Climate Change
Concerning the next several blogs of the “Sustainability Matters” series, we will consider the science behind climate change.
What we learn from climate science is one of the most compelling arguments for developing and adopting renewable energy technologies.
What science tells us is, there is a direct connection between the burning of fossil fuels and climate change. For that reason, it is logical to stop burning fossil fuels and get our energy elsewhere, presumably from renewable energy sources which do not emit greenhouse gases.
The fact that humans have the power to change the climate is not a new idea, nor is the controversy surrounding both the science and implications of climate change.
Louis Agassiz suggested in 1837 that the earth had undergone a series of what he called “Ice Ages”. If this was true then the earth must have varied in temperature which meant the climate was not static.
In 1824 Joseph Fourier, found that the atmosphere let shortwave radiation pass through it, but limited the exit of the long wave infrared radiation emitted back by the earth. Fourier had previously experimented with a greenhouses’ effect at holding heat and hypothesized that the atmosphere kept the surface of the earth warmer than it would be without it. He also suggests that human’s action might change the climate.
“The establishment and progress of human societies, the action of natural forces, can notably change, and in vast regions, the state of the surface, the distribution of water and the great movements of the air. Such effects are able to make to vary, in the course of many centuries, the average degree of heat; because the analytic expressions contain coefficients relating to the state of the surface and which greatly influence the temperature.”
In 1856 Eunice Foote discovered that both water and CO2 effectively absorb (the reflected) infra-red radiation. This is the mechanism by which the atmosphere holds heat like a “Greenhouse”:
“Thirdly, the highest effect of the sun’s rays I have found to be in carbonic acid gas.” (carbon dioxide) She continued: “An atmosphere of that gas would give to our earth a high temperature; and if, as some suppose, at one period of its history, the air had mixed with it a larger proportion than at present, an increased temperature from its own action, as well as from increased weight, must have necessarily resulted.”
In 1896 Svante Arrhenius who would later win a Nobel Prize for his work, figured that if CO2 was so effective at absorbing heat, perhaps a drop in CO2 levels would explain the cold climate needed for an ice age. He calculated that such a drop of 50% would drop the atmospheric temperature as much as 9 degrees. Conversely if the Carbon Dioxide levels doubled, it would raise the atmospheric temperature by as much as 9 degrees. He went on to predict that the burning of coal would raise the earth’s temperature. Based on the rates of coal use in 1896 he calculated that it would be thousands of years before that burning would have an effect on humans.
Recapping, before 1900, we knew that atmospheric temperature was affected by Carbon Dioxide. We understood how and why that happens and there was a prediction that continued burning of coal would cause the earth’s temperature to rise.
In 1955 Gilbert Plass, a professor at Rutgers University published The Carbon Dioxide Theory of Climate Change which connected CO2 emissions from human activity and a warming climate. In 1956 a Bell Telephone Science Hour, a popular science TV program featured an episode called “Unchained Goddess” which clearly identified CO2 emissions from automobiles with climate change.
In a commencement address in San Diego 1966, Dr. Glenn Seaborg, director of the Atomic Energy Commission said this:
Glen Seaborg
A recently released document from the Richard Nixon Presidential Library reveals that in 1969:
“Nixon advisor Daniel Patrick Moynihan counseled the Nixon administration to initiate a worldwide system of monitoring carbon dioxide in the atmosphere, decades before the issue of global warming came to the public’s attention. There is widespread agreement that carbon dioxide content will rise 25 percent by 2000, Moynihan wrote in a September 1969 memo.”
The concept Moynihan brought to President Nixon was correct, but his early predictions were off by a few years. Based on 1969 levels, we didn’t reach a 25 percent increase in atmospheric CO2 levels by 2000, that occurred in 2016, but we are currently seeing Moynihan’s predicted increase.
Concerning the long-term effects, Moynihan said:
“This could increase the average temperature near the earth’s surface by 7 degrees Fahrenheit,” he wrote. “This in turn could raise the level of the sea by 10 feet. Goodbye New York. Goodbye Washington, for that matter.”
This prediction was received with a rather skeptical response from the administration’s Office of Science and Technology to his January 26, 1970 inquiry, which acknowledged:
“Atmospheric temperature rise was an issue that should be looked at……The more I get into this, the more I find two classes of doom-sayers, with, of course, the silent majority in between…. One group says we will turn into snow-tripping mastodons because of the atmospheric dust and the other says we will have to grow gills to survive the increased ocean level due to the temperature rise.”
Over the next decades, evidence for this theory mounted and in 1988 the Intergovernmental Panel on Climate Change (IPCC) was established to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.
“…to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation. IPCC reports should be neutral with respect to policy, although they may need to deal objectively with scientific, technical and socio-economic factors relevant to the application of particular policies.”
Made up of experts in a range of disciplines and from every participating country in the world, the IPCC is making a comprehensive study of climate change. They periodically issue reports. Before a report is issued there must be agreement among all participants before something is adopted and included in a report. The IPCC Fifth Assessment Report came out in 2014 with its strongest statement on the subject reporting:
“Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history. Recent climate changes have had widespread impacts on human and natural systems.”
“Warming of the climate system is unequivocal, and since the 1950’s many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.”
Greenhouse gases act like blankets holding heat in the atmosphere. Despite the evidence, public controversy continues to rage on regarding whether or not climate change is “real,” and what actions, if any, to take.
What is this evidence? How did we make the connection between the emissions of greenhouse gases and rising temperatures? How do we know this is not part of a normal (non-human) process or cycle? These are legitimate questions which deserve answers.
We’ll first look at some of the evidence that we can see and measure today. Then we will examine the climate records of the recent past. We’ll also look at various techniques used to establish temperature and atmospheric composition in the distant past. Finally, we’ll look at how models are used to suggest what future conditions are likely to be.
Is there any evidence we can observe from the weather?
The short-term conditions of temperature, humidity and wind – what we call weather – has extreme variability. One day it’s cold and the next day it’s hot. One winter is very snowy and the next winter there’s hardly any snow. These variable weather conditions do not, by themselves, represent the long-term climate.
Climate represents the weather conditions over a long period of time meaning decades to centuries. Climate includes all the variable weather patterns. Put another way, weather becomes climate in the rear-view mirror. When yesterday’s weather becomes part of a large amount of data over a long period of time, those long-term conditions and patterns reveal climate and climate changes.
Like a movie made of thousands, perhaps millions, of individual images, one image or even 1000 images may or may not give an indication of the plot of the movie. Similarly, the day-to-day weather conditions at a given location may or may not be representative of the long-term climate or changes in a climate. Each event must be put into context.
How Do We Know the Earth is Warming?
In the 1590’s, Galileo invented a precursor to the thermometer, what could be called a thermoscope, an instrument that indicated temperature differences in 1612, Santorio invented the alcohol thermometer. A German physicist named Daniel Gabriel Fahrenheit introduced the mercury thermometer in 1714. Fahrenheit also introduced a scale of measurement, so temperatures could be recorded and compared in time and place. His original temperature scale was between 0 and 90 with 0 being the temperature of a water-salt-ice mixture, 30 being the temperature at which ice began to form on a freezing body of water, and 90 being the temperature of the human body (measured under arm or in mouth). Later, both freezing and body temperatures were adjusted as more accurate calibrations were done.
Though the thermometer and a measurement scale of temperature was invented by Fahrenheit, most of the world uses the Celsius scale where 0 represents the temperature at which water freezes and 100 represents its boiling point. One degree C equals 1.8 degrees Fahrenheit.
Humans have been taking air temperatures since the thermometer was invented, and starting around 1880, we had recorded enough data to make estimates of worldwide temperature trends. The graph below shows average global thermometer records over the past 135 years.
Fig. 3-1: Global Surface Temperature (1880-2019)
This data is taken from thousands of readings from around the world. As we discussed earlier, in any scientific endeavor, the greater the precision and smaller the margin of error is, the more accurate the data will be. Obviously, there are inherent problems with thousands of people taking temperature readings over 135 years. Suppose my thermometer reads a degree and a half higher than yours? Taken over time, that would give inaccurate information. However, if we measure the relative change at each of our stations, we can incorporate our data together in a more meaningful way. This is what was done to make the above chart.
The graph above (Figure 3-1) shows relatively roughly constant average temperatures until the early 20th century, when temperatures begin to rise and then increase sharply into 21st century. Figure 3-2 below shows this period of sharp rise in more detail.
Figure 3-2: Seasonally averaged temperature anomalies (1880–2019).
As you would imagine, the science of taking measurements around the world has gotten more precise since 1880. That is to say, measurements are more consistent. It is believed that prior to 1950, the estimates in Figure 3-1 have a +/- 0.2°C range of error, that is to say, they could be anywhere from +.02°C greater than reported to -.02°C less than reported. After 1950 +/- 0.05°C range of error. The accuracy of the graph, or how close to ‘the truth’ the graph gets, reflects these improvements.
Next week we’ll discuss climate change in further detail!
What did you learn from this week’s blog?
