Marihat Research Station (MRS), nowadays known as RISPA and located in Medan, is the first research centre for Palm Oil Plantation for Indonesia. One of its well-known experts in soil, who has now retired, was Ir. Petrus Purba. In August 2011, the governor of Aceh issued a permit for Indonesian palm oil firm PT Kallista Alam to develop around 1,600 hectares in Tripa. Indonesian palm oil producer Triputra Agro Persada will reportedly increase its planted area by about two-thirds from 2013 by 2015. Since agricultural land is limited, in order to plant monocultures of oil palms, land used for other cultivations or the tropical forest need to be cleared. Of the total logging in Indonesia, up to 80% is reported to be performed illegally. A major environmental threat is then the destruction of rainforests in Indonesia, which was estimated at 0.84 Mha of primary forest per year from 2000 to 2012. From 1990 to 2005, 108,110 square miles of Indonesian forest were taken down from logging, 77% of this forest had never even been touched. Deforestation also makes Indonesia one of the biggest emitters of greenhouse gases. Carbon Dioxide (CO2) is released in the atmosphere massively with the cutting of tropical peatlands, which are carbon sinks, according to Greenpeace. Deforestation is also caused by illegal forest fires to clear land for palm oil plantations. According to WWF for example, in 1997 around 0.81 to 2.57 gigatons of carbon were released by the fires which represented "13-40% of the mean annual global carbon emissions from fossil fuels that year". As of 2013, Indonesia ranked number eight among countries worldwide for overall greenhouse gas emissions. According to the World Resources Institute, 65.5% of these greenhouse gas emissions can be attributed to land use change and forestry; the palm oil industry in Indonesia is a major contributing factor towards this trend. Industrial palm tree plantations also impacts negatively the quality of soils, water and the air because they often rely on the use of agrochemicals products, such as pesticides or fertilizers. The drainage, burning, and plantation building on former peat lands releases large quantities of carbon dioxide, so negating their value as so-called 'carbon sinks' (stores of carbon). The carbon sinks “store more carbon per unit area than any other ecosystem in the world”. One study found that destroying the carbon sink peat bogs in Southeast Asia could release as much carbon as nine years of fossil fuel that is used globally.