It is well-known that sea levels are rising in line with the increase in the average global temperature. But how dramatic can the changes in sea level be in our lifetime, and how much changes would be notice in our own country?

The scientific consensus is that the change in sea level will not be particularly dramatic: we are unlikely to see any significant parts of Malta claimed by the waves. However, a slight rise in sea level would still leave a considerable impact, and the climate change which would have brought it about is likely to leave an even more significant one.

Rising temperatures contribute to an increase in sea levels for two main reasons. The first is thermal expansion: water expands as it heats up, a phenomenon believed to account for around half of the rise in sea level since the Industrial Revolution. The second reason is the melting of large ice formations, particularly within the ice sheets covering Antarctica and Greenland.

Sea levels have risen by around 20cm since 1870, but the average annual rise is increasing. It presently exceeds 3mm a year, and is likely to grow further if present trends continue.

Projections for 2100 vary, depending on the source, but conservative estimates tend to hover around the 30cm mark – thus assuming that the rise in sea level remains practically constant. Realistic worst-case scenarios tend not to exceed 2m.

But sea levels are expected to continue rising for centuries yet to come, and climate change may yet trigger an unexpected catastrophic event – such as the collapse of a major ice sheet – which could increase global sea levels considerably.

In this article, The Malta Independent will be going over a few scenarios, starting from the 2m mark. While such an increase may be experienced by people who are alive today, other scenarios are unlikely to present themselves so soon – the last scenario may verge on the fanciful – but may still be possible, depending on what the future holds.

The only consideration made in the scenarios is an increase in sea level: the effect of erosion, coastal defences and other factors is not taken into account. The data is sourced from flood.firetree.net, a simulation which itself uses data from Google and from NASA.

A 2m rise

A 2m rise in sea level may not seem like much, and in fact there would be few visible changes in a map of the island.

However, the changes would still leave a significant impact on many coastal areas.

Existing beaches would be mostly submerged: finding a spot in the sand, particularly, would be much harder. Various coastal promenade, such as the one in Sliema, would likely directly overlook the sea as seawater submerges the underlying rocky coast.

In other cases, however, even coastal roads would not be safe from rising sea levels. Travelling to and from Gozo, for instance, becomes a considerably more complicated affair since the sea would have started flooding the roads beside Xemxija and Ghadira bays.

There would be another complication to travelling between the two islands: seawater would also start submerging Malta’s port infrastructure, including the ferry terminals in Cirkewwa and Mgarr along with the Freeport and the Grand Harbour. These harbours would likely have to be adapted to the new reality, likely at a considerable expense.

A 5m rise

Sea levels are believed to have been approximately 5m higher around 125,000 years ago, during the last interglacial period. The earth is nearly as warm now as it was then, and atmospheric levels of carbon dioxide – a greenhouse gas – are considerably higher.

A map of Malta would still be very much recognisable, but there will now be very noticeable changes, particularly in four valley systems.

In Marsa, the Grand Harbour would reach as far inland as the horse racing track, covering much of the sports club and rendering Aldo Moro Road unusable.

Another road that would be breached by sea water – at various points – is the Coast Road: in Salina, the sea would submerge many of the low-lying fields presently separating Burmarrad from the coast.

Xemxija Bay would extend inland by close to a kilometre as seawater starts flooding the low-lying Pwales Valley.

Further north, the Mellieha Holiday Centre would be transformed into a mini-peninsula as Ghadira Bay extends into the valley systems to its north and south.

While coastal areas in Gozo would inevitably be affected – not least Marsalforn – the island’s shape has changed much less than that of Malta, as the island has relatively few low-lying coastal areas.

10m rise

Barring any unexpected catastrophic event, it would take centuries for sea levels to rise by 10m, even under a worst-scenario in which greenhouse gas emissions are left unchecked.

Existing coastal areas, inevitably, would be devastated, and a number of new islands would actually be created as rising sea levels separate promontories from the mainland.

The biggest new island would be in Marsascala, as St Thomas Bay and Marsascala Bay join up through what had been the Maghluq saline marshlands. The sea would also flow into the lower limits of the Sant’Antnin Family Park.

Senglea would also be cut off from the mainland and become an island: it had actually been one in mediaeval times, as reflected by its Maltese name l-Isla. Nearby Fort St Angelo would also be cut off from the rest of Vittoriosa.

Seawater would also submerge more of the valley systems mentioned above.

Qormi and Burmarrad would become coastal localities, as they are known to have been centuries ago: the Bur prefix betrays the latter locality’s history as a port town.

Xemxija Bay would extend nearly as far as Manikata, while Ghadira Bay nearly cuts off the northernmost part of Malta from the rest of the island.

30m rise

No such rise is predicted in the foreseeable future – even in the long-term. However, the melting of the ice sheets in Antarctica and Greenland alone would cause sea levels to rise by over twice that amount, without accounting for thermal expansion.

At this point, the sea claims a number of islands in the Maltese archipelago, including Cominotto, Manoel Island and St Paul’s Island. But it would also carve new islands out of what used to be the island of Malta.

The Grand Harbour and Marsamxett Harbour merge, cutting off Floriana and Valletta as a single island and nearby Gwardamanga Hill as another one and turning Kappara, Birkirkara, Santa Venera, Hamrun, Luqa and Fgura into coastal communities. Save for the tops of buildings, Senglea and Birgu are mostly underwater, although a larger portion of Cospicua remains on dry land.

Marsascala practically disappears, and the waters extend to the built-up areas of Zejtun and Zabbar. Marsaxlokk and Birzebbuga are similarly flooded almost in their entirety.

The west coast remains relatively unchanged – although its cliffs are somewhat less impressive. But the north of the country is a different scenario entirely.

Much of St Paul’s Bay is now underwater, including Burmarrad: two small islands are all that remains of Bugibba and Qawra, as the sea now extends to just beneath Mosta Fort.

Xemxija Bay and Golden Bay converge, creating a channel which cuts off Mellieha from the rest of the island.

But Mellieha itself becomes a three-island archipelago as the Ghadira Bay itself is turned into a channel.

The largest of these islands includes Mellieha and Manikata, while the second-largest includes what is left of Cirkewwa, Armier and nearby areas. The smallest island is made up of the top of the flat hill behind Ghadira Bay.

The changes in Gozo are considerably more significant this time round, with Marsalforn, Xlendi and Mgarr disappearing. The Azure Window in Dwejra becomes a diving attraction, and the Inland Sea loses its distinctive status.

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Caption: a map of Malta showing the effect of a 30m rise in sea level. Such a rise is unlikely to present itself until far into the future, if at all, but may be possible should a considerable proportion of existing ice sheets melt.