Solar Power Education Series

Solar Power 101- A Community Education Series

Congresswoman Gabrielle Giffords in partnership with Pima County Public Library presents Solar Power 101: A Community Education Series on Solar Energy.

Space is limited for each session. PLEASE RSVP to or 881-3588.

Wednesday, May 14, 2008
Joel D. Valdez Main Library
The community education series will conclude this month. Today’s topic is: “The Potential of the Solar Industry,” with solar-energy advocates Valerie Rauluk and Tom Alston speaking about economic and technological opportunities and obstacles, as well as policy issues and hurdles.

Invasive, Indeed

One species-Homo sapiens-consumes nearly a quarter of Earth’s natural productivity

by Sid Perkins
Science News, Oct. 13, 2007, Vol 172, #15, pg 235

Some people live lightly on the land: Bedouin clans roam the deserts of the Middle East and North Africa; small groups of indigenous people follow reindeer herds across frigid Arctic terrain; and tribes of hunter-gatherers forage the plains of southern Africa and the forests of Amazonia and Papua New Guinea.

LAND GRAB. About half of the 15.6 billion metric tons of carbon that people remove from Earth’s ecosystems each year is harvested in the form of crops.

Then there’s the other 6.6 billion of us.

When we farm, clear forests, and build cities, dams, and roads, we dramatically alter the landscape. In some places, we increase the land’s productivity-measured as the amount of plant life at the base of the food chain-by adding immense amounts of water and fertilizer. New research indicates that on the whole, however, human presence significantly decreases Earth’s biological productivity. For instance, many of today’s cities occupy large patches of what had been some of the world’s most fertile land.

Of the biological productivity that remains, people are gathering an ever-increasing share, sometimes by boosting their quality of life, but often merely by dint of their burgeoning numbers. In some regions, each spanning millions of square kilometers, human activity consumes almost two-thirds of the biological productivity that would otherwise be available.

“We were surprised how intensively these regions were being affected” by human presence, says K. Heinz Erb, an ecologist at Klagenfurt University in Vienna. “Only one-third of the natural productivity is left for all the other species.”

Overall, nearly one-quarter of Earth’s land-based biological productivity ends up in people’s hands and bellies, Erb and his colleagues estimate. Other research suggests that people appropriate a comparable, but slightly smaller, share of the ocean’s productivity-defined as the mass of photosynthetic organisms at the base of the sea’s food chain.

A projected 25 percent increase in the world’s population by 2030 is bound to strain ecosystems even further. Increasing agricultural efficiency by irrigating and fertilizing the land can add to the strain by boosting erosion and the nutrient runoff that creates toxic algal blooms and large anoxic zones in oceans. Adding insult to injury, proposals to transition from fossil fuels to renewable biofuels would place yet more of Earth’s productivity in people’s hands.

Some scientists now wonder: At what point do the world’s ecosystems begin to break down? Or, more frighteningly, has that process already begun?

Reaping, sowing

Before people invented agriculture, they roamed the landscape in search of sustenance. When resources became too scarce to nourish the group, it was time to move on. When people began to farm the land, however, their habits changed considerably, to the detriment of many ecosystems. Settlers built year-round shelters and often cleared acreage for their crops.

“The rise of modern agriculture and forestry has been one of the most transformative events in human history,” says Jonathan A. Foley, an environmental scientist at the University of Wisconsin-Madison.

Practices vary somewhat, but typically, people heavily farm the most fertile land, use marginal lands for grazing domestic animals, and plant single-species tree farms in areas where forests once stood. Whatever the use, the production of forest or agricultural goods comes at the expense of natural ecosystems, observes Foley.

Today, croplands and pastures are among the largest ecosystems on the planet. People farm about 12 percent of the land outside of Antarctica and Greenland and use about 23 percent for grazing, says Foley. Together, land devoted to these uses equals the 35 percent of Earth’s surface that natural forests occupy, he notes.

To estimate the effect that humans wreak on the world’s land-based ecosystems, Erb and his colleagues used agricultural and forestry statistics compiled for 161 nations that account for 97.4 percent of Earth’s icefree land. Most of the remaining area is located on small, uninhabited islands, Erb notes. In their computer model, the researchers divided the planet’s land surface into grid squares no larger than 10 kilometers per side.

The team estimates that if people weren’t around to alter the landscape, the world’s natural vegetation would absorb enough carbon dioxide from the atmosphere to lock away about 65.5 billion metric tons of carbon each year. However, in 2000, the year for which the data were compiled, Earth’s vegetation locked away only about 59.2 billion metric tons of carbon, or 9.6 percent less than it should have, says Erb. Of that smaller carbon total, human activities removed about 15.6 billion metric tons-a whopping 23.8 percent-from the world’s ecosystems. A little more than half of the carbon that people appropriated was harvested and used as food, forage, and wood, Erb and his colleagues note in the July 31 Proceedings of the National Academy of Sciences. Most of the rest was lost to inefficiencies of agriculture, including the inability of crops to store as much carbon as natural vegetation would have stored. A small amount, about 7 percent of the carbon that people take out of the system, went up in smoke produced primarily by slash-and-burn agriculture, says Erb. All of this human-appropriated carbon became unavailable to other species.

Human harvests don’t stop at the shoreline, either. The world’s most productive fisheries typically lie in and near the shallow waters that fringe the coasts of large islands and continents, says Daniel Pauly, a fisheries biologist at the University of British Columbia in Vancouver. Scientists have divided such coastal waters into 64 large marine ecosystems. These areas can vary in character and inhabitants as much as arctic tundra differs from an Amazonian rain forest.

About 95 percent of the world’s fish catch comes from large marine ecosystems, says Pauly. For the past decade or so, that haul has represented about 20 percent of the natural productivity of those regions, as measured by the amount of carbon locked away by organisms at the base of the ocean’s food chain.

Efficiency matters

While wilderness areas remain relatively unaffected by people, other parts of the world are packed cheek by jowl with cities, farms, and other human imprints.

Southern Asia, a 6.7-million-square-kilometer region that includes India, is one of the most densely populated and heavily irrigated regions on the planet, says Erb. There, human activity co-opts about 63 percent of the area’s natural productivity each year, he and his colleagues estimate. In eastern and southeastern Europe, people appropriate about 52 percent of the land’s productivity.

At the other extreme, in Australia, central Asia, and Latin America, the percentage of productivity that ends up in human hands ranges between 11 and 16 percent. Increasing the use of fertilizers and irrigation could boost those percentages and help meet the needs of a growing world population. However, long-term irrigation sometimes renders the soil too salty for crops, and fertilizer, if used unsparingly, runs off into rivers and streams and ends up in the ocean, where it overfertilizes algae and thus creates huge zones devoid of other life. “There’s no free biomass,” Erb cautions.

In the stampede to replace fossil fuels, some scientists have proposed the large-scale cultivation of crops that can be transformed into supposedly eco-friendly biofuels. That, too, might be ecologically unwise.

“If the whole world begins to look like Iowa cornfields, we’ll have to take an even larger share of global biological production into human hands, and that leaves a lot less for other things,” says Foley. “And those other things won’t be just pretty butterflies and tigers and charismatic animals, they’ll be things that matter to us, like the things that clean our water, preserve our soils, clean our atmosphere, and pollinate our crops.”

“At what point does human activity begin to compromise a lot of our environmental systems?” Foley continues. “At what point does this get to be scary?”

Mesquite Pancake Breakfast

The 5th annual Desert Harvesters Mesquite Milling Fiesta and Mesquite Pancake Breakfast will be held at the Dunbar/Sring Organic Community Garden, located at the NW corner of North 11th Ave and West University Blvd. The pancake breakfast starts at 9:00 am and goes until the batter runs out. Prickly pear, mesquite, and maple syrups will be provided.

You can bring your mesquite pods to mill into flour. A $3 minimum donation is requested for the milling.

Sustainable Design Weekend Intensive

Sustainable Design Weekend Intensive – Cosponsored by Tucson Permaculture Guild and Sustainable Tucson

This weekend class, a short version of the 72 hour Permaculture design course, will help you develop practical design skills using Permaculture principles, ethics, and a unique design process. Participants will complete a site analysis on a place of their choosing (their home and yard for example) the first day of class; then based on that analysis, complete a master design plan on the second day. With an integrated master plan each part of the design nestles together in a functional and beautiful way. The master plan also acts as a blueprint to start take action toward sustainability. The site analysis and design work with be intermixed with short hands-on classes on practical permaculture skills.

Location: Mesquite Tree Permaculture Site, one and a half miles north of downtown Tucson, 221 E. Linden St. a few blocks south of Grant and 6th Ave.

Time: Sat, Nov 10th 9:30 AM to 4:30 PM, Sun, Nov. 11th 10:00 AM to 4:00PM. For registration info contact Dan Dorsey, 624-8030, Cost $90 to $135 sliding fee scale, which includes all handouts for the class.

What to bring: Your lunch both days and a drawing of your house and property (with the acutal dimensions if you know them)

The sketch doesn’t have to be to scale, but show all existing buildings, vegetation, and a north arrow.

Snacks and tea will be provided.

frequently asked questions about Fall 2007 courses…

How do I register for a class(es)?

You are registered for a class(es) when we receive your payment. There are three ways of registering and paying for a class:

1.You can pay via mail with a check or money order made out to NEST/Sonoran Permaculture Guild. Mail it to Dan Dorsey, 221 E. Linden Tucson, AZ 85705 Please don’t send cash in the mail. Please include your contact info including e-mail. We will send you an e-receipt confirming your registration and payment.

2.You can pay cash by visiting us in person and we will give you a receipt for your payment and registration. Call the contact person for the course and make arrangements to meet.

3.You can pay via major credit card, as we are set up with PayPal to receive payments. E-mail your request to pay with a credit card to the contact person for the class, and we will e-mail back with instructions on how to pay via the secure Paypal website.

If after I register and pay for a course, what if I have something come up and I need to cancel out of a class?

Our refund policy is as follows:

Full refund up to 7 days before the class begins.

50% refund up to three days before the class begins, but you may apply part of your fee to a future class.

No refund within three days of class, but you may apply part of your fee to a future class.

If the class is full with a waiting list, and we can find someone from the list to take your place, we will refund your payment in full.

Mesquite Tree Permaculture Site – a demonstration and teaching site for learning how to live a sustainable lifestyle.

We are located about one and a half miles north of downtown Tucson , AZ near 6th Ave.

Brief History

This site, owned in 1994 by a non-profit corporation, consisted of a small slump block house built in 1949 on a bare, compacted one fifth acre. The current owner, Dan Dorsey, bought the property in 1994. He completed a site assessment of the property during the first three months, studying patterns like wind, sun, rain, and noise and light pollution (to name a few) that affected the site. He also observed and mapped existing conditions on the site like the soil, the human and animal traffic patterns, and the sparse existing vegetation. Using a contour mapping tool, he established elevations and contour lines on the site to better look at slope and wate flow. He also studied existing maps of the neighborhood available from the City of Tucson .

Then using his completed site assessment and a sustainable design process called Permaculture (which is an environmental design process based on natural ecosystems), Dan began to put into place regerative strategies to help the land recover.

The result today is a rich multi-use – but drought tolerant – landscape with over 120 species of plants, animals, and insects. The plants produce food, medicine, mulch, shade, and wildlife habitat. Since all rainwater from roof surfaces is harvested into water cisterns, and the overflow directed into basins that water the landscape, the annual water use for the site is far below the Tucson residential average, even with the extensive landscape.

Other features at Mesquite Tree include:

*A strawbale office studio and small guest house, which demonstrate energy efficient passive solar design.

*A renovated slump block residence which demonstrates numerous strategies for appropriate housing in hot dry climates ( including a solar panel array on the roof, passive solar design, tree shading on the west side, and a wrap of the original block walls with insulation).

*A multi use ramada classroom, where ongoing classes and courses on sustainability are held throughout the year.

*A small scale intensive food garden watered solely from rainwater in the cisterns.

*A graywater system to re-use shower and bathroom sink water in the landscape.

*A commercial made solar oven that heats to over 400 degrees F.

*One of the best examples in Tucson of a sustainable urban site using Permaculture principles.

Please call Dan Dorsey at (520) 624-8030 or e-mail for more info.

Also check out our website at

Teacher Bio
Dan Dorsey, B.S., teaches courses on environmental design, water harvesting, natural building, and many other topics that help people live a sustainable lifestyle. He is an adjunct faculty member of Pima Community College and Prescott College , and a member of the Sonoran Permaculture Guild teaching team. Dan offers Permaculture design and consultation services, having designed over 60 permitted energy saving homes and auxiliary buildings in Pima County and the City of Tucson . He also designs multiple use sustainable landscapes that produce food, reduce home energy bills, attract wildlife, and perform other beneficial functions. Working with neighborhood associations, non-profits, and businesses, Dan uses a Permaculture based design process that gets people in organizations working together to arrive at their own environmental solutions – solutions that can take care of people while at the same time take care of the environment. Dan lives at his teaching and demonstration site, Mesquite Tree, one mile north of downtown Tucson , where he lives the low impact environmental lifestyle he teaches.

His contact info is (520) 624-8030 or e-mail