To the editor:

The author of ‘Feedback loops’ (Dec. 15) attempts to show us that feedback loops linked to CO2 gas produced by burning fossil fuels is causing global warming. I have yet to see sound ’empirical’ evidence showing how man’s microscopic CO2 contribution to nature’s massive atmospheric and oceanic CO2 reserves is able to man-handle the global weather system. Is earth’s temperature going up because the carbon dioxide level is going up? Or, is carbon dioxide going up because the earth’s temperature is going up? Look at the NOAA annual mean growth rate of CO2 chart at Mauna Loa observatory. The steady growth rate drops to .28 and .48 ppm for years 1964 and 1992. Did people suddenly burn less coal and oil those years? No, it was Mt. Agung (1963-64) and Mt. Pinatubo (1991-92) blasting about one cubic mile of ash into the air to a height of some 22 miles. This causes a shading/cooling effect on the ocean which then expels less CO2.

There are 40,000 miles of volcanic mid-ocean mountain ranges that inject tremendous heat into the ocean (in some places the water is over 700 degrees), along with gases like CO2 & sulfur dioxide, (which will also affect water acidity). Rising water temperature drives out dissolved CO2 at a higher rate into the atmosphere. So until we get a better handle on what the big “tank heater” is doing down there, we can’t be preaching man-made global warming.

At a February 2015 AAAS conference in San Jose, geo-engineering scientists said we may have to look at ways of blocking the sun’s rays to cool the planet. Well, we already have empirical evidence on how it’s done: In 1816 Mt. Tambora volcano gave the northern hemisphere the disastrous ‘Year without summer’. Satellite imaging analysis shows a rise in temperature as coal power-plants and ocean-going ships cut back on emissions. Long before the Industrial Revolution, we had the Medieval Warm Period, then came the Little Ice Age, now another warm up. It’s a cyclic thing in which sun, volcanoes and cloud cover are the main climate drivers — not man.

Phil Drietz

Delhi