The world human population has grown vigorously in two hundred years and until today, the world population has reached more than seven billion. Furthermore, suitable land that is now used for agricultural purposes is also degrading at a rapid rate. A food crisis could occur if the food we currently have is not enough for the world's population. So we should not convert agricultural land for biofuel production. For this reason, people started to find new lands instead of using cultivated land and most of them chose rainforest, peatlands and grasslands. When these lands are converted for planting raw materials, they have lost their function as a stabilizer of the global climate, a source of raw materials and medicines, or a protection for humans from natural disasters. Additionally, the habitat of many plants and animals would be transformed into concentrated monocultures. For example, much of the Amazon rainforest has been transformed into soybean plantations and the lowland rainforest of Malaysia has also been transformed into oil palm plantations. Land conversion has resulted in loss of habitat for living species and 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, Malaysian tigers, Sumatran rhinos and Bornean elephant, when the forest is converted in oil palm plantations. This also caused the extinction of living species. In South America, the Alagoas curassow has become extinct because its habitat was demolished for sugarcane biofuel production in Brazil. Carbon debt Land use changes induced by biofuel production have also unintentionally created carbon debt. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essayThe term carbon debt or can be called 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 produced approximately 17 to 420 times more carbon dioxide than the annual reduction in greenhouse gases. greenhouse gas that biofuel would release by replacing fossil fuels. Initially, biofuel acted as a renewable energy, aiming to replace fossil fuels and mitigate climate change. But biofuel production was found to create more greenhouse gas emissions. Today, carbon debt accumulates until it takes over a hundred years to pay off. For example, to pay off the carbon debt created when the Amazon rainforest is transformed into a soy field for soy biodiesel production will take around 300 years. In Malaysia and Indonesia, it takes around 400 years to pay off the carbon debt linked to palm oil production. Most greenhouse gases are released primarily through deforestation, raw material growth and fertilizer use. These three factors will be discussed in more detail in the next topic. Greenhouse gas emissions Greenhouse gases (GHGs) are the 1% of gases that absorb and release radioactive thermal radiation from the sun. Some examples of greenhouse gases are carbon dioxide, methane andchlorofluorocarbons. These gases can be emitted in several ways, such as deforestation, growing raw materials and using fertilizers. Deforestation Deforestation is defined as the removal of forest or other trees, caused by the exploitation of natural resources for the development of the human population. 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 linked to commercial agriculture and firewood extraction, as rainforest, grasslands, peatlands and savannah are converted to plant-based raw materials such as corn, canola, potato, sugar cane, soybean, poplar and willow (UNFCCC, 2007). Figure 1: Causes of deforestation Trees are a gift from Mother Earth as a human protector. It can capture carbon dioxide through the process of photosynthesis. The tree itself contains around 50% carbon and some will be emitted through the respiration process. But when there are deforestation activities, tons of carbon dioxide are released by the microorganism metabolizing dead wood or other organic matter. It is estimated that the forests of the United States of America can help offset 20 to 46 percent of GHG emissions, as trees absorb up to three million tons of carbon dioxide per year. Taking land conversion for biofuel corn production in the United States of America as an example, 1.8 tonnes of carbon dioxide are released per hectare 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 carbon dioxide than converting grasslands. The growth of the basic trees is expected to be a cleaner atmosphere, absorbing carbon dioxide and reducing greenhouse gas emissions. At the same time, they can be used to replace fossil fuels. But trees can actually make the situation worse. A study shows that perennial lignocellulosic plants such as poplars, willows and eucalyptus release a kind of dangerous chemicals called isoprene. These plants are used as renewable wood fuel. They grow faster than other normal trees and can be planted on poor quality land. Poplars, willows and eucalyptus also required less management and low fossil fuel input. For these reasons, they are widely used today. But as they grew, they released a large amount of isoprene. Isoprene will react with air pollutants such as carbon dioxide and methane exposed to sunlight to form ozone. Research is being conducted and they estimate that ozone produced from firewood in order to meet the European Union's 2020 target will cause 1,400 premature deaths per 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: Deaths due to increased tree planting for biofuel production in Europe. Use of fertilizer Fertilizer contained three main macronutrient elements which are nitrogen, potassium and phosphorus. It is mainly used to provide nutrients to plants and increase crop yields. Fertilizers have brought many benefits, but fertilizers, especially fertilizers based on.