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:
“As regards the celebrated “struggle for life,” it seems to me for the present to have been rather asserted than proved. It does occur, but as the exception; the general aspect of life is not hunger and distress, but rather wealth, luxury, even absurd prodigality—where there is a struggle it is a struggle for power.”
—Friedrich Nietzsche (1844–1900)
“The second day of Christmas,
My true love sent to me
Two turtle doves,”
—Unknown. The Twelve Days of Christmas (l. 4–6)