We know, and scientists should, that CO2 atmospheric concentrations have been much higher in the Earth’s past. That CO2 was absorbed by plants that took it to their graves. We call that carbon coal and oil. This site explains that distant past:

Average global temperatures in the Early Carboniferous Period were hot- approximately 20° C (68° F). However, cooling during the Middle Carboniferous reduced average global temperatures to about 12° C (54° F). As shown on the chart below, this is comparable to the average global temperature on Earth today!

Similarly, atmospheric concentrations of carbon dioxide (CO2) in the Early Carboniferous Period were approximately 1500 ppm (parts per million), but by the Middle Carboniferous had declined to about 350 ppm — comparable to average CO2 concentrations today!

Earth’s atmosphere today contains about 380 ppm CO2 (0.038%). Compared to former geologic times, our present atmosphere, like the Late Carboniferous atmosphere, is CO2– impoverished! In the last 600 million years of Earth’s history only the Carboniferous Period and our present age, the Quaternary Period, have witnessed CO2 levels less than 400 ppm.

If you check out the chart at the link you will see little correlation between CO2 concentration and global temperatures.

We know, and scientists should, that we are currently in an interglacial period. Within that relatively balmy period global temperatures have fluctuated. History has recorded the impact of those fluctuations on humanity. Hillbilly White Trash links to a climate history lesson from The Great Mortality:

In the European heartland the Little Optimum gave way to the Little Ice Age around 1300 [3]. People noticed that the winters were growing colder, but it was the summers, suddenly cool and very wet, that alarmed them. By 1314 a string of poor and mediocre harvests had sent food prices skyrocketing. That fall, every peasant in every sodden field knew: one more cold, wet summer, and people would be reduced to eating dogs, cats, effuse – anything they could get their hands on. As the summer of 1315 approached, prayers were offered up for the return of the sun, but, like a truculent child, the cold and wet persisted. March was so chilly, some wondered if spring would ever return to the meadows of Europe. Then, in April, the gray skies turned a wicked black, and the Rain came down in a manner no one had ever seen before: it was cold, hard, and pelting; it stung the skin, hurt the eyes, reddened the face, and tore at the soft, wet ground with the force of a plow blade. In parts of southern Yorkshire, torrential downpours washed away the topsoil, exposing the underlying rock. In other areas, fields turned into raging rivers. Elsewhere in Europe in the bitter spring of 1315, men and animals stood shivering under trees, their heads and backs turned against the fierce wind and rain.

[. . .]

The early winter months of 1316 brought more suffering. As food grew costlier, people ate bird dung, family pets, mildewed wheat, corn and finally, in desperation, they ate one another. In Ireland, where the thud of shovels and the tearing of flesh from bone echoed through the dark, wet nights, the starving “extracted the bodies of the dead from the cemeteries and dug out the flesh from their skulls and ate it.” In England, where they consider the Irish indecorous, only prisoners ate one another. “Incarcerated thieves,” wrote the monk John de Trokelowe, “. . . devoured each other when they were half alive.” As the hunger intensified, the unspeakable became spoken about. “Certain people. . . because of excessive hunger devoured their own children,” wrote a German monk; another contemporary reported, “In many places, parents, after slaying their children, and children their parents, devoured the remains.”

Nice times indeed but the Global Warming Alarmists would have us belive those bad time never happened and the slight warming during the last century is a catastrophe rather than a relief from the horrible little ice age. The next ice age is coming. Our real task is to figure out how to prevent it. If recycling fossilized CO2 back into the atmosphere would help, then we just need to do it.