How is global warming affecting water resources and distribution throughout the world.

Water is essential to life on this planet. Yet there are signs that freshwater supplies are becoming more and more scarce. According to the UN, around 2 billion people – over 25% of the global population – already live in countries experiencing high water stress and it's predicted that around 700 million people could be displaced by extreme water scarcity by 2030. One of the key challenges is climate change, which is disrupting the global water cycle and affecting water supplies in a number of ways.

Evaporation And Precipitation – Changes to The Water Cycle

One of the key effects of global warming is on the water cycle. Water on the planet evaporates into the atmosphere and is returned through precipitation (rain) as part of an ongoing cycle. Climate change affects the amount of water the atmosphere can hold. Essentially, warmer climates can hold more water in the atmosphere. This will then fall in greater amounts when the atmosphere cools.

As the planet heats up, there is an increased risk of both droughts and floods as the water cycle is disrupted. In some warmer areas, this can cause what is known as “precipitation volatility” which is dramatic shifts between drought and flood – such as in California. Weather patterns can intensify. Both Europe and the US have seen an increase in floods in the north and droughts in the south over the past century. Research suggests that global warming is one of the chief drivers of both droughts and floods. This affects both water and food supplies as well as causing damage to marine and wildlife.

Global Warming and Melting Glacier Caps

Another effect of global warming is on the water supplies stored in glacier ice caps. Only around 2% of the world's water is freshwater (most of the remainder being saltwater and brackish water found in oceans, rivers and other waterways) and approximately 70% of this is stored in ice caps. Climate change has caused glaciers to shrink, with research suggesting that glaciers are shrinking by around 227-32 gigatonnes a year.

Glaciers provide water to many areas via meltwater and runoff during the drier seasons, when ice and snow melts and replenishes freshwater supplies. However, warmer temperatures have led to excessive meltwater which has overwhelmed the freshwater basins and ended up lost to the oceans. This has been exacerbated by more precipitation falling as rain rather than snow. Glaciers are thus less able to provide a sustainable longer-term freshwater supply. One study on mountains in Asia found that the glaciers there could lose up to one-third of their mass by the end of this century.

Changes to Water Quality

Climate change impacts water quality in at least three ways. Firstly, the increased flooding that occurs can quickly overwhelm sewage and water treatment plants. Stormwater runoff can wash wastewater containing harmful pathogens and pollutants into waterways and the water supply.

Secondly, rising sea levels brought about by the melting of ice caps can result in seawater flowing into freshwater supplies and contaminating them.

Finally, the increase in water temperature caused by global warming can change the oxygen levels in the water. This can be harmful to some marine species and lead to a bloom in microbial populations that contaminate the water.

What Can Be Done?

In addition to properly tackling climate change to bring down global carbon emissions, there are a number of things that we can do to protect the world's water supply. After all, global warming is only one factor affecting water supplies.

Much can be done to reduce our water use and wastewater discharge, such as greatly improving water recycling to lessen the pressure on freshwater resources. We can also improve our water infrastructure by reducing leaks and looking at decentralized ways of supplying water. Another option is to invest in technology such as desalination systems or wastewater recycling systems which will create additional sources of fresh drinkable water.

Water Experts can help you reduce your water footprint by helping you to find sustainable ways to use and manage your water supply. We can perform a full water audit to lower water consumption, design wastewater treatment plants to lower the pressure on the environment and investigate technology to reuse water and move towards circular water use in your organisation. Do you want to lower your impact?

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