Water: Too much, too little


Climate change may accentuate seasonal differences in moisture availability

Climate change will reduce water availability during dry seasons and increase it during wet seasons around the globe, new research suggests. It also finds there will be large regional variations in water-related impacts. Some areas may see an increase in both droughts and floods by the later part of the 21st century.

“Climate models have been saying for quite a while now that wet regions would get wetter and dry regions would get drier,” said NCAR scientist David Lawrence, who participated in the study. “This research provides a more nuanced view, because we find that there are lots of places around the world where overall precipitation is projected to go up, but at the same time the dry season would still get drier.”

To reconcile previous research suggesting that climate change will bring both increased precipitation and increased drought, researchers developed a new metric for measuring monthly water fluctuations. The Available Water (AW) index accounts for seasonal changes in both precipitation and evapotranspiration (evaporation from water bodies as well as water put into the air by plants). AW allows for interseasonal comparisons that are unavailable from other indices, such as the Palmer Drought Severity Index or the Standardized Precipitation Index.

“Evapotranspiration becomes increasingly important in climate projections because global warming affects humidity much more than precipitation,” said NCAR visiting scientist Sanjiv Kumar, the lead author on an article recently published in Earth’s Future describing the research. Kumar participated in the research as a multi-institutional post-doctoral fellow at NCAR and COLA (the Center for Ocean-Land-Atmosphere Studies).

The researchers calculated AW for global regions using results from 20 climate models from phase 5 of the Coupled Model Intercomparison Project (CMIP5), which simulated 20th-century climate and projected future climate conditions.

When they compared the historical available water from 1961–1990 with model projections of the world in 2070–2099, 46 percent of the global land areas showed a significant decrease in dry season AW, whereas only 15 percent had significantly more water available in the dry season. Northern North America, central Europe, Russia, parts of China and India, and east central Africa were among the areas the researchers found would see significantly drier dry seasons.

Similarly, 60 percent of the global land area showed a significant increase in wet season AW, while 10 percent had significant decreases, including Mexico, southwestern Africa, the Mediterranean region, and parts of South America. The researchers did not find significant changes in wet season AW for the Amazon region and Australia.

“It’s important to note that we have only considered biophysical constraints on water availability,” Kumar said. “Growing human populations will increase water demands to meet their rising agricultural, industrial, and domestic water needs, putting added stress on water resources.”

Kumar, S., D. M. Lawrence, P. A. Dirmeyer, and J. Sheffield (2013), Less reliable water availability in the 21st century climate projectionsEarth’s Future, doi:10.1002/2013EF000159.


5 Responses to Water: Too much, too little

  1. Mathew Harris (u14171181) May 1, 2014 at 9:17 am #

    The question that I keep asking myself when I read this article and articles of this kind are is climate change real? Is it as bad as people make it out to be? and if it isn’t real who is to blame? Reading articles about climate change always sets off alarm bells in my head and it is always a good idea to get both sides of the story before a conclusion is drawn. Articles such as this http://www.globalresearch.ca/copenhagen-and-global-warming-ten-facts-and-ten-myths-on-climate-change/16467 give good insight into both the facts and the myths of climate change. Although changing weather patterns are of major concern an question that always springs to mind is what can we as humans do, or is it just the natural cycle of the earth, going from ice age to ice age. Thus I think that it is important to take both sides of the story into consideration, do research from both points of view and then make a calculated assumption when it comes to topics such as climate change as so often in life we only hear one side of the story and think that, that is the truth.

  2. Saffiya 14056102 April 25, 2014 at 8:35 am #

    Both of you provide excellent points: while mankind definitely has proved its will to adapt and manipulate its circumstances to suite itself, it would indeed be better to not find ourselves in such precarious circumstances in the first place.
    The main problem is that we create the circumstances that require manipulation through our manipulation of our previously self-created circumstances. Climate change is occurring and spurred on through our abuse of natural resources, which are being depleted because of trying to meet the demands of our ever growing population and make our lives easier. There really doesn’t seem to be any end to this circle that we’ve placed ourselves in.
    Conservation has always been a major issue. The problem is that people cant be forced to conserve water. Everyone knows the importance but not everyone obliges. Like the famous saying: You can take a donkey to the water but you can’t make it drink.
    In this case: you can teach people the importance of conserving water but it doesn’t mean they will.
    However, it would be wrong of me to assume that most people don’t conserve water so maybe that isn’t the biggest issue. Which once again leaves us only with this: human interference in nature is worsening our climate situation.

  3. Michaela April 24, 2014 at 12:04 pm #

    Water is one of the most important resources in the world. Without it there would be no life on planet earth as nothing can survive without water, and therefore it is classified as a crucial resource.
    Unfortunately, weather patterns are changing and due to global warming, water is being affected. People may be negatively affected by this because if the drier areas get drier they will experience more droughts. And during a rought it is very difficult to survive as food production minimises due to not having enough water. Saying this, the other negative effect will be experienced by the wet areas that are going to get wetter. Although a drought is bad, a flood can be just as bad. During floods, crops can be washed away, there can be mud slides and people can die, and houses and cars can also be washed away.
    It is too late to fix the water issue now, but what one can do is prepare for it as best as one can. Farmers can participate in contour ploughing and terracing in order to prevent crops being washed away during floods. Houses can be built on stalks in order to prevent them from being flooded. To be sustainable during droughts, people can store water before the drought occurs, such as in dams. Food can also be kept for when the drought occurs, so that people will still have access to food.
    Although droughts and floods are not always welcome in peoples lives as their effects can be devastating, the only way to deal with them is to prepare for them. The population on planet earth increases everday which means the demand for water increases everyday.
    People must use water as sufficientky as possible, and not waste it at all. Everyone can participate in improving water consumption.

    Michaela Fyfe 14019753

  4. Bokang 13324102 April 21, 2014 at 5:30 am #

    I do agree with you Lucky 24041344 about us humans in finding a way to prevent the possibility of water shortage. As Ester Boserup have theorised “The power of ingenuity would always outmatch that of demand” so whatever we have placed our under, come the need to survive we will surely find the possibility to conquer whatever the difficulties. However this does not mean we shouldn’t try to conserve water just because we think we can deal with whatever the world presents to us. After all it is always wise to prevent rather than to cure. We should by all means try to think of the future generations upon misung water. This because I believe then purified water does not provide as much life essentials to our health as compared to natural fresh water.

  5. Lucky 24041344 April 21, 2014 at 4:43 am #

    That climate change would bring about intense weather patterns is an undeniable fact. What is important is how humankind adapts to this inevitable consequence of our meddling in the natural environment by introducing the greenhouse gases to our planet.Humans since time memorial have proven to have this ability to adapt to changing climatic conditions.Human ingenuity will prevail and come up with appropriate technologies to take advantage of these changing climatic conditions for the benefit of mankind.An example would be the production of seedling which would require less water for survival, strains of drought resistant crops, e.t.c. For water conservation, appropriate technologies are already available for water storage,purifying e.t.c, It is important that extensive educational campaigns are undertaken or sponsored by the United Nations on the ways in which water usage/wastage could be minimized since climate change transcends boundaries.
    While it is important that strong alarm is sounded on the potential devastating effects of climate change, it is always wiser to look at the ways in which these changes might have positive benefits to the environment and ecosystems, for example the encroachment of grasslands to previously drier areas bringing in with it diverse fauna which can be exploited for Eco-tourism. When life gives you lemons, you can always make lemon juice!

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