Aren’t budgets all about money? Don’t they track how many $$$ come in and how many $$$ go out?
That’s right; so what’s a carbon budget? A carbon budget tracks how much carbon, C, goes in and out of a natural area.
Right now, we’re worried about too much C going into our planet’s atmosphere. This excess C is causing global warming, sea level rise, ocean acidification and other environmental problems. These are BIG problems! We can begin to fix these problems if we do a carbon budget and really know how much carbon is where.
Courtesy Sergio Signorini, North American Carbon ProgramAlong with others, scientists at the Center for Microbial Oceanography: Research & Education (C-MORE), based at the University of Hawai`i, have begun to track C in the ocean off the eastern United States. The study area includes a LOT of water! -- all the seawater from high tide out to 500 meters deep, shown by the black line in the map, in the Gulf of Maine (GoM), the Mid-Atlantic Bight (MAB), and the South Atlantic Bight (SAB.)
Imagine your money budget. Let’s say we track your $$$ in and out of 4 categories. Money comes into your pocket from 2 categories, mowing the neighbor’s lawn and babysitting. Money goes out when you pay for movies and snacks.
In the same way, scientists want to track C as it moves between the coastal water “pocket” and 4 nearby areas: the coastal land, the atmosphere above, seafloor below, and the deeper ocean offshore. Where is C leaving the coastal water? Where is it entering?
But wait! Coastal zones are only small slivers of water, compared to the open ocean around the world. Why bother to track carbon in coastal waters?
Ah ha! Coastal waters are very important in C budgeting. Notice the red color in the map above. Red means there's a lot of chlorophyll. Chlorophyll is the green pigment important in photosynthesis, the process that plants use to take in C and fix it as sugar. The red in the map shows that coastal waters are richer in carbon than the open ocean.
Understanding the C budget of coastal waters is one small but important step in solving global warming and other environmental problems.
Sperm whales are the particular focus of this study. The population of sperm whales in the Southern Ocean (the waters around Antarctica) is thought to be about 12,000. (There are more sperm whales in the world, but the study looked at Southern Ocean sperm whales.) Those 12,000 whales are thought to put about 200,000 metric tons of the greenhouse gas carbon dioxide into the atmosphere each year. That’s about the same amount that 40,000 passenger cars contribute each year. Destroy those polluting whales, right?
Wrong! See, it turns out that these sperm whales are also responsible for the removal of 400,000 metric tons of CO2 each year, making up for the amount they produce two times over. Their secret is this: they poop iron.
They don’t only poop iron, but sperm whales poop a lot of iron—each whale is thought to defecate about 50 metric tons of iron each year. That’s over 300 pounds a day! Obviously the whales aren’t pooping out solid iron ingots, though. It’s mixed in with their liquid feces. And that’s important.
The whales themselves don’t remove those 400,000 tons of CO2. They’re removed by phytoplankton. Phytoplankton are microscopic organisms that, like plants, use sunlight and CO2 to build their bodies. And they feed on iron.
The whales have lots of iron in their diets, because of the large amounts of fish and squid they eat. So the iron-rich whale poop is an ideal nutrient for phytoplankton. When the phytoplankton dies, the carbon they contain falls to the bottom of the ocean instead of being released back into the atmosphere. Where more carbon is trapped than is released back into the atmosphere, it’s called a “carbon sink,” and that’s what whale poop and phytoplankton create in the Southern Ocean.
Other parts of the ocean may naturally contain more iron for phytoplankton, but the Southern Ocean is poor in the nutrient, and the microorganisms rely on an iron cycle that the whales apparently play a large part in. More whales, greater carbon sink. Fewer whales, less whale poop, more atmospheric carbon.
Coincidentally, the International Whaling Commission will be meeting next week, to discuss regulations on how many whales can be harvested from the oceans each year. It’s a complicated world, isn’t it?
*I thought about making the headline “Whale poop is ‘green’” but… yuck.
Courtesy Mark GobleScientists know that the Amazon rainforest can help to slow down climate change. The trees not only take in carbon dioxide and release oxygen, but they also are made of carbon. All living things are made of carbon, and when these things die that carbon is released.
There was an unusually severe drought in 2005, which gave scientists a preview of the Amazon's future climate. Scientists think the rainforest will see hotter and more intense dry seasons with climate change. When Oliver Phillips a professor at the University of Leeds, looked at the effects of the drought, he found that it caused carbon losses in the rainforest. This is bad for us, because we rely on the Amazon to take in carbon dioxide, not release it!
In most years the Amazon absorbs almost 2 billion tons of carbon dioxide. In 2005, the trees did not absorb that much carbon dioxide, but the forest lost more than 3 billion tons. The losses were caused by all the trees that died in the drought. The impact of the drought, 5 billion extra tons of carbon dioxide is more than the annual emissions of Europe and Japan put together.