Letter to the editor: Humans have changed the climate cycle

The writer of the letter “Climate change is cyclical” (March 27, TribLIVE) rehashes the faulty reasoning that still leads some to deny climate change. He wrongly states that “experts” predicted a coming ice age in the 1970s. In fact, even in those early days of climate modeling, the published record shows that most studies predicted warming.

By 1990 the scientific consensus — as reported by the Intergovernmental Panel on Climate Change (IPCC) — correctly predicted that Earth would now be 2 degrees Fahrenheit warmer than preindustrial times.

The writer highlights the cyclical ice ages Earth experienced over the past few million years. Those ice ages resulted from periodic changes in Earth’s orbit, tilt and precession. In fact, those changes would now be cooling our planet if humans hadn’t increased greenhouse gases to their highest levels in at least 3 million years.

Rather than seriously trying to understand climate science, the writer seems to be ideologically motivated — by conspiracy theories about a mysterious elite gaining “more power and control over society.” Those who really want to “do the research” will find an objective analysis in the latest IPPC summary report published last month.

Robert R. Mitchell

Murrysville