More details can be found in the following report:

Potential impacts of climate change on river water quality, Science Report – SC070043/SR1, © Environment Agency – May 2008

Some highlights in the mentioned report:

There is considerable uncertainty associated with a cascade of issues. For example, there is uncertainty over the quantification of the driving global climate processes, over the procedures for downscaling from global to local riverine situations, over the processes controlling behavior in freshwater systems and over the complex interactions between hydrology, chemistry and biology.

- Water quality will be affected by changes in flow regime.

- Lower minimum flows imply less volume for dilution and hence higher concentrations downstream of point discharges.

- Enhanced growth of algal blooms in rivers and reservoirs could affect levels of dissolved oxygen and the costs of treating water for potable supply.

- Increased storm events, especially in summer, could cause more frequent incidence of combined sewer overflows, discharging highly polluted waters into receiving water bodies. The potential impacts on urban water quality will be largely driven by these changes in short duration rainfall intensity overwhelming drainage systems, as well as rising sea levels affecting combined sewerage outfalls.

- The most immediate reaction to climate change is expected to be an increase in river and lake water temperatures.

- More intense rainfall and flooding could result in increased suspended solids, sediment yields and associated contaminant metal fluxes.

- Nutrient loads are expected to increase.

- In shallow lakes, oxygen levels may decline and cyanobacteria blooms may become more extensive.

- In the UK, there has been relatively little research on toxins in streams, lakes and sediments, as the problems are thought to be limited. However, climate change may alter this perception.

Golam you have put a very complex question. The simplest answer is yes there will be affect on global water quality due to climate change. On marine environment it is sea surface temperature rise, ocean acidification, rise in mean sea level. higher salinities etc. On terrestrial environment excessive evaporation due to increasing temperature, melting of glaciers, drop in groundwater level, increase in TDS, increase in cropwater requirement due to higher ET and ET0. It can be a very long exhaustive discussion. Let me know if you are llooking at some specific issue, I will be very happy to discuss that.

Golam, this is a very complex and interesting question indeed.

Climate change will definitely impact the water quality - regardless our work against it I think. There is an increasing demand for water, expecially for irrigation all over the world. But there is a "competition" between the sectors of agriculture (fishing, horticulture etc.) and even between food production and transportation.

The floods are rapid and it is very expensive (and sometimes impossible) to build enough reservoirs to hold back water to compensate the drought in Summers. Most of the developing countries simply can't afford it.

Besides the rivers, the lakes get even more pollution from the intensive agriculture and from the cities as well which causes algal bloom (therefore increasing fish mortality) in Summer. The decreasing fish catch is a serious problem in developing countries where fish are the main source of protein for humans.

According to my little knowledge,

Higher air/water temperatures leads to earlier snowmelt, decreases the summer precipitation, and consequently increase the risk of drought/deficit especially in river flow amount.

Lower amount of river discharge could increase the concentration of pollutant materials (while, higher flow discharges have less pollutant material due to dilution effect). In other words, the quality of water in low flow periods appears to be relatively large.

I agree with all the above and more. As with all environmental issues such as this, the impact is often made much worse by people's inability to cope and adapt. When water becomes scarce wells go deeper, water tables are overdrawn, salt water incursion takes place, and of course surface contamination from sewage and livestock during periodic floods can make all this worse.

Poverty compounds disaster.

I do agree that we should consider ocean water quality as a key indicator. Acidification is the major problem, but eutrophication and sediment load in many coastal zones is worsening... and yes these can be related to climate change (more sediment with increased aridity and more flash flooding, and more fertilizer as people try to increase yields in shorter growing seasons.

More details can be found in the following report:

Potential impacts of climate change on river water quality, Science Report – SC070043/SR1, © Environment Agency – May 2008

Some highlights in the mentioned report:

There is considerable uncertainty associated with a cascade of issues. For example, there is uncertainty over the quantification of the driving global climate processes, over the procedures for downscaling from global to local riverine situations, over the processes controlling behavior in freshwater systems and over the complex interactions between hydrology, chemistry and biology.

- Water quality will be affected by changes in flow regime.

- Lower minimum flows imply less volume for dilution and hence higher concentrations downstream of point discharges.

- Enhanced growth of algal blooms in rivers and reservoirs could affect levels of dissolved oxygen and the costs of treating water for potable supply.

- Increased storm events, especially in summer, could cause more frequent incidence of combined sewer overflows, discharging highly polluted waters into receiving water bodies. The potential impacts on urban water quality will be largely driven by these changes in short duration rainfall intensity overwhelming drainage systems, as well as rising sea levels affecting combined sewerage outfalls.

- The most immediate reaction to climate change is expected to be an increase in river and lake water temperatures.

- More intense rainfall and flooding could result in increased suspended solids, sediment yields and associated contaminant metal fluxes.

- Nutrient loads are expected to increase.

- In shallow lakes, oxygen levels may decline and cyanobacteria blooms may become more extensive.

- In the UK, there has been relatively little research on toxins in streams, lakes and sediments, as the problems are thought to be limited. However, climate change may alter this perception.

If you notice the trend is toward more pronounced weather problems.

This is the Earth's countermeasure to increased heating, by increasing the

amount of water retained in the atmosphere, and by releasing more

water to effect more cooling. Unfortunately, the release of energy is not

uniform, but occurs in more powerful storms, that occur more frequently.

If you live in the wrong place, like narrow stream valleys, you are going to

pay a higher price for the release of energy. if you live near the oceans,

you are going to get more frequent tastes of " Katrinas ".

When the oceans rise in elevation, the continents will be at a lower elevation,

and thus will be hotter at all locations and elevations.

As a species we will either adapt, or go extinct.

Thanks Michael, Atul, Raoof, David, Inga, Ronald, Saif for your valuable inputs

Summary: From your inputs, I can summarize that climate change will impact on WQ via nutrient load, algal blooms, low DO, toxins inputs, sewerage overflow, suspended solids, sediment and metal influx, ocean acidification, salinization of sweet water and groundwater. Major disasters like Katrina, USA (2005) and Floods in Pakistan (2010) may cause significant pollutant inputs including microbial pathogens, thus on WQ. It appears that in marine/coastal areas, ocean acidification, and salinization of aquifers whereas in inland areas nutrient inputs, algal blooms and chemical/toxin inputs may dominate

Hi Golam: As you summarized nicely with information provided by various learned researchers. Yes it is true that Climate change will increase the water quality problem across the globe. I would like to add that recent floods in Uttarakhand (2013) and Kashmir (2014) in India have added loads of pollutants in to major rivers, polluted and eutrophy streams. Eroded soils deposited in various dams and become the cause of devastation. Not only floods even draught areas ground water being emptied continuously causes falling water table which causes for increasing salinity also invite increase in sea water intrusion. Thanks 

Hii Golam: 

Every one know climate change is a big problem now a day. Climate change directly and indirectly affected the quality of water, as well as decrease the water level.

Thanks

Dear @Golam, we had massive floods in Serbia! In some areas, increases in runoff, flooding, or sea level rise are a concern. These effects can reduce the quality of water and can damage the infrastructure that we use to treat, transport and deliver water.

Furthermore, water-energy relation is important one, as well as impacts on ocean acidification! Many bad things happen regarding water quality!

http://www.climate.org/topics/water.html

http://www.epa.gov/climatechange/impacts-adaptation/international.html

http://water.epa.gov/scitech/climatechange/Water-Impacts-of-Climate-Change.cfm

http://water.epa.gov/scitech/climatechange/Water-Impacts-of-Climate-Change.cfm#quality

Dear Raoof,

How can decrease earlier snowmelt the summer precipitation (quantity or distribution) ? I think earlier melting cannot happen simultaneously in different continents and areas.

Dear All,

I think, it is not possible to examine climate effects alone without other disturbing influences like acceleration of population growth which is a significant pollution source. There are very carelessly managed hydrologic areas where there is petrol production. At these areas the water quality is intolerable. The climate change increases these troubles. These days many billion people cannot get the necessary quantity and quality water. According to military forecasting the water shortage may cause serious conflicts.

The global problem with water is surely primarily a question of quantity rather than quality, the main driver of this being pressure from overpopulation.  Worrying about potential climate change is a useful displacement activity so that we do not have to address the real problem.

Please see reports of the meeting "High-Level Event on Climate Change and Transboundary Cooperation in The Dniester River Basin" (UNEP, UNECE, EU) (including my report for water balance).

https://www2.unece.org/ehlm/platform/display/ClimateChange/Dniestr+meeting%2C+Kiev%2C+22-23+april+2015

This contribution belongs to this thread! 

GREENHOUSE GASES CAUSED GLACIAL RETREAT DURING LAST ICE AGE!

"Carbon dioxide levels are now significantly higher than they were at that time, as a result of the Industrial Revolution and other human activities since then. Because of that, the study confirms predictions of future glacial retreat, and that most of the world’s glaciers may disappear in the next few centuries...

"This shows that at the end of the last Ice Age, it was only the increase in carbon dioxide and other greenhouse gases that could have caused the loss of glaciers around the world at the same time,” said Peter Clark, a professor in the OSU College of Earth, Ocean and Atmospheric Sciences, and co-author on the study..."

http://myscienceacademy.org/2015/08/21/greenhouse-gases-caused-glacial-retreat-during-last-ice-age/

"This shows that at the end of the last Ice Age, it was only the increase in carbon dioxide and other greenhouse gases that could have caused the loss of glaciers around the world at the same time"

I don't see how this is relevant at all:

I am going to take an opposing view.  I suspect that more rainfall will move the pollutants from higher elevations to lower elevations, so upland areas will reamain cleaner while coastal areas will see more accumulation of pollutants, and the sediment accumulations on the Ocean floor will show the results of the removal of polutants from the land, and the added accumulation of pollutants on the Ocean floor , and in the sedimentary layers.  There will be areas, especially in Deltas where pollutants will be highly concentrated when compared to the average sedimentary areas on the Ocean floors.

There is some hope, I have been watching the trains moving East from Denver, Colorado carrying hundreds of component for the three bladed wind towers. Masts are in 3 Parts, I counted 138 blades on one train alone, and today, the giant gear boxes with electrical generators inside.

The Blades alone would imply 46 new wind turbines in the last month. 500  plus new wind turbines per year from one manufacturing facility.