Several comments to the climate report brought up good subjects.
One person said that sea levels had risen and fallen 30-feet, from time to time in the past. These were likely minor cycles, within the thousands-year-long Ice Age histories. My environmental bible, National Geographic, says that Ice Ages are probably caused by cyclical changes in the Earth's oval orbit around Sol. From the height of the last ice caps, 18,000 years ago, the oceans have risen 360 feet. Since 360 feet is 1/15 of a mile, about 11 million cubic-miles of ice must have melted, spreading 10MCM of water over Earth's 140,000,000 square-miles of ocean.
The remaining ice in Greenland (which is melting more rapidly each year) has the potential to raise sea levels by 20-22 feet. The West Antarctic ice shelf contains slightly more ice; enough for an additional 24-foot rise. This shelf has disappeared several times in geologic history; the last time being 600,000 years ago, so experts are clearly worried about its stability. The East Antarctic ice cap is even more massive, and its melting could raise levels more than 200 feet. This is not a worry to experts, since this ice cap has been stable for 15 millions years.
Another comment was about Sol, our Sun. Sol is a variable star, but just slightly; its output changes only slowly over long periods. During 70 years, near the middle of the Little Ice Age (1645-1715), Earth's temperature dropped an additional 3-degrees F, due to lower energy output from Sol. Something like this, right now, would give humanity time to get its clean energy act together, but that can't be estimated because long-term data is not yet available. However, Sol's energy can be measured quite closely. From 1955 to 2000, Earth's oceans have warmed by 0.7-degrees F, but Sol's energy output has increased less than one-tenth of one-percent, not near enough to cause the warming (Scripps Institute of Oceanography).
One person said that sea levels had risen and fallen 30-feet, from time to time in the past. These were likely minor cycles, within the thousands-year-long Ice Age histories. My environmental bible, National Geographic, says that Ice Ages are probably caused by cyclical changes in the Earth's oval orbit around Sol. From the height of the last ice caps, 18,000 years ago, the oceans have risen 360 feet. Since 360 feet is 1/15 of a mile, about 11 million cubic-miles of ice must have melted, spreading 10MCM of water over Earth's 140,000,000 square-miles of ocean.
The remaining ice in Greenland (which is melting more rapidly each year) has the potential to raise sea levels by 20-22 feet. The West Antarctic ice shelf contains slightly more ice; enough for an additional 24-foot rise. This shelf has disappeared several times in geologic history; the last time being 600,000 years ago, so experts are clearly worried about its stability. The East Antarctic ice cap is even more massive, and its melting could raise levels more than 200 feet. This is not a worry to experts, since this ice cap has been stable for 15 millions years.
Another comment was about Sol, our Sun. Sol is a variable star, but just slightly; its output changes only slowly over long periods. During 70 years, near the middle of the Little Ice Age (1645-1715), Earth's temperature dropped an additional 3-degrees F, due to lower energy output from Sol. Something like this, right now, would give humanity time to get its clean energy act together, but that can't be estimated because long-term data is not yet available. However, Sol's energy can be measured quite closely. From 1955 to 2000, Earth's oceans have warmed by 0.7-degrees F, but Sol's energy output has increased less than one-tenth of one-percent, not near enough to cause the warming (Scripps Institute of Oceanography).
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