After several years of researching the subject of global warming or climate change, it is time that I organized my thoughts and formulated an opinion for my readers. In spite of what alarmists like to call a consensus, there is very
little agreement on the subject, whether between scientists, bloggers and journalists, or the people on the street. There are extreme opinions ranging from imminent catastrophic climate change, as a result of anthropogenic influence, to a total denial of significant
change or of a human factor in climate variability. Sorting it out is difficult and time consuming and the attempt would not have been possible if it was not a retirement project.
I have no profit motive
to influence me in any way. There is no advertising on this site and I have nothing to sell. I believe I can be as objective as is possible. I do not believe in the infallibility of science or scientists and I do not believe that any supreme beings will save
us from our own actions. I do not have much faith in governments or politicians actually perceiving real problems or implementing the right actions. Nor do I think that they really put the fate of mankind above their need for votes, popularity or power.
I have used three processes in formulating an opinion.
The first is is research of relevant scientific publications and the reading of the opinions of learned
scientists, bloggers and journalists, and following public debate. Most of this research is via the internet and there is considerable difficulty in sorting the “wheat from the chaff”. There is a lot of unsupported conjecture and outright falsehood
presented as fact. The profit motive and bias, for any reason, is rampant.
The second is to use current observations (or data), by scientists and others, of changes in the natural world that might support
The third is personal experience. I have been aware of my environment for at least 65 years and I have an excellent memory. I think my own observations should have some value.
In this post I am going to deal specifically with the reality (or not) of global warming since there can really not be any reasonable argument about the reality of climate change.
going to start with the last. Since we are concerned with climate change and in particular global warming, I have thought carefully of the changes I have noticed in the last 60 plus years. Some of these changes may not be directly related to climate, but are,
Has our climate warmed? My experience would suggest it has. In my area the frost free growing period seems to have lengthened a bit and we seem to have fewer extremely cold days
in winter. I have not noticed an increase in hot days during summer and the opposite might be true. It is still difficult to accumulate enough heat units to mature corn in my garden, in spite if the longer growing season. My conclusion would be that our local
seasonal temperature variations have moderated. From my perspective, our local climate has improved.
What about the frequency and intensity of damaging storms? No change seems to be obvious. The amount of
damage from extreme weather has certainly increased, but that is probably due to a much increased population density and widespread development.
If I were to make a judgment based on personal local observation,
I would say that our climate has changed very little, with only an insignificant warming. What have you seen?
To broaden the outlook a bit I have to rely on news reports, scientific assessments and internet
sources to put some global perspective on climate change, as indicated by my first method. To identify temperature trends we have access to ground-based instrumental records, satellite measurements and observations of phenomenon such as sea level rise, glacial
retreat and sea ice coverage. For longer periods into the past, we have proxy evidence which include tree ring records, ice sheet cores, lake and ocean bottom sediment cores and other fossil evidence.
instrumental measurements have been recorded for about a century and a half. This is a pitiably short period in geologic time, but is relative to the time period in which humanity could have had a significant effect on global climate. These instrumental records
suffer from multiple sources of error and require picking of the best data and adjustments (perhaps not not always appropriate). In spite of these short-comings most researchers seem to agree that we have seen a warming trend of the near surface atmosphere,
amounting to about 0.85 degrees C from 1880 to 2000. It is somewhat controversial if this is a significant or consequential amount of warming.
Since about 1979, we have also had satellite measurements of
atmospheric temperatures. They provide a much broader coverage which includes an equal sampling of much of the earth's surface, including sea surface area. This would appear to provide much more accurate and valuable datum, usually expressed as an anomaly
from the 1980 to 2010 averages. Their data also show a warming trend, although somewhat less than that inferred from the ground-based instrumental record.
Much has been made of the apparent hiatus of significant
warming in the period between 1998 and 2015. I don't believe it means much, but it does emphasize the spiked nature of any warming trend that may exist. One problem with starting from 1880 is that this was apparently a somewhat cooler period (a downward spike.)
Perhaps the warming is a little less significant. Another problem is that our current warming is not unusual when compared to other inter glacial periods in the planets past.
A little further back in geologic
time is the Eocene epoch, a period in prehistory beginning about 56 million years ago and ending about 34 mya. In the early Eocene the Earths average temperature is estimated to have been about 8 degrees C warmer than the present, although I have seen
studies that theorize spikes as much as 17 degrees over current values. The end of the Eocene is also when our current cycle of ice ages seems to have begun.
Life at the time (early ancestors of much of
today's existing life) seems to have flourished. At least until the glaciations began. It was a period long before any semblance of human life appeared.
The Eocene, and previous inter glacial periods, illustrates
that current warming is not unique or unprecedented, and to apply these terms to it one must impose arbitrarily short time periods. Of course, the argument is put forward that the rapidity of change is unprecedented. I haven't seen any convincing evidence
to support this.
The Eocene does provide evidence that the earth can become much warmer without dire consequences to life on the planet. It also indicates that cooling can be initiated naturally and result
In our second method of reasoning we look at the natural occurrences in nature that may provide evidence of warming or not.
One of the
most used arguments for global warming (we will put aside the anthropogenic factor for now) is the retreat of glaciers and the reduction in sea ice area. There is no doubt that most alpine glaciers have been retreating and little doubt that some grounded ice
sheets are losing mass.
Is this evidence of a warming climate? Perhaps, perhaps not. It is possible that the climate has been warm enough that ice would continue to melt back without an increase in temperature.
Many other factors influence the growth or retreat of glaciers, the most significant of which is winter precipitation. A warmer climate may actually encourage the growth of glaciers by increasing precipitation. It seems that glaciers advance and retreat unpredictably
over longer periods although the more general glaciations have followed a perceptible pattern.
Grounded ice sheets present another enigma. While ice sheets in the Northern hemisphere seem to be losing mass
the opposite may be true for the massive ice sheets of Antarctica.
The reduction of sea ice area is most evident in the arctic ocean.
Although presented by many as being significant and the imminent disappearance has been predicted, by some for decades, not a lot seems to have happened. Modern satellite measurements have only been available for a few decades The reduction may not even be
unprecedented. There is some evidence that coverage may have been even less as recently as 1940. Of course, the presence of fossils on arctic islands indicate that the Arctic has been much warmer in prehistory. Again, there are other possible factors,
such as warmer ocean currents. Then there are the albedo changes which poses the question of cause and effect. Is there less ice because of a warmer climate or a warmer climate because of less ice?
have postulated that the loss of arctic ice would impact polar bears and reduce populations. Recent research has indicated that most populations have not been negatively impacted and numbers have actually increased. This does not mean that reduced ice area is an advantage for them
as other factors such as reduced hunting may be at play. It does suggest that the impact of global warming may not be that significant.
Sea level rise is also presented as evidence of warming. It is attributed
to the melting of land fast ice sheets and glaciers, and to thermal expansion of the waters.
It is evident that sea levels are rising. We seem to have had a rise of about 7 inches in the past century. This is about par with the rise we have seen in the last several centuries as we gradually continue
to emerge from the last glaciation. There is an argument that sea levels are recently rising at a faster pace but I have not seen much valid support for this. There is no real reason for levels to rise at a steady rate and it seems likely that it will proceed
in spurts, similarly to global warming.
Our concern would be the loss of land near sea level due to rising waters. There is considerable development in coastal areas, but it seems that most of it would be
obsolete before sea levels that threaten it becomes uncontrollable. Some people are at risk of eventually losing their land and homes to the sea, but there are also many people at risk from volcanoes, earthquakes and other extreme events which are infinitely
less predictable, and with more dangerous and immediate consequences. There is a lot of time to plan for avoiding most of the negative consequences of sea level rise.
A recent study that came to my attention has shown, that in recent history, we have gained more coastal land from the sea than has been lost to sea level rise.
The impact of sea level rise is felt differently in different areas. It is only important in relation to the adjacent coastal communities. Some cities have been subsiding due to the drawing of groundwater or oil and gas. Some have already sunk below sea level. Other Northern areas are actually rising as the earth rebounds from the
weight of the last glaciation.
Another quoted indicator of a warming climate has been the northward (or southward in the southern hemisphere) migration of warm weather plants and animal life. This could
be a fact, but there is another possible reason for at least part of the phenomenon. Increased CO2 seems to increase cold and heat tolerance in plants and this could account for them increasing their range. Animals and insects, of course, follow their food
Although this discourse may seem long it is actually only a very brief examination of the evidence for or against a warming global climate. Other aspects of climate change and the human factor have
been mostly ignored, so far. It has been an attempt to condense the most relative evidence of a warming climate (or not) and to reach a reasonable conclusion based on that evidence. The question we are considering is simply, is our climate warming in a significant
Has our climate warmed in the last 150 years? My answer would have to be, yes it has, but the degree of warming that has occurred is not that significant or consequential, up to now.
Has our climate warmed from 16000 years ago? Again the answer is a definite yes, and the warming, in this case, has been significant and consequential. As in any comparison, the starting point is important
Is our climate warmer than during the Eocene or during more recent inter-glacial periods? I think the answer would be no, and the indication is that current warmth is not unprecedented.
are, of course, many more questions about climate change that need to be considered. A couple of the more important would be whether the planet will continue to warm and what the contribution of human activity is. I will attempt to deal with these in my next