The present interglacial interval -- which has now lasted for about 10,000 years -- represents a climatic regime that is relatively rare during the past million years, most of which has been occupied by colder, glacial regimes. Only during about 8 percent of the past 700,000 years has the earth experienced climates as warm or warmer than the present.
The penultimate interglacial age began about 125,000 years ago, and lasted for approximately 10,000 years. Similar interglacial ages -- each lasting 10,000 plus or minus 2000 years and each followed by a glacial maximum -- have occurred on the average every 100,000 years during at least the past half-million years.
During this period, fluctuations of the northern hemisphere ice sheets caused sea level variations of the order of 100 meters.
~"Understanding Climate Change", published by the National Academy of Sciences in 1975 -- page 181.
On page 189 they asked:
When will the present interglacial [period] end?
Their answer:
Few paleoclimatoligists would dispute that the prominent warm periods (or interglacials) that have followed each of the terminations of the major glaciations have had durations of 10,000 plus or minus 2000 years. In each case, a period of considerably colder climate has followed immediately after the interglacial interval.
Since about 10,000 years have passed since the onset of the present period of prominent warmth, the question naturally arises as to whether we are indeed on the brink of a period of colder climate.
The question remains unsolved. If the end of the interglacial is episodic in character, we are moving toward a rather sudden climatic change of unknown timing ... if on the other hand, these changes are more sinusoidal in character, then the climate should decline gradually over a period of a thousand years.
Another study prepared for the 95th Congress in 1978 agreed with the National Academy of Sciences position as explained in the above-quoted study.
The document "Weather Modification: Programs, Problems, Policy and Potential" warned:
In geological prospective, the case for cooling is strong ... If this interglacial age lasts no longer than a dozen earlier ones in the past million years, as recorded in deep sea sediments, we may reasonably suppose the world is about due to slide into the next ice age.
The penultimate interglacial age began about 125,000 years ago, and lasted for approximately 10,000 years. Similar interglacial ages -- each lasting 10,000 plus or minus 2000 years and each followed by a glacial maximum -- have occurred on the average every 100,000 years during at least the past half-million years.
During this period, fluctuations of the northern hemisphere ice sheets caused sea level variations of the order of 100 meters.
~"Understanding Climate Change", published by the National Academy of Sciences in 1975 -- page 181.
On page 189 they asked:
When will the present interglacial [period] end?
Their answer:
Few paleoclimatoligists would dispute that the prominent warm periods (or interglacials) that have followed each of the terminations of the major glaciations have had durations of 10,000 plus or minus 2000 years. In each case, a period of considerably colder climate has followed immediately after the interglacial interval.
Since about 10,000 years have passed since the onset of the present period of prominent warmth, the question naturally arises as to whether we are indeed on the brink of a period of colder climate.
The question remains unsolved. If the end of the interglacial is episodic in character, we are moving toward a rather sudden climatic change of unknown timing ... if on the other hand, these changes are more sinusoidal in character, then the climate should decline gradually over a period of a thousand years.
Another study prepared for the 95th Congress in 1978 agreed with the National Academy of Sciences position as explained in the above-quoted study.
The document "Weather Modification: Programs, Problems, Policy and Potential" warned:
In geological prospective, the case for cooling is strong ... If this interglacial age lasts no longer than a dozen earlier ones in the past million years, as recorded in deep sea sediments, we may reasonably suppose the world is about due to slide into the next ice age.
