Just Getting Started

Another blog about climate change? Aren't there enough already?

There certainly are a lot of them. I monitor a number of websites that span the full continuum
of opinions from those that claim that Anthropogenic Global Warming (AGW) is a hoax to
websites at the other end of the spectrum that claim a climate catastrophe is near unless
we drastically reduce the use of fossil fuels. 

The vast majority of these websites are at one extreme or the other.  This issue is similar
to many other issues that we face, such as politics, where individuals pick their team and
then they subsequently tend to disregard any information that conflicts with that team's
worldview.  

I personally don’t want to be on a team.  As naive as it sounds, I consider myself a seeker
of truth, or as an empiricist with a scientific background, I seek the closest approximation
to truths that we can find. It's pretty hard to do this when you're on a team.  As I make
additional posts to this blog, I hope that I will receive comments that provide me with
new information or perspectives that might sway my beliefs. 

No one can be completely free of biases - so what are mine?

My views on AGW have evolved, just as the name of the issue has evolved and now is
described as the all-encompassing climate change (CC). In the last two decades of the 20th
century I would describe myself as moderately concerned about CC. So much so that I
supported proposals such as implementing a carbon tax. 

My skeptical period  started around the time (circa 2000) of the famous (or infamous) Michael
Mann "hockey stick” historical  temperature plot. For those too young to remember, or just
generally unaware of the history of the whole climate change debate, Michael Mann's
historical temperature analysis claimed that global temperatures over the last 1000 years
had essentially been flat until around the year 1900, at which point temperatures started to
rise rapidly. Naturally it received tremendous publicity and was presented as Exhibit A
in the CC Alarmist position.  But as a scientist, I was extremely offended by the manner
in which Mann’s temperature analysis was instantly accepted as the gospel truth despite
conflicting with numerous historical accounts that documented significantly warmer and
cooler periods over the last millenium that had been referred to as the medieval warm period
and the little ice age. Typically science doesn't work like that. If a researcher presents data
or analysis that attempts to change the existing paradigm, that analysis is treated skeptically
and the onus is on the researcher to present strong enough evidence. That's not what
happened. It didn't help that Mann would not share his data, analysis or methods
so his work could not be reproduced. 

My skepticism peaked after the Climategate Scandal, where stolen emails showed that
Mann and cohorts had unscientifically (fraudulently?)  concatenated data sets in his
meta-analysis to get the plot to show the desired recent spike AND that he actively used
his influence to prevent dissenting opinions from being published while simultaneously many
were claiming that there was scientific consensus on climate change.  (Full disclosure: Mann
has many defenders and he was cleared of several charges including academic misconduct
by several investigative boards.) I plan a future post to this blog to answer the question:
“Why are there climate change Skeptics?” 

More recently, I have gravitated back towards the concerned end of the spectrum. While I
still believe the most prominent voices in the climate change community are full of
exaggeration and hyperbole, there is no doubt that anthropogenic CO2 emissions are causing
the Earth to warm with resulting changes to the climate. How severe these changes will be,
what will be the consequences, and what can be done about it are intended areas for future
posts, which will hopefully include all valid perspectives and not just those from either team.

This blog is intended to document my search for the current state of knowledge regarding
numerous climate change issues of interest to me and also provide a concise and accessible
reference source on CC issues for those who don't have the time or inclination to do
a deep dive into hundreds of research articles necessary to separate the hyperbole from fact.

Global Warming - It's All Relative Part I

Evidence that the global average temperature has increased over the last century is overwhelming.  Measurements from various sources, including ground stations, satellites, weather balloons, and from the sea, while varying in time dependence and magnitude of the temperature increase, all demonstrate clearly that the Earth is warming.  This warming is believed by many climate scientists to be the cause of some currently occurring changes in climate, and is expected to be the cause of potentially greater climate changes in the future if the increase continues. 

A critical question is to what degree is mankind responsible for the warming since the beginning of the Industrial Age, when we started to unintentionally modify the atmosphere?  The most recent complete report (AR5) by the Intergovernmental Panel on Climate Change (IPCC) asserted that is “extremely likely” that human activities are the dominant cause of the warming of the planet since the mid-twentieth century.  What is the evidence to support this claim? 

One way to evaluate this claim is to compare recent temperature and temperature increases with conditions that have occurred naturally in earlier periods of the Earth's history.  If the temperature or warming rate over the last 50 to 150 years is unprecedented that would provide key evidence that mankind is responsible for the majority of recent warming.

But defining and measuring the global average temperature is not as easy as it might seem. Figure 1 below shows one of the most commonly accepted Global Surface Temperature (GST) histories from NASA's Goddard Institute for Space Studies (GISS).  It is the historical global temperature record created from a network of ground stations and measurements at sea using thermometers. (Note that the temperature is displayed as an aberration from a mean reference temperature as is typically done when discussing climate change.)

Fig. 1 By NASA Goddard Institute for Space Studies - https://data.giss.nasa.gov/gistemp/graphs_v4/, Public

Domain, https://commons.wikimedia.org/w/index.php?curid=24363898

When newspaper & website articles or segments on the evening news report that the latest year is one of the hottest on record, they're frequently referring to data from GISS.

But, there are critics of this claimed historical temperature record. One common complaint is that this temperature record has been manipulated to try to accentuate the recent increase.  This complaint is not without merit. Two of the principals at GISS, first James Hansen and then Gavin Schmidt, have been among the loudest proponents of drastic climate change action.  Critics claim that the numerous adjustments to this temperature record always accentuate recent increases to bolster the alarmist position. The GISS website acknowledges the modifications to the historical record with the graph below in Fig. 2 which shows GISS historical temperature analysis at several different years in the past compared to the present analysis. 

Fig. 2. Graphical display of GISS temperature history adjustments

While it is true that the GISS adjustments to the temperature data have accentuated recent temperature increases, it's also true that temperature is clearly rising in the GISS data no matter how the data has been analyzed.

A more valid criticism of this temperature analysis is that the temperature record from land based stations has been polluted by the urban heat island (UHI) effect.  Almost everyone who lives near a large urban center is aware that the temperature in the urban core can typically be many degrees higher than surrounding areas. Over the last century, as towns having temperature stations grew into cities, the average of recorded temperatures would rise along with the degree of urbanization. This temperature increase introduces a false positive trend to GST over time which is difficult to address via adjustments.  In addition to the UHI effect, the thermometer-based temperature record has other issues such as some of stations being moved from one place to another and changes in the technology and measurement methodology over the last century. 

To quantify the urban heat island effect and other possible inaccuracies let’s compare the GISS temperature history with the temperature history measured by satellites, which provide the most accurate and comprehensive historical global temperature record since 1979.  Fig. 3 below shows a plot of the global temperature anomaly in the lower troposphere (LT) from satellites provided by the University of Alabama Huntsville (UAH).

Fig. 3.  Temperature history from satellite measurements

This temperature analysis is consistent with temperature analysis done by other groups

studying satellite data (RSS), as well as, temperatures recorded from weather balloons.  The lower troposphere in this analysis corresponds to the atmosphere between the surface and approximately three miles from the surface.  

Both the GISS and UAH temperature analysis from 1979 to 2020 show a temperature increase that is close to linear, with fluctuations superimposed upon the linear trend.  The big difference is that the GISS temperature trend is increasing at a rate 43% higher than the data from satellites. It's possible that a portion of this large difference in the temperature increases over the last 40 years reflects a real temperature difference between the earth’s surface and the lower troposphere, but as neither theory or models predict such a large difference, it is more likely due to the limitations and issues in the data and analysis used to create Fig. 1.  For all subsequent posts and analysis we will assume that the global temperature is increasing approximately 0.14 degrees C/decade as derived from the more reliable satellite data. 

The next blog Global Warming - It’s All Relative Part II will investigate how the current temperature and rate of change compare with earlier periods of Earth’s history.