Rockström warns – a threat is quietly escalating
In an opinion piece recently published in the swedish daily newspaper, Svenska Dagbladet, Johan Rockström, Professor of Earth System Science, and his colleague Wendy Broadgate, PhD in Marine Chemistry, describe the importance of the Swedish Government drawing up a contingency plan as a matter of urgency in the event that the AMOC ocean current system were to slow down or collapse.
Text: Marika Griehsel
The AMOC (Atlantic Meridional Overturning Circulation) is the vast system of ocean currents that plays a crucial role in regulating Europe’s climate. A collapse would have devastating consequences, with significantly colder winters, not least in the Nordic region.
The two climate experts describe a potential change in the AMOC as a threat that is quietly escalating off the coast of Sweden. Rockström and Broadgate call for commitment and swift action from decision-makers and authorities, writing as follows:
In 2021, the UN’s Intergovernmental Panel on Climate Change (IPCC) assessed that an AMOC collapse is unlikely before the year 2100, but more recent research points to a significantly higher risk. This is not based on individual studies with extreme assumptions, but on new climate analyses based on IPCC data.
We conservatively estimate the probability of a drastic slowdown or even collapse to be 10 per cent or more. What was once seen as a remote risk is now a real threat.
Johan Rockström and Wendy Broadgate propose, amongst other things, that Sweden commission a government inquiry to investigate the risks to food production, infrastructure and security. They call for Sweden to take the lead and, in collaboration with other Nordic countries and the EU, ensure that the issue of the AMOC is not treated merely as an environmental issue, but that both economic and national security are taken into account. They also call for an advanced monitoring system for ocean currents and for the Swedish government to work towards a drastic reduction in greenhouse gas emissions.
The AMOC carries warm water from the tropics northwards towards the Arctic, and this flow of warm water helps to give Europe mild winters. However, rising global temperatures are accelerating the melting of Arctic ice and causing meltwater from Greenland’s ice sheet to flow into the sea. It is primarily this cold fresh water that could disrupt the current, scientists warn.
A potential collapse could trigger a modern ice age, in which winter temperatures across Northern Europe would plummet to new, extreme lows, bringing significantly more snow and ice.
In Iceland, the authorities have already classified a potential collapse of this vital Atlantic ocean current system as a matter of national security and an existential threat.
The government has begun drawing up strategies for worst-case scenarios, the country’s climate minister, Johann Pall Johannsson, told Reuters news agency.
´It is a direct threat to our national resilience and security, writes Johann Pall Johannsson in an e-mail. This is the first time a specific climate-related phenomenon has been formally brought before the National Security Council as a potential existential threat.´
A breakdown in the Atlantic Current could have consequences far beyond Northern Europe. According to researchers, it could potentially destabilise the long-term rainfall patterns on which subsistence farmers in Africa, India and South America depend. It could also contribute to faster warming in Antarctica, where the sea ice surrounding the southernmost continent, as well as the ice sheet on top of it, is already threatened by climate change.
´Iceland is taking no risks, now that the rate of warming is increasing and greenhouse gas emissions continue to rise, says Johann Pall Johannsson. Sea ice can affect maritime transport; extreme weather can seriously impact our ability to sustain agriculture and fisheries, which are central to our economy and our food systems.´
´We cannot afford to wait for definitive, long-term research findings before we take action.´
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The Atlantic Meridional Overturning Circulation, or AMOC, is one of the most important ocean current systems on Earth. Since the end of the last ice age, more than 10,000 years ago, the AMOC has helped to ensure that the climate in north-western Europe has been considerably milder than it would otherwise have been, creating the conditions that enabled the emergence of agriculture and human societies in the region.
The AMOC has collapsed before – most notably prior to the last ice age, which ended around
12,000 years ago.
