1.Itwasscientistswhowarnedthatgreenhousegaseswouldwarmtheearthbytrappingheatenergyintheatmosphere.

　　2.Itisthegreenhouseeffectthatgivestheearth'ssurfacetheaveragetemperatureof15

　　3.Itisfossilfuelsthatmuchoftheenergyusedtolightandheatourhomescomesfrom.

　　4.Itisthedevelopedcountriesthatconsumethemostenergyintheworld.

　　5.Itisforcenturiesthatcarbondioxidehasthetendencytostayintheatmospherewhileothergreenhousegasesstayintheatmosphereonlyforadayorless.

　　6.Itistheirveryexistencethatlow-lyingcountriesfeelisindangerfromrisingsealevels.

　　7.Itisenvironmentalistswhohavetriedtostoptheearth'stemperaturerising.

　　8.Itisfutureclimatechangesandtheireffectsonourenvironmentthatscientistswanttofindoutabout.

　　9.Itisbyseveralmetresthattheleveloftheseacouldriseintheyearsaheadbecauseofglobalwarming.

　　10.Itisouterspacethatmightprovideuswithnewenergysourcesinthefuture.