official inventory of all greenhouse gases: the provisional figure for 2021 is 395 Mt CO2eq. Climate Trace use space-based measurements of carbon dioxide to quantify large emission sources, like major coal-fired power stations in Turkey. According to them forestry and land use was a net emitter in 2021, and even without that 615 million tonnes of GHG was emitted that year. Monitoring, reporting and verification Monitoring, reporting and verification (MRV) includes sharing information and lessons learned, which strengthens the trust of international climate finance donors. The Turkish government's Statistical Institute (Turkstat) follows the United Nations Framework Convention on Climate Change (UNFCCC) reporting guidelines, so uses production-based GHG accounting to compile the country's greenhouse gas inventory. , using consumption-based accounting would give a total over 10% higher, as manufacturing the products imported to Turkey emits more GHG than manufacturing its exports. Turkstat sends the data and accompanying report to the UNFCCC each April, about 15 months after the end of the reported year. Emissions from fuels sold in the country for international aviation and shipping are accounted separately in reports to the UNFCCC, and are not included in a country's total. In 2020 jet kerosene, supplied at Turkish airports and burnt by international flights, emitted 6 Mt e (carbon dioxide equivalent); and diesel oil and residual fuel oil from Turkish ports powering international shipping 2 Mt e. The Intergovernmental Panel on Climate Change (IPCC) defines three methodological tiers to measure emissions. Tier 1 uses global defaults and simplified assumptions, so is the easiest but least accurate. Tier 2 uses country specific values and more detailed data. Tier 3 uses the most detailed data and modelling, so is the most difficult to compile but the most accurate. To make best use of human resources each nation may decide to only use higher tiers to estimate its particular "key categories". Turkstat selects these categories depending on either the absolute level of emissions from that category, or whether it is trending steeply upwards. For example, from wastewater treatment and discharge was a key category for 2020 solely because of its quickly rising emissions. Nevertheless, most of the thirty key categories selected in 2020 are the largest emitting sectors, cement production for example. Turkey uses Tier 2 and Tier 3 methodology for some key categories, for example a power plant might analyse the lignite it burns, which differs from mine to mine.Although road transport is