Query: The top five countries for passenger aviation-related carbon emissions were rounded out by China, the United Kingdom, Japan, and Germany.

Relevant passages:
Germany <=SEP=> Germany ( listen ) , is a federal parliamentary republic in central-western Europe . It includes 16 constituent states , covers an area of 357,021 km2 , and has a largely temperate seasonal climate . With about 82 million inhabitants , Germany is the most populous member state of the European Union . After the United States , it is the second most popular immigration destination in the world . Germany 's capital and largest metropolis is Berlin , while its largest conurbation is the Ruhr ( main centres : Dortmund and Essen ) . The country 's other major cities are Hamburg , Munich , Cologne , Frankfurt , Stuttgart , Düsseldorf , Leipzig , Bremen , Dresden , Hannover and Nuremberg .   Various Germanic tribes have inhabited the northern parts of modern Germany since classical antiquity . A region named Germania was documented before 100 AD . During the Migration Period the Germanic tribes expanded southward . Beginning in the 10th century , German territories formed a central part of the Holy Roman Empire . During the 16th century , northern German regions became the centre of the Protestant Reformation . The remains of the Holy Roman Empire formed the German Confederation in 1815 , while the German revolutions of 1848 -- 49 established major democratic rights first .   In 1871 , Germany became a nation state when most of the German states were unified into the Prussian-dominated German Empire . After World War I and the German Revolution of 1918 -- 1919 , the Empire was replaced by the parliamentary Weimar Republic . In 1933 the Nazi seizure of power quickly led to the establishment of Nazi Germany which was built upon a dictatorship and consequently led to World War II and one of the biggest genocides in history , the Holocaust . By 1945 Germany and most of Europe were left in destruction and ruins . After the end of World War II in Europe and a period of Allied occupation , two German states were founded : the democratic Federal Republic of Germany ( commonly known as West Germany ) and the socialist German Democratic Republic ( commonly known as East Germany ) . A wall encircling West Berlin was created on August 13 , 1961 , and was torn down on November 9 , 1989 . On 3 October 1990 , the country was reunified .   In the 21st century , Germany is a great power and has the world 's fourth-largest economy by nominal GDP , as well as the fifth-largest by PPP . As a global leader in several industrial and technological sectors , it is both the world 's third-largest exporter and importer of goods . Germany is a developed country with a very high standard of living sustained by a skilled and productive society . It upholds a social security and universal health care system , environmental protection and a tuition-free university education .   The Federal Republic of Germany was a founding member of the European Economic Community in 1957 and the European Union in 1993 . It is part of the Schengen Area , and became a co-founder of the Eurozone in 1999 . Germany is a member of the United Nations , NATO , the G8 , the G20 , and the OECD . The national military expenditure is the 9th highest in the world . Known for its rich cultural history , Germany has been continuously the home of influential and successful artists , philosophers , musicians , sportspeople , entrepreneurs , scientists , engineers , and inventors .

Greenhouse gas <=SEP=> A greenhouse gas ( abbrev . GHG ) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range . This process is the fundamental cause of the greenhouse effect . The primary greenhouse gases in Earth 's atmosphere are water vapor , carbon dioxide , methane , nitrous oxide , and ozone . Without greenhouse gases , the average temperature of Earth 's surface would be about -18 ° C , rather than the present average of 15 ° C . In the Solar System , the atmospheres of Venus , Mars and Titan also contain gases that cause a greenhouse effect .   Human activities since the beginning of the Industrial Revolution ( taken as the year 1750 ) have produced a 40 % increase in the atmospheric concentration of carbon dioxide , from 280 ppm in 1750 to 406 ppm in early 2017 . This increase has occurred despite the uptake of a large portion of the emissions by various natural `` sinks '' involved in the carbon cycle . Anthropogenic carbon dioxide emissions ( i.e. , emissions produced by human activities ) come from combustion of fossil fuels , principally coal , oil , and natural gas , along with deforestation , soil erosion and animal agriculture .   It has been estimated that if greenhouse gas emissions continue at the present rate , Earth 's surface temperature could exceed historical values as early as 2047 , with potentially harmful effects on ecosystems , biodiversity and the livelihoods of people worldwide . Recent estimates suggest that on the current emissions trajectory the Earth could pass a threshold of 2 ° C global warming , which the United Nations ' IPCC designated as the upper limit to avoid `` dangerous '' global warming , by 2036 .

Environmental impact of aviation <=SEP=> The environmental impact of aviation occurs because aircraft engines emit heat , noise , particulates and gases which contribute to climate change and global dimming . Among others airplanes emit particles and gases such as carbon dioxide , water vapor , hydrocarbons , carbon monoxide , nitrogen oxides , sulfur oxides , lead and black carbon which interact among themselves and with the atmosphere .   Despite emission reductions from automobiles and more fuel-efficient and less polluting turbofan and turboprop engines , the rapid growth of air travel in recent years contributes to an increase in total pollution attributable to aviation . From 1992 to 2005 , passenger kilometers increased 5.2 % per year . And in the European Union , greenhouse gas emissions from aviation increased by 87 % between 1990 and 2006 .   Comprehensive research shows that despite anticipated efficiency innovations to airframes , engines , aerodynamics and flight operations , there is no end in sight -- even many decades out -- to rapid growth in CO2 emissions from air travel and air freight , due to projected continual growth in air travel . This is because international aviation emissions have escaped international regulation up to the ICAO triennial conference in October 2016 agreed on the CORSIA offset scheme , and because of the lack of taxes on aviation fuel worldwide , lower fares become more frequent than otherwise which gives a competitive advantage over other transportation modes . Unless market constraints are put in place this growth in aviation 's emissions will result in the sector 's emissions amounting to all or nearly all of the annual global emissions budget by mid-century , if climate change is to be held to a temperature increase of 2 ° C or less .   There is an ongoing debate about possible taxation of air travel and the inclusion of aviation in an emissions trading scheme , with a view to ensuring that the total external costs of aviation are taken into account .

Environmental impact of aviation in the United Kingdom <=SEP=> The environmental impact of aviation in the United Kingdom is increasing due to the increasing demand for air travel in the country . In the past 25 years the UK air transport industry has seen sustained growth , and the demand for passenger air travel in particular is forecast to increase more than twofold , to 465 million passengers , by 2030 . Two airports ; London Heathrow Airport and London Gatwick Airport , are amongst the top ten busiest airports in the world for international passenger traffic . Whilst more than half of all passengers travelling by air in the UK currently travel via the five London area airports , regional airports have experienced the most growth in recent years , due to the success of ` no-frills ' airlines over the last decade .   The ability of the existing airport infrastructure to meet forecast demand is limited , and government policy published in 2003 supports the development of additional airport capacity by 2030 to address this . The strategy is generally based on making the best use of existing facilities , although an additional five new runways nationwide are considered to be necessary , three of them at the London airports of Stansted , Heathrow and , towards the end of the timeframe involved , Gatwick . This policy is designed to be a balanced and measured approach to the future of the air transport industry ; one that recognises both an economic advantage in providing for growth in demand for air travel and also the need to address the consequent environmental impacts . The strategy has been criticised by the House of Commons Environmental Audit Select Committee , by environmentalist and campaign groups , and in research papers , for implementing a predict and provide model that overstates the economic advantages whilst paying insufficient heed to the environmental consequences .   Support for airport expansion is based on an economic case that regards the air transport industry not only as an important industry in its own right , but also as a facilitator of growth for the economy as a whole . One study predicts that the government 's strategy will realise an additional # 13 billion per annum in Gross Domestic Product ( GDP ) by 2030 . Another study which is critical of the government approach , and which favours addressing environmental impacts through increased taxation of air transport , indicates a negative economic benefit resulting from airport expansion . In 2006 the industry was responsible for over 6 per cent of all UK carbon emissions , a figure that is set to rise as demand increases . Under current strategies of emissions reduction and growth in air transport , air travel in the UK could account for up to 50 per cent of the UK carbon budget by 2050 . Industry attempts to address this issue are longer term efforts based on technological and operational improvements , whilst government policy is based on the inclusion of air transport within emissions trading schemes . Critics advocate a shift in government policy to address environmental impacts by constraining the growth in demand for air travel , primarily through the use of economic instruments to price air travel less attractively . Local environmental issues include noise and air quality , and the impact of these , particularly in the case of the former , is subject to debate . Government policy generally is that these are local issues best addressed locally , and has introduced legislation designed to facilitate this .