Scientists have come up with an entirely new way to monitor the health of Earth’s plants from space. In work published in Geophysical Research Letters , researchers working at NASA’s Jet Propulsion Laboratory (JPL) and in Germany and Japan report on how measurements taken from space can open a whole new window onto the planet’s carbon cycle.
Carbon is a building block of life. It is also a key component of our climate. Carbon dioxide — a gas that exists naturally in the air, but is also produced by humans when we burn fossil fuels, drive cars and chop down trees — acts as a thermostat that controls the temperature of the planet. As a “greenhouse gas,” it acts like a blanket that traps heat close to the surface of the Earth. The more carbon dioxide we emit, the more the warming. Since the beginning of the industrial age, carbon dioxide levels have gone up by nearly 40 percent, and the world’s average temperature has risen by about 0.5 degrees Celsius (nearly 1 degree Fahrenheit) as a result. Knowing how much carbon is going into and out of the Earth’s land, air and oceans — the carbon cycle — is critical for understanding how much global warming is likely to happen to our planet in the future. And plants and vegetation are a key part of this cycle.
When plants photosynthesize, they use energy from sunlight to turn carbon dioxide from the air into sugars used to live and grow. In doing so, they give off a fluorescent light — a glow that can’t be seen with the naked eye, but that can be seen with the right instruments. More photosynthesis translates into more fluorescence, meaning that the plants are very productive in taking up carbon dioxide. The amount of carbon dioxide taken up by plants is called “gross primary productivity,” and is the largest part of the global carbon cycle. (read more)