Greening Earth

Every year, human activities result in 7 billion tons of carbon released into Earth’s atmosphere.

Scientists, like Ranga Myneni at Boston University, are trying to figure out where all this carbon goes.

Ranga Myneni: So what happens is we are trying to do a budget of carbon. It’s just like, you know, doing a household budget or an institutional budget. We know how much carbon we are putting in the atmosphere each year. That is presently at about 7 billion tons, so naturally at the end of the year, you would expect that the amount of carbon in the atmosphere should increase by 7 billion tons. But we see that it only increases by half that much.

So where does this extra carbon go? Some goes into the ocean, but some 1.5 billion tons of carbon are still unaccounted for.

Meanwhile, plants are known to “breathe in” carbon dioxide. And, in the past two decades, there’s been an increase in the length of the growing season at higher latitudes. Spring starts about a week earlier, and fall begins a week later.

And satellite images taken over the last 22 years show that Earth is getting greener. It’s possible plants are swallowing the missing carbon to make more leaves — as the growing season lengthens — in a warming world.

What you have in your mind?