Was the Earth Warmer before? Sea Level Higher? CO2 Higher? There are many frequently asked questions (FAQs), some of which are addressed here.
IPCC: Global average sea level in the last interglacial (Eemian) period (130,000-111,000 years ago) was likely 13 to 20 feet (4 to 6 meters) higher than during the 20th century, mainly due to the retreat of polar ice. Ice core data indicate that average Arctic temperatures at that time were 5.7 to 9.5 deg. F (3 to 5 deg. C) higher than present, because of differences in the Earth’s orbit. The Greenland ice sheet and other Arctic ice fields likely contributed no more than 13 feet (4 meters) of the observed sea level rise. There may also have been a contribution from Antarctica. Note in the chart how the rate of sea level rise is very low compared to that when the ice age wanes. (IPCC 2007).
NOAA: The Mid-Cretaceous period is one period in the geologic past that stands out as distinctly warmer than today, particularly at high latitudes. During the mid-Cretaceous Period, 120-90 million years ago, fossil remains of plants and animals believed to inhabit warm environments, were found at much higher latitudes. Breadfruit trees apparently grew as far north as Greenland (55° N), and in the oceans, warm water corals grew farther away from the equator in both hemispheres……. The mid-Cretaceous was characterized by geography and an ocean circulation that was vastly different from today; as well as higher carbon dioxide levels (at least 2 to 4 times higher than today). This indicates that the mid-Cretaceous climate system was different from that of today or any we might have in the future. Explanations evoking ocean and atmospheric circulation patterns radically different from today have been proposed to explain the climate of the mid-Cretaceous; however, there is no scientific consensus on how the Mid-Cretaceous warm climate came about (source: NOAA Paleo Climatology program). In some ancient times when CO2 levels were very high, ocean organisms with shells based on silica replaced those with shells based on calcium.
During the Mid-Pliocene (about 3 million years ago) global temperatures were substantially warmer for a sustained period and are similar to those forecast by IPCC, with similar CO2 and sea levels of 15-25 meters (50-82 ft.) greater than today. Most of the warming was in the high northern latitudes with little warming in the tropics. Even just 7 thousand years ago, in the midst of the present period (Holocene) between glaciation, the Russian Arctic, at least, was 2.5-7 deg.C (4-12 F) warmer than today (Quartenary Research).
Dr. Nils-Axel Mörner (leading expert on sea level): “If you go around the globe, you find no rise anywhere. But they need the rise, because if there is no rise, there is no death threat. They say there is nothing good to come from a sea-level rise, only problems, coastal problems. If you have a temperature rise, if it’s a problem in one area, it’s beneficial in another area. But sea level is the real “bad guy,” and therefore they have talked very much about it. But the real thing is, that it doesn’t exist in observational data, only in computer modeling.” Dr. Mörner’s credentials. In a 2009 study, the authors used GPS measurement to correct for local vertical movement of the Earth at key tide gages, finding a “global rate of geocentric sea level rise of 1.61 ± 0.19mm/yr over the past century” Their study shows no acceleration and no changes in rate during warm or cold periods of the last 110 years. It is a monotonic rate of increase, independent of Earth’s temperature. However, more recent data from NOAA show a rise of about 3.4 mm/yr but with little to no acceleration.