If the oceans stop saving us, there will be no Plan B

Climate change is a buzzword that sounds abstract to too many people. Prof. Jacek Piskozub, a marine physicist and atmospheric scientist, brings it back to prominence by telling us about the mechanisms that not only drive the crisis, but may also make it irreversible. In a conversation with Agnieszka Hobot, he explains what will happen when the oceans stop absorbing carbon dioxide, why Poland is already drifting into a permanent drought, and how the loss of Atlantic circulation could chill Europe. He strips us of the illusion that we have time and asks the question – are we capable of planning beyond the end of the term?

Agnieszka Hobot: What do people most often not realize when they say climate change?

Jacek Piskozub: I would say from the consequences of rising sea levels. For coastal localities, it’s a matter of life or death, or at least survival over the next few hundred years. Of course, I realize that not everyone is directly affected. In the case of Poland, a much more serious and noticeable problem is drought.

Increasing temperatures unfortunately mean an increasingly dry climate. Why? Because evaporation is increasing and precipitation is not keeping up. Each additional degree Celsius means about 7 percent more evaporation, while precipitation is not increasing at the same rate – in many places it is even decreasing. As a result, Poland is already entering a permanent water shortage. And all indications are that the situation will get worse.

A.H.: Since you mentioned the oceans, I’d like to stop by this thread, since this is an area in which you are a recognized expert. We hear more and more that the oceans play a key role in mitigating global warming – they absorb both carbon dioxide and excess heat. But what if this mechanism stops working? Is there a real risk that the oceans will stop performing their lifesaving function?

J.P.: Of the emissions we produce – mainly by burning oil, gas, coal and deforestation – about half remain in the atmosphere. Roughly half of that other half – or a quarter of total emissions – ends up in the ocean, dissolving in its waters. And while it may seem that the ocean could absorb more, it’s not that simple.

First, the ocean mixes very slowly – that is, the gases dissolved in the water take tens or even hundreds of years to reach the depths from the surface. This means that the ocean’s ability to continue absorbing CO₂ is limited by the rate of this circulation. Second, the warmer the water is, the less carbon dioxide it can dissolve in it – a law of physics. Unfortunately, as the oceans warm, their ability to absorb CO₂ decreases.

For now, the rate of emissions has the upper hand, meaning we are forcing the ocean to absorb more and more carbon dioxide. But if this trend continues, and the temperature of the oceans continues to rise, their ability to absorb carbon could fall below current levels, or a quarter of global emissions.

And here we come to another problem: even if we were to completely stop emissions in the future, there would still be a huge amount of carbon dioxide left in the climate system – both in the atmosphere and in the oceans. And it is this sum that we will have to deal with.

If we do not implement large-scale technology to remove CO₂ from the atmosphere – and today there is no indication that this will become feasible on an industrial scale – the problem will remain with us for hundreds or even thousands of years. Paleoclimatic data prove that after large natural emissions of carbon dioxide – such as an asteroid impact or a massive release of methane from the oceans – the Earth remained much warmer for about 100,000 years. This shows how permanent the effects of excess carbon are in our planet’s system.

It is important to remember that the removal of CO₂ from the atmosphere and oceans occurs very slowly – eventually the carbon is deposited as calcium carbonate on the ocean floor. And this process, through the slow circulation of deep-sea water, takes tens of thousands of years.

A.H.: We are talking about issues of concern – can we talk about so-called tipping points in the climate system? Are there mechanisms that can irreversibly accelerate climate change?

J.P.: Science has identified several potential tipping points that, if crossed, can trigger processes that are difficult to stop. The first is the breakup of the ice sheet, especially the active part of it that does not rest directly on the ocean floor. West Antarctica is an example. If it were not for the ice sheet, the sea level in this area would reach 3 km in places.

The problem is that seawater has a much higher heat capacity than air. A difference of just 1-2°C is enough for it to start effectively melting the ice from below – much faster than warm air from above. If this process begins, the glacier could break away from the ground. In such a scenario, the entire West Antarctic region could be deprived of ice – and that would mean a global sea level rise of several meters.

Another potential mechanism is the release of methane from hydrates – this is ice containing gas molecules trapped in bottom sediments at depths of less than 400 meters. Hydrates are stable only at high pressure and low temperature, but if the water continues to warm, they may decompose. Some of the methane, by the time it reaches the surface, will be oxidized to CO₂, but will still be an additional contribution to warming.

The third threat is permafrost – formerly called permafrost, which in itself shows how our consciousness is changing. It contains huge amounts of organic matter and methane. If it thaws, this gas can enter the atmosphere, increasing the greenhouse effect and accelerating climate change – regardless of our emissions from burning fossil fuels.

Another critical point is the possible collapse of the Atlantic thermohaline circulation, known as AMOC. This system transports heat from the tropics northward and is responsible for, among other things, mild winters in Western Europe. The waters flowing from the south of the Atlantic give up gigantic amounts of heat to the atmosphere – as much as 1,000 W/m² in winter, which is as much as we get from the sun in summer.

Melting Greenland introduces large amounts of fresh water into the ocean, which disrupts the descent processes of this cold, saline water, and this is the key to driving the entire circulation. If the above process is halted, the warm water will stop reaching the north, and its energy will no longer be given back to the atmosphere.

A.H.: Does this mean that Europe – paradoxically – may be cooling down, despite the warming of the whole world?

J.P.: Yes, especially Northwest Europe: Ireland, the UK, Scandinavia, as well as Iceland. Models indicate that even a partial slowdown in circulation of 30-40 percent by the end of this century could mean winters several degrees colder. At the same time, sea levels in the North Atlantic would rise by an additional 10-30 cm due to changes in the distribution of water masses.

It is worth understanding that sea level rise is not only the result of melting ice, but also dynamic changes, that is, the system of currents and eddying ocean structures. This works like an interconnected system of vessels, but disturbed by local differences. A change in circulation could mean that sea levels in the Baltic or Mediterranean regions will rise more than in other parts of the world.

In the case of Poland, this would mean a threat to the coast – from Gdansk, through Kolobrzeg to Swinoujscie. Particularly vulnerable are the Zulawy, where we have more than 1,600 kilometers of dikes, adapted to conditions in the 20th century. And yet we are talking about changes that could come in a generation.

A.H.: My next question actually relates to what you have already mentioned. Should residents of Polish coastal cities realistically prepare for the dangers of sea level rise? I understand that the scale of the problem may depend on which generation will be more affected by it – whether current residents or rather their children and grandchildren.

J.P.: It’s primarily a matter of long-term thinking and investment planning. There are already questions about whether it’s worth building houses in parts of Gdansk located below 2 meters above sea level. If someone is ready for the fact that the basements of houses – theirs or their children’s – will be flooded every winter, then yes, one can invest there. But one should be aware that buildings are not put up for a few years, but for a few decades, often with future generations in mind.

On the other hand, there are solutions that can effectively protect coastal cities. But they require advance planning and adequate investment. An example? Gdansk. The city has the peculiarity that the so-called Dead Vistula flows through its territory – cut off from the main current of the river. This provides a real opportunity to technically protect the city from flooding from the sea by building floodgates in two places: at the mouth of the Dead Vistula and at the mouth of the Bold Vistula.

At the time of a storm emergency, these gates could be closed. Since the Vistula in this area does not carry a high flow, the city’s water level would not rise significantly – except for local rainfall, which the sewer system could still effectively drain for a few days. As a result, Gdansk could survive not only the most dangerous storms of the current century, but also part of the next.

Only that such solutions require not only planning, but also investment decisions. We should be thinking about their implementation today – even if the actual activities were to start in 20-30 years. If we start thinking about it only in 30 years, it will be too late. And to put it bluntly – I know what it usually looks like in Poland.

Usually, it is only after a disaster that money is sought and protection programs are launched. I’m afraid it will be the same in this case: if a sea flood inundates Gdansk or, worse, Zulawy, there will suddenly be the political will to save the coast. But before then – despite the warnings – the money and decisions will probably not be there.

A.H.: The concept of ocean acidification has not yet been mentioned in our conversation. It is known that it affects marine life, but could it also be relevant to humans?

J.P.: The acidification of the oceans will indeed affect us – although in the first instance, rather those who want to dive on coral reefs. Because many of the species that make them up are not adapted to an environment where there is so much dissolved carbon dioxide in the water. And it is CO₂ that is the source of acidification – making it difficult for organisms to build calcareous skeletons.

The Baltic Sea is less affected by this phenomenon – it is, after all, almost fresh water, and in principle there are already problems with shell formation. Species that can build shells in these conditions are likely to continue to do so because they are adapted to it. And the world ocean? The idea is to prevent it from becoming as impoverished as the Baltic. And the depletion of ocean life would be a huge loss.

I don’t think ocean acidification is the most serious problem facing humanity at the moment, but it is important nonetheless. Especially for communities living by the ocean and subsisting on fishing or seafood harvesting – there it can be a fundamental problem.

Of course, coastal protection also remains a challenge, but the key is the realization that we are destroying some of the most beautiful ecosystems that still exist on Earth. And we can’t see that stopping us – after all, new plans for deep-sea mining are emerging. This means destroying more ecosystems, the last ones we haven’t yet touched. And things happen very slowly in the deep ocean – and what is destroyed there may not recover for hundreds, if not thousands of years.

That’s why I don’t watch nature programs anymore, for example those of David Attenborough, because it’s too painful for me. I look at these magnificent fragments of the underwater world and think: how much longer will they look like this? The destruction is progressing piece by piece.

A.H.: Finally, a concluding question. If you had the opportunity to influence one government decision on tackling climate change in Poland, what would it be?

J.P.: The most fundamental decision that would need to be made, unfortunately, goes beyond Poland – it’s a global shift away from burning oil, gas and coal. But let’s be realistic: even if we in Poland did it immediately, it would not change the global balance of emissions. We are just one country. Meanwhile, much larger countries – the United States, for example – are today pursuing policies that can hardly be described otherwise than as the planned destruction of the planet. I am thinking in particular of Donald Trump’s decisions.

At our national level, however, there are two things we really can and should do. First – stop draining wetlands and start doing exactly the opposite. Restore wetlands, landscape retention and other forms of natural water storage – as preparation for more frequent and severe droughts. Secondly – think in a planned way about protecting coastal areas: Zulawy, Hel, Ustka and all other localities exposed to the effects of sea level rise. Both drought and the threat of flooding from the sea are real problems of this century. Both will affect us later this century.

Unfortunately, politicians most often think in terms of one term. But if someone really wants to leave behind something lasting – a monument that will last – then they should start thinking well beyond the next election.