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NASA’s OCO-3 measures how plants grow - and glow

09 April 2019

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When plants take in too much energy, they don't get fat — they lighten up. They absorb more sunlight than they need to power photosynthesis, and they get rid of the excess solar energy by emitting it as a very faint glow. The light is far too dim for us to notice under normal circumstances, but it can be measured with a spectrometer. Called solar-induced fluorescence (SIF), it's the most accurate signal of photosynthesis that can be observed from space.

That's important because, as Earth's climate changes, growing seasons worldwide are also changing in both timing and length. These changes may affect world food production and the pace of greenhouse warming. It's not possible to measure photosynthesis globally from ground level, and lab experiments can't easily replicate all of the environmental factors affecting plant growth, such as water availability, wildfires and competition from other plants — factors that also are changing with the climate.

Source: NASA

Image credit: ©Craig P. Burrows - This honeysuckle is glowing in response to a high-energy ultraviolet light rather than to the Sun, but its shine is similar to the solar-induced fluorescence that OCO-3 will measure.

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