The notion of man's use of CO2 as a possible driver of climate has been the subject of several recent Letters to the Editor in the Sun-News. Over geologic time. there has been 15 to 25 times more CO2 than current concentrations; the claim that this time we will reach a tipping point is alarmist, ludicrous, and totally without foundation.

CO2 is a colorless, odorless gas, and essential to life; to regard it as a pollutant is just wrong.

Let us deal with facts - not activism, alarmism, or hyperbole.

The polar bear population is more than 250,000 years old. We are in an interglacial period called the Holocene, a geological epoch now 18,000 years old into which human civilization dates entirely.

About 130,000 years ago, the previous interglacial period, known as the Eemian, was warmer than the Holocene, with sea levels some 15 feet higher than today. Scandinavia was an island and North Cape, Norway, now tundra, was home to forests.

Eemian beaches 15 feet above present sea levels are present in the Bahamas. The polar bear survived the Eemian with warmer temperatures and much less ice than is present today.

During the Holocene, we have had a number of warm and cold periods. The Roman Warm Period, warmer than today, was followed by the Dark Ages, when the Nile froze twice, the weather was cold, cloudy and dark. Crops failed and many babies did not survive. This is why it is called the Dark Ages.

During the Medieval Warm Period (MWP), the temperatures were significantly warmer than today. Today, you can see the 1,000-year-old trunk of a Foxtail Pine on the Bighorn Plateau in Sequoia National Park in California, which is well above today's tree line, proving the MWP was warmer than today.

Want more proof?

We know from history that Eric the Red discovered Greenland about the year 1,000, and at least the fringes were green at that time. It was warm enough to settle and there was a Norse colony on Greenland until the Little Ice Age when it died out.

Generations of Norse colonists were buried in a graveyard, but Lord Moncton reports that the Norse Graveyard on Greenland is now permafrost.

Chaucer wrote during the MWP that there were vineyards in the north of England, but today's climate will not support vineyards in that part of England. Rather than being a cause of alarm, the MWP was a time of riches when the great cathedrals of Europe were constructed.

Then came the Little Ice Age when the Thames froze often; the Brits had ice fairs during the winter on the frozen river. During the 30 Years' War, the Swedes invaded what is now Germany, dragging their canons across the frozen Baltic Sea.

Let us not forget Washington crossing an iced-clogged Delaware River, Christmas 1776, and the cold weather Washington and his troops suffered at Valley Forge during our recorded history!

The warmest year of the 20th century, as measured by thermometers in the U.S., was 1934. This was well before World War II and the post-war industrial boom when CO2 output increased dramatically. The coldest year of the 21st century was 2008. Global temperatures are falling and the Arctic ice sheet is growing.

This means that present temperatures are well within temperatures observed during the past 1,000 years, and CO2 concentrations of up to 25 times higher than now occurred during the time of the dinosaurs with no "tipping point" of "runaway global warming."

By entering "polar bear census" into a Web browser and reading some of the results, the following becomes apparent. There is no accurate census of polar bears. Some census estimates use light aircraft in an attempt to find white polar bears on white ice, a difficult task in smooth air, let alone in turbulent skies with poor visibility and low sun elevations.

There is an estimate in the literature from Vspensky (1961) that sets the world polar bear population at 5,000 to 8,000 animals but, recently, the International Union for the Conservation of Nature (IUCN) reported, "The total number of polar bears worldwide is estimated to be 20,000-25,000."

Robert W. Endlich provided weather and toxic-corridor support to the High Energy Laser Systems Test Facility at White Sands Missile Range from 1984-1993. He served as a weather officer in the U.S. Air Force for 21 years, and has published papers in the technical literature. At present, he tests weather software at the Physical Sciences Laboratory at NMSU. He has degrees in geology and meteorology from Rutgers University and the Pennsylvania State University, respectively.