A day after Thanksgiving, the Trump administration released the Fourth National Climate Assessment, a report assessing the science of climate change and impacts across the United States. The nearly 2,000-page report which comes out every four years warns that the effects of global warming are already evident in the United States and are expected to further disrupt many areas of life.
The report is divided into 12 chapters, one of which is dedicated to the water sector. According to the 13 federal agencies responsible for the latest National Climate Assessment, the nation’s water sector is one of the most impacted by climate change and its water security is increasingly in jeopardy.
Figure 1. Total number of water-related billion-dollar disaster events each year in the United States
Focusing on three keys messages, the scientific report highlights firstly, that there are significant changes in water quantity and quality across the U.S. The increasing heavy downpours are mobilizing pollutants like sediments and nutrients into surface water and affecting its quality. Moreover, the timing of water supply and demand are being altered due to reduced snow-to-rain ratios, and intensifying droughts are responsible for the decrease of water quantity.
Figure 2. Depletion of Groundwater in major U.S. Regional Aquifers
The second key message focuses on the nation’s water infrastructure. Most of the dams, drainage systems, sewers, aqueducts and other components are aging and need an overhaul. Built before the impact of climate change was so visible, the infrastructure will tend to fail as floods become more severe and droughts become longer.
Lastly, the authors of the water chapter emphasize the need to design water management strategies which take into account future climate changes. Currently, no report exists on the vulnerabilities faced by the nation’s water infrastructure in relation to global warming and there is still an enormous breach between research and implementation.