Posted by: shipbright | October 26, 2009

Climate Change and freshwater Part 1…hydrologic cycle turbocharged

As you know from a previous post, the hydrologic cycle is the engine of the world’s freshwater.  It creates freshwater and moves it around the globe, but it doesn’t distribute it equally nor does it deliver the water to where we humans are in the quantities we need.

The effect on the hydrologic cycle from climate change is the introduction of more “energy” into the system because of warmer temperatures which leads to more moisture being put into the cycle through evaporation and transpiration.  Climate change “turbo-charges” the hydrologic cycle….on the face of it that seems like that would be a good thing.  The world’s freshwater factory is creating more freshwater for our rapidly expanding world population!  Unfortunately it’s not as simple as that…

With all that new energy in the hydrologic cycle we also “turbocharge” our precipitation events with the wet get wetter and the dry get drier…Here’s a video from the US National Oceanographic and Atmospheric Administration [NOAA] that explains this very well:

The United Nations Intergovernmental Panel on Climate Change [IPCC] and the United States Environmental Protection Agency [EPA] are excellent resources on the issue of climate change.  The IPCC is a global consortium of the worlds leading scientists and experts on climate change.  I’ve posted links on the right hand column of this blog for future reference.

Here is some information on climate change and freshwater from the EPA:

“Water Resources: All regions of the world show an overall net negative impact of climate change on water resources and freshwater ecosystems. Areas in which runoff is projected to decline are likely to face a reduction in the value of the services provided by water resources. The beneficial impacts of increased annual runoff in other areas are likely to be tempered in some areas by negative effects of increased precipitation variability and seasonal runoff shifts on water supply, water quality and flood risks (IPCC, 2007).

The future effects of climate change on water resources in the U.S. and other parts of the world will depend on trends in both climatic and non-climatic factors. Evaluating these impacts is challenging because water availability, quality and streamflow are sensitive to changes in temperature and precipitation. Other important factors include increased demand for water caused by population growth, changes in the economy, development of new technologies, changes in watershed characteristics and water management decisions.

torrential rainWater Availability: An increase in net solar radiation or temperature will effectively speed up the processes within [the hydrologic] cycle (evaporation, condensation, precipitation, etc).  Due to complex interactions of changes in the hydrologic cycle with global circulation patterns and local weather patterns, an increase in energy in the hydrologic cycle does not necessarily translate into an increase in precipitation in all geographic regions.  It is difficult to predict future changes in regional precipitation patterns. Predicting regional changes in streamflow and groundwater recharge due to climate change also remains challenging, particularly because of the uncertainty in regional projections of how precipitation may change (IPCC, 2007).

glacierMeltingChanges in temperature, precipitation patterns and snowmelt can have impacts on water availability. Temperature is predicted to rise in most areas, but is generally expected to increase more in inland areas and at higher latitudes. Higher temperatures will increase loss of water through evaporation. The net impact on water supplies will depend on changes in precipitation (including changes in the total amount, form, and seasonal timing of precipitation). Generally speaking, in areas where precipitation increases sufficiently, net water supplies may not be affected or they may even increase. In other areas where precipitation remains the same or decreases, net water supplies would decrease. Where water supplies decrease, there is also likely to be an increase in demand, which could be particularly significant for agriculture (the largest consumer of water) and also for municipal, industrial and other uses.

Increases in temperature can affect the amount and duration of snow cover which, in turn, can affect timing of streamflow. Glaciers are expected to continue retreating, and many small glaciers may disappear entirely. Peak streamflow may move from late spring to early spring/late winter in those areas where snowpack is important in determining water availability. Changes in streamflow have important implications for water and flood management, irrigation, and planning. If supplies are reduced, off-stream users of water such as irrigated agriculture and in-stream users such as hydropower, fisheries, recreation and navigation, could be most directly affected (IPCC, 2007)….

…Flood magnitudes and frequencies will very likely increase in most regions — mainly a result of increased precipitation intensity and variability — and increasing temperatures are expected to intensify the climate’s hydrologic cycle and melt snowpacks more rapidly (IPCC, 2007). Flooding can affect water quality, as large volumes of water can transport contaminants into water bodies and also overload storm and wastewater systems.

Higher temperatures, particularly in the summer, earlier snowmelt, and potential decreases in summer precipitation could increase risk of drought. The frequency and intensity of floods and droughts could increase, even in the same areas.


Sea level rise may also affect freshwater quality by increasing the salinity of coastal rivers and bays and causing saltwater intrusion, movement of saline water into fresh ground water resources in coastal regions”

Commentary: The more one knows about climate change, even with a skeptical eye, the more informed our civil discourse on what action[s] we should be taking becomes.  We may debate the severity and extent of change it may have in all of our lives but it demands our attention and our action.  As you read in the previous post, former skeptics and very conservative people are acknowledging the science is becoming more and more compelling.

I was a member and former Chairman of the United States Federal Invasive Species Advisory Committee [ISAC] under the Bush Administration.  We all know that the Bush Administration fought the notion of climate change for most of the two terms [8 years] Bush was in office.  We saw this firsthand on the ISAC and the parade of political appointees who poo-poo’ed the notion of climate change, and if there was climate change then Man wasn’t responsible, and if Man was responsible then we had no obligation to do anything about it.   I can also testify firsthand that in the last 18 months of the Administration there was a turnaround in attitude towards climate change.  It was quiet and without fanfare, perhaps to “save face”, but it was real.  Too late and too little for any meaningful policy changes but Executive Branch professionals were able to voice their concerns without fear of political backlash.


The mounting scientific evidence was convincing and many die-hard skeptics, many of whom had a political agenda to protect, did what any reasonable person does when faced with new information–they changed their mind.  Some still fight the growing global evidence…there are some people out there who still think the world is flat, there was no holocaust, and that the moon landing was done in a movie set.  In the words of my kids:  whatever… [usually said to me with a LOT more attitude…].

We humans are reluctant to accept anything new without questioning it.  We’re a skeptical bunch for the most part and that’s a healthy survival trait that has been ingrained in us from the ages [such as being skeptical that one can telepathically communicate with a wild grizzly bear is healthy skepticism].  But survival is about adaptation to a constantly changing environment and we are in a state of constant change in this world and in our own personal lives.  As new information becomes apparent to us we evolve our thinking, our attitudes and our behavior…those that do survive, those that don’t do not.

We must evolve our thinking on freshwater because:

no water…no civility…no civilization

In the next couple of posts we’ll look at retreating sea ice, melting glaciers, thermal expansion of the oceans and rising sea levels and what that means for freshwater…especially for small island nations…



  1. that photo is so cool!!!!!!!!!!!!!!!!!!!!!!

  2. Hey dad! Everyone seems to think that the blog is really really cool!

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