The population of the human world has grown vigorously over two hundred years, and to date the world's population has reached more than seven billion. Furthermore, even suitable land that is now used for agricultural purposes is rapidly degrading. The food crisis could occur if the food we have today is not enough for the world's population. Therefore, we should not convert agricultural land for the production of biofuels as feedstocks. Because of this, people started finding new land instead of using cropland and most of them chose rainforest, peat bogs and grasslands. When these lands are converted for the plantation of raw materials, they lose their function as a global climate stabilizer, a source of raw materials and medicines or as a protector of humanity from natural disasters. Furthermore, the habitat of many plants and animals would be transformed into concentrated monocultures. For example, much of the Amazon rainforest has been converted to soy cultivation, and Malaysia's lowland rainforest has also been transformed into oil palm plantations. Land conversion has caused living species to lose their habitat and has caused damage to the ecology of microorganisms (Biofuel.org.uk, 2018). Taking the case of Malaysia and Indonesia as an example, some animal species would face an extinction crisis, for example the Malaysian tigers, the Sumatran rhinoceros and the Borneo elephant if the forest were converted into oil plantations palm. It also caused the extinction of living species. In South America, the Alagoas curassow became extinct because its vital habitat was demolished for sugarcane biofuel production in Brazil. Carbon debt Land use changes brought about by biofuel production have also unintentionally caused a carbon debt. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essayThe term carbon debt or can be defined as greenhouse debt can be defined as the amount of greenhouse gases released during the conversion of land for the production of biofuels (Fargione et al, 2008). According to some research, the conversion of land in Southeast Asia, Brazil and the United States of America into commodity plantations has produced 17 to 420 times more carbon dioxide than the annual reduction in greenhouse gases that biofuel would have released replacing fossil fuels. Initially, biofuel served as renewable energy, aiming to replace fossil fuels and mitigate climate change. But it turned out that biofuel production created more greenhouse gas emissions. Nowadays, carbon debt is accumulated until it takes more than a hundred years to repay the debt. For example, it takes about 300 years to pay off the carbon debt created when the Amazon forest is turned into a soybean field for the production of soybean biodiesel. While in Malaysia and Indonesia it will take around 400 years to repay the carbon debt for palm oil production. Most greenhouse gases are released primarily through deforestation, commodity growth and fertilizer use. These three factors will be discussed further in the next topic. Greenhouse Gas Emissions Greenhouse gases (GHG) are the 1% of gases that absorb and release radioactive thermal radiation from sunlight. Some examples of greenhouse gases are carbon dioxide, methane and chlorofluorocarbons. These gases can be emitted in different ways, such asdeforestation, the growth of raw materials and the use of fertilizers. Deforestation Deforestation is defined as the removal of forest or other trees, caused by the exploitation of natural resources for the development of human populations. Figure 1 shows the causes of deforestation. According to a study conducted by the secretariat of the United Nations Framework Convention on Climate Change (UNFCCC), the agricultural sector contributes the most to deforestation. Biofuel production can be related to commercial agriculture and fuelwood removal as rainforest, grasslands, peatlands and savannah are converted to plant feedstocks such as corn, rapeseed, potatoes, sugarcane, soybeans, poplar and willow (UNFCCC, 2007). Figure 1: Causes of Deforestation Trees are the gift of mother earth as a human protector. It can capture carbon dioxide through the process of photosynthesis. The tree itself contained about 50% carbon, and some of it will be emitted through the process of respiration. But when deforestation activities occur, tones of carbon dioxide are released through the microorganism that metabolizes dead wood or other organic substances. It is believed that forestry in the United States of America can help offset 20% to 46% of greenhouse gas emissions as trees absorb up to three million tons of carbon dioxide per year. Taking land conversion for corn biofuel production in the United States of America as an example, 1.8 tons of carbon dioxide per hectare are released each year. According to one study, deforestation of grasslands will produce 300 tons per hectare of carbon dioxide while deforestation of forests will produce two to three times more energy than conversion of grasslands. The growth of raw material trees is expected to clean the atmosphere, absorb carbon dioxide and reduce greenhouse gas emissions. At the same time, it can be used to replace fossil fuels. But trees can actually make the condition worse. The study shows that perennial lignocellulosic plants such as poplar, willow and eucalyptus release a kind of dangerous chemicals called isoprene. These plants are used as renewable fuel. They grow faster than other normal trees and can plant on low-quality soil. Poplars, willows and eucalyptus trees also required less management and low fossil fuel inputs. For these reasons they are widely used nowadays. But as they grew, they released large amounts of isoprene. Isoprene will react with air pollutants such as carbon dioxide and methane in sunlight to form ozone. Research is conducted and it is estimated that ozone produced from wood fuel energy to meet the European Union's 2020 target will cause 1400 premature deaths each year (Smith, 2013). The red dots in Figure 2 clearly show that the number of deaths is likely to increase due to the increase in the number of tree plantations for biofuel production. Figure 2: Death due to increased tree plantations for biofuel production in Europe. Using Fertilizer The fertilizer contained three main macronutrients: nitrogen, potassium and phosphorus. It is mainly used to provide nutrients to plants and increase crop yields. Fertilizer has provided many benefits, but fertilizers, especially nitrogen fertilizers, have released more dangerous greenhouse gases called nitrous oxide (N_2 O) which has about 310 times greater global warming potential than carbon dioxide. This means that one kilogram of nitrous oxide.