Il Ponte – a student periodical based at bratislava international school of liberal arts (bisla)

Climatologist Jozef Pecho:  "It can very well happen that global warming will spin out of our control"

Climatologist Jozef Pecho: "It can very well happen that global warming will spin out of our control"

Climatologist Jozef Pecho

Climatologist Jozef Pecho

Peter Sterančák / June 15, 2019

( 16 min read )

In April some of us, in Il Ponte, attended discussion about climate change at Comenius University, in Bratislava. One of the panellists there was a climatologist Jozef Pecho. Mgr. Jozef Pecho works at Slovak Hydro-meteorology Institute (SHMÚ) and regularly gives interviews, or attends discussions on the problem. I recently visited him at SHMÚ and made this long interview where we covered almost everything one needs to know about climate change. In the interview, you will get the answers to the following questions:

  • What is the difference between climate change and global warming?

  • How did scientists figure out it is caused by human behaviour?

  • What does he think of climate change sceptics and why they are wrong?

  • Where do we stand with climate change today?

  • What should we do to avert the total disintegration of our civilization as we know it today?

  • Can capitalism solve the problem, or do we need a completely new socio-economic system to survive?

  • What does he think of the effort of the famous teenager activist Greta Thunberg? 

  • Why world’s forests do not help us anymore?

  • How will Slovakia be affected by climate change in years to come?

  • What books, films or website does Mr. Pecho recommend to learn more about climate change? (at the very end of the interview)

Climate change is a complex problem. Many people mix two terms together: global warming and climate change. So what is climate change and what is the difference between global warming and climate change?

The difference is, of course, semantic. Because the first sign that climatologists noticed back in the 60s and 70s of the changing climate was exactly the warming up of the planet’s atmosphere. Logically, the term global warming settled down, although many climatologists objected because perhaps, even back then, the term did not really fit the whole problem. Gradually, in the 70s and 80s, the term evolved into what we now know as climate change, which unlike global warming, describes the whole set of complex reactions of the planetary climate system. It includes not only the warming of the atmosphere, but also changes in the oceans, biosphere, pedosphere, cryosphere, and other subsystems which the planetary climate system contains. The warming of the atmosphere is only the first sign that we can observe due to the increased greenhouse effect. After that, other subsystems of our planetary climate system follow.

All of these subsystems react to the warming of the atmosphere in different ways. Glaciers melt, which is one crucial reaction to it and, as a result, the sea levels rise. With that comes the change in our reservoirs of groundwater, which are increasing in some places and decreasing in others. There are also some complex changes in the Arctic, where the surface is less and less covered with snow due to increasingly high temperatures, mostly during the spring months. This then reinforces the whole cycle because when you have less of the Arctic’s surface covered with snow during the spring, as a result the temperatures rise as the atmosphere warms up quicker. So there are many such complex reactions that the term climate change covers. Perhaps the most complex are on the level of the biosphere, where warm climate zones are gradually advancing into colder ones. This shift then causes migration of plants and animals, which then destabilize the eco-systems in those regions. New species come to these territories and most often they are invasive species. So, all of those complex changes are incorporated in the term climate change.

So climate change incorporates all of these changes, while the term global warming refers only to the warming of the atmosphere?


Deflection of the global temperature (1850-1900; 5-years avarages) since 1850 until 2018 according to 5 different sources (NASA, NOAA, CRU, JMA and ECMWF) [Source: WMO]

Deflection of the global temperature (1850-1900; 5-years avarages) since 1850 until 2018 according to 5 different sources (NASA, NOAA, CRU, JMA and ECMWF) [Source: WMO]

How did scientists come to the conclusion that behind the warming of the atmosphere is our own human behaviour?

Well, I would say that proving this causality was not easy. It may be paradoxical that the realization that the planet will keep warming was already presented by a very well-known Swedish chemist, Svante Arrhenius, at the end of the 19th century. By the way, he is the great-grandfather of [teenage climate change activist] Greta Thunberg. She comes from his family line.

He conducted, in principle, a very simple experiment. He did it only on paper, using calculations. He wrote down a very simple balance model of the atmosphere and radiation. He started with a thought experiment: what would happen if the amount of carbon dioxide in the atmosphere were to double, in comparison to the amount which was known to be there in his time? It was somewhere around 280 parts per million (ppm), so he increased it in his experiment to 560 ppm. From this very simple balance model, he concluded that the atmosphere would warm up by 3 °C. Today we know this under the term climate sensitivity. It is a very significant characteristic which is modelled by the climate models that we have today. They suggest that Svante Arrhenius was not wrong, despite his simple method. Today the value of climate sensitivity is between 3.5 °C and 4 °C. Although he underestimated the number, he was still quite close. This experiment was the first such of its kind. Arrhenius suggested, even back then, that if we keep releasing carbon dioxide to the atmosphere (because the industrial revolution had already started and carbon dioxide was known as a molecule), it can lead to long-term warming and climate change.

I said ‘paradoxically’ because in Arrhenius’ times no changes in climate were observed.

When exactly was this?

It was in around 1896 that he first conducted the experiment. At the end of the 19th century there was no observed trend of warming. We observed the trend of warming for the first time, only in the 1930s. The British engineer and inventor Guy Stewart Callendar had developed a theory linking rising carbon dioxide concentrations in the atmosphere to global warming. He published his analysis in 1938. In it, he suggested, for the first time, that the global temperature was rising. This information provoked mostly mockery so his work stayed unnoticed for a long time. Later, in the 1960s, 70s, and 80s, it became apparent that the global temperature was rising relatively quickly, so scientists started to create their complex circulation models fed by all the new data from the oceans, atmosphere and even cryosphere. For the first time the suggestion that glaciers might melt was mentioned. Models that originate from pure atmospheric physics discovered that it is precisely the increased amount of greenhouse gases that contribute to the warming of the atmosphere. Today we do comparative model simulations where you can separate the pure anthropogenic (human-caused) and natural influences. When you separate those two, and only work with the intensity of sunlight, volcano eruptions, and other natural phenomenon, you can model simulations in order to know what are the conditions of rising temperatures in the atmosphere.

The result of such simulations is that when you only work with natural influences on climate, the temperature tends to go down. So it deviates from what we measure in reality. On the other hand, when you fit in the greenhouse effect and anthropogenic influences, you get a very close approximation to the real temperature. This is one empirical proof, apart from the early theories. Besides, today we can measure the intensity of the greenhouse effect in the atmosphere using satellites. They orbit on low polar orbits. They can scan the temperature field of the planet with spectrometers. The temperature field of planet is basically the long-length radiation that leaks from the Earth’s atmosphere. Through such observations we see that greenhouse gases, such as carbon dioxide, can retain a certain amount of the heat. The more greenhouse effect you have, the greater the intensity of this capture is. In the spectrum that we can observe through satellites, we can see that the greenhouse effect is getting stronger.

Climatologist Jozef Pecho.

Climatologist Jozef Pecho.

The argument most used by sceptics is that it’s the Sun, not human activity, that warms up the planet...

We can already disprove that today. It is not the case, because the intensity of the Sun’s light has actually been decreasing a little bit over the last 50 years. It is possible, actually, that in the next Sun cycle, by which I mean one of its famous 11-year cycles, that we will experience an attenuation of the Sun’s activity. As I already said, the climate models that work with all the parameters (so, even with Sun’s activity), we can measure the intensity of sunlight quite accurately. So, today we can already say that the Sun’s activity is decreasing and that it does not directly cause any of the global warming symptoms. This is also proven astro-physically. So this sceptical argument is now overcome.

How do we stand today with our data and predictions for the next 20, 30 years? We had the Paris Agreement, however, many of its critics are concerned that it is not enough –  that it is already too late and that states are not acting on it...

Unfortunately, this may be true. We should not give in to any illusions. It was clear already before the arrival of state delegations in Paris that many of the proposed commitments were too weak. Whether it’s the United States, Australia, or Japan, we can look up the real numbers regarding their commitments. Everybody knew about it. However, the positive message was that the whole global community, represented by 197 nations, was willing to come up with their own arbitrary commitments. The fact that, after signing to the agreement some states like, for example, the United States, abandoned the agreement, although not ‘de jure’, is unfortunate. Other special examples are India, Brazil and China. These are large countries which are still considered to be developing countries today, but produce the most emissions: Brazil due to deforestation; China from the burning of fossil fuels, mostly coal; India ditto. Besides, India and China have extremely large populations whose needs they need to satisfy. China, unfortunately, told the world that it is not going to commit to it before 2030, shortly after the US announced its withdrawal from the Paris agreement. So, no reduction in emissions, just pure growth. The probable trajectories of global emissions are adjusted to global economic  development, so we can be sure that China will stick to its plan not to commit to the Paris Agreement until 2030. The reality is, however, that we need to cut emissions by 2020.

What could actually happen if this continues? What will the world look like in 2030 if we are not able to commit fully to the Paris Agreement?

Well, up until now the planet warmed up by 1 °C and we can already see some critical changes. Perhaps the most important change is the decline of biodiversity, which is caused, aside from other factors, directly by climate change. Then there is the death of coral reefs, which is already massive due to oceans warming up. Another problem is the biosphere on land. There we can see that due to more frequent droughts and higher temperatures, plants are unable to catch the carbon from the atmosphere and instead produce it now. Hence, the arguments that forests will save us from climate change are too optimistic. They are not based on our current data: logically, this should not be the case, but unfortunately it is. Forests will not save us. Another problem is that of mass migration of people. Between 2008 and 2013, some 23 to 25 million people migrated because of extreme weather, which is three times more than due to war conflicts. We are speaking mostly of Asia and Africa. That is a huge problem because when mass migration on such a scale is uncoordinated it can cause a lot of troubles in places where those people arrive.

We saw an example in Syria, where it indirectly led to civil war. In 2006-2011 Syria suffered from extreme drought which forced more than 1,5 million countrymen (mostly farmers) to migrate to big Syrian cities in the West, and North-West of the country. This internal migration deepened already bad situation in those cities – homelessness and unemployment had risen up and the tension grew. The government of Bashar al-Assad had neglected the problem from the beginning and when the protests began their only response was a brutal violent suppression of the unrest. All this, in combination with other problems in Syria, had indirectly led to the civil war which claimed lives of almost half a million people, since 2011 and had displaced more than 6,5 million. So, these are problems we already face today. If we try to limit the warming to under 1.5 °C , in the best-case scenario, then we can avoid even more catastrophic events. The recent IPCC report, published in October 2018, tried to quantify differences between the impact of staying bellow 1.5 °C warming, and the impact of staying bellow 2 °C warming. The differences were extremely huge.

Is going above 2 °C a real possibility for us?

Currently it seems like that, because we can say already today that there is enough carbon in the atmosphere for such a warming. If you count how much carbon is in the atmosphere right now, we are on the level of approximately 415 ppm. If we somehow stopped all emissions tomorrow, then we are going to reach approximately 2 °C to 2.4 °C.

So the consequences will be catastrophic anyway...

The thing is that we cannot even imagine such consequences. This is why we are trying to avoid that. But if we cannot imagine it then we cannot know what we will need to do to adapt to such a change. It will be a problem. Besides, what can also happen is that we will reach the level of unpredictability. Because if the global climate warms by more than 2 °C then not only will the consequences be catastrophic, but there is a possibility that the global climate system will start to warm up uncontrollably. In other words, in the global climate system there are several elements that can slow down warming, like are oceans, ocean currents, the cryosphere, or the Amazonian rainforest. All those elements that slow down the warming could be totally destabilized. Basically, this is already happening in the Amazonian rainforest because it is withering. We would expect that with higher global temperature trees would “eat” the carbon from the atmosphere quicker, however, they don’t. Exactly because of there being more and more drought and wildfires in the Amazon, the photosynthesis of trees is not active enough, and so trees in the Amazonian forest do not behave as an inhibitor of global warming, but actually release even more carbon dioxide into the atmosphere, and accelerate global warming.

There is a strong positive feedback loop at work here, and it can backfire on us. We count on trees to function as they always have, but it does not have to be the case. That’s a problem. Another strong feedback is in the tundra (Ed. note: Northern Russia, Sweden, and Finland). There is a huge amount of carbon hidden in the permafrost. That is frozen land. If the carbon smoulders there, it decays and is released into the atmosphere in form of methane. Methane is, in its first 10 years, 100 times more effective as a greenhouse gas than carbon dioxide. So, it can cause even more damage than carbon dioxide.

So to conclude, it can very well happen that global warming will spin out of our control. If that happens we probably won’t be able to do anything to reverse it any more. It’s a pessimistic and extreme scenario, but it is possible.

Birds fly past at sun set as smoke emits from a chimney at a factory in Ahmadabad, India, Monday, Dec. 8, 2014. Credit : AP

Birds fly past at sun set as smoke emits from a chimney at a factory in Ahmadabad, India, Monday, Dec. 8, 2014. Credit : AP

Recently, a map was published on the internet, composed of data from 2017, by Carbon Majors report. It shows that 100 corporations produce together 71% of all emissions. So us taking shorter showers or switching off the light more often will not work, right?

This is a very good remark, because it seems that such multinational corporations begin to hamper our global efforts to solve the climate change. For them, sustaining the status quo is a priority because it suits them. I know we are going beyond climatology now, but since quick profit is the primary value, for those corporations, we will need, perhaps, to solve this above the level of market, to rule out their powerful interests and to push them to cut down their emissions.

Perhaps the question, then, is: Can capitalism, as we know it today, survive while we try to solve the climate change? Or, do we need to think about some more sustainable socio-economic system to solve the climate change?

I would say that both capitalism and socialism are equally dysfunctional in terms of climate change, and to come up with something that we have already had before is, perhaps, not the right solution. However, capitalism as we know it today doesn’t seem to have the capability to solve the climate change. It’s also probable that if climate change continues at this pace, capitalism will not survive. On the other hand, I think that capitalism itself may not be the problem. It is maybe enough to just reform it a bit. The important thing here is to tax all those economic externalities that refer to unlimited use of resources and energy. Whether it is a carbon tax or other flexible taxes that could be employed here, we need to make sure that it will not affect the poorest.

There should be pressure both on individuals, so that they realize what they buy, but also on corporations in form of some useful legislation which would limit their use of resources, while at the same time offering them a plan to use carbon resources that are less harmful to the atmosphere. Capitalism could even help in this effort. If you impose high taxes on the products that have big carbon footprints, then they will become unpopular for the general population, too. This is the concept of the carbon tax that already works, for example, in British Colombia or Sweden, where they have succeeded in cutting down their emissions thanks to such a tax. So it can work in reality, but we need to make sure to pressure politicians and multinational corporations to adopt this tax system.

Earlier you mentioned Greta Thunberg from Sweden. She is currently, perhaps, the most popular schoolgirl in the world. Many people are excited by her campaign, and many others are very critical of her effort. They accuse her of naivety, a thirst for popularity, etc. How do you see young activists like Greta?

It hasn’t helped in a specific way so far. And it might, perhaps, be naive to hope that pressure from children will be as effective as some expect. On the other hand, I would not underestimate her influence. It’s an important step in activism because of the way children speak in such matters. They are direct and open in their actions, so they can win over a lot people. As I said, her influence is currently minimal but, on the other hand, it’s very positive that so many young people are beginning to think and speak about climate change today – and not just superficially, but in their everyday actions. This is great because this is the young generation that will inherit the future. In this case, it’s not even that important that they don’t understand the complexity of climate change that much. The question, however, is whether it’s not already too late. That’s because climate change is accelerating. So starting to be aware of the problem may soon not be enough. On the other hand, I feel there has been a positive change in the perception of climate change in the general population over the last two years.

People are beginning to be aware of the problem and want to do something about it. Of course, the first strikes to “rescue the climate” were a bit naive. These people had no clear vision of what it means to actually solve the climate problem. Nowadays, though, it’s better. Perhaps, there is a lively discussion inside of these movements, either between youngsters and adults, or among young people themselves. Now, they can direct their demands towards politicians better. Also, they are more aware of positive change at the individual level.

Swedish climate activist Greta Thunberg (R) speaks during a debate with the EU Environment, Public Health and Food Safety Committee during a session at the European Parliament on April 16, 2019 in Strasbourg, France. Credit: AFP Archive.

Swedish climate activist Greta Thunberg (R) speaks during a debate with the EU Environment, Public Health and Food Safety Committee during a session at the European Parliament on April 16, 2019 in Strasbourg, France. Credit: AFP Archive.

So, how to direct our efforts, both at the individual and the collective level?

That’s a very difficult question. Among today’s activists there are some very good demands. For example, a moratorium on coal mining. That should be the first basic demand. Then there is the demand to support a quicker transformation to renewable resources. What I miss in the activist’s demands, however, is quicker enlightenment. Unfortunately, education about and overall understanding of climate change among both young people and adults is, for example here in Slovakia, very poor. Often the need for self-reflection on one’s own lifestyle is missing. For example, how to use energy more efficiently at home, or in transportation. Many people think that it is enough to recycle. We have the Zero Waste movement and their idea is nice, to produce less waste, or the idea to plant more trees to solve climate change.

This is, however, not enough. It can help for a while but the trees don’t have the ability to balance the huge amount of emissions we produce today. So, it is not enough just to put up your banner during protests in front of parliament, but it is important to think about what we really need to do. We need to keep looking and verifying the information we have and also fight myths that say doing this or that is enough. I’m afraid that this young movement will assert such a political pressure that politicians will resort to some quick-fix solutions. For example, one such easy and attractive “solution” for climate change is so-called geo-engineering. It is a targeted intervention into the atmosphere so that we can cool it down and slow down the warming, for us to buy the time for adaptation. Yet this is like using a new patch to cover the old one. In the long term it will not help us. It’s also very dangerous, so I am worried that we will resort to such dangerous quick solutions.

Climate strike of Slovak highschoolers in April, Bratislava. Organized by: Fridays for Future. Source: Peter Hanák/

Climate strike of Slovak highschoolers in April, Bratislava. Organized by: Fridays for Future. Source: Peter Hanák/

How about Slovakia and climate change? What is the biggest problem, in terms of climate change, for Slovakia? Some experts warn against possible water scarcity in the near future, or talk about the danger of deforestation.

I think you said it already. The problem is water. Due to us being an inland country, most of our water resources come from rainfall and snow cover. Due to climate change our own climate begins to resemble more and more a Mediterranean climate, which has a long and dry summer, and a relatively short and rainy winter. This is already happening here, we are moving south, in terms of the climate. There is a real risk that if that shift completes itself, then the rainfall will be very irregular. In such a scenario Slovakia could have a real problem with water scarcity.

Because the rainfall will be irregular and sudden, and we will not be able to capture enough water?

The biggest problem of drought in Slovakia is that even though there will still be a lot of rain, it will quickly evaporate into the atmosphere. Logically then, the more drought you have the more intensive is the cycle I just described. Even if the amount of rainfall stays the same, the surface loses a great amount of water because the water evaporates and it is then transported, through the atmosphere, out of our region. That is how a drought happens. This is the first problem.

Then we are also losing the snow, mostly in the lower altitudes. We have less snow cover and it stays for shorter periods of time. It’s also unstable and so we have problems mostly during the spring.  The water that had accumulated in the snow cover drains out already in January or February, and so we depend on the rainfall already in March, while in the past, we still could derive water from the snow cover. As a result, we already have droughts in the spring. This was the case this year, last year and for many years back. The situation worsens repeatedly.

Does it mean that every following year in Slovakia is now warmer?

It does not need to be the rule. We had a record-breaking year in 2014 in Slovakia. The following year we had a very warm summer but the year, in general, was slightly colder than in 2014. However, last year [2018], was again a record-breaking warm year. So it varies, but the long-term trend is clearly rising.

Personal recommendations of Jozef Pecho, for further studying:


However, Mr. Pecho says that this film (Before the Flood) places too much emphasis on technological solutions and too little about individual changes in consumerist lifestyles.


Mr. Pecho comments: “Not primarily about climate change but it offers great insights into why we, as people, behave the way we do. And also why we prefer to believe in delusions than face reality. I think every person that thinks about climate change should read it.”


For changes in individual lifestyle:

For trustworthy data and information about the climate change itself:

On sharing economy:

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The age of digital identity: the trap for political action

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