Venice is Sinking: Part 2, Human Causes

Venice is Sinking: Part 2, Human Causes

The Thief Lord: A STEM Side Trip

Human activity is causing Venice to sink in several ways. In this lesson we'll look at a few of them: climate change, sea level rise & tourism.

Climate Change

Some of the causes of the flooding in Venice are natural, but humans have been making the problem worse with pollution caused by burning fossil fuels. Fossil fuels are things we dig out of the earth like coal and oil. These fuels are made of fossils of things that have been dead a very long time.

Fossil Fuels & Greenhouse Gases

When we burn fossil fuels (like coal, oil, and gas) to drive cars or make electricity, they release gases called greenhouse gases. These gases build up in the air and trap heat from the Sun, kind of like a blanket around Earth. This extra trapped heat changes Earth’s climate in ways that make flooding worse in places like Venice. Learn how on the next slide.

Sea Level Rise From Melting Ice Caps

A build-up of greenhouse gases causes many problems on earth, and one that impacts Venice is rising sea levels. When the trapped heat melts the ice at the north and south poles, the melted ice adds water to the ocean that has nowhere to go except onto the land.

Sea Level Rise From Thermal Expansion

Water expands when it heats up. Warmer ocean water takes up more space and sometimes overflows onto land, like it does around Venice when it floods. This is called thermal expansion.

Watch the video on the next slide to see an experiment that shows how thermal expansion works

Multiple Choice

What is one major consequence of water expanding due to heat?

• It causes sea level to rise

• Water evaporates instantly when heated.
• Water remains unchanged regardless of temperature.
• Water contracts and decreases in volume.

Multiple Select

What are two causes of sea level rise? Choose 2.

• earthquakes

• ice melting

• wind

• thermal expansion

Multiple Choice

What does thermal expansion have to do with sea level rise?

• warmer water expands so it takes up more space and raises the sea level

• cold water from melting icecaps makes the ocean shrink

• thermal expansion causes pollution

Multiple Choice

What does the rising sea level have to do with why Venice is sinking?

• Rising sea levels cause the ocean to freeze.

• Sea levels are rising above what the lagoon around Venice can hold so the water floods into the city.

• Tourists in Venice pour their leftover drinks into the sea so it's overflowing.

Sea Level "Lock-in"

Sea levels don’t respond instantly to warming, just as an ice cube doesn’t melt instantly when you take it out of the freezer. But it does melt eventually.

Once pollution enters the atmosphere (air & other gases surrounding the planet), it continues heating the planet for thousands of years.

No Going Back

Even if we stop polluting right away, the earth will hold on to the trapped heat for hundreds and thousands of years into the future. Scientists call this sea level “lock-in.”

The more we pollute, the more we lock these changes into the future without any way of reversing them. This chart shows how many people live in places that will be underwater by the year 2100.

This chart shows how many years it will take for the cities here to sink into the sea. The white numbers on the left are years.

Multiple Choice

According to the chart on the last slide, if we keep polluting the way we are now, how many years will it take for Venice to be completely under water?

• 20

• 100

• 1000

Multiple Choice

What is sea level "lock-in"?

• "Lock-in" means ice at the north and south pole can't melt anymore

• "Lock-in" is a system of collecting the acqua alta water to recycle.

• "Lock-in" means even if we start polluting less, there's no way to undo the sea level rise.

Open Ended

What are changes we could make to keep earth's cities from sinking into the ocean?

Multiple Select

What are changes we could make to keep earth's cities from sinking into the ocean? Choose 4.

• Plant trees, which absorb carbon dioxide from the air.

• Use less plastic, since making it and throwing it in landfills creates greenhouse gases

• Walk, bike, or take public transportation instead of always riding in cars.

• Drive gas-powered cars less.

• Use more plastic, since it’s lighter than other materials.

Tourism & Flooding in Venice

As you learned in Part 1 of this lesson, Venice is build on sediment that naturally sinks as the layers build up. Humans are speeding up this sinking by overwhelming the city with visits! Watch the video on the next slide to learn how.

Multiple Choice

How is tourism causing Venice to flood more?

• The weight of millions of tourists adds pressure on the city’s weak foundations, making it sink faster.

• Tourists are spilling drinks into the canals, which causes overflowing.

• Increased tourism leads to more rainfall in Venice.
• Tourists’ boat rides pump air under the city, causing it to collapse.