All regions of the world show an overall net negative impact of climate change on water resources and freshwater ecosystems.

Today is World Water Day — a day established to recognize the importance of water to the nations and people of the world. Nearly one billion people around the world don’t have clean drinking water and 2.6 billion still lack basic sanitation. So the challenge confronting the world today is daunting and critical as clean water sustains life (and lack of water makes life difficult). And it will be made worse, with the impacts on water projected under global warming.

Some signs of the water impacts from global warming are already occurring today in the U.S. and around the world (as you can see in this great photo collection). For example (a brief overview is available in the IPCC summary on page 27):

  • Deserts are spreading, fueling armed conflict and putting families on the move in places like Sudan, Kenya, and Somalia. Concern about armed conflicts from global warming has led to the creation within the U.S. Central Intelligence Agency of the Center on Climate Change and National Security, to assess the national security risks posed to the United States by widening desertification; rising sea levels; population shifts and increasing competition for food, land, and fresh water.
  • The Oceans are acidifying (as NRDC has summarized). Over the last 250 years, oceans have absorbed 530 billion tons of CO2, triggering a 30 percent increase in ocean acidity. Researchers predict that if carbon emissions continue at their current rate, ocean acidity will more than double by 2100.  Acidification threatens the future of ocean protein sources which is a major concern since the oceans currently provide around 17 percent of the protein that humans consume — and as the world is struggling to feed the current population any disruption is very problematic.
  • Sea level is rising. Higher temperatures are expected to further raise sea level by expanding ocean water, melting mountain glaciers and small ice caps, and causing portions of Greenland and the Antarctic ice sheets to melt. The IPCC estimates that the global average sea level will rise between 0.6 and 2 feet in the next century (as discussed in this post). This would cause: huge populations to be at risk as a lot of the world’s population lives on or near coasts, land loss, increased vulnerability of coastal areas to flooding during storms, disrupting water supply through “saltwater intrusion,” etc. (as this U.S. government site highlights and as you can see in this photo collection).
  • Water everywhere but not always when it is needed, in quantities that can be used, and in places that need it. Heavy precipitation events are more likely as a result of global warming which can cause severe flooding. Snow cover area is projected to contract as are a number of glaciers (as you can see in this photo collection) around the world which is a major concern as many population centers of the world depend on melting snow and glaciers for their freshwater, supply of water for agriculture, and electricity from hydropower (e.g., billions of people in Asia depend at least partially on Himalayan meltwater). And as I recently discussed Amazon rainforest is still very susceptible to dieback due to climate change.
  • Agriculture production? Water is critical for agriculture production, so any change in the pattern of rainfall (e.g., later wet seasons, heavier rainfall, droughts, etc.) can have a significant impact on ability of the world (and key countries) to feed humans. Global warming’s impact on agriculture varies by region but could have serious impacts in a number of regions (as the IPCC highlights), including in the U.S. (where the predicted damage is estimated to be $950 billion by 2100).       

So if any of these potential impacts on water resources from global warming are of concern to you, then Water Day (or any day for that matter) is a good day to take some key steps to help avoid these stresses on water, including:

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