Question

what does Al Gore , author of An Inconvenient Truth , demonstrate about the level of atmospheric carbon dioxide levels ?

Each year , thr CO2 level rises and then falls. Over the past 50 years , it has steadily increased

Each year , the CO2 levels increase at a faster rate . Over the past 50 years , it has nearly doubled

Each year , the CO2 levels decrease . Over the past 50 years , it has steadily decreased