I’m a biochemist, so I enjoy dealing with systems on a molecular level, but I’ve mentioned before that this isn’t the whole story. Sometimes it is necessary to consider the global scale. In my field, the molecular details of photosynthesis hold the keys to unlocking the hidden potential of plants and opening new energy production possibilities. On the other end of the spectrum, monitoring photosynthesis on a global scale provides information on nutrient cycling and overall primary productivity in the context of changing environmental conditions. Astonishingly, photosynthetic activity can be measured over this broad dynamic range using the same basic methods- spectroscopy to detect color and chlorophyll fluorescence. Today’s post will highlight two projects working on measuring photosynthesis on a global scale… from space!
The SeaWifS (Sea-viewing Wide Field-of-view Sensor) Project recorded information on ocean color as a census for photosynthetic productivity in the oceans. It was launched in 1997 and collected data until the satellite was no longer functional in 2010. At the onset of the project, collecting this kind of color data was considered to be only marginally useful, but with the success of the SeaWiFS project, ocean color is a ‘must measure’ parameter for all future missions. Check out the video below for some nice pictures. It provides a great illustration of just how much the Earth’s oceans contribute to primary productivity.
Remember those dead zones? The sudden appearance of photosynthetic life is the first sign of potential hypoxic areas, and now this can be visualized from space for earlier monitoring.
Now scientists can even measure chlorophyll fluorescence to monitor photosynthetic capacity from space. Plants absorb most of the sunlight that shines on them and put it to use for driving photosynthesis. However, they cannot use all of it. This excess light is emitted back out of the plants as a fluorescent glow at a different wavelength (i.e. red light). Joanna Joiner and her group at NASA’s Goddard Space Flight Center developed a way to accurately tease this red fluorescence from plants apart from the rest of the light reflected from Earth. These data are used to make maps that detect how sensitive plants are to environmental conditions. This kind of information will help farmers detect stress in the crops earlier than they otherwise would as well as help scientists understand global nutrient cycles. Check out their results in the video below.
So, while I am in the lab measuring individual plants, satellites are orbiting the Earth collecting the same data on a global scale.