In his June 21 letter to the editor (“Is man-made climate change really here?”), John T. Kolackovsky espoused a position denying the reality of anthropogenic climate change (global warming and its attendant consequences of melting ice shelves, glaciers and permafrost, rising sea levels, intensifying storms, altering weather patterns and ailing ecosystems). His argument involves dismissing as fraudulent the robust scientific consensus embodied in the four key reports by the Intergovernmental Panel on Climate Change while identifying and praising those few individual scientists who have expressed doubts regarding the reality or severity of anthropogenic climate change.

More than 15 years ago, I had my own doubts – wondering like Mr. Kolackovsky whether the sun’s slight variations might underlie some of the warming trends that had been observed already. But that ship has sailed. The signal has grown ever clearer, with the global average surface temperature having increased by a full degree Celsius (1.8 degrees Fahrenheit) since pre-industrial times. Moreover, more refined studies of the sun’s luminous output have laid to rest the possibility that the observed warming over this 150-year period is due to solar variations. Meanwhile, the amount of atmospheric carbon dioxide has increased by an amazing 44 percent due to our combusting ways. A marvelous animated graphic produced by Bloomberg News using data from NASA’s Goddard Institute for Space Studies shows just how critically the level of atmospheric carbon dioxide drives global surface temperatures compared to other natural and artificial influences (see https://www.bloomberg.com/graphics/2015-whats-warming-the-world/).

In my own research, using NASA planetary data, I have found that carbon dioxide is the key greenhouse gas that drives warming not just on Earth, but on Venus and Mars. Moreover, the percentile warming of each planet’s surface scales with that planet’s amount of heat-trapping atmospheric carbon dioxide. On Earth, the warming due to this gas is a 6 percent effect. Add the other greenhouse gases of methane and water vapor, and one gets the observed 14 percent warming effect (59 degrees Fahrenheit) -- enough to have kept Earth’s surface from freezing over for most of its history. On Venus, the warming due to its thick blanket of atmospheric carbon dioxide is an incredible 140 percent. The resulting temperature of 890 degrees Fahrenheit is hot enough to melt lead on a surface that would otherwise be a toasty but tolerable 110 degrees Fahrenheit in the absence of all that carbon dioxide gas.

So, warming of planetary surfaces by greenhouse gases — and carbon dioxide in particular — is an astronomical fact that should be heeded with great seriousness. We humans on Earth have benefited greatly from the energy that we have extracted by burning fossil fuels. But now the time to pay for our polluting ways is way overdue. In order to keep subsequent warming below the perilous threshold of 1.5 degrees Celsius, we will need to both de-carbonize our energy production and actively sequester the excess atmospheric carbon dioxide that we have produced. The latter imperative can be implemented quickly by preventing further cutting down of forests and by reforesting the tropics in particular (see for example https://reforestthetropics.org/).

Former NASA astrophysicist William H. Waller, Ph.D., currently teaches physical, earth and space Sciences at Rockport High School.