Several recent letters to the editor suggest that climate change is driven by natural cycles and events, and not by human activity. That’s correct: cyclical changes in the earth’s orbital geometry, volcanic eruptions, and sunspot activity are all sources of Pleistocene-Holocene climate variability.
What’s missing is that these changes occurred within a global carbon dioxide (CO2) range (footprint) of about 180 to 280 parts per million (ppm), which allowed the earth’s temperatures to stay relatively stable, and enabled Holocene civilization (agriculture, cities) to develop, beginning some 10,000 years ago.
Atmospheric C02 has now breached 410 ppm. This sharp rise in C02 level begins precisely at the start of the Industrial (fossil fuel) Revolution in the mid-19th century. Hardly climate change “belief,” this is empirical science — the same science that enables people to drive cars, saves heart patients and sends people to the moon.
Another big or little Ice Age in the distant millennia would be daunting. But our very immediate problem in this millennium is a rapidly heating planet and its unpredictable effects on human society as we know it. The fickle finger of fate, and science, points squarely at us. We are both the cause and the solution.