I have just finished the fourth and final week of learning with this online course by the University of Exeter, which I found on futurelearn.com. 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
(source: nuestrofuturocomun.com)

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: sustainablesantafe.wordpress.com)

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.

Conclusion

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! 🙂