Tag Cloud; causes climate change this page earth s temperature balancing act the greenhouse effect atmosphere retain heat changes sun energy affect much reaches system reflectivity enters points both natural human factors before humans such orbit solar activity volcanic eruptions since industrial era began have increasing adding tons heattrapping gases most observed warming mid20th century due gas emissions depends balance between leaving planet when incoming absorbed warms reflected back into space released many cause line graph show increases blue band would changed over past only forces red shows effects starts 20th just above 56 degrees fahrenheit global temperatures follows use 1900 2000 around view enlarged image models account processes able explain also emitted source 2009 which amount reaching surface these caused times together thousands years number measures ice remains ocean 1 naturally range time in prior revolution explained ghg concentrations recent however cannot alone research very activities slide alter power process its radiative forcing some forcings positive causing averaged negative cooling increased co2 concentration well known others aerosols more relatively small net large increase click open lightbox explains sunlight it either called infrared radiation ghgs like water vapor carbon dioxide methane ch4 absorb preventing warmer than role lower slideshow among other topics distant 000 ago levels glacial cycles during warm interglacial periods higher cool 2 because often feedback stacked lines top 800 bottom difference same period similar changing based core data until atmospheric vary within parts per million volume ppmv rapid rise 390 2010 shown here section nrc feedbacks a initial influences while america reports exit epa disclaimer fourth assessment report usgcrp impacts united states abrupt inevitable surprises unep wmo integrated black tropospheric ozone summary decision makers 1750 contributed substantially primary rate burning fossil fuels important directly include nitrous oxide n2o several sources below part cycle through oceanatmosphere land release continue world oceans may start less if greater example trend measured 1960 short but 320 risen preindustrial 280 approximately level least u now emit volcanoes each year 30 billion tub faucet drain take thick arrow bathtub represents fuel deforestation smaller sinks right size larger flow plants up for information see website produced agricultural three gasses low remain by similarly molecules abundant decades actions reduce create 3 varied impact contribution lifetime overall rates precipitation therefore affected organic addition trapping sulfur fgases aerosol u