Lush forests remain in the Dominican Republic, where imported propane and natural gas have diminished the need to harvest wood for fuel. Contrast this to Haiti, where lower rainfall combined with the blind response to continued population explosion–much of it brought in by French landowners developing large plantations to extract resources–has contributed most significantly to that country’s more rapid deforestation and resulting loss of soil fertility.

Bringing his examples closer to home for his audience, Diamond spoke of the Anasazi who once lived in Arizona and New Mexico. Evidence exists that the now‑desert land of the ancient Anasazi was covered with flourishing pine and juniper forests. And the Anasazi, by all records, developed an advanced society whose accomplishments include skyscrapers that remained the tallest buildings in North America until the 1870s saw the construction of steel‑girded towers in Chicago.

Diamond’s reconstruction of the Anasazi’s decline begins with the advantageous import of corn and beans from Mexico. Successful farming led to a population explosion, which, in turn, led to felling of more trees and development of more land for farming. Extensive canals supported the agriculture. But deforestation affects both water table and soil quality, and, Diamond pointed out, reforestation is much slower in drier climates like the land of the Anasazi. Irrigation canals suffered from the deep ditches cut in them from periodic heavy rains, which lowered the water table to a level too low for effective irrigation. An extended period of drought left the Anasazi unable to feed its population in the complex and interdependent society it had established, and archaeologists believe somewhere around the year 1118, after five centuries of existence, they died out. Diamond summed it up: “They made the wrong (environmental) choices to feed their population.”

In another example, Diamond underscored the importance of a society’s leaders feeling invested in the problems confronting it. Much of the habited areas of the Netherlands, he noted, is actually below sea level; if the dikes fail, the elite will drown along with the masses.

That situation, Diamond shared, was explained to him by his hosts when he visited the country, who also gave it as the reason a high percentage of the Netherlands’ population is involved in environmental causes.

Referring to the development of gated communities in his home state of California, Diamond expressed, “I’m concerned with the increasing insulation of the elite (here).”

Protecting themselves against the broader problems of society (e.g., drinking bottled water, hiring private security guards, and sending their children to private schools) may work in the short term, but, Diamond pointed out, “Insulation is no longer working. The walls of the Atlantic and Pacific Oceans no longer keep out terrorists or unstoppable waves of immigrants.”

Differences between the past and the present do exist, Diamond acknowledged. But the plus side of our present globalization by which we enjoy improved communication is countered by the fact that, because of globalization, we now run the risk of global collapse instead of localized collapse of individual societies. And while technology can play a role in solving problems, Diamond emphasized, “We need the will to use it.”

However, he cautioned, “If you do experiments on a large scale, you usually end up with unanticipated consequences, often disasters.” To this response to a question about global warming (“Arizona will be among the losers.”) and the possible benefits of a man‑made volcanic spew to buy time in the short‑term, Diamond recalled an earlier scientific breakthrough.

“Dangerous refrigerator gases were replaced with CFCs, and look what happened. It destroyed the ozone layer.”

Diamond expressed his hope that present societies can learn, through studies of archaeology and history, from societies remote in both time and geography.

He closed by sharing with the audience the responses he had received from students in the classes he teaches at UCLA. Asked what they imagined were the words of the Anasazi who chopped down the last tree, they suggested:

“Never fear; technology will solve our problems. We’ll find another source for wood.”

“This is the American West. This land is my private property. Respect my property rights and keep government issues off my back.”

“I am so sick and tired of you lily‑livered tree huggers. You care more about trees than you do about the jobs of us loggers.”

“Fear is premature. What we really need is more research.”

Phoenix’s Mayor Phil Gordon acknowledged his support for environmental action, preceding the guest speaker at the podium and proclaiming December 1 “Change a Light, Change the World Day” in Phoenix. APS, in support of Valley Forward’s newly launched pledge drive to increase usage of compact fluorescent light bulbs (CFLs) that use one‑quarter the energy and can last 10 times longer than incandescent bulbs, provided a CFL bulb to each attendee to take home.