Saturday, February 27, 2010

You Can't Throw It Away

Redworms, Eisenia andrei to be exact, used in vermicomposting

Two years ago, the City of Raleigh, North Carolina proposed a ban of in-sink garbage disposals. It was a teachable moment, though city officials ultimately failed to take advantage of the moment. The ban was rescinded after a brief but loud public outcry.

The lesson that might have been taught would have reminded us that we all live in an ecosystem and a river basin, where everything is connected eventually to nearly everything else.

Throwing something in the trash or down the sink is not really throwing it "away". In an ecosystem, there is no "away"! We may embrace the concept, and practice something we call "throw it away", but ecologists know we are fooling ourselves. Each of us must learn a little about being good ecologists.

We burn gasoline in trucks hauling the contents of our trash cans to a landfill, where they take up space that could be forest or farm. The garbage very slowly decomposes, generating methane gas, and leaching toxins into the ground.

We must capture the methane lest it contribute to global warming more powerfully per molecule than carbon dioxide. We must collect the toxins so they won't poison groundwater beneath the landfill. And a lot of that stuff in the landfill, despite our recycling efforts, is valuable raw material today, or will be years from now. So much for throwing it all away.

Liquid and some solid wastes go down a pipe in toilets, dishwashers, clotheswashers, and sinks. These wastes go to a sewage treatment plant, a wonderful invention which breaks down the pathogenic, or disease-causing bacteria and viruses that can accompany the by-products of our lives.

When you also dump food or grease down your sink with the help of that garbage disposal and lots of water to hurry it along and keep the pipes from getting clogged, the food and grease goes to the sewage treatment plant. Problem #1 today, that is a waste of water. And as wonderful as sewage treatment plants are at killing bacteria and viruses, they are not so great at breaking down the nutrients in wastes and food. That is Problem #2.

In fact, the nutrients that a sewage treatment plant is not so good at breaking down, constitute the most important sources of water pollution today. Here's why.

First, these "nutrients" are essential chemicals that plants need to grow. Like fertilizer, they stimulate rapid growth of tiny plants called algae in a river or lake.

What's wrong with algae growing in a lake? Like all plants, algae produce more oxygen than they use, and that is good. But though a little is okay, too much means trouble, and we're not talking about the oxygen. The tiny algae do not live very long. As suddenly as they blossomed in response to the excess nutrients, they die and sink to the bottom of the lake.

Dead algae make good food for bacteria, so following the die-off of the algae comes a massive growth of bacteria. Although the bacteria themselves are not pathogenic, they require a lot of oxygen to grow.

The population explosion of bacteria decomposing the dead algae uses up all the oxygen in the water. Without oxygen in the water, the fish, indeed every living thing in the river or lake, dies.

So food scraps and grease that go down your drain add to the most important water pollution problem facing America today. But put them in the trash and they go to a landfill, which has an array of problems all its own. What can you do?

This is the part an ecologist loves.

Start a compost bin in your backyard! Composting allows us to "close the loop" on a lot of things we would otherwise "throw away". All those food scraps, egg shells, indeed, everything but meat scraps (which can attract unwanted animals), along with paper napkins, paper towels, even grass clippings and those leaves you love to rake up in the fall, all can contribute to the recycling of valuable nutrients in a compost bin.

And here's the exciting finale, what to do with the compost you create? Spread it in your garden, under plants in your yard or in a "natural area", you could even sprinkle a little as a natural fertilizer in your lawn. All those nutrients left over from delicious meals and lawn care can be recycled and reused. Spread and mixed into the ground, compost enriches soil, promoting better plant growth.

As ecologists we know we can't really throw anything away. But ecologists also know how to save water, reuse nutrients, protect water quality, limit landfills, enrich soil, and promote the growth of the beautiful trees, shrubs, flowers, and vegetables that can grace yards large and small.

Find out more about composting at

Wednesday, February 24, 2010

Spring Vegetables On The Way!

In less than two months, this little seedling will be feeding me delicious spinach greens in a salad! And most of the solid material for the growth that will make that possible will come from the thin air surrounding the leaves. Carbon dioxide, a gas that makes up a growing proportion of our atmosphere, is the sole source for all of the carbon that will form the backbone of the proteins, carbohydrates, and fats contained in this plant. Water, of course, along with essential elements such as nitrogen, phosphorus, and potassium, will come up from the soil through the belowground roots.

All of that carbon dioxide will enter my spinach plant through many thousands of tiny pores spread all over the surface of the leaves, called stomates. Thus does most of the solid mass of any plant first pass through a microscopic hole in a leaf as a gas molecule - a gas molecule that currently makes up just under one-half of one percent of the air!

The energy to get this lettuce seedling to burst out of its seed capsule, still attached, and grow up through the soil, came from molecules stored in the first, specialized leaves, called cotyledons. The two cotyledons are at the top of the short stalk, already turning green with chlorophyll and switching from using the energy that they came with inside the seed to the energy from the light bathing them almost 12 hours every day. With the energy from that light, the chlorophyll molecules will work with the other cellular machinery in these leaves to split carbon from oxygen in the carbon dioxide coming into the leaf. That energy will also be used to split hydrogen from oxygen in water coming up from the roots, and then to attach the carbon atoms to each other and to other atoms to make more cells and grow this lettuce plant from a tiny seedling to a delicious meal.

Sunday, February 14, 2010

Why Sterilize Soil Before Sowing Seeds?

What better way to anticipate the coming spring amidst all this cold weather than to plan your vegetable garden. With that in mind, as you collect your supplies and get ready to plant your seeds, consider this. If you ever wondered why agricultural extension folks suggest sterilizing your soil before starting seeds for your vegetable garden, this picture might be worth all those words you didn't read. Each of the four small compartments received 10 clover seeds on February 3rd. As you can see, the two compartments on the left held soil that had been sterilized, in this case meaning the soil was heated to 200 degrees F for 20 minutes in a microwave oven in my kitchen. Two days later seeds were germinating in all compartments.

It is worth noting that I set up this little test to see if the sterilization process released any toxins into the soil that might inhibit seed germination, as that is one danger of heating soil to 200 degrees. So when the seeds in the sterilized soil germinated as readily as those in the untreated soil, I felt confident that I could use the sterilized soil to start the seeds for this coming spring's vegetable garden.

As the seeds came up, I continued to keep track of how many successfully germinated in both sterilized and unsterilized soil. Here are some of the results:

Yesterday, day 10, I first noticed that a couple of the seedlings in the unsterilized soil collapsed. Today, day 11, I took the picture above. Fungus is more than likely responsible, fungus that heating to 200 degrees F killed. In this case the fungus did not inhibit seed germination, but did kill several of the very young seedlings.

Saturday, February 13, 2010

Climate Change and Snowstorms - It's All About the Energy

Snow on rosemary, 2/13/2010, Cary, NC

The story of climate change is the story of energy, in particular, the Earth's balance between incoming and outgoing energy. Our planet's energy equation begins with sunlight. More and more sunlight energy arrives at Earth with each passing day. That sunlight energy warms the ground, bodies of water, plants and animals. Each of those objects in turn radiates its own energy according to its temperature. Since those objects are much cooler than the sun, they radiate energy of a different wavelength than the sun. The sun radiates in the visible wavelengths, but the Earth and everything on it radiates in the infrared wavelengths, which are invisible to our eyes.

Greenhouse gases such as carbon dioxide and methane in our atmosphere are transparent to sunlight just like the nitrogen and oxygen that make up most of our air. However, what makes CO2 and methane effective greenhouse gases is their ability to absorb infrared radiation, something nitrogen and oxygen cannot do. So the greenhouse gases let in sunlight, which warms the Earth, but they do not let infrared radiation escape. Instead, they absorb that infrared radiation and themselves get warmer. As CO2 and methane get warmer, they radiate more infrared radiation themselves, much of it heading back towards the Earth, adding to the warming effects of sunlight.

So the more greenhouse gases reach the atmosphere, the more infrared radiation is absorbed, and the warmer the entire planet becomes. But why would a warmer planet mean more snow or more severe storms?

It's all about the energy. More sunlight coming in and less infrared radiation going out means more energy here. And more energy means higher temperatures, on average. But how can higher temperatures mean more snow?

Because it takes energy to evaporate water. As temperatures rise everywhere, water evaporates faster and faster. More water evaporates from the oceans, from lakes and rivers, even from moist soil. More water even evaporates through the tiny pores covering the leaves of plants growing around the world.

More water evaporation means more total water vapor in the atmosphere, and that inevitably leads to more precipitation. With temperatures above freezing, that precipitation comes down as rain. Drop the temperature below 32°F, and the precipitation comes down as snow or sleet or freezing rain.

Ask a native of Buffalo, New York about the role that water evaporation plays in snowfall. "Lake effect" snow results when water evaporates from a nearby lake - in the case of Buffalo, Lake Erie to the west or Lake Ontario to the north. More water evaporating into the air means more precipitation, and in the winter, even with the greenhouse effect, temperatures can drop below freezing and that precipitation will be frozen. And remember that one inch of rainfall can, if frozen, produce somewhere between 6 and 10 inches of snow.

What is it about a warmer planet that can lead to more severe storms? Storms, with strong winds, heavy precipitation, perhaps even lightning, release a great deal of energy. Where does that energy come from?

Much of the energy in a storm comes from the water vapor in the air within the storm. Remember that it took energy to evaporate that water in the first place. Water vapor carries all the energy it took to evaporate it up into the atmosphere. And as that air rises it cools, and the water vapor cools with it. Eventually the cooling water vapor does not have enough energy to stay a gas, and condenses back into tiny droplets of liquid water, forming clouds. Condensation releases the energy it took to evaporate the water, and that released energy passes to the surrounding air, adding to the strength of the storm.

Global warming driven by a stronger greenhouse effect upsets the energy balance of the planet. More energy evaporates more water. More water vapor makes more precipitation and stronger storms. And in the winter, more precipitation and stronger storms can mean snow and blizzard conditions. Greg Craven, a high school physics teacher, suggested global "weirding" might be a better title than global warming. And that was before the 2010 snowpocalypse hit the mid-Atlantic states.

Tuesday, February 2, 2010

More on James Hansen's UNC Presentation

Dr. Hansen described the three categories of evidence used to understand climate change. The historical record of temperature and carbon dioxide concentration is first in line, whether that record comes from instruments deployed around the world for which 130-years of data are available, or air trapped in glacial ice, for which data goes back 800,000 years. I would add that the historical record for CO2 and temperature now goes back 20 million years with the publication by Aradhna Tripati of her work with the foraminifera.

The next line of evidence includes current atmospheric and climate conditions, such as temperature data from around the world, glacier conditions in mountains and at the poles, and ocean chemistry.

Third-ranked by Hansen are computer-based climate simulations.

Dr. Hansen went to some length to explain the causes of historical climate variability. In addition to the climate forcings related to the Milankovitch cycles, he mentioned plate tectonic activity. When India was an island continent south of Asia, it was moving north through the Indian Ocean. During this time period, Hansen suggested that large amounts of carbon dioxide were released by volcanic activity triggered by this plate movement. This corresponds to a very warm period on the planet, much warmer than today, when sea levels were considerably higher as there were no large glaciers.

Some mention was also made of the oceans as a sink for atmospheric carbon dioxide, but I missed the reference (2009) and have not been able to find it. The new finding was of carbon measurements down to a depth of 2 km below the ocean's surface, and Hansen was quite excited about it. If any readers out there know of this study, please advise!

Monday, February 1, 2010

James Hansen at UNC Chapel Hill

James Hansen, director of the NASA Goddard Institute for Space Studies, spoke at UNC Chapel Hill earlier this evening. As he put it himself, he is not a communicator, but a scientist who feels compelled to speak out because the gap between what is known by climate scientists and what is understood by a seeming majority of the public is very large and growing.

That he feels so compelled may be the most significant story, but it is not one that I want to tell.

I want to relate the important science story that he told.

He spoke of the inertia in a climate system that encompasses the entire planet. Estimates suggest that we have experienced about half of the warming expected based on the increases in atmospheric carbon dioxide since it was 280 ppm. That means if we immediately reduced our carbon emissions to the point where the atmospheric concentration rose no higher than it is today, we would continue to experience climate change and global warming for some time to come, and about double what has occurred thus far.

Dr. Hansen also spoke about tipping points, moments in time where the climate system may begin to change in ways and at rates over which we will have no control. These tipping points have most to do with positive feedbacks that may begin to operate. There are two big ones according to Hansen. First - melting ice sheets resulting in decreased surface albedo or reflectivity causing more absorption of sunlight and more heating, melting more ice sheets in a spiraling of warming.

Second, the danger of warming oceans allowing methane hydrates on the floor of the shallow areas of the oceans to "thaw" and bubble up to the surface and enter the atmosphere. Methane's greenhouse gas efficiency is more than 20 times that of carbon dioxide. More methane means more heating, meaning warmer oceans, causing the release of more ocean floor methane in a runaway greenhouse scenario. A 2009 story I summarized a while back goes into a little more detail on this feedback loop's scary possibilities.

There were a few other key concepts that will have to wait for a later posting. For now, the take home lesson is that Opa Hansen wants to remind us that global climate change's big losers have either only recently arrived on planet Earth, or have not yet even been born. The decisions we make in the next couple of decades will shape the face of this planet, and strongly influence the quality of life for our grandchildren, great grandchildren, and great great grandchildren.