Today I have the great honor to present a topic I find greatly important and necessary to bring into discussion in front of you all. I will be talking about the massive effect climate change will have on our environment, especially putting my focus on the hot desert biome. Bill Nye captures the reason for my presence at this event today with this quote: “Climate change is happening, humans are causing it, and I think this is perhaps the most serious environmental issue facing us.” Before we can start looking at the consequences facing the hot deserts however, we must firstly understand the current situation and which factors this biome comprises. Most of the world’s hot deserts lie between 20° and 35° north and south of the equator, whereas the main temperate deserts are found in the middle latitudes. To begin with I will outline the climate of these areas.
According to the Köppen climate classification, the hot desert climate is mostly either a BWh or a BWk climate, in other words a hot desert climate or a cold desert climate. The hot deserts are located close to the Tropics of Cancer and Capricorn. Because of this the angles of insolation are very high throughout the year, hence the average temperatures during the year remaining high, namely between 30 and 40 degrees celsius. This, as well as the large temperature amplitude, ranging from 0 degrees to 50 degrees celsius, lead to the correct assumption that this is a highly diurnal climate. There is very low and unreliable rainfall that is under 250mm per year on average and furthermore because desert air is dry there is little moisture to hold onto the heat of the day. Hot deserts have very hot summers, whereas Cold deserts can have hot summers as well, but the winters are usually very cold. They are usually at high altitudes and can be drier than hot deserts.Equally as important in the composition of this biome is the soil.
Most desert soils are called Aridisols (dry soil). However, in really dry regions of the Sahara and Australian outback, the soil orders are called Entisols. Entisols are ne w soils, like sand dunes, which are too dry for any major soil horizon development. They also occur in floodplains after a spring flood, which is why they can occur in the desert.
The desert may look dry, but it still contains a lot of living organisms. This includes a living, biological crust, which is formed by algae, moss, and lichens in a group. Aridisols are very fertile, however, often don’t have the rainfall to sustain life. The permanent vegetation growing on desert soils is very well adapted to living without moisture for long periods of time.
The plants have adapted to their surroundings by e.g. growing fewer leaves to reduce transpiration as well as growing long, water-seeking roots and developing the ability to store water. We differentiate between two main types of vegetation found in deserts: Tropical scrub, namely acaia, cacti, succulents and many more can be found on the margins of hot deserts and Temperate scrub, for instance maquis, chaparral and garrigue can be found on the margins of temperate deserts. Finally, the last important factor worth mentioning are the animals and organisms.
These have adapted to the difficult living conditions of the arid hot desert biome in many aspects over time. The most universal behavioral adaptation used by small mammals, reptiles, and insects to deal with high temperatures is staying in the shade of plants or rocks, thus avoiding the direct rays of the Sun. Other adaptational characteristics include nocturnal activity to avoid the heat of the day, burrowing by day, panting and developed big ears to reduce body heat, seasonal migration and long-term aestivation that ends only when triggered by moisture and temperature conditions. To conclude my presentation I will move on to the the crucial issue at hand: the severe effects climate change will have on the hot deserts.
Above all, global warming will be the cause of rapidly rising temperatures, and therefore the living conditions of plants and animals will be endangered since they’ve adapted to life in such an arid climate over thousands of years. Global warming will not only threaten the quality of life in hot deserts, but also supposedly increase the amount of deserts, which already cover a quarter of Earth. The increase of temperature will most likely also lead to increased evapotranspiration and consequently drying up of water holes, as well as an increasing number of wildfires. Salt levels in the ground caused by irrigation used for agriculture might also cause a loss of plant species. In conclusion, the gist of this problem is basically that global warming will disrupt the balance of our hot deserts, which means, as professor Andrew Warren said, “We risk losing not only astounding landscapes and ancient cultures, but also some amazing wild species, which, may hold some keys to our survival.” Thank you for your attention.