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Because of global warming, there has been concern in the United States and internationally, that the country should reduce total greenhouse gas which is relatively high per capita. In 2012, the United States experienced its warmest year on record. , the thirteen warmest years for the entire planet have all occurred since 1998, transcending those from 1880.〔(''There’s Still Hope for the Planet'' ) July 21, 2012 New York Times by David Leonhardt〕〔(''By The Numbers: The U.S.'s Warmest Year Yet'' ) January 31, 2013 Popular Science〕 From 1950 to 2009, the American government's surface temperature record shows an increase by , approximately. Global warming has caused many changes in the U.S. According to a 2009 statement by the National Oceanic and Atmospheric Administration (NOAA), trends include lake and river ice melting earlier in the spring, plants blooming earlier, multiple animal species shifting their habitat ranges northward, and reductions in the size of glaciers.〔()〕 Predicting future climate changes are fraught with difficultly. Some research has warned against possible problems due to American climate changes such as the spread of invasive species and possibilities of floods as well as droughts.〔 Changes in climate in the regions of the United States appear significant. Drought conditions appear to be worsening in the southwest while improving in the northeast for example.〔 President Barack Obama committed in the December 2009 Copenhagen Climate Change Summit to reduce carbon dioxide emissions in the range of 17% below 2005 levels by 2020, 42% below 2005 levels by 2030, and 83% below 2005 levels by 2050.〔(NRDC: From Copenhagen Accord to Climate Action: Tracking National Commitments to Curb Global Warming )〕 In an address towards the U.S. Congress in June 2013, Obama detailed a specific action plan to achieve the 17% carbon emissions cut from 2005 by 2020. He included such measures as shifting from coal-based power generation to solar and natural gas production.〔(Barack Obama pledges to bypass Congress to tackle climate change ) 25 June 2013〕 In 2015, according to The New York Times and others, oil companies knew that burning oil and gas could cause global warming since the 1970s but, nonetheless, funded deniers for years.〔〔 ==Greenhouse gas emissions by the United States== (詳細はdeforestation-related changes, in 2005. Specifically, the U.S. produced 6,930 mt (15.7% of the world's total). In the cumulative emissions between 1850 and 2007, the U.S. was at the top in terms of all world nations, involved with 28.8% of the world's total. China's emissions have outpaced the U.S. in CO2 from 2006 onward. The U.S. produced 5.8 billion metric tons of CO2 in 2006, compared to the 6.23 billion coming from China. Per capita emission figures of China are about one quarter of those of the U.S. population. The single largest source of greenhouse gas emissions in the U.S. is power generation. For example, data from 2012 put that share as 32% of the total compared to the 28% of emissions related to transportation, 20% from industry, and 20% from other sources.〔 According to data from the US Energy Information Administration the top emitters by fossil fuels CO2 in 2009 were: China: 7,710 million tonnes (mt) (25.4%), US: 5,420 mt (17.8%), India: 5.3%, Russia: 5.2% and Japan: 3.6%.〔 In the cumulative emissions between 1850 and 2007 the top emitters were: 1. US 28.8%, 2. China: 9.0%, 3. Russia: 8.0%, 4. Germany 6.9%, 5. UK 5.8%, 6. Japan: 3.9%, 7. France: 2.8%, 8. India 2.4%, 9. Canada: 2.2% and 10. Ukraine 2.2%.〔(Which nations are most responsible for climate change? ) Guardian 21 April 2011〕 In terms of trends, carbon dioxide emissions were around 5,000 mt in 1990 and gradually increased to around 6,000 mt, with a peak occurring in 2008. The subsequent decline went on such that 2012 saw about 5,400 mt emitted.〔(Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990–2012 (April 2014) )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Climate change in the United States」の詳細全文を読む スポンサード リンク
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