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 day, present and/or day:
“One of the most singular facts about the unwritten history of this country is the consummate ability with which Southern influence, Southern ideas and Southern ideals, have from the very beginning even up to the present day, dictated to and domineered over the brain and sinew of this nation.”
—Anna Julia Cooper (1859–1964)
“The present hour is always wealthiest when it is poorer than the future ones, as that is the pleasantest site which affords the pleasantest prospects.”
—Henry David Thoreau (1817–1862)
“Your child should feel entitled to cry when you leave; crying is a natural thing for a child to do when she feels bad. The fact that your child cries when you go doesn’t mean she will never like day care. It just means she wants you to stay.”
—Amy Laura Dombro (20th century)