How much of terrestrial plant and animal life can humanity safely consume without seriously damaging the live-support systems of our planet? It has been challenging to answer that question because of the difficulty of measuring how much biomass is produced annually on land and how much of this yearly production humans co-opt.
Huge regional variability exists in terrestrial productivity from year to year because of heat, cold, floods and droughts but what is striking from recent reviews of more than 30 years of satellite imagery is how little global variability there is annually. Each year, terrestrial plants fix about 53.6 petagrams of biomass – a gigantic quantity but what matters is not so much the size of annual biomass production but rather that it seems to vary by only about two percent per year.
Recent estimates from satellite imagery indicate that humans now appropriate 38 percent of all terrestrial biomass generated annually. That would seem to leave 62 percent on the table for expanded human consumption but the vast majority of this biomass appears to be not harvestable because it includes root growth below ground and biomass production on lands in parks or wilderness areas that are either protected or inaccessible.
It appears likely that the upper limit for how much of terrestrial biomass that humans can co-opt annually is only about ten percent more for a total of 48 percent. Current land use patterns and projections that the global human population may reach nine billion by 2050 suggest that this 48 percent of all available terrestrial biomass may be reached within the next few decades.
Courtesy NOAANitrogen is an essential nutrient for plants. So how can nitrogen limit plant growth, given that nitrogen comprises 79 percent of the atmosphere? But atmospheric nitrogen is composed of molecules consisting of two atoms of nitrogen and this form of nitrogen cannot be used by plants.
Farmers have for centuries spread animal manure on fields or plowed under leguminous crops (such as alfalfa which has microbial communities living on its roots that fix nitrogen) to add useful, reactive forms of nitrogen to soils. German ingenuity in the early 20th century invented an industrial process that made it possible for the first time to manufacture plant-usable forms of nitrogen, which made possible the artificial fertilizing of crops.
Manmade production of ammonia and nitrate fertilizers has exploded in recent decades and now vastly exceeds the amount of atmospheric nitrogen converted into reactive nitrogen by microbial organisms around the world. At the same time, the burning of ever-increasing quantities of coal, oil and natural gas converts some atmospheric nitrogen into oxides of nitrogen (NOx). NOx emissions can both increase crop growth and diminish it because NOx gases help catalyze the formation of ground-level ozone and this gas is toxic to plant life.
The huge increases of human-produced forms of nitrogen that are applied to croplands and that are released into the atmosphere and eventually settle out have many unintended consequences. In particular, excess nitrogen washes off of agricultural and urban landscapes and is accelerating the destructive growth of algae in lakes, rivers and coastal estuaries around the world.
The connections between manmade carbon dioxide emissions and climate change are quite worrying and receive much scientific and media attention. Nitrogen pollution receives much less notice but is a dramatic example of how human activities now dominate many of the chemical, physical and biological processes that make this plant so amenable to human life.
This amazing video from NASA (via EarthSky) shows an incredibly gigantic eruption on the Sun's surface that produced three different types of events: a solar flare, a coronal mass ejection (CME), and a really interesting and rare phenomenon known as coronal rain.
Coronal rain occurs when hot plasma in the eruption cools and condenses then follows the outline of the normally invisible magnetic fields as it rains back to the Sun's chromosphere. I found that particularly amazing to see.
The images were gathered on July 19, 2012 by the Solar Dynamics Observatory’s AIA instrument. One frame was shot every 12 seconds over a span of 21.5 hours from 12:30 a.m. EDT to 10:00 p.m. EDT. The video plays at a rate of 30 frames per second, so each second equals 6 minutes of real time.
What's extra cool is when the scale of this thing is compared to the size of Earth. If you were feeling small earlier today, you should be feeling microscopic after watching this.
Courtesy NASA/JPLLast week could have been called "Chicken Little Week" with the near miss of Earth by an asteroid and and the dazzling, but havoc-producing meteor crossing through the Russian skies. Have you taken off your safety helmet yet?
While it takes an extraordinary week like that to make most of us think about the dangers looming out in space, there are researchers dedicated to tracking the dangerous projectiles in space. Here's a great report on public and private research groups keeping track of the random traffic in the skies.
Interestingly, they claim that we only really spot about 10 percent of the miscellaneous space stuff that could collide with Earth. And, they're not just settling for trying to pinpoint where the problems are. They're trying to figure out ways to deflect or break-up potentially damaging space threats. Taking it one step higher, some are even investigating ways to mine key minerals from these threats to Earth.
Courtesy NISE NetworkWhen things get really really small (nanoscale small), they behave completely differently! For example, gold at the nanoscale can look purple, orange, or red; static electricity has a greater effect on nanoparticles than gravity; and aluminum (the stuff your benign soda cans are made of) is explosive at the nanoscale!
If you want to experience some of these nanoscale phenomena first-hand, check out whatisnano.org, or download the DIY Nano app. The website and the app were both created by the Nanoscale Informal Science Education Network (NISE Net for short), and have videos and activity guides, complete with instructions and material lists, so you can do some nano experiments at home! The app was a Parents' Choice award winner for 2012, and was featured in Wired Magazine's review of apps. Definitely worth a look!
Have fun exploring nanoscale properties!
Courtesy NASAWe like to think of our home planet – Earth – as a pretty unique place. It's the only planet in our solar system capable of sustaining life. We look through telescopes and to see exotic looking planets of various sizes and shapes. But we're the one and only Earth, right?
A new census of planets in the Milky Way galaxy shakes up that thinking. New data collected by NASA's Kepler spacecraft pegs one in six stars in the Milky Way of having planets that are the same size as Earth. That one-sixth fraction translates into an estimate of about 17 billion planets that are the same approximate size as our home.
So we're not as exclusive as might like to think. But the exclusivity meters edges back toward us when you factor in the Goldilocks zone – a distance from the host star that's not too hot nor too cold to sustain life. So far, extended research on the new-found planets has identified only four Earth-sized planets that could possibly reside in a Goldilocks zone. The Kepler project has identified a total of 2,740 potential new planets with more research ongoing.
Courtesy GLOBE at Night(This post is a copy and paste of an email I received for this interesting citizen scientist activity...)
What would it be like without stars at night? What is it we lose? Starry night skies have given us poetry, art, music and the wonder to explore. A bright night sky (aka light pollution) affects energy consumption, health and wildlife too. Spend a few minutes to help scientists by measuring the brightness of your night sky. Join the GLOBE at Night citizen-science campaign. There are 5 GLOBE at Night campaigns in 2013: January 3 - 12, January 31 - February 9, March 3 - 12, March 31 - April 9, and April 29 - May 8. Make a difference and join the GLOBE at Night campaign.
GLOBE at Night is a worldwide, hands-on science and education program to encourage citizen-scientists worldwide to record the brightness of their night sky. During five select sets of dates in 2013, children and adults match the appearance of a constellation (Orion or Leo in the northern hemisphere, and Orion and Crux in the southern hemisphere) with seven star charts of progressively fainter stars. Participants then submit their choice of star chart with their date, time and location. This can be done by computer (after the measurement) or by smart phone or pad (during the measurement). From these data an interactive map of all worldwide observations is created. Over the past 7 years of 10-day campaigns, people in 115 countries have contributed over 83,000 measurements, making GLOBE at Night the most successful, light pollution citizen-science campaign to date. The GLOBE at Night website is easy to use, comprehensive, and holds an abundance of background information. Through GLOBE at Night, students, teachers, parents and community members are amassing a data set from which they can explore the nature of light pollution locally and across the globe.
Listen to a fun skit on GLOBE at Night in a 7-minute audio podcast here.
Courtesy Mark RyanWhat a difference a year can make. The water levels of the Mississippi River this year are at their lowest on record, yet just last year, in the spring of 2011, extreme flooding of Ol’ Muddy was a source of deep concern for those living along its eroding banks.
NASA’s Earth Observatory page shows the striking difference in the river’s appearance near Memphis using two Landsat satellite images taken a year apart. One photograph shows the river in August of 2011 just after the river returned to its pre-flood levels. But if you compare it to a more recent image, its obvious that water levels have gone the opposite direction from flooding. The site conveniently allows you to combine the two views into a single image with a scroll bar you can manipulate back and forth over to see “then and now” differences (just click on the "View Image Comparison" button below the photos).
The lower levels of 2012 have allowed the US Army Corp of Engineers to patch and reinforce some of the levees built along the river to hold back flood waters, but tons of sediment from last year’s floods have reshaped river traffic corridors, reducing barge holding capacities and adding additional shipping costs.
Tonight, as you're wondering if your level 81 dark elf mage and her sweet double-enchanted dragonscale armor makes up for the girlfriend you lost playing Skyrim, turn your xbox over to the live streaming of the landing of the new Mars rover, Curiosity. Because it's right there on your console's dashboard!
It's really a win-win situation. Arborea Darkshadow can wait a few minutes, I'm sure, and you'll either get to witness an action-packed landing of a big new Mars rover, or you'll get to see the hopes and dreams of hundreds of scientists and engineers crash and disintegrate on the cold surface of a dead planet millions of miles away!
You know what JGordon will be doing approximately 12 hours from now? Definitely not watching the Curiosity landing! But that's only because I don't have an internet connection at my apartment. No, I'll probably be forcing the cat to participate in the St. Paul Cat Olympics. As far as I know, there will be only one contestant, but it promises to be hilarious! Why? Because she probably can't swim very well.
Mars! Be there!
Courtesy NASA JPLWait, who was I quoting in that headline? Me. I was quoting me, from when I described the upcoming Mars rover landing in my head as "pretty frickin' awesome." Or ... that was very nearly what I thought, but the specifics of what goes on in my brain pit are for adult ears only.
Which adult? This one. Me.
Anyway, NASA's Jet Propulsion Laboratory has produced a video about how the landing of the Mars rover Curiosity will go down, when the spacecraft carrying it reaches the Martian atmosphere on August 4. As you'll see when you watch the video below, there's dramatic music, scientists and engineers speaking dramatically, and dramatic flashing graphics. All very nice and of high production value, but it makes me want to say, "Hey, don't be dorks, dorks. Geez."
But I can't. Because it actually looks pretty awesome. The spacecraft is going to enter the atmosphere going 13,000 miles an hour, which will heat it up to about 1600 degrees. Then a giant, super tough parachute will shoot out, and slow it down to a couple hundred miles an hour. And then the capsule will break open (before it hits the ground), and another flying device will fall out, the "Sky Crane." The Sky Crane will use rockets to zoom away, and then hover above the surface of the planet. It will then lower the actual rover down on a cable. Once the rover touches down, the crane will blast off again, so it doesn't crash into the rover. Pretty amazing. Take a look: