The writer of a Jan. 8 Letter headlined "Global warming: 'A hoax'" raises a good question about scientists changing views on global warming; however, his assertion that “man has been recording Earth’s climate only since 1880” is false. Examinations of ice cores and lake sediments give us climate information over hundreds of thousands of years.
The answer to the writer's question about why should we believe current scientists' prediction of global warming when in the '60s they were predicting global cooling is that the scientists were correct both times. His question should have been - What has happened in 50 years to make scientists change their climate predictions?
You have free articles remaining.
The Earth has experienced global cooling every 100,000 years. That cycle is driven by changes over which humans have no control.
The sun’s magnetic field reverses every 11,000 years, which varies the energy the Earth receives by 0.2 watts/square meter/day from its normal 240 watts/square meter/day. The angle the Earth’s axis makes with a plane intersecting the centers of the Earth and sun varies from its normal 23 degrees in a 25,000-year cycle. Earth’s orbit varies slightly over a 100,000-year cycle. These variations acting together create an ice age every 100,000 years and the Earth’s climate should be entering a cooling period.
The fact that our climate should be cooling rather than warming demonstrates that our climate is drastically different than millions of years of ice core studies would predict. That difference is the CO2, methane and ammonia that humans are discharging in ever-increasing quantities into Earth’s atmosphere. Douglas VanDerVoort, Sioux City