What's the big deal?

Even though some people are still in denial, I think it is almost safe to say that Global Warming and Climate Change are accepted by the majority nowadays. I remember the cover of Bloomberg Businessweek after Hurricane Sandy hit New York City in 2012. The cover showed a flooded street with a title of “IT’S GLOBAL WARMING, STUPID”. As an Environmental Engineering student at that time, I really liked the blunt title -still do. You can have a look at it HERE.

Figure 1-Bloomberg magazine cover after Hurricane Sandy

When it comes to Climate Change, Intergovernmental Panel on Climate Change (IPCC) is one of the well-known international bodies that publishes different reports, assessments and technical papers that are widely used as references.

In the IPCC Technical Paper VI - June 2008 , the observed changes of climate and how they are linked to water are categorized into precipitation, snow and land ice, sea level, evapotranspiration, soil moisture, runoff and river discharge, and patterns of large-scale variability. In this post we are going to look into some of the named categories. 

In order to better understand how one thing can influence another thing when it comes to water cycle, I made the below diagram simplifying and summarizing some of the papers I read - sometimes visualization aid is quite useful (maybe a mini model?). Now let’s go over the diagram.

Global warming and rising temperature of the oceans have acted as a driving force to change our climate. Hydrological cycle is closely linked to atmospheric changes of temperature as well as climatic changes. Hence we see GW and CC as the main change initiatives in the diagram. However, other contributing factors to water availability and changes of water cycle should not be overlooked. Other non-climatic factors such as  population growth, land-use change- affecting the local water cycle, changes in population location(e.g. people moving to urban areas and hence changes to patterns of water use ),  water pollution (Grafton and Hussey,2011), and changing lifestyles (Ludwig, Slobbe, and Cofino, 2013) also have an influence on water resources. These factors are shown by colored circles in the diagram.

Looking at the diagram we see that GW has caused increased evaporation which means more atmospheric water vapor, hence more cloud formation and more precipitation for some regions. Evaporation and changes in precipitation patterns can also bring droughts for some areas. 

Alteration in precipitation pattern has an impact on river flow regime and river discharge , thus the surface water availability gets affected as well. These changes differ for each region . For instance for regions in higher latitudes there has been an increase in river flow while some parts of west Africa , southern Europe, and southern America have been experiencing a decrease (Babel,Agarwal,and Shinde, 2014). And that does not end there, changes in river flow regime can change seasonality and cause more extreme conditions. For example in Asia , while the maximum monthly flow for the Mekong is expected to increase by 35%-41%. For the years 2010-2038, the minimum monthly flows are projected to decrease by 17%-24% in the basin. This suggests that there is a risk of flooding during wet season and possibility of water shortage during dry season (IPCC,2008).

Ground water is an important water resource that has served humans for centuries. This awesome resource of water gets affected by GW and CC. Factors such as increased evapotranspiration and reduced rainfall will reduce the aquifer recharge.  On the other hand,   increased flooding results in increased aquifer recharge. Another important factor regarding aquifer recharge is how the timing of the recharge is influenced by the volume of snow-melt and distribution of rainfall(Babel,Agarwal,and Shinde, 2014). Lastly, lets talk about sea level rise- a serious risk for both humanity and ecosystems. The fact that 60% of the world’s 39 metropolises with a population of over 5 million are located within 100 km of the coastal region , including 12 of the world’s 16 cities with populations greater than 10 million (IPCC,2007) , makes it even scarier.

Even from the simple diagram in this post ,it can be seen how far the impacts of Climate Change on water can go and how intertwined the system is. And hopefully we now know why it is a big deal. In the coming posts we try to investigate the challenges of managing water resources considering the mechanisms discussed today.

Sometimes we are told not to make a big deal out of something, well today is your lucky day cause you are allowed to make a big deal out of this as much as you like! or better said you SHOULD make a big deal out of this...

So long,