A Warm Period by Any Other Name – The Climatic Optimum

Written by Dr Tim Ball

There is frustration and reward when an article appears on the same topic of an article you are completing – in this case the Holocene. Such was the case this week with Andy May’s article “A Review of temperature reconstructions.” Andy points out the basic problems of reconstruction using proxy data for the most recent half of the Holocene – an issue central to historical climate and climate change studies. His paper did not alter my paper except as it reinforces some arguments.

This article examines the entire Holocene and illustrates the history that influenced the studies. There are two distinct parts to the studies, the pre and post Intergovernmental Panel on Climate Change (IPCC). The former is a genuine scientific struggle with issues of terminology and reconstruction, and the latter a scientific struggle to impose a political perspective regardless of the evidence. Because of the damage done to climatology by the proponents of anthropogenic global warming (AGW), both parts require explanation.

The title of this article lists all the names given to a single geologic period. It reflects the problem of inconsistent terminology in the early days of historic climate reconstruction. The names were a result of regional studies reflecting the lack of coordination in a pre-global village world. They were attempts to improve and advance scientific knowledge and understanding, but only created confusion because of failure to agree on the start and end points and duration of the period. The concept of relative homogeneity is critical to determine if a climatic change was regional, hemispheric or global. You cannot achieve accurate analysis if the sequence of events is unknown or incorrect – a point noted in May’s article.

Even a cursory examination of the Holocene shows why the period is problematic for promoters of anthropogenic global warming (AGW). As Steve McIntyre pointed out, the problems began when skeptics noted that the temperature for most of the Holocene contradicted their claim that the latter part of the 20th century was the warmest ever. I know they never used the term ‘ever’, rather, it was left unsaid but implied in the message to the public and not contradicted when used by the media.

McIntyre wrote;

The Team has taken a preditable (sic) position on the Holocene Optimum: that it’s a regional and restricted event.

It was predictable because it was the same argument they used for the Medieval Warm Period (MWP). Prove an event was regional, and you essentially eliminate the Sun as a mechanism of change – an issue central to the AGW CO2 argument. The restriction included the claim that only summer temperatures were warmer. Even if true, it is not possible to say based on proxy records with 40 to 70-year smoothing averages applied. Interestingly, the IPCC clung to this “Team” view as recently as AR4 (2007).

The temperature evolution over the Holocene has been established for many different regions, often with centennial-resolution proxy records more sensitive to specific seasons.

Of course, this was before Climategate and the leaked emails that destroyed the Team’s credibility.

The problem of terminology impacted global reconstruction when attempts were made to synchronize glacial/interglacial events in Europe and North America. European glacial events were labelled in 1909 by Albrecht Penck (1858-1945) and Eduard Bruckner (1862-1927) from the oldest to the most recent, the Gunz, Mindel, Riss, and Wurm. In North America, led by the work of Thomas Chamberlin (1843-1928) and Frank Leverett (1859-1943) the sequence was the Nebraskan, Kansan, Illinoian, and Wisconsin. This helped define what happened within the Pleistocene but didn’t help in defining the end and beginning of the following period or synchronicity.

The term Holocene means most recent and was first suggested by Geologist Charles Lyell whose work influenced Darwin. He anticipated the modern environmental activists because he suggested it marked the human era. The problem is human history covers a few million years, and there is no evidence the Pleistocene is ended. Although Lyell’s claim was unjustified, the idea continues today as some call the Holocene The Age of Man. Regardless, there is no doubt we are in an interglacial but is it just that, and attempts to define shorter periods only part of the political game of blaming humans for all change.

The game continues with the proposal to name the most recent portion of the Holocene the Anthropocene. The definition underscores the politicization of science. However, it requires reassessment because what occurred during the period contradicts the claims for the Anthropocene defined as.

“Relating to or denoting the current geological age, viewed as the period during which human activity has been the dominant influence on climate and the environment.”

This is false if we accept the IPCC conclusion, the human influence on climate is discernible only after 1950.


Correlating Events


Another book I consider significant in the attempts to match the various records wasClimate, Man, and History by Robert Claiborne published in 1970. It spoke to the contradictory dates used in different disciplines. He wanted to write a doctoral thesis on the conflicting dates and incompatibility of events used by glaciologists and anthropologists, but the idea was rejected. As a result, he quit university, the supposed bastion of innovative thought, and wrote the book. He referred to the closed mind of academia in the first sentence.

“This book will probably annoy quite a number of scientists.”

Naturally, it was immediately attacked because it questioned the prevailing wisdom and worse, crossed the boundary between science and arts. The following comment illustrates the confused reaction by obliquely acknowledging the problem but then equally obliquely questioning Claiborne.

Claiborne’s caveat in the preface to this thoroughgoing study of climate and culture is that he’s going to venture some opinions of his own, attack others’, and, in general, try to dispel the fog that has enveloped many scientific studies of man in nature. He does this somewhat modestly at the beginning, coping with the complex, often conflicting theories on the causes, conditions, and timing of the last ice ages, and then increasingly with a more idiosyncratic style and sharper tongue.

There are parallels between Claiborne’s experiences and the claims made about the weather, climate, and history today. The official story of weather and climate promulgated by governments through the IPCC and environmentalists’ state that current weather and climate are anomalous and exhibiting more extreme conditions than ever before. The message is amplified and further distorted by a complicit and duplicitous media. Recently, a UK Daily Mail headline read,

“Sizzling UK records hottest day ever.”

The story did not qualify the word “ever” by saying it was the record within the modern span of thermometer measurements. The headline is what stays with the uninformed. Put the claim in the larger perspective of the Holocene and a completely different picture emerges about the official claims. They are creating the Anthropocene to isolate it from the Holocene because it gives the lie to the entire anthropogenic global warming deception. Judith Curry provided an interesting discussion about the lack of evidence for the Anthropocene, especially its mythical threat to humanity.

Weather and climate conditions through the Anthropocene are normal; that is, they are well within the range of all previous weather and climate variations. Despite official and media claims to the contrary, there are no dramatic increases in temperature, precipitation, hurricanes, tornadoes, or any other severe weather. The climate is changing just as it always has and always will, and the rate of change is perfectly normal. Of course, that is not what the government, environmentalists, or the media promote and as a result most of the public believe. The misconception is deliberate and central to the exploitation of global warming and climate change as the vehicle for a political agenda.

What The Public Need To Know

The following is not new to skeptics but identifies issues the public need to know to understand the AGW deception. Figure 1 shows one reconstruction of the temperature of the Northern Hemisphere derived from Greenland ice cores. It provides a brief context to show the wider natural range of temperature over the last 10,000 years. It shows the meaningless identification of the Anthropocene identified by the small red bar.


Figure 1

The accuracy of the climate record is critical for determining underlying mechanisms. It is critical if you want to identify specific periods but is still difficult because of determining points of starting and ending. Figure 1 appears to show a clear start of the Holocene with a dramatic warming around 10,500 years ago, but many place the onset at 11,700 years ago. Figure 2 shows why it is not clear cut. Is the Younger Dryas part of the Holocene? Is the extent of a geologic period determined by the major causative mechanism or some arbitrary temperature threshold? Search for an explanation of the Younger Dryas generated many speculative papers. There is an entire journal The Holocene devoted to the period.


Figure 2

The Younger Dryas is the focus of intense research, but also great speculation about the causative mechanism.

Other important points from Figures 1, 2 and 3 expose the lies and distortions about the last 120 years being anomalous include,

  • Current temperatures are proclaimed as the warmest on record. In fact, the world was warmer than today for 97 percent of the last 10,000 years.
  • The Medieval Warm Period (MWP) just 1000 years ago was 2°C warmer than today. The public is told that a similar warming will be catastrophic.
  • The Minoan warm period approximately 3500 years ago was 4°C warmer than today.
  • We are told the amount and rate of temperature increase in the last 100 years is abnormal. Compare the slope with any of the previous increases in Figure 2.



Figure 3.

· Figure 3 shows the CO2 trend over the Holocene. CO2 rose as temperature declined over the last 8000 years.

The Holocene is also problematic for AGW proponents because the major causative mechanism appears to be the changing precession, one of the Milankovitch Effect (ME) trilogy along with orbital eccentricity and axial tilt. A recent article at WUWT cites from Bender’s book Paleoclimate

“The orientation of Earth’s spin axis has changed over the past 10 Kyr so that northern summers now occur when Earth is farthest from the sun, whereas at 10 Ka [10,000 BP] they occurred when Earth was closest to the sun. Northern summertime insolation reached a maximum at about 10 Ka and has declined to the present, when it is near the minimum.”

The IPCC AR4 Physical Science Basis FAQ section provides the only reference to the ME. This includes the remarkable observation that

These examples illustrate that different climate changes in the past had different causes. The fact that natural factors caused climate changes in the past does not mean that the current climate change is natural.

True, but it was the same IPCC report that said natural changes became insignificant after 1950. They ‘proved’ this by eliminating most natural changes from their reports and their computer models. The IPCC is only comfortable discussing ME on time scales greater than the Holocene. AR5 says,

There is high confidence that orbital forcing is the primary external driver of glacial cycles (Kawamura et al,. 2007; Cheng et al., 2009; Lisiecki, 2010; Huybers, 2011).

But they couldn’t leave that comment unqualified, so they added,

However, atmospheric CO2 content plays an important internal feedback role.

There is no reference to the ME in the AR5 FAQ section or the Glossary of AR4 or AR5. This supports the information that it is not included in the IPCC computer models. The justification for exclusion is the time scale, but even in the 120 years of the Anthropocene, the impact is at least marginally significant relative to CO2 changes. The bigger problem is the inability to validate the models by recreating previous conditions without including the ME.

The Holocene is an interesting warm period that many believe marks the end of the last ice advance of the Pleistocene. It fascinated early scientific attempts to understand the events and mechanisms in the early days of climate reconstructions, which were complicated by a lack of standardized terminologies and central collections of data. For example, I recall long discussions about the need for centralized data banks on tree rings. The Holocene became ignored or distorted after the advent of AGW and the IPCC because the evidence of its existence contradicted most of their claims.

Read more by Tim Ball at drtimball.com