Query: Over the past eight years, the United States has reduced our total carbon pollution more than any other nation on Earth.

Relevant passages:
Air pollution <=SEP=> Air pollution occurs when harmful substances including particulates and biological molecules are introduced into Earth 's atmosphere . It may cause diseases , allergies or death in humans ; it may also cause harm to other living organisms such as animals and food crops , and may damage the natural or built environment . Human activity and natural processes can both generate air pollution .   Indoor air pollution and poor urban air quality are listed as two of the world 's worst toxic pollution problems in the 2008 Blacksmith Institute World 's Worst Polluted Places report . According to the 2014 WHO report , air pollution in 2012 caused the deaths of around 7 million people worldwide , an estimate roughly matched by the International Energy Agency .

Recycling <=SEP=> Recycling is the process of converting waste materials into new materials and objects . It is an alternative to `` conventional '' waste disposal that can save material and help lower greenhouse gas emissions ( compared to plastic production , for example ) . Recycling can prevent the waste of potentially useful materials and reduce the consumption of fresh raw materials , thereby reducing : energy usage , air pollution ( from incineration ) , and water pollution ( from landfilling ) .   Recycling is a key component of modern waste reduction and is the third component of the `` Reduce , Reuse , and Recycle '' waste hierarchy .   There are some ISO standards related to recycling such as ISO 15270:2008 for plastics waste and ISO 14001:2004 for environmental management control of recycling practice .   Recyclable materials include many kinds of glass , paper , and cardboard , metal , plastic , tires , textiles , and electronics . The composting or other reuse of biodegradable waste -- such as food or garden waste -- is also considered recycling . Materials to be recycled are either brought to a collection centre or picked up from the curbside , then sorted , cleaned , and reprocessed into new materials destined for manufacturing .   In the strictest sense , recycling of a material would produce a fresh supply of the same material -- for example , used office paper would be converted into new office paper or used polystyrene foam into new polystyrene . However , this is often difficult or too expensive ( compared with producing the same product from raw materials or other sources ) , so `` recycling '' of many products or materials involves their reuse in producing different materials ( for example , paperboard ) instead . Another form of recycling is the salvage of certain materials from complex products , either due to their intrinsic value ( such as lead from car batteries , or gold from circuit boards ) , or due to their hazardous nature ( e.g. , removal and reuse of mercury from thermometers and thermostats ) .

Climate change in the United States <=SEP=> 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 .   From 1950 to 2009 , the American government 's surface temperature record shows an increase by 1 F-change , 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 difficulty . 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 . 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 .   Climate change is seen as a national security threat to the United States .   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 .   2016 was an historic year for billion-dollar weather and climate disasters in U.S.