Itwasscientistswhowarnedthatgreenhousegaseswouldwarmtheearthbytrappingheatenergyintheatmosphere.

　　Itisthegreenhouseeffectthatgivestheearth'ssurfacetheaveragetemperatureof15

　　Itisfossilfuelsthatmuchoftheenergyusedtolightandheatourhomescomesfrom.

　　Itisthedevelopedcountriesthatconsumethemostenergyintheworld.

　　Itisforcenturiesthatcarbondioxidehasthetendencytostayintheatmospherewhileothergreenhousegasesstayintheatmosphereonlyforadayorless.

　　Itistheirveryexistencethatlow-lyingcountriesfeelisindangerfromrisingsealevels.

　　Itisenvironmentalistswhohavetriedtostoptheearth'stemperaturerising.

　　Itisfutureclimatechangesandtheireffectsonourenvironmentthatscientistswanttofindoutabout.

　　Itisbyseveralmetresthattheleveloftheseacouldriseintheyearsaheadbecauseofglobalwarming.

　　Itisouterspacethatmightprovideuswithnewenergysourcesinthefuture.