NASA Satellite Measures Earth's Carbon Metabolism

Roland Piquepaille writes "To celebrate Earth Day, the NASA Earth Observatory recently revealed global measurements of the Earth's metabolism. 'Combining space-based measurements of a range of plant properties collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) with a suite of other satellite and surface-based measurements, NASA scientists produce composite maps of our world's 'net primary production' every 8 days. This new measurement is called net production because it indicates how much carbon dioxide is taken in by vegetation during photosynthesis minus how much is given off during respiration.' Check this column for a summary including the usefulness of such measurements. You'll also find maps showing the seasonal variation of Earth's net primary production."

These kinds of studies...

[Ratphace]

...are really important IMHO. Studying the carbon dioxide levels of any system is important because with the talks about someday inhabiting other planets like Mars, one of our first objectives would be getting greenhouse gases into the planet's atmosphere and then waiting many years for the planet to warm up enough to be inhabitable, both from a temperature standpoint and melting the ice caps at the poles (speaking of Mars of course).

I am glad to see some useful studies being done. Once a planet warms up enough with green house gases, we can get some plant life on the planet to assist in the creation of oxygen through this same cycle and eventually make a planet liveable. Though it's not something we'll see in our lifetimes, studies such as these benefit the species as a whole in the long run (i.e. big picture of time).

Coniferous forests

[Anonymous Coward]

I'm surprised that the coniferous forests in far north North America and Eurasia are more productive than the deciduous forests of more temperate climates. I'm wondering if the results of this are skewed because the temperate regions produce more carbon dioxide in the form of combustion emissions.

Interesting

[Musashi Miyamoto]

If I understand the pictures correctly, it's amazing to see how much carbon is converted in the northern hemisphere... in Canada and Russia. It counters the conventional wisdom of the Amazon as being the primary oxygen producing region.

It will make me doubt all those "save the rain forest" tree-huggers.

I wonder if they could do the same thing to show the amount of carbon being produced.

The Oceans

[jolyonr]

It's quite interesting to see how much carbon is being soaked up by the oceans. Much of this carbon eventually ends up as deposits on the sea floor and, after millions of years, limestone. It may be a lower amount of carbon intake than the forests, but then forest fires and biological action on dead trees can eventually release a percentage of the carbon that's trapped by trees.

Re:These kinds of studies...

[Daniel Dvorkin]

It seems to me that both the Earth and Mars are far below the limit of possible atmospheric density for their size. Consider Venus: slightly smaller than Earth, but it has a much, much denser atmosphere. If that kind of stuff scales linearly (and I don't have any idea of it does; I'm just guessing) then Mars would have no trouble holding on to an atmosphere as dense as Earth's.

I think I remember reading somewhere that the Moon -- with its surface gravity of 1/6 g -- could hold on to an Earth-density atmosphere for something like 10,000 years. Wish I could remember more.

Re:Lazy Oceans

[matt_morgan]

The Oceans are probably a buffered carbon dioxide sink. A LOT of climate research goes into the topic of how much CO2 they contain, and how much more they might contain.

For example, CO2 appears not to be increasing in the atmosphere as fast as it should be, given increased emissions. One likely carbon sink may be forests--that is, maybe production in forests increases when CO2 availability increases. However, many people doubt that forests are CO2-limited in terms of their growth. More likely, there's more than enough CO2 to go around and trees don't grow more than they do because they're limited by some other necessary ingredient (phosphorous, nitrogen, micro-nutrients, etc.). Of course, it's possible that forests are expanding--it's probably not the case, but it's conceivable given that large, previously cleared areas (the suburban northeast of the US) are growing more trees back.

The Oceans also may be absorbing CO2. One great environmental fear is that there is a limit to this absorption. Remember how buffered solutions worked in Chemistry 1? The ph goes down really slowly as you add acid, until the buffering is overwhelmed and then wham!, the ph increases rapidly with additional acid. Same thing with CO2 buffering in the Oceans, only we don't know when the buffering may be overwhelmed. If that happens, global warming rates should dramatically increase over what we see today.

Wally Broecker from Lamont-Dougherty Earth Observatory [columbia.edu] used to do a lot of work on this. I don't know if he still does, or who else might be doing it now.

Re:Coniferous forests

[SEWilco]

Um.. That's relatively more productive. See how much more active the Amazon area is? Now, that blue ring southeast of it is not a desert, it is merely covered with trees and grass similar to what you'd imagine the Iowa farmland to be (yes, the color of Minas Gerais and Iowa are similar). The purple is less active, like the grasslands of Wyoming (indeed, the "northeast Brazil [terravista.pt]" area is known for its dry land and ranchers, as are the pampas further south).

The forests along the east coast of the USA include those on the minor mountains of the Appalatian range -- a difficult area to farm. Also in there are the Smoky Mountains, named because often there is a haze due to the volatile chemicals (terpenes) released by the forest there.

Re:Coniferous forests

[Porag_Spliffing]

The old rain forests are in equilibrium. Old trees die and rot (or burn) and only some carbon is fixed most is re-released and balanced out by the growth replacing the old trees.

The coniferous forests of the northern hemisphere are often actively logged so have much young vigourous carbon fixing growth with the carbon being cut down and dragged off to make paper/ikea furniture.

Re:Coniferous forests

[SEWilco]

Any area which is extracting more carbon than is emitted will build up soil. That's why the prairies of the US midwest had six feet of black dirt.

There are many reports that the layer of topsoil in the Amazon is thin, which indicates it either is in a delicate balance or, more likely, negative balance. Probably a lot of the carbon is being washed away, and the forest is living on the recently produced soil. The Amazon is consuming more carbon than it emits in the air, but is leaking carbon downstream.

As long as the soil replacement is keeping ahead of the erosion this will work. Note that "erosion" can include holes carved by floods, which are then filled in -- a marsh becomes a black dirt plain in a short geologic time. Erosion down toward sea level can continue as long as that thin layer of topsoil slows it down, else a desert or canyon appears. Upstream of the Amazon are mountain ranges which can keep providing minerals for quite a while.

I suppose harvesting forests and locking the carbon in paper and wooden furniture/walls is a form of erosion also...

Geeky SIde of NPP Calculation.

[JungleBoy]

The Land NPP algorithm was developed at the NTSG [umt.edu] at the University of Montana [umt.edu]. I am the Sys Admin for this group.

We developed the software to do the Gross and Net primary productivity calculations (as well as some others), but the main production runs are done at the Goddard Space Flight Center in a room full of SGI Origin servers. Our development environment consists of several smallish linux beowulf clusters (32x1Ghz P3), a few Althon MP boxes, some old AIX dev boxes, and one SGI Oxygen for nasa code certification. Our largest resource is disk space, we have about 12TB of capacity. Keep in mind that this is just for algorithm development and testing. Goddard's production facility is huge, but that's becuase they are producing tons of other data products as well including all the land, ocean, and atmospheric products off of both the Terra [nasa.gov] and Aqua [nasa.gov] Satellites. This land productivity data (MOD17 in nasa speak) is derived in part from the MODIS [nasa.gov] sensor on Terra.

Both of these satellites are in sun syncronous polar orbits meaning that they come down over the earth's day side. This is because many of the sensors (like MODIS) are passive. Terra is the 'AM' satellite, it crosses the equator about mid morning local time, and Aqua being the 'PM' satellite crosses in the afternoon. The reason for this is because there is a significance in AM and PM cloud cover. Cloud cover is difficult to correct for (in fact with MODIS, sometimes you can't correct).

-JungleBoy (aka tweaker)
Melt our server room Axis Camera [umt.edu]
Automated GPP Images Site (in devel) [umt.edu]
My Lame Website. [tweaker.tv]