Present climate change, as epitomised in the climate-sensitive polar regions, has not been outside the bounds of natural variability during the last 15,000 years.
Unfortunately, critical scientific research does not always filter through to the public. Consequently, climate alarmists are getting away with blue murder pretending that we are on the edge of a climate precipice. These activists argue we are in a new era of catastrophic climate change. Make any reference to the historic past to gain some perspective and you will be howled down. Persist and you will be told that the pace of modern climate change is so rapid any perspective gained from examining the past is meaningless. They argue history must be whitewashed as we are in a ‘totally unique’ period; the Anthropocene.
Once case in point concerns carbon dioxide levels that have risen from 280 to 410 parts per million since the mid-19th century. These levels are historically low. At various times for millions of years plants and animals have happily lived and thrived in levels between 1,500 and 2,000 parts per million; over four times the carbon dioxide levels of today. Climate events in the last 15,000 years have been as dramatic and rapid as any seen today. As such, those changes totally disprove the panic stories spread by activists.
Why incite panic about the present retreat of polar glaciers when the retreat of polar glaciers in West Antarctica was even more dramatic 8,000 years ago? Why talk about the ‘unprecedented’ rate of modern warming when the rate of warming in West Antarctica was greater in the mid-18th and mid-19th centuries than in recent decades? Why pretend an ice-free Arctic Ocean would be a sign of dramatic climate change when the Arctic Ocean was ice-free at various times between 14,700 and 6,000 years ago? Why panic about ice loss in Greenland when the Greenland ice sheet was much smaller 10,000 to 6000 years ago?
When the climate changes there is little temperature change in the tropics but there is amplified climate change in polar regions. A general term describing this gradient change is ‘polar amplification’. Consequently, historic climate changes in polar regions place climate change in the 20th and 21st centuries in better perspective. In Antarctica, alarmists point to the present retreat of the Pine Island and Thwaites glaciers. But how can this retreat be unprecedented and indicative of catastrophic global warming when geological fieldwork indicates these glaciers retreated further 8,000 years ago?
Alarmists may allege that the present rate of glacial retreat outstrips that of the past. But ice cores show such an argument is unwarranted. Dr Elizabeth Thomas and other scientists from Cambridge, England have examined Bruce Plateau, Ferrigno, and Siple Station ice-cores. These show the most dramatic rates of warming per decade in the last 308 years were not in recent decades, but in the decades between 1740 1789 and 1839 1888.
Surface temperature records taken at West Antarctic stations tell an enigmatic story that is not consistent with the anthropogenic warming narratives of the alarmists. While the Argentine Orcadas Station on Laurie Island has a temperature record going back to 1903, most Antarctic temperature records come from stations set up since the 1950s or from automatic weather stations added since the 1980s.
The overall pattern in these records shows warming since the 1950s and overall cooling or level temperatures since 1999. Such a pattern is not consistent with the alarmist narrative.
There are other climatic surprises in Antarctica. The most surprising has been a general increase in Southern Ocean pack ice (sea ice) over the last 40 years at the same time there has been a significant decrease of the Arctic Ocean pack ice. And (surprise, surprise!) at various times in the last 10,000 years the oceans have been much warmer than today. Professor Yair Rosenthal and others have used chemical analyses of marine fossils to show that ‘the deep ocean heat content in both hemispheres today is not only less than in the Medieval Warm Period (i.e. 1,000 years ago), but it is well below the deep ocean heat content in the very warm period scientists call the Middle Holocene Thermal Maximum, which occurred 10,000 years ago.’