Long-term average temperatures in the Navajo Nation have been increasing, and future projections strongly suggest that temperatures will continue to rise. This will stress already vulnerable water sources, decreasing both the amount of water available and the quality of what water remains. Our solutions aim to increase water availability and water quality to offset these effects.
Drought
According to a 2013 climate change report published by the U.S. Department of the Interior Indian Affairs, annual average temperatures in Southwestern regions of the US have increased by 1.6°F±0.5°F between 1901 and 2010 (Garfin et al, 2013). In the next century, global temperatures are projected to rise between 2°F and 9°F depending on emission levels (NASA).
Even with a 1.6°F global temperature rise, the Navajo nation is already experiencing drought. The nation has been experiencing long-term drought since 1994, although the region experienced more severe droughts in the 17th-19th century. More intense, more frequent droughts are expected to hit the region in the next century (Crimmins, 2013).
Fig 1: Global temperature trends, NASA Earth Observatory
Decline in Water Quality
Water quality is expected to decline with warming temperatures due to higher intensity storms and flooding that may cause higher pollutant loadings in surface water. The presence of pollutants could potentially increase the frequency of waterborne diseases in drinking water and surface water reservoirs (Nania and Cozzetto, et al, 2014).
Increasing water needs, if improperly managed, will lead to aquifer overdraft, a condition in which water is taken from the ground at a faster rate than it can be recharged, effectively depleting the source. Depletion of these sources will clearly lead to less water availability as well as an increased concentration of salinity and contaminants such as heavy metals.
Decline in Crop Yields
The combined factors described above could lead to declining crop yields. As temperatures continue to increase, they may go beyond the optimal temperature required to grow certain plants and thus lead to decreasing crop yields. Increasing temperatures could also lengthen the period of the growing season which would increase biomass production by plants.
Climate change may have negative effects on pollinator activity, especially the honey bee – an insect that ensures the fertilization of the ovules in flowers by bringing pollen grains. Pest survival rates and population might also increase due to the change in weather conditions – a phenomenon which further depletes crop yields.
Increasing carbon dioxide concentrations in the atmosphere may cause similar issues
C3 and C4 plants
Photosynthesis relies on an enzyme called Rubisco, which catalyzes carbon reduction, which is vital in fixing the carbon from CO2 into sugars (Modes of Photosynthesis). There are several variants of ways to use this enzyme, the two most relevant to our mission being C3 and C4 photosynthesis.
Rate of photosynthesis in C3 and C4 plants as CO2 concentrations increase
With the increase in atmospheric CO2 concentration, C3 plants are becoming more competitive. There is now an increase in the photosynthetic rates of C3 plants (the most common pathway, used by 95% of plant species including weeds), making C4 plants less competitive. Because many crops, most importantly corn are C4 plants, there is a trend toward crowding out of C4 plants by C3 weeds, affecting agriculture by decreasing yield and increasing the need for weed removal. Additionally, higher CO2 concentrations reduce the protein concentration of C4 plants, which do not fix nitrogen (Nania and Cozzetto, et al, 2014).
Depletion of Water Resources
Early snowmelt and less precipitation may lead to less runoff in late spring and summer. This will decrease snowmelt irrigation and as droughts continue to occur, increased reliance on groundwater pumping can deplete groundwater sources. According to the Nevada Division of Water Resources (NDWR), “the vulnerability of Navajo farmers to drought depends in part on whether or not they have access to irrigation water and, if they do, the source and priority of the irrigation water. Thus, water rights issues that face the Navajo Nation will have a major impact on the extent that water issues factor into agricultural needs” (NDWR, 2011).
Shortages are shared with San Juan River, so the Navajo Indian Irrigation Project (NIIP), which is an irrigation program that provides water to large swaths of agricultural land on the reservation may have fewer water provisions during shortages.
Damage to Infrastructure
Rising temperatures may also damage infrastructure important for the transport of water for both household and agricultural use. Thermal expansion also increases the softening of pavements, widens the size of potholes and causes stress on bridge joints (Nania and Cozzetto, et al, 2014). It is worth noting that 30% of Navajo households are not served by public water systems, and thus haul water from either potable watering points maintained by the Navajo Tribal Utility Authority (NTUA) or from non-potable sources such as private wells and spring sources (Crimmins, 2013). Thus, infrastructural damage may negatively impact the ability of people to obtain water.