Letter: Global warming is natural, inevitable

Saturday, June 23, 2007 | 7:13 a.m.

In his June 19 letter, Virgil Sestini stated that global warming is undeniable because of the significant melting of global ice, and he implied it is a serious problem because the 12 hottest years in the recorded history of the planet have occurred since 1990. He combined global warming and the hottest years to imply humans are on the road to extinction unless we take action.

It is true that since temperature recording started 150 to 250 years ago, the temperature has been generally rising. This is because the Earth has been coming out of the little ice age that occurred around 1600-1700, so naturally the global temperature is rising.

Before the little ice age, the Earth had been much warmer than current temperatures. For example, there were grapes growing in England in Roman times. Additionally, a Web search of "Paleocene-Eocene Thermal Maximum" shows that around 55 million years ago the ocean was more than 15 degrees hotter than today, Antarctica had temperate forests, the Earth had no permanent polar ice caps and the atmospheric carbon content was more than 2,000 parts per million (ppm) as compared to 380 ppm today.

The existing scientific proof is that the Earth today is warming, but is far from being the hottest it has ever been. The Earth's temperature has been changing throughout all history, and all this occurred without any human interference.

It is unlikely that humans can change the natural variations. Even if humans could control global temperature changes, it probably would not be wise because we have no good way to understand the consequences of such actions, which could be disastrous.

The Earth has been warmer in the past than today. To conclude that today's warming, which is less than other recent warm spells and a long way from previous warming peak temperatures, will cause human extinction is real speculation.

Dirk Dahlgren, Las Vegas