Water from Icebergs
Nearly 200 hundred years ago, the English poet Samuel Coleridge wrote the now famous phrase “Water, water, everywhere, Nor any drop to drink.” The painful dilemma of a man becalmed at sea with no fresh water immortalized in the Rime of the Ancient Mariner now faces far more than a few unlucky sailors. Very little of Earth’s water is fresh – less than 3% of the total. As the human population grows, as industrial and agricultural water demands escalate, and as streams and groundwater sources become more and more polluted, chronic and acute water shortages are becoming increasingly common. Already 40% of the world’s population lives in areas subject to severe water shortages.
The planet’s greatest stores of freshwater lie far away from the arid, heavily populated regions that need it the most. Nearly 70% of all fresh water is locked in the polar ice caps. Just the new icebergs that form every year around Antarctica hold enough water to meet the needs of every person on Earth for several months. Longstanding proposals to tow icebergs to lower latitudes where their valuable water can be harvested have been met with both skepticism and interest. To date, no successful attempts have been made.
In this activity, you will investigate some of the logistical problems involved in moving enormous chunks of ice long distances through often turbulent seas.
Instructions: The exercise below gives you six opportunities to witness an iceberg in tow, being hauled to a seaport where fresh water is needed. Click through the images and observe what happens. View all six scenarios, and then answer the questions that follow.
Note - animations are not to scale.
- There’s water all over the planet. Why even consider going all the way to the poles and back to get icebergs?
Although water is abundant on Earth, fresh water is very rare. As demand grows and conventional sources like rivers and lakes and groundwater get used up or polluted, new supplies are needed. And the biggest reservoirs of fresh water are the polar icecaps. This water also has the advantage of being very pure, since most of the ice formed before the Industrial Revolution.
- Then why aren’t icebergs being towed to where their water can be used by humans? (Consider the results of the simulations above, and consult the additional resources.)
Distance is one factor - most of the very arid lands that need water are about as far away from the poles as possible. Sea surface water temperatures rise rapidly, by 20-30ºC between the poles and the equator, so a lot of ice would melt before the berg reached its destination. To survive, the iceberg would have to be very large, which would make it hard to move and steer. On the way, the iceberg would encounter high waves (often 4-5 meters of more high) and strong currents, which would make it harder to control, slow the journey considerably, and even cause the iceberg to break apart. All of these factors make towing an iceberg a difficult and expensive, time-consuming process. As long as other water sources are cheaper and easier to obtain, icebergs aren’t likely to be used.
- Suggest solutions to avoid or minimize the problems that led to failure in the towing simulations.
If an iceberg is located near or could be pushed into one of the major currents that move from the poles towards the equator, nature would help to move it along. The exposed part of the iceberg could be covered to reduce sun exposure and slow melting. Instead of towing an iceberg all the way to where its water is needed, perhaps it could be broken into small pieces and loaded into the holds of ships, or it could be towed to a nearby land mass and processed into water that could be loaded into barrels for shipboard transport.
- Discuss environmental damage that large scale iceberg moving could cause, at both ends of the journey.
If large numbers of ships began regular visits to polar waters, and if facilities were established to aid them, it is likely that the activity would disrupt wildlife and that the inevitable pollution would damage the fragile ecosystems found in the extreme conditions that characterize the Arctic and Antarctic.
As an iceberg neared its destination, it would be shedding large volumes of very cold fresh water into warm coastal waters. This could be very harmful to local ecosystems. The iceberg may also start to drag against the seafloor, crushing bottom communities, kicking up clouds of debris into the water, and damaging topographic features.
- Can you think of other issues involved in the use of icebergs for fresh water, other than the economic and environmental ones already mentioned?
If icebergs become valuable resources, it seems inevitable that conflicts will arise over their use and control. Who owns the icecaps and icebergs, and who will regulate their use and movement - the nearest countries? Whoever can grab onto them? The United Nations? What about the poorer countries, or those with no seaports - these are in many cases the ones that need water the most.
- One area of the world that has both the economic resources and the water shortages to make polar ice seem attractive is the Middle East. Imagine you have been hired to haul icebergs to Saudi Arabia. What are some of the factors to consider in choosing where to get the ice and in mapping out your route?
Arctic icebergs drift down into the North Atlantic on their own, and could be steered into the colder currents that flow south past Europe. But a large iceberg would probably not be able to travel into and through the shallow warm water entrance to the Mediterranean for the final part of the trip.
Antarctic icebergs are larger and more stable. And the route from Antarctica to Saudi Arabia through the Indian Ocean is open and deep. But the waters between Antarctica and southern Saudi Arabia have very high waves, and the iceberg would have to be towed across strong, warm currents.