Today, NASA announced a new plan for studying growing carbon emissions, but instead of focusing on the carbon that's trapped in our atmosphere, the space agency said it plans to focus on analyzing the "other half" of the carbon that humans emit — the half that gets absorbed by Earth's oceans and plant life. NASA wants to know how ocean waters and plant ecosystems take up carbon, and if the warming climate will prevent them from doing so in the future. Because if these ecosystems someday stop absorbing carbon, the effects of climate change could be much more severe.

Over time, human activities like the burning of fossil fuels have released huge amounts of carbon dioxide, a gas that traps heat, into the air. The gas has accumulated in our atmosphere more and more since the industrial revolution, slowly increasing the world's temperatures. NASA estimates that the amount of carbon dioxide in the atmosphere is around 400 parts per million (ppm) — the highest level in the last 400,000 years. And that amount is going up by about 2 ppm each year. Methane, another carbon-based gas that stems from natural gas production, has also built up in our air over time and is currently at levels that are 2.5 times higher than they were during the industrial era.

"The land and the ocean are really doing us a big favor."

Those numbers would be way worse, however, if it weren't for the various terrestrial plants that take in carbon dioxide during photosynthesis. Forests are found to be major carbon sinks, for example, taking in carbon from the air and storing it in their trunks and roots for years. Oceans are also responsible for absorbing the carbon we emit; the salty waters take in carbon dioxide, while marine plants and animals — like phytoplankton — also take in CO2 through photosynthesis. NASA estimates that nearly half of the carbon emitted by humans is absorbed through these natural land and marine processes. "The land and the ocean are really doing us a big favor," said Lesley Ott, an atmospheric scientist at NASA's Goddard Space Flight Center.

But NASA is worried that may change. As the carbon in the atmosphere warms up the climate, the heat may alter how marine and land ecosystems absorb carbon. They could take in more of the gas over time, or they could become less efficient at the process, allowing more carbon to remain in the atmosphere. Researchers simply don't know.

To better understand how these natural carbon absorption processes work, NASA plans to use data gathered from upcoming NASA satellite missions and multi-year field campaigns to create models of how these ecosystems work. NASA has already gathered data for this purpose using its Orbiting Carbon Observatory-2, a satellite launched last year to measure carbon dioxide from the top of the atmosphere down to the planet's surface. OCO-2 has revealed the areas emitting the most carbon dioxide and the regions in which the gas is being absorbed heavily.

Other missions will involve flying over coral reefs and phytoplankton blooms to see how they've been influenced by climate and changing ocean chemistry. The space agency also noted that new instruments will be added to the International Space Station to better observe plants and forests. Together, all of these instruments, satellite data, and field research will be used to create scientific models that can better predict how carbon-absorbing ecosystems will react to the changing climate. That way, we'll know if our natural carbon storage systems will continue to work to our advantage.

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