The Present Day
Currently, we are in an icehouse climate state. About 34 million years ago, we started our icehouse state, as ice sheets began to form in Antarctica; the ice sheets in the Arctic didn’t start forming until 2 million years ago. Some processes that may have led to our current icehouse may be connected to the development of the Himalayan Mountains and the opening of the Drake Passage between South America and Antarctica. Scientists have been attempting to compare the past transitions between icehouse and greenhouse, and vice versa to understand where our planet is now heading.
Without the human influence on the greenhouse gas concentration we would be heading back towards a glacial period. Predicted changes in orbital forcing suggest that in absence of human-made global warming the next glacial period would begin at least 50,000 years from now (see Milankovitch cycles).
But due to the ongoing anthopogenic climate change we are heading now towards a greenhouse Earth period. Permanent ice is actually a rare phenomenon in the history of the Earth, occurring only during the 20% of the time that the planet is under an icehouse effect.
Read more about this topic: Greenhouse And Icehouse Earth
Famous quotes containing the words present and/or day:
“Stevenson had noble ideas—as did the young Franklin for that matter. But Stevenson felt that the way to implement them was to present himself as a thoughtful idealist and wait for the world to flock to him. He considered it below him, or wrong, to scramble out among the people and ask them what they wanted. Roosevelt grappled voters to him. Stevenson shied off from them. Some thought him too pure to desire power, though he showed ambition when it mattered.”
—Garry Wills, U.S. historian. Certain Trumpets: The Call of Leaders, ch. 9, Simon & Schuster (1994)
“Early in the morning, when day breaks, when all is fresh, in the dawn of one’s strength—to read a book at such a time is simply depraved!”
—Friedrich Nietzsche (1844–1900)