By Sara Corben
This week, President Obama spoke on climate change, unveiling new plans to cut down on carbon emissions nationwide and providing direction for the United States to deal with the implications of climate change. According to the President’s speech, “The 12 warmest years in recorded history have all come in the last 15 years.” With the evidence of climate change becoming impossible to ignore, and with conversation centering on climate change, many are asking how these global changes will affect water scarcity.
According to the Intergovernmental Panel on Climate Change (IPCC), global surface temperature has risen by 0.74oC in the past 100 years, with temperatures increasing more rapidly in the past 50 years. Heat and water are closely linked, and in recent decades, warming trends have led to changes in the hydrologic cycle. These changes include increased atmospheric water vapor content, changing precipitation patterns, intensity and extremes, reduced snow cover, widespread melting of ice, and changes in soil moisture and runoff.
The impacts of these hydrologic changes vary based on location; since the 1970s, records show that precipitation has mostly increased over land in northern latitudes, while decreased precipitation has characterized those areas from 10oS to 30oN. With some areas receiving increased rainfall and others experiencing decreased precipitation, some question whether the changes made by global warming will be beneficial, harmful or neutral overall.
In their Fourth Analysis Report on Climate Change, the IPCC concluded that globally, climate change will have an overall net negative impact on fresh water resources. The area of land classified as “very dry” has doubled since the 1970s, and will continue to increase in extent in the future, with Europe, the Mediterranean and southern areas of Australia expected to suffer from increasingly dry climates. By 2025, the number of people without access to water is expected to increase from 1.1 billion to between 2.7 and 3.5 billion. In addition, higher water temperatures are projected to affect water quality and result in increased pollution3.
In a UNESCO study of recent environmental and social factors affecting water scarcity, the World Water Assessment Program determined that while climate change will have an important impact on water scarcity, other factors, like population growth, unsustainable consumption patterns and uncontrolled usage, may have more significant consequences for the global water crisis. However, they classified climate change differently from other stressors, as it affects the supply rather than the demand for water. It is because of this classification that climate change must be factored in to water management plans, as precipitation becomes more and more inconsistent.
A number of factors will ultimately come together to determine the future of water scarcity, but the impact of climate change on water availability cannot be ignored. Joe Alcamo, chief scientist of the UN Environmental Program and former co-chair of the GWSP, summed up man’s relation to water, saying “Humanity changes the way water moves around the globe like never before, causing dramatic harm.” Climate change may not be the only factor driving the world’s water challenges, but it will certainly make finding solutions more urgent.