Ports face challenging calculations in combatting sea-level rise

Ports face challenging calculations in combatting sea-level rise

A new set of predictions published in Nature in October 2019 suggests that sea level rise could threaten triple the number of people than previously thought. Port cities are due to bear the brunt of these effects.

A new set of predictions published in Nature in October 2019 suggests that sea level rise could threaten triple the number of people than previously thought. Port cities are due to bear the brunt of these effects.

Asian ports are particularly crucial to the health of the global economy as they include nine of the world’s top 10 largest capacity trading locations. Researchers warn, however, that low-lying Asian countries are expected to be the worst-affected by rising sea levels, and ports will be the first to feel some of the most dramatic effects.

The landmark 2015 Paris Agreement has been important in helping world governments commit to lower emissions in an attempt to soften the impact of climate change. But even if all the commitments are met as planned, it won’t stop sea levels from rising over the next two centuries.

Most of the effects of sea level rise are “locked-in” because the sea warms at different speeds, explains Ivan Haigh, an associate professor of Coastal Oceanography at Southampton University.

“Even if we were to go to negative emissions tomorrow, sea levels are still going to rise for hundreds if not for thousands of years,” he says. “This is for two reasons: one is that we’ve only heated the surface of the ocean, and that heat takes a long time to travel down into the depths. The second is that once you start melting ice, it carries on melting even if you change the temperature.”

“Whatever happens, we are going to experience at least a metre of sea level rise. It’s just a matter of when: is it going to be this century or over the next 200 years?” says Haigh. 

A 2018 research paper Haigh co-authored found that sea levels would continue to rise until 2300 because of the long timescales it takes for the ocean and ice caps to respond to changes in global warming.

“Even with climate change mitigation, the land area exposed to coastal flooding will continue to increase for centuries. Adapting the coast to cope with rising sea levels is inevitably required,” the study concludes. 

Weighing the costs of climate change

Elevating Asia’s ports could provide some level of shield from rising sea levels, but this move would be costly, according to a 2018 report by Asia Engage.

Countries would have to spend up to EUR 45 billion to raise up 53 of the region’s largest ports, analysts found.

Shanghai is the busiest port in the world, handling 647 million tonnes of cargo volume every year. To future-proof it against rising storm surges and other climate effects would cost between EUR 340 million and EUR 550 million, according to the report.

In South Korea, the higher price of construction along with other factors like larger warehouse areas, means the Gwangyang port in the country’s South Jeolla province would have to pay between EUR 1.45 billion and EUR 3.25 billion to ready it for expected large sea level rises.

These adaption costs also represent a significant portion of the entire amount required to build new ports. In Singapore, for example, construction of the fully-automated Tuas megaport is underway and is expected to be fully completed in 2040. It is being opened in stages, with phase one ready to start taking in cargo by 2021. Asia Engage estimates the cost of altering the port to adapt to sea level rises to be EUR 1.1 billion, some 19% of the full price of building the giant 8.6km-long terminal. The maritime sector adds around 7% a year to Singapore’s GDP growth, with 170,000 people currently working in the industry. 

Planning for sea level rise

There is some hope to be had from state-level intervention, however. Singapore’s port could be shielded from some of the worst effects of climate change because of its government’s foresight in putting protective regulation in place.

Tuas is being built on land reclaimed from the sea: since 1960, the island of Singapore has actually grown by 25% to cover 724 sq km through this land reclamation process. In 2011, Singapore raised the minimum height requirements for reclaimed land from 3 metres to 4 metres above sea level.

Intervention costs are incredibly high, though, no matter which option is chosen. A 2015 paper for Stanford University, for example, estimated the expected costs to US ports of intervention to protect against sea level rise and found the price of sea wall and bulkhead construction to be between EUR 750,000 per km and EUR 2 million per km, while building dikes or levees to protect against one metre of sea level rise varied from EUR 1 million per km to EUR 4 million per km.

A paper published in the 2019 Maritime Economics and Logistics journal called ‘Sea-level rise in ports: a wider focus on impacts’ notes: “Main adaption steps include storm defences, elevation to compensate for projected sea levels and even relocation.”

It would be very surprising if a port operator decided to move somewhere else because of the effects of worsening sea level rise, says Jim Hall, Professor of Climate and Environmental Risk at Oxford University’s school of geography and the environment.

“The question they really face is how much will they have to invest to maintain the reliability of their port, to avoid things like unacceptable amounts of downtime, non-navigability, and physical damage to the port infrastructure?”

Every port is going to have to adapt, according to Hall.

“What you need to be looking at is the economics of the core operations — where are the areas where my business case is already marginal and the cost of adaptation is going to mean that it’s no longer viable,” Hall says. “So, you have to think about it as, what’s the expected damage if we multiply the probability of the consequences together then if we invest how much might the expected damage go down by?”

Port operators will have to consider this very challenging cost-benefit analysis when determining how to revamp their infrastructure to deal with the accelerating effects of climate change. Given the reality of rising sea levels, not acting at all is no longer a viable choice.

Written by
Tom Rodgers