Why are the sea levels rising?
Semih ESENDEMİR, Emine Emir Şahbaz Science and Art Center / Turkey
Global warming causes many important problems affecting our lives. These problems not only affect our present, but also create troublesome situations for our future. In this activity, it is aimed to raise awareness on a global problem that has not been emphasized much. The change in the seas due to the increase in global temperature is the starting point of this activity. Sea levels are rising rapidly, even if we are not aware of it. The causes and effects of the rise in sea levels are discussed in this activity through an interdisciplinary approach.
Implementation of the activity
When the activity starts, students are shown a beautiful photo of Venice. Then a photo of Venice is shown underwater, with the statement that ‘Venice may be submerged by 2100’, announced by the Italian Agency for Sustainable Economic Development, Technology and Energy (Enea). “Why Venice is at risk of being completely submerged in 100 years” is discussed.
Students are asked to examine on the risk zone map how possible sea level rises will affect the coastal areas. Students can study their own country or any coastal region they wish. Students who realize that the rise of sea levels will affect all sea coasts in the near future are asked to read the article “Sea level rise” and answer the following questions.
• “What could be the reasons for the rise in sea levels?
• “What negative effects might the rise in sea levels have?”
After the discussion, students are asked “How do we know that sea levels are rising?” and information is given about the scientific studies and measurement tools (satellites, coastal tides, and drilling measurements) necessary to obtain data showing the rise in water levels.
Students who have learned how to collect data on sea level rise are asked to review NASA Sea Level charts that include satellite, historical data, and coastal tide data. They are asked to compare the data received from the satellites with the coastal tide data. By watching animation“Evidence of sea level ‘fingerprints‘”, they observe the change in sea levels according to the data received from the GRACE satellite.
Students are asked whether global warming and greenhouse gases are effective in rising sea levels. To answer this question, students are asked to examine NASA’s data and graphs of changes in global surface temperature according to average temperatures between 1880 and 2020. They watch the animation on the same web page showing the global temperature change between 1884-2021. Afterwards, all graphs are examined, and it is discussed with the reasons whether there is a relationship between the temperature change data and the rise in sea levels.
Along with the global temperature increase, the main factors that cause sea level rise, melting mountain glaciers, melting polar ice caps [Terrestrial glaciers (Fresh water or snow) and Sea ice (Salt sea water)] and thermal expansion of water.
Considering that the melting of glaciers is the main source of the rise of sea levels, the following questions about the concept of ice are discussed.
• How much of the world is icy?
• Where on Earth is ice found?
• So where on Earth is there a lot of ice? On land or at sea?
Students are asked what the difference might be between land ice and sea ice. It is stated that the correct information “Melting ice causes sea level rise”. However, the students are asked, “Does the melting of ice at sea or on land affect the rise of sea levels?” and “Is there a difference between having ice on land and being on the sea?”. Possible answers are taken. The following experimental setup is designed to show whether there is a difference between the ice being on land and in the sea.
The construction stages of the experiment
Pressing an equal amount of play dough onto one side of both plastic cups creates a smooth and flat surface that represents the land rising from the ocean.
Equal amounts of ice are placed in both plastic cups. Ice is placed on the play dough in the first cup and on the bottom in the second cup.
By connecting the water sensor and micro:bit to the point where the water level of both cups is, the change in water levels is measured.
The observation is continued until the ice in both cups completely melts. A time-water level graph is drawn according to the measurement results.
As a result of the experiment, discussion begins on the following questions.
- Does the melting of the world’s glaciers contribute to sea level rise?
- Has the water level rised in both cups?
- In which cup did the water level rise more?
- So why didn’t the water level rise in the cup representing the land glaciers, while the water level did not rise in the cup representing the sea ice?
As a result, icebergs and frozen sea water, namely sea ice, melt in warm weather, but do not cause sea level rise. This is because they are already in water and its density is lower than water (Mathematical equations for density are given at this stage). The volume of water they displace as ice is approximately the same as the volume of water they add to the ocean when they melt. When sea ice melts, it does not cause sea level rise.
In addition, students are asked to examine “How glaciers, continental ice caps and sea ice around the world are affected by climate change” by the global ice viewer.
By traveling in time by the Climate Time Machine, they are asked to study the change of Artic Sea ice and the ice cap on the island of Greenland over time.
At the end of the activity, a game is played to draw attention to the melting of glaciers.
• Groups of at least four people are formed. Each group is given 6 cups on which the factors that cause sea level rise are written, a rubber band, a rope for each student, a ping pong ball and a cup containing an ice cube.
How to play:
• As soon as the game starts, an ice cube is placed in a cup of the group.
• As the game starts, the groups must build towers from cups with the factors that cause the sea level to rise and by using ropes
• After finishing the tower, they must knock down the tower with a ping pong ball from a certain distance.
• The aim of the game is to build and demolish the tower as soon as possible without melting the ice that the groups have.
• The group that melts the least amount of ice wins the game.
The students, who did not see the rise in sea levels as a serious problem at the beginning, defined the rise of sea levels as a serious problem as a result of the articles, data, graphics and animations they examined during the activity. They discovered the causes and consequences of the rise in sea levels. With regard to ice melt, which is one of the most important causes of the rise in sea levels, they discovered the difference between the melting of land ice and sea ice by experimenting. During the experiment, the students wrote a code to measure the water level via the micro:bit makecode and measured the water level by the water sensor they connected to the micro:bit. In addition, as a result of the experiment, they explained the fact that the water level did not rise as a result of the melting of sea ice, with the density formula. They experienced how to analyze data through graphs. Thus, the activity was implemented in an interdisciplinary manner by establishing technology and mathematics connections. By the game played at the end of the activity, the causes and consequences of the rise in sea levels were revised in an entertaining way.
During the implementation of the activity, different local or global examples, pictures and articles can be included. If micro:bit cannot be used during the experiment, measurements can be made with the help of a ruler and the results can be compared. Preliminary work can be done with students on density formula, graph drawing and analysis in accordance with the student’s age level.