largest oil shale reserves in Europe. It is the world's leading natural gas exporter, the second-largest natural gas producer, and the second-largest oil exporter, and producer. Fossil fuels cause most of the greenhouse gas emissions by Russia. The country is the world's fourth-largest electricity producer, and the ninth-largest renewable energy producer in 2019. Russia was also the world's first country to develop civilian nuclear power, and to construct the world's first nuclear power plant. In 2019, It was the world's fourth-largest nuclear energy producer. Mining Russia is also a leading producer and exporter of minerals and gold. Russia is the largest diamond-producing nation in the world, estimated to produce over 33 million carats in 2013, or 25% of global output valued at over $3.4 billion, with state-owned ALROSA accounting for approximately 95% of all Russian production. In 2019, the country was the 3rd world producer of gold; 2nd worldwide producer of platinum; 4th worldwide producer of silver; 9th largest world producer of copper; 3rd largest world producer of nickel; 6th largest world producer of lead; 9th largest world producer of bauxite; 10th largest world producer of zinc; 2nd worldwide producer of vanadium; 2nd largest world producer of cobalt; 5th largest world producer of iron ore; 7th largest world producer of boron; 9th largest world producer of molybdenum; 13th largest world producer of tin; 3rd largest world producer of sulfur; 4th largest world producer of phosphate; 8th largest world producer of gypsum; in addition to being the world's 10th largest producer of salt. It was the world's 6th largest producer of uranium in 2018. Agriculture Russia's agriculture sector contributes about 5% of the country's total GDP, although the sector employs about one-eighth of the total labour force. It has the world's third-largest cultivated area, at . However, due to the harshness of its environment, about 13.1% of its land is agricultural, and only 7.4% of its land is arable. The main product of Russian farming has always been grain, which occupies considerably more than half of the cropland. Russia is the world's largest exporter of wheat, and is the largest producer of barley, buckwheat, oats, and rye, and the second-largest producer of sunflower seed. Various analysts of climate change adaptation foresee large opportunities for Russian agriculture during the rest of the 21st century as arability increases in Siberia, which would lead to both internal and external migration to the region. More