UnAustralian Ken Miles has a reflexive whinge about an article in yesterday’s Australian newspaper by noted geologist Professor Ian Plimer. Why? Well, I can’t be sure because I didn’t buy yesterday’s Oz, and the article isn’t online (at least not for free). But it’s a fair bet that Plimer’s article was a spin-off from a paper he presented at a Climate Change Conference sponsored by the Institute of Public Affairs earlier this year.
Of course, the identity of the sponsor will have already induced most leftie readers to close their minds and conclusively assume that Plimer must be one of those ratbag fringe scientists they can safely ignore. Their worst fears would be confirmed if they bothered to read the paper, which does indeed challenge the Henny Penny dogmatic views on global warming of bloggers like Ken Miles. For those with open minds on the issue, however, Plimer’s paper contains a wealth of fascinating information and a valuable perspective on climate change over geological time. Here’s a substantial extract:
The northern polar ice sheet started to melt 14,700 years ago. There were very rapid and major temperature fluctuations, sea level rose and fell and the total sea level rise over the last 14,700 years has been at least 130 metres. Land masses previously covered with ice started to rise. For example, Scandinavia is still rising and has risen more than 340 metres over the last 14,700 years. As a counterbalance, the Netherlands, south eastern England, Schleswig-Holstein and Denmark are sinking. The breaching of dams of melt waters filled the oceans with cold surface waters 12,000-11,000 and 8,500-8,000 years ago resulting in changed climates, an increase in sea level and changes to ocean currents. After these intensely cool periods, temperatures rose by 5-10 °C in the space of a few decades. Sea level rise resulted in the breaching of the Mediterranean into the Black Sea Basin some 7,600 years ago and is probably the origin of the Sumarian, Babylonian and biblical stories of a great flood.
One of the consequences of a massive sea level rise over the last 14,700 years is that the West Antarctic Ice Sheet was no longer unpinned by the land. Two thirds of the West Antarctic Ice Sheet collapsed into the oceans and sea level rose 12 metres. The final third of the West Antarctic Ice Sheet has yet to collapse to produce a 6 metre sea level rise as part of the dynamic post-glacial climate on Earth. Climate changes induced by changes in ocean currents cooled North Africa, grasslands changed to a desert, humans migrated and the great Mesopotamian cities were established.
Sea levels were 1-3 metres higher in a greenhouse 6,000 years ago. There was 20% more rainfall. Cold dry periods, glacier expansion and crop failures between 5,800 and 4,900 years ago resulted in deforestation, flooding, silting of irrigation channels, salinisation and the collapse of the Sumerian city states. Long periods of El Nino-induced drought resulted in the abandonment of Middle Eastern, Indian and North American towns. In 1470 BC (?), Thira exploded and threw 30 cubic kilometers of dust into the atmosphere. The tsunami, ash blanket and destruction of Thira greatly weakened the dominant Minoans. This led to the rise of the Mycaeneans and Greeks. One volcano changed the course of western history.
Global cooling from 1,300 to 500 BC gave rise to the advance of glaciers, migration, invasion and famine. Global warming commenced again at 500 BC, there was an excess of food and great empires such as the Ashoka, Ch’hin and the Romans grew. Contemporary records and Roman clothing shows that conditions were some 5 °C warmer than today.
In 535 AD Krakatoa exploded, as did Rabaul in 536 AD. The Earth passed through cometary dust in 536 AD. The dusty atmosphere reflected heat and darkness prevailed and, as a result, the climate cooled and there was famine and warfare. Changes in ocean currents resulted in the Medieval Warm Period from 900 to 1300 AD. The first to feel the change were the Vikings who were able to navigate the northern waters, colonized Newfoundland, colonized Greenland and established extensive trade routes as far south as the modern Gulf States. On Greenland, crops were grown and there were cattle. This would not be possible today. The warmer wetter climate of Europe produced excess crops and wealth which resulted in the building of castles, cathedrals and monastries. As with previous greenhouse events, there was great prosperity.
In 1280 AD, volcanic eruptions on Iceland and a change in ocean currents started the Little Ice Age which finished in 1920. The North Sea froze in 1303 and 1306-1307, there was massive famine in 1315 and the plague pandemic attacked the weakened population in 1347-1349. There was massive depopulation and it took Europe 250 years to reach the population of 1280 AD. During the Little Ice Age, there were warmer periods associated with sunspot activity. During minimum sunspot activity (1440-1460, 1687-1703 and 1808-1821), the intensely cold conditions were recorded by the Dutch masters and King Henry VIII was able to roast oxen on the frozen Thames. There were food shortages. Short cold periods occurred after the eruptions of Tambora (1815) and Krakatoa (1883) respectively. In fact, 1816 was known as the ‘year without a summer’. This was the time when Turner painted stormy oceans and skies full of volcanic dust, Mary Shelley wrote Frankenstein and Byron wrote Darkness.
The twentieth Century and early 21st Century AD are times of natural post-glacial rebound. Ice sheets, a rare phenomenon in the history of time, still exist. Sea level is relatively low, as are global temperatures and atmospheric CO2. Between 1920 and 1945, there was a period of warming (0.37 °C) and another that commenced in 1976 (0.32 °C). In 1976-1977, global temperatures in the lower atmosphere jumped 0.3 °C, sea surface temperature in the equatorial Pacific jumped 0.6 °C, sea surface temperature during upwelling increased 1.5 to 3 °C but there was reduced upwelling, the heat content of the upper 300 metres of the world’s oceans increased, there was increased wave activity in the North Sea and the length of the day changed. The stepwise increase in temperature in 1976-1977 shows that there was a major re-ordering of the ocean heat transport coinciding with an orbital change expressed as a change in the length of the day. Maybe global warming of the 20th Century is just a measure of the variability on a dynamic evolving planet?
To put such measurements into perspective over the history of time, changes in atmospheric temperature in the 20th Century can only be considered small and slow. A 24 year global coverage of satellite atmosphere temperatures shows only modest warming in the Northern Hemisphere and a slight cooling in the Southern Hemisphere. Temperature measurements from balloons agree with the satellite measurements for the period of overlap. Because greenhouse warming is a phenomenon of the atmosphere, significant changes should have been recorded. They have not.
Science is married to evidence and bathes in modest uncertainty. The nature of science is skepticism and science encourages argument and dissent. Scientific evidence is derived from reproducible observation, measurement, experiment and calculation. Evidence in geology is interdisciplinary, terrestrial and extra-terrestrial and shows the complex and fascinating intertwining of evolving natural processes on a dynamic planet. Scientists engage in healthy argument about the veracity of evidence. On the basis of evidence, an explanation called a scientific theory is constructed. A scientific theory is the best available explanation of evidence, it may change with new evidence and it must be coherent with the existing body of knowledge. Scientists also argue about scientific theory. Scientific theories are testable and once the scientific theory has been tested over time, it becomes accepted into the body of knowledge. The word belief is not used in science because belief is untestable. This process has not taken place with the construction of what is popularly called the greenhouse effect. Furthermore, science is unable to make judgments about what is good or bad. These are judgments with vary with time and are based on contemporary politics, religion, aesthetics and culture.
Underpinning the global warming and climate change mantra is the imputation that humans live on a non-dynamic planet. On all scales of observation and measurement, sea level and climate are not constant. Change is normal and is driven by a large number of natural forces. Change can be slow or very fast. However, we see political slogans such as Stop Climate Change or government publications such as Living with Climate Change demonstrating that both the community and government believe that climate variability and change are not normal. By using the past as the key to the present, we are facing the next inevitable glaciation yet the climate, economic, political and social models of today assess the impact of a very slight warming and do not evaluate the higher risk of yet another glaciation. Geology, archaeology and history show that during glaciation, famine, war, depopulation and extinction are the norm.
In 1831, Admiral Sir James Robert George Graham had the Union Jack hoisted on a volcanic land mass that suddenly appeared near Sicily. It was called Graham Bank and was claimed by England. It was also claimed by the Kingdom of the Two Sicilies who called it Isola Ferdinandea, the French (L’Isle Julia) and other powers who variously named it Nerita, Hotham, Scicca and Corrao. In the subsequent dispute over ownership, France and the Kingdom of the Two Sicilies almost came to war and England and the Two Kingdoms of Sicily had a diplomatic row. During the intense diplomatic dispute, the island quietly slipped back underwater. In 1987, US warplanes thought the dark mass 8 metres below sea level was a Libyan submarine and attacked it with depth charges. In February 2000 when the volcano again stirred, Domenico Macalusa, a surgeon, diver and the Honorary Inspector of Sicilian Cultural Relics, took action. He persuaded Charles and Camilla, the last two surviving relatives of the Bourbon Kings of the Two Sicilies to fund the bolting of a 150 kg marble plaque to the volcano at some 20 metres below sea level. The plaque pre-empted ownership if the volcano ever again rose above sea level. It was placed underwater in September 2001, by November 2002, person or persons unknown had smashed the plaque into 12 pieces. This rock is worth nothing, is of no use as a territorial possession and is of no scientific interest and yet the French and Bourbons nearly came to war 170 years ago and the English and Italians are still in dispute. Graham Banks serves to show that whatever political decisions we humans make, the land rises and falls, sea level rises and fall and climates change as they have done since the dawn of time.