important that we get our voices heard and inspire other people.

The ‘Great Acceleration’

The ‘Great Acceleration’ has a lot do with the Anthropocene. It describes the speed up in consumption after World War II. The Holocene, a geological epoch which began around 11,700 years ago, had been characterised by a fairly stable climate until greenhouse gas emissions, ocean acidification, global warming, deforestation, land-use change, energy use and world population started rising dramatically from the industrial era onwards, using the world’s resources at an unsustainable rate.

Earth system trends
(source: online course)

In several of the curves on the right, there is a marked kink around 1950, which is the start of the ‘Great Acceleration’ and a potential start date for the Anthropocene as changes to the Earth System, which are beyond the range of variability of the Holocene and driven by humans, have only been taking place after this date.

Moreover, as human activities have also eroded the land surface and greatly increased the rate of sedimentation in oceans, scientists are arguing about which signal in the geological strata should be used to mark the start of the Anthropocene. The favourite candidate is a layer of radioactive nucleotides deposited by atom bomb tests after World War II, which also fits nicely with the idea that the Anthropocene started with the ‘Great Acceleration’.

Other proposals for when the Anthropocene started are the industrial revolution or even agricultural activity & land-use modification that started 8,000 years ago and has been linked to increases in atmospheric methane. It is also argued that carbon dioxide oscillations of about 10ppm in the last 1000 years are too large to be explained by solar-volcanic forcing, and that the observed carbon dioxide decreases were rather due to widespread forest-regrowth after people abandoned their farms as a result of plague outbreaks.

Lastly, the course reminded us that, no matter when the Anthropocene started, it is clear that the acceleration of human impact on the climate cannot continue on a finite planet.

Total real GDP since 1750

A graph that can be compared very well to the graphs above is that which shows the changes in total real GDP. It, too,shows dramatic acceleration since 1950. I do believe that we have to think about the question if capitalism can still serve us at a time when we are facing immense environmental challenges. It is hard to find an alternative, as it seems like all the economic systems we have tried out so far failed in one way or another. And the fact that the whole issue is quite a sensitive topic to talk about only makes matters worse. In my opinion, the least we have to do is change how profit and power are the primary goals of our economy and of most people at the moment. Things like environmental sustainability, strong communities, health and justice should definitely be valued much more.

Climate change mitigation & adaption

During the course, we repeatedly studied the effects of climate change on the Mekong Delta in Vietnam and we learned that it experiences strong seasonality, storms, floods, droughts, sea-level rise and salinity intrusion, which all represent threats to one of the biggest industries in the region: agriculture.

Thus, the area is in desperate need of solutions to mitigate and adapt to climate change. There is no better mitigation than to reduce greenhouse gas emissions and prevent the dangerous effects of climate change from ever happening. When it comes to adaption, there are multiple ways to improve the resilience of a community, for example through diversifying the economy of the region, educating the population, introducing salt resilient crops, and restoring mangroves (protect coastlines from erosion).

Fishery in the centre of Vietnam (source: online course)

The IPCC said in a statement that intervention already underway in the delta in the form of dams will limit the flooding of the summer season and the reduced flow of the dry season. Moreover, it warns that there will likely be further intrusion of salinity into the freshwater system, which will have a significant impact on the type of fish that can be farmed. However, according to the panel, yields should not be affected, which is a reassurance to the 40 million people active in fisheries there. Still, techniques like raising fisheries above the river next to them (picture) may become more common to protect them from salinity or drought.

Furthermore, a study of current residents of the area showed that 33% have insufficient skills to adapt their present livelihoods and that 48% would not wish to move from their ancestor’s village. Residents in the city of Can Tho, who are identified as being highly vulnerable, have been shown to have an adaptive capacity of 0.4%. With the help of this imformation, it was underlined in the course that there might be social resistances towards identifying solutions to climate change and that these need to be addressed alongside any top-down implemented response.

I agree with this last point, because I think it is crucial that good communication takes place between the residents of an affected area and the group of people who want to implement changes in order to make the community more resilient to environmental impacts. Especially nowadays, when there is quite a lot of pressure to act on climate change, there is the danger of helpers not respecting the fact that the local population might have other ideas and wishes about what changes should or should not be made to their home. Even if the government or and international organisation means well, it might in fact be quite unsustainable to just push people to change certain things in their behaviour or in the infrastructure of their community. It could lead to them rejecting the foreign help completely and barely making any changes to become more resilient. Thus, I agree that a lot of attention should be paid to social resistances.

Environmental Demonstration
(source: online course)

Taking action

Lastly, the online course encouraged us learners to “think global, act local”, as some of the most promising collective actions are happening at the local level. We were reminded that this kind of action will determine the future of the climate for many generations to come, which means that it is crucial that we participate in every way we can.

Moreover, it mentioned the Paris agreement and said that it signified a landmark commitment to limit global warming to 1.5 degrees. I agree that the deal has a lot of potential, however, I am worried that this potential will not be used as all I have been hearing about it recently was that certain leaders want to or have already withdrawn from the deal.

In terms of concrete action, the University of Exeter mentioned what it is doing to achieve its goals of cutting the university’s emissions by 40% until 2020: draft proofing, improvement of light controls, improvement of controls on boilers, ground source heating pumps, and biomass boilers. At home and in the workplace, it was suggested that you insulate the loft, install double glazing, lower the central heating thermostat, and switch off lights when you do not need them. I would add that the best thing you can do is “reduce, refuse, reuse, repurpose, recyle” (+ repair), and to get the things you do need to buy locally. Moreover, try to use all the opportunities you get, especially nowadays with the internet, to inspire others to live more sustainably as well.

Farmer’s market (source:

Many people say that the smaller actions we take at home and encourage our friends to take as well are not enough to combat climate change. In terms of their direct impact today, they are probably right. In the system we live in, we largely have to wait for the richest and most powerful to join a cause until we can see the really significant results. That’s why I definitely agree that we should do things like vote for politicians concerned with the environment. Through voting, we can have a direct impact on an area much larger than that which we normally have an influence on.

However, all of that is no reason to cast aside the importance of local action. The fact is that we as individuals can best promote a cause by bringing about change on the local level first. This can have a ripple effect and cause a significant amount of people to be inspired and to take action as well. I am sure people don’t mean it this way, but when someone says that personal and local action is just a gesture without real impact, it makes me sad because it sounds like giving up, as we as individuals can hardly expect to have more of a direct impact.


I have enjoyed this online course a lot. It was very informative and helped me to understand why climate change is happening and how it is already impacting ecosystems and communities. I think the most important message to take away is that immediate and drastic changes are needed to make sure that no part of the world has to experience any devestating, irreversible impacts of climate change. To achieve this, each of us can take action by changing some of their habits and by engaging in local and online initiatives. Because remember: You may be a small part of this world, but you are not insignificant! 🙂

Climate Change: The Science (week 3)

I just finished the third week of learning with this online course by the University of Exeter, which I found on This post is supposed to help me summarise what I have learnt, check my understanding, and make comments or ask questions. I hope that it will also be interesting or helpful to you! 🙂 (My comments and questions are in bold).

What was covered?

To put it in a nutshell, this past week, I have learnt a lot about how climate change affects the world’s ice sheets, permafrost regions and oceans and about what consequences the resulting changes might have.

Retreat & disappearance of glaciers

I learned that the world’s glaciers have shown a rapid response to global warming over the past two decades, with increased ice loss, rising flow speed, frontal retreat and thinning of the ice. In Greenland, half of the total mass loss is due to surface melt, the remainder is due to blocks of ice breaking off and forming icebergs where the glacier meets the sea (calving).

The amount of ice lost as iceberg calving is increasing as the ice sheets are spreading out faster. Glaciers spread out under their own weight. When the ice is softer because of warming, it spreads out more easily and more ice reaches the edges of the glacier, where it calves off and is lost to the ocean.

Draining of lakes of meltwater having lubricating effect
(source: online course)

Moreover, the ice is also flowing faster because lakes of meltwater on the surface of the ice sheet can drain abruptly, because of which meltwater reaches the bed, where it has a lubricating effect on ice sheet flow. The results of this are a short-lived acceleration and more ice calving off at the margins. The lakes, which emerge because meltwater collects in topographic depressions on the surface, can drain so abruptly because they have a warming effect on the underlying ice as their surface is darker and thus has a lower albedo than the surrounding ice. The meltwater also transports heat to the interior of the ice sheet, which causes it to soften and flow even faster.

Floating ice tongue
(source: online course)

I learned that buttressing is a process which opposes spreading of the ice sheet and which is being compromised by rising temperatures. When an ice sheet spreads to the coast under its own weight, it either runs aground on a high spot in the bed, is topographically constrained, or flows over the ocean forming a floating ice shelf. When water and air temperatures increase, floating ice shelves start to melt and may be lost completely eventually. When this happens, a friction component is removed, which causes the glacier to flow faster and to lose more mass at its edges. As I had already learnt in the previous weeks, the loss of floating ice to the ocean does not contribute to sea level rise. However, more land ice being lost because of the glacier flowing faster does.

I did not fully understand why a floating ice tongue is such an important friction component for a glacier, as ice seems to float and move around so easily on water. Is that little bit of friction already enough to reduce the amount of land ice calving off at the edges of the glacier?

Normally, in the summer, half of the surface of the Greenland ice sheet naturally melts. At high elevations, most of the resulting meltwater quickly refreezes in place. Near the coast, some of it is retained by the ice sheet, the rest is lost to the ocean. Thus, it is important to note that calving, just like melting, is a natural ablation mechanism, which is not automatically evidence of climate change. Furthermore, it is still necessary to learn more about ice sheets to determine how big the influence of climate change is, as they are also influenced by other processes like changes in ocean currents or shifting of the North Atlantic pressure systems.

However, the points mentioned above show that factors like air temperature and water temperature can significantly change how much ice calves off, which is why it does make sense to see a connection between rising global temperatures and the rapid increase in ice loss from glaciers.

Retreat of the Muir Glacier, Alaska, 1941-2004 (source:

The online course gave multiple examples of significant and unusual calving events and of glacial retreat in the last years. One was that of the July 2012 calving event at the Helheim glacier in South East Greenland, during which 1.5 cubic kilometres of ice were lost to the ocean. 0.25 cubic kilometres of this ice had been above sea-level, which means that it contributed to sea level rise after it broke off. The force of the iceberg impacting the fjord bottom as it rotated produced an earthquake that was measured by seisometers around the world. That summer, Greenland experienced the largest melt extent in the satellite era. We were also shown pictures of the retreat of the Muir Glacier in Alaska and told that glaciers in that part of the world are not only retreating, but disappearing, which is extremely worrying when we think about the albedo feedback and sea level rise.

Determining the health of a glacier

Accumulation & ablation zones of glaciers (source: online course)

To determine the health of a glacier, you have to look at its mass balance, which means that you have to measure the normal inputs against the normal outputs. Glaciers gain mass in their highest altitudes through snowfall, avalanches and wind-blown snow and lose mass because of calving, melting, and avalanches. The area of the glacier that gains more mass than it loses is called the accumulation zone, while the area that loses more mass than it gains is called the ablation zone. If accumulation is higher than ablation, the glacier has positive mass balance, if it is the other way around, it has a negative mass balance.

The most obvious way to measure the input and output of a glacier is to take field measurements using a stick. You can just drive a stick into the ice, see how thick it is, come back a couple of months later, and see what has changed. However, this process would have to be repeated multiple times all across the glacier to get a good amount of information, so it is much more accurate and less time consuming to use observations of the Earth from satellites or aircrafts, a method called remote sensing. This way, thickening and thinning of the ice, the retreat of the edge of the glacier, and the weight of the ice sheet can be measured. With this information, the sensitivity of the glacier to climate change can be determined.

One observation from this that was talked about in the online course is that the equilibrium line altitude is rising as more of the glacier is in net ablation. This means that as temperatures are rising, a glacier has to be located ever higher up in order to experience temperatures at which the size of its ice sheet does not decline.


Permafrost (source: online course)

Permafrost is soil in the high latitudes which remains below freezing all year round. Fifteen percent of the Northern Hemisphere is underlain by permafrost to some extent and it is so globally important because it stores around 1.6 trillion tonnes of carbon. This carbon could be released if the ground thaws, which would effectively be irreversible on relevant time scales because it has the potential to unleash a significant positive feedback mechanism (rising temperatures -> will thaw permafrost regions most (warming greatest in the Arctic) -> rapid decomposition of carbon stores -> carbon dioxide & methane released into atmosphere -> thickened blanket -> further warming -> more permafrost thaw…).

It was pointed out in the course that the Arctic has already warmed by one degree Celsius and that it has been observed that there are now thicker active layers (thawed soils above permafrost) and more lakes from melt water in permafrost regions.

Permafrost thaw ponds in Hudson Bay, Canada, 2008 (By Steve Jurvetson –, CC BY 2.0, Link)

Furthermore, if permafrost regions thaw, they turn into wetlands where large thermokarst lakes form that tend to be depleted in oxygen. When that is the case, decomposition in those lakes is anaerobic, which means that methane instead of carbon dioxide is released. Methane has a warming potential rougly 25 times greater than carbon dioxide.

Moreover, there are potentially 400 billion tonnes of methane hydrates (pockets of methane gas trapped within frozen water lattices that are formed at low temperatures and high pressure) deep within the permafrost regions. If only a small fraction of this is released, it could have global implications in terms of amplifying warming.

Currently, methane hydrates are only exposed along coastlines due to erosion from the sea and only eight percent of global atmospheric methane comes from permafrost regions. However, we still should not neglect the danger of it as it could trigger a vicious cycle and a runaway warming process and as some energy companies are apparently seriously looking at methane hydrates as potential fuels.

Reasons for ocean acidification


At the beginning of learning about this new topic, I was reminded of how important the oceans are not only for Earth’s biodiversity, but also for our health. They contain 99% of the living space for animals on Earth, are home to 250,000 species that we know about (there are probably a lot more), and its phytoplankton provide the oxygen for at least one in three breaths we take. Additionally, the oceans are an important source of food for us and they take up about a fourth of man-made carbon dioxide emissions.

Even though the oceans have been more acidic in the past, the rate of change was generally slow enough for organisms to adapt. The rare occasions when ocean acidification happened rapidly brought about mass extinctions of marine calcifying organisms. The chemical reactions that are leading to ocean acidification today are caused by carbon dioxide dissolving into seawater.

When carbon dioxide is taken up by the ocean , it reacts with water to form carbonic acid, which is unstable and quickly dissociates (CO+ H2O <=> H2CO3 <=> HCO3 + H+, so carbon dioxide + water <=> carbonic acid <=> bicarbonate ion + hydrogen ion). The hydrogen ions have an acidifying effect on the water and as the carbon dioxide levels in the atmosphere increase, so does the concentration of hydrogen ions in the oceans.

Channels carved into limestone by chemical weathering (by Stephen Wilkinson, source:

The ocean has a natural buffering system for this, called the carbonate buffer. Carbonate ions, which enter the seawater through natural weathering of rocks or from the shells of dead marine animals, soak up the hydrogen ions as they are released. This has kept the pH of the oceans stable for millions of years (CO32- + H<=> HCO3 , so carbonate ion + hydrogen ion <=> bicarbonate ion). The bicarbonate ions have an alkalising effect on the water.

At this point, i had a question about this carbonate buffer. If the bicarbonate ions have an alkalising effect on the seawater, and if they occur together with the hydrogen ions when carbonic acid dissociates, why does this process cause ocean acidification at all? Or is the acidifying effect of the hydrogen ions stronger than the alkalising effect of the bicarbonate ions? Could that be the reason why you need extra carbonate ions to form more bicarbonate ions?

It is only explained that the processes which put carbonate ions into seawater are quite slow, which is why they cannot keep up with the rate of carbon dioxide being released into the atmosphere and taken up by the oceans. As a result, the oceans are acidifying. The effect of bicarbonate ions is not explained.

Furthermore, I learned that the pH of the ocean has fallen by 0.1 of a pH unit since the industrial revolution, which is equivalent to a 30% increase in the hydrogen concentration. This kind of change is a real shock to marine animals and it is only expected to become much worse, with predictions stating that there will be a 120% increase in the hydrogen concentration by the end of the century. The pH of seawater is now 8.1 and is expected to fall to 7.6 by 2100 if we continue to release carbon at the rates that are currently predicted.

Effects of ocean acidification on marine invertebrates

Shell dissolving in hydrochloric acid (pH 1) -> more extreme than what will happen in oceans, but same process (source: online course)

Marine invertebrates make up the biggest proportion of ocean biodiversity with 76%. They are very important bottom of the food chain animals, which means that any effects of climate change on them will escalate up the food chain to the fish that we rely on as food. A large number of marine invertebrates have calcium carbonate skeletons. Once formed, these structures are quite vulnerable to dissolution unless they are surrounded by seawater saturated with calcium carbonate. As the seawater becomes under saturated with carbonate ions because they are soaking up hydrogen ions, there is a tendency for the calcium carbonate skeletons of marine invertebrates to start dissolving and there is much less carbonate available for the forming of new structures.

Moreover, as all organisms produce carbon dioxide when they respire, they all have to get rid of it in order to prevent becoming acidic. The buffering system in us organisms is much the same as that of seawater: we can use bicarbonate inside our cells to buffer any acidosis from increased carbon dioxide. However, some animals are much better at controlling their internal carbon dioxide levels than others and there are some marine animals that are quite susceptible to having internal acidosis from ocean acidification.

Sea urchin shells

Furthermore, ocean acidification can also impact the reproduction of marine invertebrates, which is a very sensitive part of any animal’s life cycle. Marine invertebrates reproduce by releasing eggs & sperm directly into the seawater, where fertilisation takes place. Eggs and sperm are very small and less able to control the conditions inside them, which is why they can easily be affected by more acidic conditions in the ocean. There is also a problem for sea urchin larvae, who have to grow tiny calcium carbonate shells in order to swim and feed properly. Their shells do not form properly when exposed to conditions expected for the end of the century. The result will be that much less sea urchin larvae will make it to adult phases, which will also affect the populations of other marine animals.

When it comes to the implications ocean acidification has for marine invertebrates, there are still a lot of questions that are being asked. For example, it would be interesting to know which species will be most affected and which might cope and how. Additionally, scientists are not sure how ocean acidification might interact with other stresses like environmental pollution and chemical contamination.

Ocean warming

Next, I learned that most of the heat trapped by the thickening blanket of greenhouses gases (over 90% of excess heat in recent decades) is going into the oceans, which is warming them from the top down. Most of it is being absorbed by the top 700 metres. The result of this is thermal expansion and sea level rise.

Coral bleaching

Moreover, the heat stress on coral reef environments may lead to bleaching, where corals lose their colour because their photosynthetic symbiont is expelled and starve. I was given an example of an extreme bleaching event which happened after the 2016/17 El Niño event. 90% of corals in the northern section of the Great Barrier Reef bleached. The IPCC warns that two degrees Celsius of global warming (which we are currently on track for) will result in the loss of 99% of warm water corals by 2100. When a reef is tipped into a declining state, algae may take over, which can have a range of negative environmental impacts because of the amount of oxygen they use and of toxins they produce.

Ocean pollution

Plastic pollution (source: online course)

Ocean pollution was briefly mentioned, too, even though it is not strictly related to climate change. It is probably the human effect on the environment that most people know and are passionate about because it is the one that is most visible. Examples for ocean pollution are oil spills like the 2010 oil spill in the Gulf of Mexico and plastic pollution, which both have devestating effects on the marine environment.

Oil as well as plastic can kill marine animals by being ingested by them, by trapping them, or by suffocating them. In one study, 90% of sea birds apparently had plastic in their stomachs and research from the University of Exeter shows that plastic micro-beads, which are found in everyday cosmetics, are eaten by tiny marine animals and enter the food chain. As a result, a plate of six oysters can have around 50 plastic micro-beads in it. I learned that there is no marine ecosystem where we have looked so far that does not contain this micro-plastic, not even in the Arctic: 1 litre of Arctic sea ice has been found to contain 12,000 pieces of micro-plastic!

Sea-level rise

Flooding in the Philippines (by Geirge Steinmetz, source:

Lastly, I learned a little more about this topic that has been continuously coming up throughout the online course: sea-level rise. It was discussed how both sea-level rise and ocean acidification could have severe economic impacts on communities, especially on poorer communities on the coast. Sea-level rise is already impacting people’s ability to have homes and to grow food where they live near the coast, as houses and fields are being flooded.

The IPCC predicts that sea-levels will rise anywhere between 26 to 98cm until 2100, with there probably being a lot of regional variations. The most notable short-term impact of sea-level rise is likely to be salinity intrusion, where salty water from the ocean is able to infiltrate the groundwater further inland. This groundwater is used for agriculture and is a very important source for drinking water in many parts of the world. Thus, there are plans underway in some areas to combine hard mitigation solutions like dykes, embankments and dams with soft adaption solutions like education, relocation and salt-tolerant crops.

Mauritius shoreline

Another economic impact of sea-level rise will be that on the tourism industry, as the shorelines are already starting to retreat. The income from this industry is crucial for a lot of developing countries that have a coast. Thus, sea-level rise might hit them very hard economically, in multiple ways.

At the same time, ocean acidification and ocean warming might have negative effects on fisheries as fish populations might drastically decline and many people who have the choice might stop eating fish as marine animals ingest more and more plastic.


This week has again shown me how important it is that we reduce our use of fossil fuels dramatically and as fast as possible. It is maybe easy for us to underestimate the role the Earth’s ice sheets and oceans play in our well-being, as they are not our typical environments, but it is a fact that they have an immense impact on the answer to the question whether we are or are not able to survive on the planet. The lifestyle of excess and unnecessary consumption of one group of people on the planet is having a devastating effect not only on ecosystems but also on other peoples’ livelihoods.

We have some very good answers to the question “What can we do?”, some regarding technology, some social and economic changes, some addressing personal lifestyle. It is largely up to the wealthier part of the population, mostly people in developed countries, to decide whether they really want to live the way they are living if it is costing the planet’s ecosystems and millions of fellow humans. Each of us should make a decision and act on it, because each of us can actually make a difference. Because remember: You may be a small part of this world, but you are not insignificant!

Overthinking about the past

When I was first told that I might be a perfectionist, I vehemently denied it, citing my reason as “not being very neat at all”. I knew that wasn’t really what she meant – but in that moment, I refused to believe it. I tried to dismiss it.

However, to my surprise, the idea kept creeping back to me – and as the days passed, I realized that, in a strange sort of way, she did have a point.

Every night, I would replay every single event I deemed as a “mistake” in my mind over and over again, in all its horrific glory – like a broken record tape I had absolutely no control over. And I would fall into the all-too-familiar cycle of overthinking about it until it nearly drove me crazy.

And of course, this kind of thinking only brings you misery; and suddenly life starts to become a collection of all the mistakes that you’ve ever made.

So how do I get over this?

Your mindset is a powerful tool – it can either be your problem or your solution. But changing it is easier said than done, and that’s why the first ingredient is time. This might seem slightly obvious – but don’t expect things to magically get better as soon as you set out to change things. Be patient with yourself.

The important thing is to avoid the temptation to fall into the pit hole of negativity. It’s so, so easy to fall into the abyss of overthinking. Of course, it’s hard to cut negativity out of your mind altogether completely. If a not-so-positive thought finds its way up to the surface, chances are, if you immediately try to force it down, it’ll probably come back to haunt you, whether you like it or not.  (kind of like a yo-yo, just not as fun.)

Recognize that point where you know you’re about to start overthinking. Pause – acknowledge it. Okay, so you’re feeling this way, and that’s perfectly valid. Try to rationalize what you’re overthinking about in your head, as if you were giving advice to a friend. Here’s an example: say you’re worried about how your teacher surely hates you now, and now you’re thinking about all the consequences that could possibly bring. You can’t help but start panicking. Your life is ruined, and you can’t go to school now and is there a way to bury yourself and never ever return –

Realistically, you know that your life is definitely not ruined in the long run, and that you probably have to go back to school. But in the moment, your emotions engulf you, and you can’t think of anything else.

So instead, you could try to think things through as logically as you can.

How do you know that your teacher definitely hates you? Are you a mind reader?

Probably not.

Is there any use worrying about it now?


Could you be doing other things right now? Things that make you happy?

Yep. Like watching that TV show you really like or talking with your friends.

If you can feel the negative thoughts pushing their way back up again, gnawing at you, trying to be noticed, remember this: the past is the past. It’s happened, and now you’re moving on to better things. It’s time to stop living your life in the past. 🙂

And finally? Love yourself a little more. You’ll find yourself enjoying life a lot more after realizing that you’re only human – a human that makes mistakes, just like everyone else.

Climate Change: The Science (week 2)

I have just finished the second week of learning with this free online course by the University of Exeter which I found on This post is supposed to help me summarise and remember what I have learned and to ask some questions or make comments about it. For everyone who has already finished this part of the online course, I would love it if you could read this post and tell me if you think I got anything wrong. If you only want to read my comments/questions, they are in bold. Thank you for visiting my website, I hope you enjoy! 🙂

What was covered?

This week was packed with lots of interesting information. To put it in a nutshell, I learned about ancient and recent past as well as contemporary climate change, the differences and similarities between them, the natural and anthropogenic forcing factors driving it and the key indicators that show our climate is changing very quickly nowadays.

Ancient past climate change

At the beginning of the week, I was taught that the Earth´s climate has self-regulated since the planet´s formation 4.5 billion years ago. Even though the sun was 25 to 30 percent less bright shortly after the birth of the solar system, there is evidence that Earth was as warm, if not warmer than today. With the blanket of warming gases we have in our atmsphere today, the Earth would have been frozen back then. Thus, there must have been a much higher atmospheric concentration of greenhouse gases present, especially of carbon dioxide and water vapour.

Chemical weathering
(source: online course)

Now the question is how all of that carbon dioxide was removed from the atmosphere as the sun became brighter. The online course explains that this was possible because of a process called chemical weathering. Chemical weathering: carbon dioxide from the atmosphere forms weak carbonic acid in rainwater -> dissolves silicate rocks when it reaches land -> washes into oceans as bicarbonate ions-> organisms use carbon for their shells -> formation of carbonate rocks from shells deposited at the bottom of the ocean (carbon dioxide from the atmosphere is transferred through the hydrosphere to be stored in the lithosphere!)

Moreover, the chemical weathering process is part of a negative feedback mechanism also involving temperature and atmospheric carbon dioxide concentration: higher temperatures -> more chemical weathering -> lower atmospheric concentration of carbon dioxide -> lower temperatures -> less chemical weathering…

At this point, I did not quite understand how temperature and chemical weathering are linked. However, a fellow learner on the course suggested that higher temperatures mean that more water evaporates, which causes more rainfall and thus more weak carbonic acid coming down with it.

Another riddle next to that about how atmospheric carbon dioxide levels were reduced as the sun became brighter is that about why the Earth froze over 2.2 billion and 700 million years ago and how this was reversed again. I learned that the reason for the occurrence of these two events is the positive ice albedo feedback triggered by the growth of continents and the subsequent higher rate of chemical weathering: growth of continents -> more chemical weathering (more rocks for carbonic acid to react with) -> lower atmospheric concentration of carbon dioxide to warm planet -> cooler temperatures -> more ice -> higher albedo -> even cooler -> more ice…

Carbon dioxide trapped in atmosphere (source: online course)

When the cooling is sufficient for the ice cover to reach the tropics, there is a tipping point and Earth freezes over completely. So how was this reversed? Because the planet was covered in ice, chemical weathering could not take place. However, volcanoes kept pumping carbon dioxide into the atmosphere and it started building up as it had nowhere to escape. Consequently, more and more heat was trapped by this thick blanket of carbon dioxide and the ice at the equator melted. The following positive feedback (less ice -> lower albedo -> hotter -> less ice) runs away in the other direction and brings about a superheated planet without ice caps if the climate is not able to stabilise itself in time.

This part of the online course taught me a very important lesson. We often think of the Earth´s systems as being extremely good at remaining in balance and maintaning the climate which supports life on the planet. Consequently, many people do not believe that our actions, like the burning of fossil fuels, could really have a significant impact on the Earth´s climate. Looking at the past and realising that the climate has key instabilities and feedback mechanisms that can really destabalise the entire system once they are triggered , can help us to realise how important it is to change our actions in order to ensure that we do not end up with a superheated or frozen planet anytime soon.

Earth orbits the sun in habitable zone (source: online course)

Furthermore, the online course talked about how the Earth orbits the sun in the habitable zone, where water occurs as a liquid. As the sun will get brighter, this habitable zone will move further outwards and Earth will come ever closer to the inner border of this zone. This will cause rising temperatures and more water to evaporate. The water vapour in the atmosphere will become very effective at trapping more heat and eventually, the oceans will have evaporated completely and our planet will see the end of the biosphere. Luckily, the sun is only getting brighter very slowly.

Thawing of methane hydrates (

Last in this section about ancient past climate change, I found out about the Paleocene-Eocene Thermal Maximum (PETM), which describes a rapid jump in global temperature about 55 million years ago. Typically, changes of 100s of parts per million in the atmospheric concentration of carbon dioxide take place over the course of hundreds of years, which allows life to adapt to the changes in climate. The PETM saw a 5 degree celsius increase in global temperatures over the course of 20,000 years. Oceans acidified and warmed by 6 degrees celsius. The warming was caused by a rapid release of greenhouse gases likely due to volcanism triggering a number of destabilising positive feedback mechanisms. Moreover, the initial rise in temperatures led to the thawing of methane hydrates, because of which large amounts of methane were released into the atmosphere, where they caused even more warming.

Recovery from the PETM was possible largely because of chemical weathering, which removed carbon dioxide from the atmosphere and helped neutralise the oceans. I was initially not sure why chemical weathering would neutralise oceans, because I had only learned about carbonic acid reacting with silicate rocks and the product being washed into the oceans. I thought it should acidify them further, if only slightly. However, I researched a bit and it seems that the bicarbonate ions, which result from the reaction of carbonic acid with the rocks, have an alkalizing effect in the water.

The PETM had similar effects on life on Earth as contemporary climate change, for example extinctions, sea-level rise, movement of ecosystems, destruction of coral reefs etc. However, during this event, our planet experienced warming of about 0.025 degrees celsius per 100 years. Nowadays, warming is on track for a 1 degree celsius increase per 100 years. It took the climate 100,000 years to recover from warming during the PETM. How long would it take the Earth to recover from contemporary climate change?

I have to say that I thought learning about the PETM was one of the most interesting, if not the most interesting part of the week. It was an unprecedented event which saw an abnormally rapid increase in global temperatures. Comparing this event, which had horrible effects on ecosystems and from which recovery took 100,000 years, to contemporary climate change really is a massive warning to us. Warming nowadays is ten times more rapid and recovery could take hundreds of thousands of years, especially if we tip the methane hydrate reservoirs into an irreversible positive feedback. We should definitely learn from past events like this, which show us that there is really no natural, non-human related explanation for the changes in climate we experience today.

Recent past climate change

Milankovitch cycles: eccentricity (source: online course)
Milankovitch cycles: obliquity and precession (source: online course)

At the start of learning about more recent past climate change, I was told that climate changes on time scales of thousands of years are highly predictable because they are connected to the way the Earth moves around the sun. Milutin Milankovitch described how the shape of the Earth´s orbit around the sun (circular or elliptical), the tilt of the Earth´s axis (between 21.4 & 24.5 degrees) and the wobbling of the Earth´s axis (like a spinning top) determine how much energy different parts of the Earth receive from the sun throughout the year and thus what the climate is like.

However, the course explained that the causes for climate changes on shorter time scales are much more unpredictable. Thus, evidence is needed to asses the impact of different influences. This evidence can come from tree rings, ice cores, pollen, ocean and lake sediments, or corals.

Tree rings: Width of ring -> rate of photosynthesis that year-> amount of sunshine during summer of that year -> temperature during summer (need of cross-dating with other trees and their ancestors -> wood from floor of forests/lakes/peat bogs)

Ice cores: carry composition of ancient atmosphere trapped in tiny bubbles -> ratio of deuterium (2H) to hydrogen (1H) & of oxygen isotopes (18O : 16O -> have different weight); 18O harder to evaporate & preferentially condensed out of atmosphere before air reaches poles; colder climate: these effects are amplified -> ice even more depleted in 18O (and in deuterium)

Different pollen for different plant species (source: online course)

Pollen: uniquely shaped to specific species; each plant has very specific needs -> soil acidity, atmospheric carbon dioxide concentrations & temperatures, precipitation levels… -> analysing pollen grain from layers of soil to reconstruct past climate

Ocean & lake sediments: 1)Ocean: ratio 18O : 16O in carbonate shells of marine organisms (colder climate -> more ice, less water evaporating -> even less evaporation of 18O than otherwise -> ocean more enriched in 18O); 2)Lake: layers like tree rings -> thickness of layers & 18O : 16O ratio -> information about past climate, e.g. amount of meltwater entering glacial lake each year, temperature, sources of precipitation, evaporation from lake

I learned that climate data from the sources listed above can be matched to events and cycles related to natural forcing factors like volcanism (It was interesting to learn that volcanic eruptions cause cooling, at least short-term, because the ash clouds block out solar radiation). However, these natural factors fail to explain the changes in climate our planet has experienced over the last 100 to 150 years. When comparing a graph showing the increase in global temperature over that period to a graph showing atmospheric carbon dioxide concentrations, one can see that there is an obvious connection between the two and conclude that carbon dioxide is the major cause for warming today.

Indicators for contemporary climate change

Lastly, I found out about the fact that climate data is collected very widely and reliably nowadays thanks to new technology and that this huge amount of data allows scientist to see the signs for contemporary climate change very clearly. The online course introduced me to the following key indicators:

Global mean temperature over land (source: online course)

Global mean temperature over land & ocean: most recent decade warmest on record; Earth now 1 degree celsius warmer than in pre-industrial times; warming not the same everywhere: higher latitude areas (e.g. Arctic) experience more warming & land warms faster than oceans; intervals of slower/faster warming (e.g. slowdown after 1997/8 El Ninõ event, but after slowdown: temperatures rising at accelerated rate)

Arctic sea ice area
(source: online course)

Sea ice extent: temperature rises are highest in Arctic (roughly twice as fast as global average) -> since 1980: surface of Arctic sea ice in summer fallen from about 4 million km2 to about 1.5 million km2; especially concerning because of ice albedo feedback; global sea ice extent 2016 lowest on record

Frequency of extreme weather events: warmer atmosphere holds more moisture; data hints global averaged precipitation may have increased over last century, is expected to increase in the future; precipitation unevenly distributed -> contrast between wet & dry regions will increase; uncertainty for future of ecosystems & societies, especially with growing population

Sea level (source: online course)

Sea-level: since 1880: steady rise in sea levels; about half of the rise due to thermal expansion, half due to melting of land ice; melting sea ice does not contribute to sea level rise -> floating ice displaces same volume of water as if it were liquid.

At this point, I had one last question, this time about the situation in Antarctica. During the online course, it was said that it is much colder in Antarctica than in the Arctic, that the ice there is not melting and that the area is thus not contributing to sea level rise. However, in an article on the NASA website, it says that “Antarctica lost about 127 billion tons of ice per year during the same time period (1993-2016)”. Maybe scientists just are not completely sure about what is going on there yet?


The message I take from this past week of learning with the online course is that evidence from sources like tree rings, ice cores or weather records as well as the comparison between contemporary and past climate change shows that natural forcing factors are not the explanation for the changes we see today. The difference between the PETM and contemporary climate change is not only that change is happening much faster this time, but also that humans are causing it and that we are aware of our responsibility as well as of the solutions to the problems we have caused.

If we do not want what happened during the PETM to happen again, we really have to change something about the way we live and about the primary goals our societies and economies are after. They should not be profit and power because that harms our environment as well as a large portion of the human population. Each of us can make a decision on how they want to impact the environment and other people, and that decision is important. Because remember: You may be a small part of this world, but you are not insignificant!

Climate Change: The Science (week 1)

Currently, I am taking a free online course by the University of Exeter on Climate Change. You can find this course on I want to share some of the new, interesting stuff that I am learning and my reflections on it on this blog in order to exchange with other learners on the course and to maybe inspire others to learn more about Climate Change. If you have not yet heard of this online course, please check it out as it is very professional and offers you great material to learn with. This post is only meant to help me remember what I have learnt and to maybe find gaps in my understanding. If you already learned the content of the first week of the online course, I would be delighted if you were able to take the time to check and see if you think I understood it correctly. If you do not really feel like doing that and are only here for some of my questions or comments, please look at the paragraphs in bold. 🙂

What was covered in week 1?

I have just finished the first week of learning with the online course and so far, I think it has given me a good basic understanding of what climate actually is and of why it is changing. The first week covered the key principles of climate change, the difference between climate and weather, types of greenhous gases, feedbacks and self-regulation and how humans have an influence on these systems.

Key principles of climate change

I have learned that the sun´s radiation reaches the earth in short waves which the molecules in the atmosphere let through. Some of it is then absorbed by the earth´s surface and the rest is re-emitted back toward space in long waves. This long-wave radiation can be absorbed by the greenhouse gas molecules in the atmosphere (water vapour, carbon dioxide, methane, nitrous oxide, ozone) and then re-emitted toward earth. Only some heat energy escapes into space or is not re-emitted by the molecules. This way, the radiation from the sun gets partly trapped in the atmosphere.

Furthermore, based on this, it is argued that we should not use the analogy of a greenhouse to explain this effect, but that of a blanket. The reason the greenhouse is warm is because it prevents airflow and thus traps the heat which it got through radiation from the sun. As this cannot be compared to molecules re-emiting heat radiation back to earth, the greenhouse analogy is not an ideal one. However, I have to say that I do not quite understand why the blanket metaphor would be better. Firstly, it completely leaves out the initial source of the heat – the sun. Secondly, I thought that blankets do just the same thing as greenhouses to keep the inside warm: prevent airflow and thus trap heat. Consequently, I have to say that both metaphors confuse me more than they help me. Maybe somebody could explain to me why the blanket effect is the better analogy in the comment section? It would be much appreciated 🙂

albedo (NASA animation)

Another thing I was taught this week is that the “albedo” is the fraction of radiation which is reflected back from the earth´s surface. How much is reflected depends on which kind of surface we are looking at. For example, ice has a very high albedo while the ocean has a low albedo as it absorbs a lot of radiation by being a dark surface. Overall, the earth has an albedo of about 0.3, which means that it reflects about 30% and absorbs about 70% of the radiation which reaches it. Without the greenhouse gases in our atmosphere and only with that 70% absorbtion rate, the average temperature on earth would be -18 degrees celsius. Thus, these gases are crucial for life on earth to exist. Only when human activity tips the balance between them and non-greenhouse gases in the atmosphere do they become dangerous. This was something I did not have any idea of previously to the course and it was really interesting to find out about the role the right amount of greenhouse gases plays in making life possible. Also, it has shown me how dangerous it is that sea ice is melting as this is turning into a vicious cycle: less sea ice -> more of the earth´s surface is dark blue ocean -> lower albedo (more absorbtion of heat radiation) -> warmer temperatures -> less sea ice…

Greenhouse gases

gases in the atmosphere

The greenhouse gases I was introduced to in the online course are water vapour, carbon dioxide, methane, nitrous oxide and ozone. I was surprised to find out that carbon dioxide makes up “only” about 0.04% (400 parts per million) of the earth´s atmosphere. The other greenhouse gases beside it are present in even smaller amounts. The majority of the atmosphere is made up of Nitrogen (78%) and Oxygen (21%).

However, this most certainly does not mean that we do not have to worry about the amount of greenhouse gases present in our atmosphere today. Carbon dioxide is released naturally through the carbon cycle but it is also a very long lived gas, which is why it is so important to maintain the fine balance between it and the non-greenhouse gases. Sadly, human acitvity is tipping that balance. The online course taught me that human activity has increased the concentration of atmospheric carbon dioxide by more than a third since the Industrial Revolution.

Another long-lived gas which is added to the atmosphere by human activity is nitrous oxide. It makes up only a small fraction of the atmosphere, but is about 300 times more potent than carbon dioxide. Human activity, like the increased fertilisation of farm fields with nitrogen, has increased the atmospheric concentration of the gas by about 15%.

Methane and ozone are more short-lived gases. However, methane is about 25 times more potent than carbon dioxide and has increased almost 3-fold due to human activity and ozone, even though it is not only short-lived but also quite scarce as a greenhouse gas, is about 1000 times more potent than carbon dioxide. I thought it was very interesting to find out that this ozone is different to that which makes up the protective layer around the earth, protecting life from ultraviolet radiation from the sun. The greenhouse gas ozone is formed near the surface of the earth when vehicle emissions react in the sunlight.

Furthermore, it was completely new to me to hear of water vapour as a greenhouse gas. I was told that it is the most abundant one in the atmosphere and that its increasing presence there is caused indirectly by human activity. The reason for this is that the thicker blanket of greenhouse gases like carbon dioxide, emitted because of human activity, makes for higher temperatures which cause more water to evaporate.

What I took from this was that it is absolutely crucial to dramatically reduce the amount of greenhouse gases which we emit. In my opinion, we will not achieve this solely through technology like electric cars or solarpanels. These changes have to go hand in hand with changes to the lifestyle of excess of so many people. I am planning on writing a post about “green-growth vs. de-growth” in the future, but let me already spoiler you here: I do not think that green-growth is going to solve the environmental problems facing us today. If we want the earth´s temperature to support the wonderful variety of life we know in the future, we cannot go on with our neverending consumption.

Difference between weather and climate

This is a pretty straightforward one but I still feel like weather and climate get mixed up way too often. Donald Trump´s tweet “Wouldn´t be bad to have a little of that good old fashioned Global Warming right now!” when there were quite severe snow storms in the U.S. during winter is only one example. Many people question climate change because they believe that it is not possible to have some colder days or even snow during the year if the climate is warming. However, this is not true and only shows how important it is to understand the difference between weather and climate. This difference was explained very well in the online course. They said that weather is the elements we see daily and something that can change very quickly, whereas changes in climate are usually measured over a period of 30 years.

climate zones

Moreover, I was shown a map and reminded of the different climate zones there are. The blue on the map shows the polar zones, the green the temperate, the yellow the arid, the red the tropical, the orange the meditarranean and the black the mountain zones.

Feedbacks and self-regulation

atmosphere, biosphere, lithosphere, hydrosphere, cryosphere

Lastly, I was taught to see the climate as a system encompassing the atmosphere, the biosphere, the hydrosphere, the cryosphere and the lithosphere. Moreover, the course reminded me that there are a series of cycles that link these different components together and that are very important to the earth´s climate. These cycles include so-called feedbacks. The three feedbacks I was introduced to are the water-vapour-feedback, the ice-albedo-feedback and the radiation-feedback. The first two are positive feedbacks, the last one is a negative feedback (positive & negative in the mathematical sense).

Water vapour feedback: increased temperature -> increased evaporation of water -> increased amount of water vapour in the atmosphere -> increased amount of radiation re-emitted to earth´s surface -> increased temperature…

Ice albedo feedback: increased temperature -> ice melting -> more surface made up of dark blue ocean -> lower albedo (more absorption of heat radiation) -> increased temperature -> ice melting…

Radiation feedback: the hotter a body the more heat it radiates, the more heat a body radiates the colder it gets

Something this part of the online course definitely taught me is how important it is not to disrupt the earth´s natural systems on a grand scale, as this can result in a global vicious cycle. And soon, we may not be able to reverse the damage done by this vicious cycle anymore. An article on the UN´s website that a friend brought to my attention recently underlines this point very well and really shows how scary and how real this scenario is.

Thank you!

Thank you so much for taking the time to read this blog post! It took me much longer than I thought it would `:) . I want to repeat how much I like this online course and how much of a professional impression it has already made on me. I recommend you check out if you have not already. This blog post probably shows you how much you can learn on that website in only a couple of hours. And again: Do not feel discouraged by how big of a challenge climate change is. You CAN make a difference. Because remember: You may be a small part of this world, but you are not insignificant!