From the Union of Concerned Scientists blog (Jose Pablo Ortiz Partida):

The World Resources Institute (WRI) updated its Global Water Risk Atlas revealing that 17 countries–home of a quarter of the world’s population–will face “extremely high” water stress within 20 years. Water stress is defined as the ratio between water withdrawals (i.e., domestic, agricultural, and industrial water uses) and available renewable water supplies. Risk categories of ‘high’ and ‘extremely high’ water stress are reached when yearly withdrawals exceed 40 percent and 80 percent of available renewable water supplies, respectively.

Some readers may remember last year when Cape Town was approaching ‘day zero’, the day when municipal water supplies were going dry. Depending on where you live, some might have wondered “how long until that happens to us?”

In the US we are not facing ‘day zero’ right now but there are people suffering from the lack of clean water. In Flint, Michigan, and Newark, New Jersey water is contaminated with lead and other toxins; in California, about one million people face water stress from groundwater depletion or pollution from nitrates, pesticides, and arsenic.

Within the U.S., 13 percent of the country’s area currently experiences ‘high’ water stress, and 7 percent faces ‘extremely high’ water stress; business as usual projections for 2040 estimate a change to 10 percent and 24 percent for these categories, respectively. Water stress conditions currently experienced only in certain areas of the California Central Valley could dramatically expand to other states by 2040, including New Mexico, Colorado, Wyoming, Utah, Kansas, and Nebraska.

Presently, three (Los Angeles, Phoenix, and San Diego) of the top ten most populous cities in the US–home to about 7 million people–are within ‘extremely high’ water stress regions. About 80 percent of the water used in Los Angeles comes from other areas, including the Colorado River and Northern California. Twenty years from now, another four cities (New York, Chicago, San Antonio, and San Jose) may experience such conditions. The last three in the top ten (Houston, Philadelphia, and Dallas) are projected to fall in the ‘high’ water stress category.

Water crisis and climate

Water crisis usually means the demand for drinking water outstrips supply. But I believe a water crisis can go beyond lack of water. A water crisis can mean being flooded by too much water, or having enough water without the minimum quality needed to use it. A water crisis may also be the lack of water management or even transboundary cooperation. According to the World Health Organization, about three in 10 people in the world lack access to clean water at home when needed.

While tremendous work has been done to reduce this number over the past decades, this means that 2 billion people still lack access to clean water at home. These water crises have resulted in a lack of sanitation and water-borne diseases, food insecurity, conflict, financial instabilities, infrastructure damage, and biodiversity loss. Most of these consequences are getting worse due to climate change.

Climate change is significantly transforming the water cycle. Higher temperatures are increasing evapotranspiration from vegetation, land, surface water, and oceans. A warmer atmosphere is holding more water. As air holds more water, more precipitation is leading to increased flooding. A warmer climate also translates to having more precipitation in the form of rain and less as snow. Snow represents natural water storage, valuable for later irrigation seasons. At the same time, areas like the Southwest of the United States will experience less precipitation because of climate change, leading to longer and more severe drought periods.

In addition, rain seasons will become shorter, creating more days when irrigation is needed and therefore increasing water demands. Warmer water in streams and rivers has an impact on metabolism, life cycle, and behavior of aquatic species. These cumulative impacts on water resources make water availability harder to predict and manage. This is intensifying problems for areas that are already experiencing such impacts and extending water stress into new places that will need to learn and adapt.

What can we do about it?

While not every element of a water crisis is related to climate, some of them are, and others have been exacerbated by it. Therefore, one way to reduce future water impacts is to reduce climate change impacts.

The leading cause of climate change is heat-trapping gases that mainly result from the burning of fossil fuels from our energy and transportation sectors. Emissions are also an animal agriculture, waste management, and industry by-product. Systemic actions to reduce heat-trapping gas emissions are our best chance to reduce climate change impacts, including the increasingly serious water crisis.

Our energy supply and transportation systems must come from renewable energy sources; we need to reduce food waste, switch towards a more plant-based diet and protect our forests. And we also need to increase education and promote reproductive health and reproductive rights. These actions must consider the needs of the most vulnerable communities, as the effects of climate change disproportionately affect them.

Even with bold actions to reduce emissions of heat-trapping gases, many of the effects will still be present, so adaptation strategies are necessary to mitigate impacts.

At a high level, adaptation strategies must include planning responses to water demands increases, overhauling some of the current water policies, and investing in research and modeling of climate risk. Also important is providing water education and training to farmers and the general public, and increasing financial instruments that allow for maintenance and re-operation of infrastructure and adoption of new technologies. Considering these strategies to develop specific actions at local, regional, and state levels would ultimately improve adaptive capacity.

The good news is that we know what it takes for communities to adapt to the impacts of climate change on their water resources. At a local level, a community with high adaptive capacity would be a community that understands how their future volume and timing of water availability may evolve. Such information may, for example, inform the type of crop most suited to the climate. The community would also be able to take strategic actions to deal with wet years (e.g., groundwater recharge), and dry years (e.g., right ratio of perennial and seasonal crops) and to make sure their infrastructure and operations are appropriate for such flexibility. Water conservation would be part of the education system and the culture of the community. Financial mechanisms would incentivize the adoption of water-efficient technologies, and fund water-related monitoring and research. Disadvantaged populations would be at the decision-making table and their interest would be equitably considered and addressed.

Reaching such adaptive capacity may take some time and won’t be easy, but ultimately will reduce the vulnerability of communities and increase their resilience as climate change puts water resources under increasing pressure.