https://www.youtube.com/watch?v=TU1Ub6aXMqA
                   

             WILL WE RUN OUT OF BREATHABLE OXYGEN ?

               Professor Ralph Keeling he is very worried . 
               He says that he is doing studies meticolously and his studies say tht the oxygen is
               dwinling .              


                        LESS OXYGEN EQUALS LESS LIFE
                        
               A long time ago The Earth was plenty of oxygen . Close to one-third of the atmosphere that
               animals grew to gargantuan sizes . For instance , the ancestors of dragonflies once had  four
               foot wingspans . Now, due to overpopulation by humans the air is decreasing and it has  
               become a diminishing resource . Pollution has also a high impact on the loss of oxygen .
              

                            WARNING SIGNS MOUNTING

       
                The first warning sign mounting occur in seas and oceans . Dead zones : zones where   
                oxygen has been depleted and life can no longer exist were first documented in the late   
                1970s . Researchers discovered dead zones were growing in size and number and some of 
                them are located for instance : near  the Baltic sea and in the Gulf of Mexico . 

    https://www.google.es/search?q=dead+zones&client=firefox-a&rls=org.mozilla:es-ES:official&   tbm=isch&imgil=vcnkJ-55iYM_FM%253A%253B-MG6yLrD4cMYCM%253Bhttp%25253A%25252F%25252Fwww.cbf.org%25252Fabout-the-bay%25252Fissues%25252Fdead-zones&source=iu&pf=m&fir=vcnkJ-55iYM_FM%253A%252C-MG6yLrD4cMYCM%252C_&usg=__pyFwD1EMxApC7FaiHfguzBEpn98%3D&biw=1600&bih=816&ved=0ahUKEwjl6q-H5oTNAhVJVhoKHetEAasQyjcINg&ei=U8RNV6X1AcmsaeuJhdgK#imgrc=vcnkJ-55iYM_FM%3A