Desertification never describes the presence of a natural desert. It is the process of making an area look like a desert, having its characteristics while it should not. It is caused by acid rain, deforestation and the setting of fires. Also, because of overgrazing when plants start to grow again after a fire. Most of the times there is a combination of some or of all those factors, which are all connected with human activities.

During desertification, many animal species die or lose their natural habitat. Plants disappear and face extinction. Valuable sources are lost, as fewer plants produce less oxygen. Thus, it is connected with global warming and climate change. Moreover, desertification often results in floods, as there are no trees to keep the soil steady with their roots. Floods harm both natural ecosystems and human properties, sometimes including death tolls.

Consequently, desertification is a very serious problem and should be solved. Laws ought to be passed in order to decrease the amount of trees cut down and of wooden products one can buy. Carbon dioxide emissions, by which acid rain is caused, must be reduced to prevent soil erosion. Authorities have to protect forests, by organising fire brigades and immediate reforestations. Animals that graze should be kept away from burnt areas where plants have just started to grow again.

Tropical rainforests have the largest biodiversity of all ecosystems on Earth. The soil is rather poor, but it sustains a great variety of plants. It is estimated that 65% of the known plant species are found in rainforests.

During the past three decades, rainforests have been decreasing in size for various reasons, though all of them are connected with human activities. Human populations living near rainforests had the impression that the soil must have been really fertile, as it could sustain such a variety of plants. So, when human started to need more fields for cultivation, they choose rainforests’ earth, and thus they set big fires to get rid of big trees and to obtain space. By the time it was understood that the soil wasn’t suitable for agriculture, many square kilometres of rainforests had already gone.

Apart from agricultural reasons, the rainforests are cut down in order to provide wood. Most of the paper, toilet paper or furniture manufactured nowadays is based on wood from tropical rainforests. Deforestation also takes place in order to extend cities and build roads. Increasing human needs, due to overpopulation, lead to mass deforestations all over the globe.

The pace with which it’s been done is so high, that every year an area of the size of half Greece is lost. 50 years ago rainforests would cover double the area they do today. Thousands of species, whether they are animals or plants become extinct and even more face extinction.

Humanity also depends on rainforests. A variety of building materials, food (bananas, vanilla, coffee), and even caoutchouk come from rainforests. Medical science, from the ancient times till today, also depends on substances from plants that grow there.

Quinine, a range of medicine against pain and stress are only some examples of medicine that require substances from rainforests in order to be manufactured. Nowadays, 20% of the medicines found in pharmacies are produced by the use of plants from rainforests.

Researchers have studied less than the 2% of the 100,000 species of plants that grow in rainforests, and are sure that most of them can be really useful in medicine or other fields. Though most of them point out that ”potentials for the future are endless, as long as scientists and pharmacologists reach the rainforests before chainsaws…”

And let us not forget that rainforests produce oxygen. Tropical rainforests produce 40% of Earth’s oxygen. Cutting them down means that oxygen levels decrease, while less CO2 is absorbed by plants and thus increases in the atmosphere, causing the green-house effect. Humanity has to re-examine its needs and reduce them, so that less quantities of substances from rainforests are used. We have to set limits on our activities, otherwise those huge forests will one day belong to history.

According to a recent published report, by Benjamin Halpern and his colleagues at UCSB’s National Center for Ecological Analysis and Synthesis, over 40% of the world’s oceans are heavily impacted by anthropogenic activities. Only a few, “if any”, areas are unaffected.

The report have taken four years to compile and resulted in 17 models of the earth. Each of the different models shows the damage caused by human activities such as pollution and fishing. The different models have then been merged into one showing the global effect (see image).

Benjamin Halpern explains, on the UCSB website, the process he and his colleagues followed to make the composite map:

“1. We gathered or created maps (with global coverage) of all types of human activities that directly or indirectly have an impact on the ecological communities in the ocean’s ecosystems. In total, we used maps for 17 different activities in categories like fishing, climate change, and pollution. We also gathered maps for 14 distinct marine ecosystems and modeled the distribution of 6 others.

2. To estimate the ecological consequences of these activities, we created an approach to quantify the vulnerability of different marine ecosystems (e.g., mangroves, coral reefs, or seamounts) to each of these activities, published in Conservation Biology, October 2007. For example, fertilizer runoff has been shown to have a large effect on coral reefs but a much smaller one on kelp forests.

3. We then created the cumulative impact map by overlaying the 17 threat maps onto the ecosystems, and using the vulnerability scores to translate the threats into a metric of ecological impact.

4. Finally, using global estimates of the condition of marine ecosystems from previous studies, we were able to ground-truth their impact scores.”