In mid-May, the Italian canal city of Venice was witness to an artistic intervention: Two Godly hands made out of concrete holding up a building as if to support it against the merciless currents of the canal. The intervention, entitled “Support,” was crafted by Lorenzo Quinn in preparation for this year’s LaBiennale di Venezia. Quinn’s intervention drew attention to rising sea levels, which threaten to whisk cities away – an issue that has had environmentalists fretting for years and which is particularly pressing for the canal city of Venice.

Over the past 1,000 years, sea levels have risen by 30 centimeters (11.8 inches). Scientists explain that this acceleration is due to a combination of global warming and greenhouse gas emissions leading to a higher concentration of carbon dioxide in the air. The higher temperatures cause the water to expand, while the melting of polar ice caps also contributes to rising sea levels. According to scientists at the Potsdam Institute for Climate Impact Research (PIK), sea levels have risen at an unprecedented rate in the past year. The sudden change is attributed to temperature changes, which have come as a result of the surge of greenhouse gas emissions. In fact, the best case scenario in PIK’s findings would be a sea-level rise of 20-60 centimeters (7.8-23.6 inches) by 2100.

Islands, coastal cities and canal cities are especially vulnerable to climate change. Just last year, five small Pacific islands vanished due to a combination of rising sea levels and erosion. Scientists and environmentalists consider the incident the first scientific confirmation of the impact of climate change on coastlines in the Pacific Ocean.

Between rising sea levels and regular flooding, these canal cities have already begun to show signs of caving to the pressures of climate change.

 

1. Venice

canal

Wandering Through Time And Place.

Venice, which was once-upon-a-time the most important city in the medieval economy controlling trade between the east and the west, now shelters 264,579 people on around 100 islands, making a total area of 414.57 square kilometers (160.07 square miles). In a study published this March, scientists expect the Shakespearean canal city to vanish into the water within 100 years. According to the study, the Mediterranean Sea is set to rise by between 90 centimeters (35.4 inches) and 140 centimeters (55.2 inches) before 2100, flooding Venice and 33 other Italian areas at risk.

 

2. Bangkok

canal

Eye Ubiquitous/Alamy

According to a study conducted by the Thai government in 2015, Bangkok – Thailand’s capital and most populous city – is expected to begin sinking as early as 2030. Thailand’s capital covers a total area of 1,568.737 square kilometers (605.6 square miles) and is home to a little over eight million people. The way Bangkok is structured largely contributes to that risk, but the proliferation of tall buildings and electric railways have all weighed down the city as well. In addition, the region relies heavily on underground water pumped from aquifers, and when too much water is drawn out too quickly, the land above it tends to sink.

Bangkok has always suffered from severe flooding during heavy rains. In spite of the city’s flood precautions, floods in 2011 were particularly damaging and came like a wakeup call, reminding the government that entire swaths of the city could be underwater before 2030. In that sense, sinking Bangkok isn’t exactly news, as risk assessment experts have been warning that the capital is sinking at a rate of 10 centimeters (4 inches) per year since 2008.

There have been efforts to protect the city with flood walls, however, these efforts have been impeded by political squabbles and red tape. A member of the commission studying the issue said that an urgently-needed seawall would cost at least 500 billion baht ($14.4 billion).

3. Shanghai

canal

China4You.

Liu Yi, a senior geologist from the Shanghai Institute of Geological Survey said that it was 1921 when they first realized the city was sinking. But Shanghai has continued to pump groundwater for decades since – an act that contributes significantly to the problem. By the 1950s and 1960s, Shanghai’s condition had worsened to the extent that the ground sunk by 10 centimeters (four inches) a year.

Another important factor that has contributed to the slow sinking of the city that was once dubbed “The Queen of the Orient” is the building of skyscrapers. As progress continued on Asia’s tallest skyscraper, the Shanghai Tower, the problem made a public appearance of itself embodied in cracks in nearby buildings.

However, the relationship between building and sinking goes even deeper. “As the saying goes, the more you build, the more they come,” Jiang Li, a professor of civil engineering at Baltimore’s Morgan State University who grew up in Tianjin, China, says. Pretty soon there will be 30 million people in Shanghai, which is more than the city’s resources and trembling geology can endure, accumulating problems rooted in decades of overdevelopment and overpumping of groundwater resources.