Mountain glaciers worldwide "disappearing"
Gore says that “the ice has a story to tell, and it is worldwide.” He shows several before-and-after pictures of glaciers disappearing. However, the glacial melt began in the 1820s, long before humankind could have had any effect, and has continued at a uniform rate since, showing no acceleration since humankind began increasing the quantity of CO2 in the atmosphere. Total ice volumes in three of the last four Ice Ages were lower than they are today, and “global warming” had nothing to do with that.
Sahara desert "drying"
Gore says terrible tragedies are occurring in the southern Sahara because of drought which he blames on “global warming.” There is no drought caused by “global warming.” In 2007 there were record rains across the whole of the southern Sahara. In the past 25 years the Sahara has shrunk by some 300,000 square kilometers because of additional rainfall. Some scientists think “global warming” may actually mitigate pre-existing droughts because there will be more water vapor in the atmosphere. Before 1200 AD there were frequent, prolonged and severe droughts in the Great Plains. Since 1200 AD, there has been more rainfall. Likewise, the US has had more rainfall since the 1950s than it had in the earlier part of the 20th Century, when the great droughts which were then common were described by John Steinbeck in The Grapes of Wrath. South African rainfall was also more stable in the second half of the 20th Century, when human effect on climate is said to have become significant, than in the first half.
West Antarctic ice sheet "unstable"
Gore says disturbing changes have been measured under the West Antarctic ice sheet, implicitly because of “global warming.” Yet most of the recession in this ice sheet over the past 10,000 years has occurred in the absence of any sea-level or temperature forcing. In most of Antarctica, the ice is in fact growing thicker. Mean Antarctic temperature has actually fallen throughout the past half-century. In some Antarctic glens, environmental damage has been caused by temperature decreases of up to 2 degrees Celsius. Antarctic sea-ice spread to a 30-year record extent in late 2007.
Antarctic Peninsula ice shelves "breaking up"
Gore says half a dozen ice shelves each “larger than Rhode Island” have broken up and vanished from the Antarctic Peninsula recently, implicitly because of “global warming.” Global warming is unlikely to have been the cause. Gore does not explain that the ice shelves have melted before, as studies of seabed sediments have shown. The Antarctic Peninsula accounts for about 2% of the continent, in most of which the ice is growing thicker. All the recently-melted shelves, added together, amount to an area less than one-fifty-fifth the size of Texas.
Larsen B Ice Shelf "broke up because of
Gore focuses on the Larsen B ice shelf, saying that it completely disappeared in 35 days. Yet there has been extensive ice-shelf break-up throughout the past 10,000 years, and the maximum ice-shelf extent may have been in the Little Ice Age in the late 15th century.