MS-ESS3-3: Apply scientific principles to design a method for monitoring and minimizing a human impact on the environment
MS-ESS3-4: Construct an argument supported by evidence for how increases in human population and per-capita consumption of natural resources impact Earth’s systems.
HS-ESS3-6: Use a computational representation to illustrate the relationships among Earth systems and how those relationships are being modified due to human activity.
Key Vocabulary: climate change, drought, temperature, population growth, carrying capacity, resources
The South African city of Cape Town is on the verge of running out of water. The city of nearly 4 million people is in the midst of a water crisis; as of February 2018 residents have been restricted to using only 13 gallons of water per person per day. The crisis is causing Cape Town’s citizens to use less water to drink, flush the toilet, cook meals, and bathe than the average American uses during one shower, with heavy fines for households that can consume more than their allotment.
It is projected that “Day Zero”, the day the city will have to turn off the water taps to businesses and homes, will occur within the next 6-12 months. Authorities are extremely concerned about preventing violence over water availability and how to make water accessible to all of Cape Town’s citizens. However, Cape Town’s plight may become more common in cities across the world. As the human population continues to increase and global temperatures continue to warm, the current water crisis in Cape Town could be a sign of things to come in the 21st century.
So why is Cape Town running out of water in the first place? 2015 marked the beginning of what has become a 3-year drought in a city that relies almost completely on rainwater for its water supply. The drought has proved devastating, with reservoirs down to about a 25% of their full capacity. If the reservoirs drop to around 13.5%, city officials will be forced to turn off water lines to homes and businesses. Though winter has historically been South Africa’s rainy season, the rains have come later and later in recent years. Just a few decades ago, April marked the start of the rains, but current patterns suggest this year they may come as late as July.
Cape Town is no exception to extended periods of drought. Droughts are occurring worldwide from the Southwest United States to Latin America, Africa, and the Middle East. These areas were already prone to drought, but climate change conditions may have made them more extreme and prolonged. Long-term in climate patterns have been linked to increased global temperatures due to greenhouse gas emissions. Warmer air temperatures can cause more moisture to evaporate from bodies of water, such as lakes and rivers.
This has left people dealing with not only lack of water availability, but increased risk of wildfires and desertification. Desertification the changing of semi-arid ecosystems such as prairie or steppe into deserts due to reduced precipitation. Desertification has been exacerbated by climate change and results in weakened soils, food insecurity, and degraded land. While we cannot blame any singular drought on climate change, the rising global temperatures will create conditions for droughts to be more often and longer.
Agriculture puts huge amounts of pressure on water use because of the growing demand of feeding the world’s growing population. The longer droughts caused by higher global temperatures negatively impact crops. If there is not enough water to meet the demands of farms, crops may be lost and food prices may increase.
Additionally, the human population is set to reach 8 billion people by 2023, increasing the demand for our freshwater reserves. Some researchers believe that the Earth is starting to hit its carrying capacity for humans. Carrying capacity is the total number of individuals an environment can support, which is dictated by the amount of available resources. The growing human population and more prolonged droughts exacerbated by climate change will put enormous amounts of pressure on water availability and could increase conflict among people between land and resources.
While there is no one solution that will fix the water crisis in Cape Town, there are some lessons to be learned from other cities. From 1997 to 2010, Melbourne, Australia experienced a similar water shortage and the government had to find a way to drastically cut water consumption. Residents were given rebates for reducing their water consumption and encouraged to use water-efficient dishwashers and washing machines. Educational materials outlining how to reduce water use was distributed to local schools and universities and ads were placed in newspapers and on television. The coordinated effort paid off: water consumption was reduced by half, from 167,000 liters per person annually to 86,000 liters in 2016.
But to really start conserving water, some new technologies will have to be developed. The WaterSeer is a large-scale technology that resembles a well, but rather than extracting groundwater, the WaterSeer extracts water from the atmosphere. This offers one solution, potentially collecting 37 of liters of water per day. There is also a Drinkable Book, which acts like a coffee filter and purifies water by removing 99.9% of bacteria. David Knighton, CEO of Creative Water Solutions, found a natural solution to creating cleaner water by using moss, which can filter water and remove chemicals such as chlorine. Technologies, such as drought-tolerant seeds and conservative irrigation systems, have to be discussed and implemented to ensure the security of crop production without the cost of exhausting the water supply.
Cape Town will not be the last city to face a water crisis of this level; the problem and will only be exacerbated as temperatures continue to rise, droughts become more frequent, and populations continue to grow at alarming rates. National, regional, and local governments need to act now and start planning for a more water-scarce future.