Ancients stood on shore and watched the tall masts of ships appear and disappear over the horizon. They observed the shape of the moon. They, also, observed lunar and solar eclipses. The educated people who were astute knew that the Earth was curved, hence round. This, combined with other observations, enabled them to then calculate the size of the Earth. The average man could have understood that the planet was round if it'd been explained properly, though he'd not have necessarily understood the geometry used to determine its size. The rigid minded person would not have been willing to comprehend these inferences.
Today, we see ancient glaciers in Greenland melting away and ice shelves calving huge icebergs as ocean levels rise. World temperatures are slowly and steadily increasing as weather patterns shift. We observe increasing CO2 levels in the atmosphere and the acidification of the oceans. We find that methane hydrate is gassing out from ever deeper depths of the ocean as well as from the melting tundra. The inference that increasing levels of greenhouse gases being released can only amplify the temperatures now and in the future is hard to ignore.
So, are we doomed? That depends on the level of recalcitrance of our human condition. Or, to use a biblical reference, the degree of our being "stiff necked".
Evangelicals should note that though God promised us that he would not destroy mankind again, He did not indicate that He would stop us from destroying ourselves.