Global Warming 102 – Global Temperatures – Past, Present and Future

Background — After a sustained period of cooler global temperatures from 1944 to 1980, the earth began to steadily warm again in accordance with the current long term warming trend (since 1650 and a matter of NASA record since 1880). As we moved into the late 1980’s the earth’s temperature was getting increasingly warm, reaching temperature levels nearing the high temperature peaks indicated in the earth’s previous cooling/warming cycles (see figure 1).   People were beginning to get concerned.   It was known that manmade emissions of CO₂ had been increasing greatly (since about 1945) and it was known that the CO₂ in the atmosphere is a contributor (albeit a minor one) to keeping heat from escaping the earth.  Thus, it was reasonable to hypothesize that the large increase in CO₂ emissions by human activities was increasing the rate of global warming.  This was a hypothesis and like any hypothesis it needed to be examined, tested, and verified before it is accepted as fact. The hypothesis was challenged in Global Warming 101 based on empirical records showing extended periods of global temperature cooling concurrent with steadily rising emissions of CO₂.   

In Global Warming 101 using a graph showing the avg. annual global temperatures since 1880 and a second showing the rates of increase in human source carbon dioxide emissions, three basic conclusions were reached: (1) the earth is in a period of global warming and has been warming for a very long time, (2) though there is overall warming there are long periods (tens of years) of cooling or of  relative stability in global temperatures, and (3) the existence and rate of global warming is not being significantly influenced by human source CO₂.

In Global Warming 102 you will be provided with four basics relative to the global warming and “climate change” discussions.  These factual data will give you a foundation to help you read, understand, interpret and evaluate the truth or lack of it in the rhetoric heard and in the articles written on this subject.  Most of such communication commonly seen is to persuade for political or advocacy purposes. However, there have been, since the late 1980’s, a plethora of technical articles on the subject written supporting the theory that CO₂ emissions are responsible for global warming.  The articles of this bent that I have reviewed tend to be narrowly focused and very analytical, or they have been written to specifically counter some aspect of the technical opposition to this prevailing theory.  Similarly, the articles opposed to the human caused argument for global warming present their viewpoint and are biased toward that point of view.  Thus, it becomes difficult to assess the situation.  My objective is to provide you with easily understood factual data that helps in this regard.

Long Term Cyclic Temperature Record –  The first essential is to understand the context of the current discussion with respect to the very long term and the extremely long term temperature record of the planet.  We all know about glaciers and how they advanced and retreated.  The last glacial period started about 110,000 years ago and ended about 15,000 years ago.   During that time period there were about 8 advances and retreats of the glaciers as the earth alternately cooled and heated within the last glacial period.   Now, looking at the very long term there are extended periods or cycles of warming followed by extended periods of cooling.  Figure 1 shows how those cycles look based on ice core data from Antarctica.  Note how the cooling trends last for a very long time and how the warming trends tend to shoot up rapidly (speaking in terms of geologic time).  Also note how the past 3 peaks were much sharper and higher than the current peak. The reason for this is not known.

Figure 1 – Temperature changes over a period of 400,000 as derived from Antarctica ice core ( Note: similar data has been derived from ocean sediments)

Many people with knowledge of glaciation and of this long term cyclic record of the earth’s temperatures, which goes back 800,000 years, did and still do question the man caused global warming assertion promulgated by the United Nations Climate Committee in the late 1980’s.

Terminology –The second piece of basic information to understand is the relationship of the term Global Warming to the now popular but imprecise term “Climate Change” and the “non-obvious” implication of this term and, as an important detail, the ways the average global temperature is determined.

Global Warming means the year to year increase in the “average” global temperature. This “average” temperature is now measured in two ways.  (1) The first, and oldest, means of establishing this average is via a land – ocean array of sites. It is the one used in the NASA Global Temperature Index for Land & Ocean shown in Global Warming 101. (2) The second, is the average temperature of the lower troposphere (near surface layer) obtained from satellites passing over the array of measuring locations around the globe twice a day.  The satellite array (established in 1978) has the intended advantage of removing the effects of the “urban heat sinks” present in the land-ocean array.  The satellite data, are interpreted and published by two different groups that are referred to as RSS and UAH.  The UAH plot is by the University of Alabama at Huntsville and the RSS data is from Remote Sensing Systems (RSS), a scientific research company located in Northern California, specializing in satellite microwave remote sensing of the Earth.  Although the analysis techniques for interpretation of the data are different the results are quite similar.  Figure 2 shows the history of the average global temperature record since 1979 from the UAH source.  As in the land-ocean record there was a peak in 1998, however in the satellite data the peak was very sharp and since that time the satellite data show that that the 1998 average global temperature peak has not been exceeded.  That is why you will hear it reported that the “earth has been cooling for the last 18 years” and at the same time hear reports, (like President Obama’s statement in the 2014 State of the Union address), that 2014 was hottest year on record. Both statements were true, they are using different data sets.  According to the satellite data, 1998 is the hottest year on record, 2010 is next and then 2015.  According to the land-ocean data the 1998 temperature represented a local peak and since then the trend is slowly creeping upward, however there was a big increase in 2015 and that might be seen in 2016 as well as it is another El Nino year.

(1)     Figure 2 – Global temperatures from satellite data since 1979 (UAH_LT_1979 Through Dec 2014) A global temperature high (as measured from satellite data in the lower troposphere) was reached in 1998 and since that time (17 years and counting) global temperatures have been at or below that peak level.

“Climate Change” — This term is now used as a euphemism for “anthropogenic global warming” – i.e. global warming  being caused by humans.  The term appears to have been intentionally adopted as a means to focus attention on and engender concern about the recognized adverse physical effects of global warming – glaciers retreating, polar ice diminishing, and the range of plants and animals being impacted, and at the same time shrewdly imply or infer that the cause of these physical effects is human source CO₂, as though the question was settled.  It is an imprecise term technically, that has obscured the real question of whether the current warming is “anthropogenic”, or is due to natural forces.  Use of the term effectively discredits, in the public eye, the many climatologists scientists and technical people who challenge the CO_{2 –} anthropogenic global warming assertion.  This public media discrediting is easy because it infers that the “skeptics” or “deniers”  are arguing that the  “climate change” physical effects are not occurring and it makes them look totally unrealistic and out of touch.

Climate Models – The United Nations established the International Panel on Climate Change (IPCC) in 1988. The IPCC was charged to obtain, “scientific, technical and socioeconomic information relevant for the understanding of the risk of human-induced climate change.”  Notice that it appears that the IPCC was not charged with investigating the hypothesis of whether or not global warming was being influenced by human source CO2, but rather to start with that assumption and show the risks.   And as it turns out the IPCC is fulfilling their charge by conveying that there is considerable risk. The IPCC panel concluded in their first assessment report in 1990 that: “anthropogenic climate change will persist for many centuries “.   The IPCC funded an abundance of studies, resulting papers and climate models that supported their initial conclusion and a positive feedback loop developed that led to the IPCC’s subsequent assertion that human generated carbon dioxide emissions are the major cause of global warming.  The global warming models sponsored / paid for by the IPCC typically integrated or incorporated in their analytics a very adverse effect due to rising CO₂ levels.  As can be seen in Figure 3, the models greatly overestimated the actual global warming that has occurred since 1998.   The results of these models were a primary rationale for the IPCC’s ominous warnings to the international community on the expected increases in global warming and associated adverse impacts (e.g. rising ocean levels).  These results were a prime driver of the global efforts to take action to reduce carbon dioxide emissions such as the Kyoto Protocol.  Now clearly seen as overestimates, IPCC models are still being used to justify warnings.   Note that although these models clearly appear to be inaccurate because of their emphasis on incorporating  assumptions about the dramatic effects of CO₂, this is not to say that there will not be another sharp rise in global temperatures as there was post 1933 and post 1976.  The pattern of relative stable global temperatures since 1998 could well change in future years due to natural forces.

Figure 3- Climate models under IPCC auspices give projections of warming far exceeding the actual level of global warming as recorded post 1998 by the two official interpretations of the lower atmosphere temperatures based on satellite data (RSS – Remote Sensing Systems and UAH – University of Alabama at Huntsville).

World Wide CO₂ Emissions – The fourth essential to be aware of is the worldwide distribution of CO₂ emissions. For a variety of reasons US and European human source CO₂ emissions have increased only marginally since 1965 and since about 2007 are declining (see Figure 4).   Emissions from Asia-Pacific countries (primarily China) have been greatly increasing, keeping the overall global human source CO₂ emissions advancing at the steady, high rate observed in the graph presented in global warming 101.  This illustrates the  irrational efforts to restrict United States CO₂ emissions to effect “climate change” when such restrictions, (1) are based only on theory and have no verifiable evidence of a positive effect, (2) are offset many fold by the emissions being produced by Asian countries, and  (3) can adversely impact the U. S. economy and people’s livelihoods.  The first point, that there is no demonstrable empirical evidence that CO₂ restrictions can have a meaningful effect on reducing average global temperature appears to me to be irrefutable.  This is because CO2 emissions are on the rise and have been on the rise for more than a hundred years.  Thus, there has never been a sustained time period with reduced CO2 emissions to allow such evidence to be obtained.  Of course the fact that there has not been the chance to really test a global reduction in CO2 does not prove that it would not have an effect, it simply illustrates that such evidence is lacking.  Further, it does not preclude cutting CO2 based on a confident belief or hope that it would have a positive effect. However, evidence does exist that while human source CO2 emissions were increasing 4 fold over a period of 24 years (1944-1978), global temperatures decreased. Such evidence casts serious doubts about the efficacy of cutting CO2 to reduce global temperatures.   Regulations that would cut CO2 emissions would  make only a small reduction in the US contribution and as can be seen from the rate of rise in Asia Pacific emissions the US cuts would pale in comparison to the increases by the developing countries on which restrictions are not being placed.

Figure 4 – Emissions of CO₂ since 1965 – in the United States, Europe and the Asia Pacific

Based on what is known and can be observed from the historic temperature records, the long term trend of global warming will continue for an unknown time period. The trigger or triggers that have caused the global temperature cycles to reverse direction (see figure 1) are not known. Based on actual empirical evidence there is no reasonable expectation that reducing CO₂ emissions will have any significant effect on global warming, even if it could be accomplished, which appears very unlikely based on the emissions of developing nations.

The bottom line is that global warming is continuing at an irregular pace and does not appear to be significantly influenced, positively or negatively, by human produced CO₂ emissions based on empirical evidence.  Thus, with respect to global warming our nation’s efforts should be directed toward assessing and addressing the potential adverse impacts of global warming. The burning of fossil fuels should not be discounted as a problem but rather be addressed relative to the actual pollutants released by that activity.    Alternative energy sources should continue to be developed because it makes sense to do so.

Human caused global warming and the reduction of CO2 emissions to slow or reverse global warming were and still are hypotheses.  These hypotheses can be countered and shown to be doubtful using empirical data.   An impending, human induced “climate change” calamity continues to be presented to the American people and the world as if it were absolute reality, and as if something meaningful could be done to abate it.  There are apparently many in the scientific and technical community who belief this to be true. In future episodes we will examine the rationale for that belief.  There are many who simply accept that what most in the technical community believe must be true.  And there are some who use their belief in the “climate change” scenario for socio-political and personal economic purposes.  For my part, I see the empirical evidence painting a different picture.   I am trying to provide what I believe to be the factual information related to this subject. So many in the public eye talk about this topic but have no idea what the basic facts are.  I invite you to join Global Warming 103, where with this foundation of factual data as a base we will begin to trace the history of the rise of the global warming concerns and learn about the Al Gore’s “convenient omission” that led so many astray on a very important point.    Thanks, Larry Von Thun