Climate Change as The One of The Biggest Threats to Humanity Now

One of or maybe even the biggest threat to humanity now, but even more in the future, is climate change. Yet, not only we humans are endangered by climate change, but also all other species will have to live with the differences in temperature and precipitation that climate change will inevitably bring. Today I would like to have a closer look at the impact of climate change on hot deserts. First of all, however, I will inform you about the current state of the hot desert biome: hot deserts can be found between 15° and 35° latitude in both the Northern and the Southern hemisphere. The largest desert is the Sahara desert by far, followed by the Gobi desert, which is four times smaller than the Sahara. The climate in the hot desert biome can be classified as a hot desert climate (BWh) according to Koeppen, meaning that it is arid all year resulting in less than 250mm of precipitation annually.

Additionally, the average annual temperature exceeds 18° C. Hot deserts have a seasonal difference in temperature, but the daily temperature amplitude is greater, resulting in a diurnal climate. Hot deserts generally have no clear soil, nevertheless, all soils found in this biome have little organic or moisture content and few nutrients. These soils can be divided into two zones, with the upper zone being the zone of aeration and the lower zone being the zone of saturation. The zone of aeration consists of a soil water layer, followed by sand and a layer of fringe water. The zone of saturation only consists of one layer, which is composed of sand. Hot deserts have two main types of vegetation. The first one is tropical scrub which is found on the margin of hot deserts. Tropical scrub plants are acacias, cacti and other succulents, tuberous-rooted plants and herbaceous plants with the latter of the listed only growing when there is sufficient rainfall. The second type of vegetation is called temperate scrub and it can be found on the margins of temperate deserts.

An example of a vegetation that can be classified as the temperate scrub is Malee in Australia. Malee consists of dense dwarf eucalyptus. All the plants mentioned above have adjusted to the extreme changes in temperature and the long droughts in multiple ways. First, these plants grow very long roots, enabling them to access water in the deeper parts of the soil. Next, they have a minimal amount of leaves to minimize transpiration and finally succulents store water, allowing some cacti to survive without water for up to two years! Although hot deserts seem inhospitable at first, they are in fact home to many different animals, which are mostly reptiles and arthropods, nonetheless, mammals like camels and fennec foxes are also part of the fauna of hot deserts.

As for plants, the animals in hot deserts have also adapted to the climate in various ways. One way of adapting to the rigorous conditions is a nocturnal activity to evade the intense heat at daytime. Other ways of adapting are burrowing by day, aestivation, seasonal migration and special anatomic changes to reduce body heat. After hearing this information, you will probably think that climate change will not affect hot deserts as much, because it is already very hot in this biome and because most deserts are far inland[13], which suggests that both global warming and sea level rise will not bring a huge change. On the one hand it may be true that global warming will damage other ecosystems even more, on the other hand, however, this does not mean that we should not be concerned about the future of the hot desert biome. The truth is that “Life is always living on the edge in these places,” as plant scientist Andrew Young states in an article for “the Atlantic”. Just one or two degrees Celsius more and a few millimeters of precipitation less can have a huge impact. In reality, however, a UNEP investigation found out that, the temperatures in hot deserts are predicted to rise by between 1°C and 7°C (!) in the next 75-100 years.

Most species are already moving to habitats with higher elevation, due to the fact that these habitats generally have cooler temperatures and more rainfall. This development will continue over the next decades but it cannot continue forever because places with high elevation are limited, especially in the desert, so this development will lead to an enormous competition for living space. The second big problem for the hot desert biome is its loss of nitrogen, as more of the soil`s nitrogen evaporates than before. This happens because of the constantly rising temperatures and it is alarming for two reasons: first of all, nitrogen is very important for the growth of plants, so a loss of nitrogen results in a loss of soil fertility. The second problem is that nitrogen is a potent greenhouse gas thus the greenhouse effect is enhanced. As for the migration of flora and fauna, this threat to the hot desert biome will also increase, but it will increase much quicker as it is a doom loop: more heat means more evaporation of nitrogen, leads to an enhanced greenhouse effect and therefore to higher temperatures, resulting in more evaporation of nitrogen. Contrary to popular belief, some deserts will actually experience an increase in rainfall in the near future according to an article by Abc News.

Although this might sound like it is good news first, higher rainfall does not automatically mean that the wildlife will have more water to live with. This is due to an increase in evaporation because of the higher temperatures, meaning that the precipitation will evaporate so quickly that neither plants nor animals are able to benefit from it. A report by the United Nations Environment Programme states that deserts fed by glacial meltwater have even more trouble than other hot deserts because all rivers in these deserts will run dry when their glaciers have fully melted due to the global temperature increase.

The results of this growing lack of water will be an increase in salinization, which could go so far in the future, that the soil is too acid for plants to grow. In conclusion, climate change will have a huge, negative, impact on hot deserts, because:

• More parts of deserts will become inhospitable for both plants and animals.
• There will be an even bigger shortage of water than now.
•  The increased temperatures will result in a nitrogen loss, eventually enhancing climate change even further.
• Wildlife will not benefit from the predicted increase in precipitation.

Works Cited

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4. Chaffin, A. (2019). The impact of climate change on desert ecosystems. The Nature Conservancy. https://www.nature.org/en-us/about-us/where-we-work/united-states/arizona/stories-in-arizona/the-impact-of-climate-change-on-desert-ecosystems/
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