GROWING EVIDENCE OF GLOBAL WARMING

While originally eccentric, global warming was placed firmly on the agenda in 1985, at a conference in Austria of eighty-nine climate researchers participating as individuals from twenty-three countries. The researchers forecast substantial warming, unambiguously attributable to human activities.

Since that conference the researchers’ position has guided targeted empirical research, leading to supporting (and increasingly dire) evidence, resolving anomalies and winning near unanimous peer endorsement. Skeptics have been confounded and reduced to a handful, some discredited by revelations of dubious funding from fossil fuel industries.

Just before the end of the twentieth century, American researchers released ice-thickness data, gathered by nuclear submarines. The data showed that over the previous forty years the ice depth in all regions of the Arctic Ocean had declined by approximately 40 percent.

Five yearly aerial photographs show the ice cover on the Arctic Ocean at a record low, with a loss of 50 cubic kilometers annually and glacier retreat doubling to 12 kilometers a year. In September 2005 the National Aeronautics and Space Administration (NASA) doubled its estimates of the volume of melted fresh water flowing into the North Atlantic, reducing salinity and thus potentially threatening the conveyor that drives the Gulf Stream. Temperate mussels have been found in Arctic waters, and news broadcasts in 2005 and 2006 have repeatedly shown scenes of Inuit and polar bears (recently listed as endangered) cut off from their hunting grounds as the ice bridges melt.

In 2001 the Intergovernmental Panel on Climate Change (IPCC), the United Nation’s scientific panel on climate change, had predicted that Antarctica would not contribute significantly to sea level rise this century. The massive west Antarctic ice sheet was assumed to be stable. However, in June 2005 a British Antarctic survey reported measurements of the glaciers on this ice sheet shrinking. In October 2005 glaciologists reported that the edges of the Antarctic ice sheets were crumbling at an unprecedented rate and, in one area, glaciers were discharging ice three times faster than a decade earlier.

In 2005 an eight-year European study drilling Antarctic ice cores to measure the past composition of the atmosphere reported that CO2 levels were at least 30 percent higher than at any time in the last 65,000 years. The speed of the rise in CO2 was unprecedented, from 280 parts per million (ppm) before the Industrial Revolution to 388 ppm in 2006. Early in 2007 the Norwegian Polar Institute reported acceleration to a new level of 390 ppm. In January 2006 a British Antarctic survey, analyzing CO2 in crevasse ice in the Antarctic Peninsula, found levels of CO2 higher than at any time in the previous 800,000 years.

In April 2005 a NASA Goddard Institute oceanic study reported that the earth was holding on to more solar energy than it was emitting into space. The Institute’s director said: “This energy imbalance is the ‘smoking gun’ that we have been looking for” (Columbia 2005).

The second IPCC report in 1996 had predicted a maximum temperature rise of 3.5 degrees Fahrenheit by the end of the twenty-first century. The third report, in 2001, predicted a maximum rise of 5.8 degrees Fahrenheit by the end of the twenty-first century. In October 2006 Austrian glaciologists reported in Geophysical Research Letters (Kaser et al.) that almost all the world’s glaciers had been shrinking since the 1940s, and the shrinking rate had increased since 2001. None of the glaciers (contrary to skeptics) was growing. Melting glaciers could pose threats to the water supply of major South American cities and is already manifest in the appearance of many new lakes in Bhutan.

In January 2007 global average land and sea temperatures were the highest ever recorded for this month; in February 2007 the IPCC Fourth Report, expressing greater certainty and worse fears than the previous one, made headlines around the world. In 1995 few scientists believed the effects of global warming were already manifest, but by 2005 few scientists doubted it and in 2007 few politicians were willing to appear skeptical.

Although rising temperatures; melting tundra, ice and glaciers; droughts; extreme storms; stressed coral reefs; changing geographical range of plants, animals, and diseases; and sinking atolls may conceivably all be results of many temporary climate variations, their cumulative impact is hard to refute