Natural Perspectives -- Vic Leipzig and Lou Murray

Vic Leipzig and Lou Murray

We went to see the movie “Ice Age” this weekend. We enjoyed the comic

adventures of a giant sloth, a wooly mammoth and a saber-toothed tiger as

they embarked on an unlikely journey across a frozen wasteland to return

a human baby to its “herd.” The time setting was 20,000 years ago during

the Pleistocene era. The physical setting could have been here.

During the last Ice Age, huge glaciers covered most of North America,

including the mountains to the east of us. With so much of earth’s water

tied up in ice, ocean levels were 300 feet lower than they are today. But

12,000 years ago toward the end of the Pleistocene, the climate changed.

Dramatic global warming melted the ice. As the glaciers melted, torrents

of water gushed over the plains of what is now Orange County, cutting

deep river beds. The rivers that ran here then rivaled today’s Columbia

River in size.

At the Bolsa Chica wetlands, you can see the land carved by one of

those huge rivers. Bolsa Chica Mesa and Huntington Mesa rise to the north

and south of the wetlands, respectively, and define that old riverbed. At

the mouth of the Santa Ana River, we can see another old riverbed, with

Huntington Beach on the north and Costa Mesa on the south. A third

channel cuts through at Newport.

An early theory was that the Santa Ana River changed course numerous

times and carved all of these ancient riverbeds. A new theory espoused by

Dr. Ivan Colburn, a professor of geology at California State Los Angeles,

says this isn’t true. He contends that there was not one river, but

three, one for each of these main channels. He named the ancient river

that carved the lowlands between Bolsa and Huntington mesas the Bolsa

River.

During the time that the Bolsa River rushed to sea, great beasts

roamed the plains. Evidence from the La Brea tar pits in Los Angeles

tells us that wooly mammoths were here, along with giant sloths,

saber-toothed tigers, dire wolves and many other animals. We’ll probably

never know whether the cause of their extinction was climate change

associated with the rapid global warming that ended the last Ice Age,

tribes of hungry humans roaming the land with stone-tipped spears and

arrows, or a combination of these factors. We do know that many species

of large mammals went extinct about 10,000 to 12,000 years ago and,

shortly after that, mankind began engaging in agriculture. Some experts

theorize that humans domesticated plants and animals in response to a

lack of large animals to hunt.

All over the world, centers of civilization grew up around cultures

that had domesticated their local wild grains. About 10,000 years ago,

early farmers domesticated potatoes in South America, wheat in the

Mediterranean and rice in Asia. Squash and beans were domesticated in

Central America about 8,000 years ago, followed a thousand years later by

domestication of the wild grass that would become modern corn. Between

10,000 and 6,000 years ago, humans domesticated goats, sheep, cattle,

water buffalo and llamas. By 6,000 years ago, people enjoyed cultivated

crops, domesticated animals and stable societies in many regions of the

globe.

As we enter the 21st Century, we’re poised on the brink of another

period of dramatic climate change. The cause of today’s global warming

may be greenhouse gases produced by the activities of man, or it may be

merely a burp in the natural long-term cycle of Earth. It may be a

combination of the two. Either way, the effect will be the same. We’ll

see dramatic changes in climate over the next century and an end to the

unprecedented period of stable climate that has allowed human

civilization to flourish.

With global warming, storms will increase in severity and frequency.

The ocean will rise. Because our wetlands are trapped by development,

they can’t expand inland and will be reduced in extent. As the

environment changes, animals will attempt to migrate to more favorable

locations. But the earth is not the same as it was 12,000 years ago.

People now occupy much of the space formerly occupied by wildlife. Much

of the natural environment has been converted to agricultural fields,

towns and cities. Fences, highways and railroads present barriers to

migration. And there are few wild places left to migrate to.

Unfortunately, we have reduced the ability of the natural world to

rebound in the face of global climate change. Many believe that we have

entered another era of mass animal and plant extinction. Global climate

change will alter entire ecosystems and extinction that we have observed

in the last couple of centuries will pale in comparison to what is to

come.

This phenomenon that we call civilization is only a few thousand years

old. It has flourished because of a long period of stable climate. In

fewer than 10,000 years, we’ve gone from scattered bands of hunters and

gathers to organized societies that cover the face of the earth. How long

can we sustain the willy-nilly growth of humans and their domesticated

crops and animals to the detriment of all other life on this planet,

especially in the face of global climate change?

Eventually, the planet will cool again. When another Ice Age covers

Orange County, and another great river runs through the Bolsa Chica at

the end of that Ice Age, will there be any humans left to see it? Or will

we have gone the way of the giant sloth, wooly mammoth and saber-toothed

tiger?

* VIC LEIPZIG and LOU MURRAY PhD are Huntington Beach residents and

environmentalists. They can be reached at o7 [email protected] .