The basic trouble, you see, is that people think that “right” and “wrong” are absolute; that everything that isn’t perfectly and completely right is totally and equally wrong. … What actually happens is that once scientists get hold of a good concept they gradually refine and extend it with greater and greater subtlety as their instruments of measurement improve. Theories are not so much wrong as incomplete.
By feeding birds, you could alter their evolutionary future, with changes visible in the very near term, scientists now conclude. Due to winter bird-feeding, what was once a single population of birds has, in fewer than 30 generations, been split into two groups that do not interbreed, despite the fact that they continue to breed side by side in the very same forests.
… you’ll often see people arguing that since the planet’s climate has changed in the past without human intervention, there’s no reason to worry about human-generated greenhouse gasses now—which ignores evidence indicating some of those past changes have been driven by greenhouse gasses.
We are in an ice-melting phase of the Milankovitch cycle now, where the Earth’s orbit is closer to circular and the Earth’s tilt is closer to perpendicular. But CO2 levels aren’t declining – partly because we’ve chopped a lot of trees and forests down, but mostly because of anthropogenic CO2 production. Without the limiting factor of declining CO2 we’ve seen in previous Milankovitch cycles, presumably the ice is just going to keep on melting as the albedo of the Earth surface declines.
Changes in theories are never overnight revolutions, nor do theories remain unaltered for long. Instead, acceptance of a theory is a matter of consensus, achieved over many years of work. No matter how ugly a theory, no matter how unpalatable its consequences, experimental and observational evidence is the final arbiter. This, in the end, is why we do experiments.
