Antarctic
Ice Reveals Earth’s Accelerating Plant Growth
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| A boreal forest in Quebec. A new study suggests the world’s plants capture an extra 28 billion tons of carbon each year. CreditDe Agostini/Getty Images |
For decades, scientists have been
trying to figure out what all the carbon dioxide we’ve been putting into the
atmosphere has been doing to plants. It turns out that the best place to find
an answer is where no plants can survive: the icy wastes of Antarctica.
As ice forms in Antarctica, it traps
air bubbles. For thousands of years, they have preserved samples of the
atmosphere. The levels of one chemical in that mix reveal the global growth of
plants at any point in that history.
“It’s the whole Earth — it’s every
plant,” said J. Elliott Campbell of the University of California, Merced.
Analyzing the ice, Dr. Campbell and
his colleagues have discovered that in the past century, plants have been
growing at a rate far faster than at any other time in the past 54,000 years.
Writing in the journal Nature, they report that plants are converting 31
percent more carbon dioxide into organic matter than they were before the
Industrial Revolution.
The increase is due to the carbon
dioxide that humans are putting into the atmosphere, which fertilizes the
plants, Dr. Campbell said. The carbon in the extra plant growth amounts to a
staggering 28 billion tons each year. For a sense of scale, that’s three times
the carbon stored in all the crops harvested across the planet every year.
“It’s tempting to think of
photosynthesis at the scale of the entire planet as too large to be influenced
by human actions,” said Christopher B. Field, the director of the Stanford
Woods Institute for the Environment, who was not involved in the study. “But
the story here is clear. This study is a real tour de force.”
Starting in the Industrial Revolution,
humans began to pump carbon dioxide into the atmosphere at a prodigious rate.
Since 1850, the concentration of the gas has increased over 40 percent.