On my recent Amtrak trip between Tucson, AZ and Alpine, TX, I caught up on some reading. The highlight of that reading was an article by Alexandra Witze entitled “A Planetary Crisis” in the March 12, 2022 issue of Science News (pp. 16-24). This is absolutely the best article I have ever read about the history of our scientific knowledge on the topic of human-induced climate change.
One important point to call out. The Mauna Loa Observatory in Hawaii has been continuously monitoring atmospheric CO2 levels since March 1958, and the annual mean CO2 level has increased 31.8% between 1959 and 2021.
315.98 ± 0.12 ppm
416.45 ± 0.12 ppm
Annual Mean CO2 at Mauna Loa expressed as a mole fraction of dry air (micromol/mol = parts per million = ppm)
And, most recently,
Alarmingly, the rate of increase is not linear.
We know that carbon dioxide is a potent greenhouse gas. And, as Witze’s article explains, that fact has been known since 1856.
One thing is crystal clear. Human activity (mostly the burning of fossil fuels) is causing the increase in the atmospheric concentration of carbon dioxide, and that is causing our planet to warm. We need to quickly and substantially reduce the amount of CO2 we are dumping into the atmosphere—or risk catastrophic consequences. I’m trying to do my part. We just installed rooftop solar panels that should generate most or all of the electricity we consume, including that required to power an electric car. As soon as I can get one (this fall?), I will be trading in my gasoline-powered car for an electric one.
By the way, I’ve been a subscriber to Science News for the past 50 years, and in my opinion there is no better newsmagazine covering all areas of science. If you aren’t already a subscriber, please consider becoming one.
Lewis Thomas (1913-1993) wrote in his essay Late Night Thoughts on Listening to Mahler’s Ninth Symphony,
“I cannot listen to the last movement of the Mahler Ninth without the door-smashing intrusion of a huge new thought: death everywhere, the dying of everything, the end of humanity…How do the young stand it? How can they keep their sanity? If I were very young, sixteen or seventeen years old, I think I would begin, perhaps very slowly and imperceptibly, to go crazy…If I were sixteen or seventeen years old…I would know for sure that the whole world was coming unhinged. I can remember with some clarity what it was like to be sixteen…I was in no hurry…The years stretched away forever ahead, forever…It never crossed my mind to wonder about the twenty-first century; it was just there, given, somewhere in the sure distance.”
Thomas was referring to the threat of nuclear war, which is still very much with us. Now, can you imagine as bad as the COVID-19 pandemic has been, what a nuclear war would be like? We need to rid our planet of these weapons, now.
As I was listening to the final movement of Gustav Mahler’s Symphony No. 9, the Adagio, this past Monday, I was also thinking, of course, about the frightening ravages of COVID-19, but also climate change and the precipitous decline in biological diversity caused by humans. All of this is driven by the fact that there are too many people on the planet, and the answer is not to kill (by whatever means) people who are already here, but to bring fewer children into the world so we can lower human population to a sustainable level in the coming generations. We could all have a higher standard of living without trashing the planet.
On Wednesday, the 50th anniversary of Earth Day, PBS aired a new BBC documentary, Climate Change: The Facts. I was riveted by the program, presented by Sir David Attenborough, who will turn 94 next month the day before I turn 64. David Attenborough is an international treasure. Watching him so expertly present, as he always does, the urgency of this climate crisis and remembering his many outstanding documentary series such as Life on Earth and The Living Planet, I became teary eyed knowing that he will not be with us for very much longer. You wish someone like David Attenborough or Carl Sagan could live for hundreds of years. Because, when our life is over, we will cease to exist as a conscious entity, for all eternity. I am now certain of that. Realizing that this is our one and only life gives one a very different perspective on what we are doing to this world—and to each other. Humanists value the sanctity of each human life more than anyone who believes in an afterlife. Humanists fully understand the enormous responsibility each of us living in this current generation has to ensure that our civilization does not descend into a dystopian existence. There will be no salvation, just unimaginable pain, suffering, and destruction of all that is good, if we fail.
I am so inspired by young Greta Thunberg, who features prominently in the documentary. Greta and the many other young activists around the world give me hope for the future. Her words and conviction brought more tears to my eyes. I may be 63, but I’m with you 100%, Greta. Sign me up!
In 1908 and 1909, Gustav Mahler finished his last completed work, the Symphony No. 9. There was much turmoil and tragedy in Mahler’s life prior to the writing of this symphony. His beloved oldest daughter, Maria Anna Mahler, died of scarlet fever and diphtheria on 5 July 1907 at the age of 4. Immediately after Maria’s death, Mahler learned that he had a defective heart. And his relationship with his wife Alma had become strained. Gustav Mahler died on 18 May 1911. He never heard his Symphony No. 9 performed. It received its premiere on 26 June 1912 in Vienna with Bruno Walter conducting the Vienna Philharmonic Orchestra.
The final movement of Mahler’s Symphony No. 9, the Adagio, is one of the most moving pieces of music I have ever heard. While listening to it, one thinks of all the beauty that was and is in the world, and how terribly much we have lost.
The most expressive recording of the Adagio I have heard is by the Chicago Symphony Orchestra, conducted by Sir Georg Solti (Decca 473 274-2). If this movement of 24:37 does not bring you to tears, I don’t know what will.
Climate change is a serious problem requiring immediate attention. We need to reduce greenhouse gas emissions into our atmosphere as fast as possible. Half measures will not do. We are rapidly running out of time before the quality of life for all humans on planet Earth declines, especially for the economically disadvantaged.
A precipitous decline in biological diversity due to habitat loss and extinction of species is of greater concern, and yet it gets very little attention in the mainstream media. While climate change will render large areas of the Earth uninhabitable, biodiversity loss will lead to a partial or complete collapse of the ecosystem humans depend upon for food.
Getting even less attention is the cause of both of these problems: overpopulation. If you were born in 1973, the world’s human population is now twice what it was then. If you were born in 1952, there are three times as many people alive now than there were then. We have a climate emergency and a biodiversity emergency because we have a population emergency. The number of humans on this planet needs to decline, and the only humane way to accomplish that is to have fewer children. It is that simple.
And, yet, we often see this or that news article lamenting the fact that the birth rate in this or that country is too low. That’s crazy! A low birth rate should be a cause for celebration given the current state of the world and its environment. Certainly, a low birth rate does lead to some economic challenges, but these pale in comparison to the challenges we will face if population (and consumption) continue to grow.
As a humanist, I believe that we should do all we can to alleviate and eliminate human suffering. It is our highest moral calling. To be sure, some human suffering is inevitable and necessary when an individual makes poor decisions and suffers the consequences before hopefully making a mid-course correction. But the kind of suffering I am talking about is suffering that is imposed upon a person through no fault of their own, be it the cruelty of other human beings, or the cruelty of nature.
In this light we can see that our economic systems, governments, and most religions are utterly failing us. Nothing short of drastic changes will solve these problems. May wisdom, intelligence, ingenuity, and compassion guide us, rather than fear, ignorance, hatred, and dogma.
There is an organization dedicated to stabilizing human population throughout the world by lowering the birth rate: Population Connection. I encourage you to support their work as I do.
In terms of bulk properties, Venus is the most Earthlike planet in the solar system. The diameter of Venus is 95% of Earth’s diameter. The mass of Venus is 82% of Earth’s mass. It has a nearly identical composition.
But…the average surface temperature of Venus is 735 K (863˚ F) and the surface atmospheric pressure is 91 times greater than Earth’s—equivalent to the pressure 3,000 ft. below the ocean’s surface. The present atmosphere of Venus is composed of 96.5% carbon dioxide (CO2) and 3.5% nitrogen (N2), plus a number of trace elements and compounds.
Venus was not always so inhospitable. What happened?
The cratering record suggests that nearly all of Venus has been resurfaced within the last 300 – 800 Myr. Before that, Venus probably was much more hospitable, even habitable, perhaps. The Pioneer Venus large probe and infrared spectral observations from Earth of H2O and HDO (deuterated isotope of water) indicate that the deuterium-to-hydrogen ratio in the Venusian atmosphere is 120 – 157 times higher than in water on Earth, strongly suggesting that Venus was once much wetter than it is today and that it has lost much of the water it once had to space. (Hydrogen is lighter than deuterium and therefore more easily escapes to space.) In addition to deuterium abundance, measuring the isotopic abundance ratios of the noble gases krypton and xenon would help us better understand the water history of Venus. These cannot be measured remotely and requires at-Venus sampling.
Venus receives 1.92 times as much solar radiation as the Earth, and this was undoubtedly a catalyst for the runaway greenhouse effect that transformed the Venusian climate millions of years ago.
We know that CO2 is a potent greenhouse gas, but anything that increases the amount of water vapor (H2O) in the atmosphere leads to global warming as well. As do clouds.
Climate modeling shows us that that the hothouse on the surface of Venus today is due to CO2 (66.6%), the continual cloud cover (22.5%), and what little water vapor remains in the atmosphere (10.9%).
Interestingly, if all the CO2 and N2 in the Earth’s crust were somehow liberated into the atmosphere, our planet would have an atmosphere very similar to Venus.
Venus is the easiest planet to get to from Earth, requiring the least amount of rocket fuel. There is so much we still don’t understand about how Venus transformed into a hellish world, and we would be well-advised to learn more about Venus because it may inform us about Earth’s future as well.
Tessera terrain covers about 7% of the surface of Venus. These highly deformed landforms, perhaps unique in the solar system, may allow us to someday sample the only materials that existed prior to the great resurfacing event.
If living organisms ever developed on Venus, the only place they could still survive today is 30 miles or so above the surface where the atmospheric temperature and pressure are similar to the surface of the Earth.
Even four billion years ago, Venus may have been too close to the Sun for life to develop, but if it did, Venus probably remained habitable up to at least 715 Myr ago.
Now for the bad news. All main-sequence stars, including our Sun, slowly brighten as they age, and their habitable zones move outward from their original locations. Our brightening Sun will eventually render the Earth uninhabitable, certainly within the next two billion years, and our water could be lost to the atmosphere and then space within the next 13o million years, leading to a thermal runaway event and an environment similar to that of Venus. Human-induced climate change could make the Earth uninhabitable for humans and many other species long before that.
One indication that water is being lost to space and surface warming is occurring is water vapor in the stratosphere. The more water vapor that is in the stratosphere, the more water is being forever lost to space and the greater the surface warming. Careful and continuous monitoring of water vapor levels in the Earth’s stratosphere is important to our understanding of climate change on Earth.
To conclude, Arney and Kane write:
“Venus teaches us that habitability is not a static state that planets remain in throughout their entire lives. Habitability can be lost, and the runaway greenhouse is the final resting place of once watery worlds.”
Arney, G., & Kane, S. 2018, arXiv e-prints, arXiv: 1804.05889
Bézard, B., & de Bergh, C. 2007, J. Geophys. Res., 112, E04S07, doi: 10.1029/2006JE002794.
Ostberg, C., & Kane, S. R. 2019, arXiv e-prints,arXiv: 1909.07456
Serbian engineer, mathematician, and scientist Milutin Milanković was born 140 years ago on this date in 1879, in the village of Dalj on the border between Croatia and Serbia—then part of the empire of Austria-Hungary. He died in 1958 in Beograd (Belgrade), then in Yugoslavia and today in Serbia, at the age of 79.
Milanković is perhaps most famous for developing a mathematical theory of climate based on changes in the Earth’s orbit and axial orientation. There are three basic parameters that change with time—now known as the Milankovitch cycles—that affect the amount of solar energy the Earth receives and how it is distributed upon the Earth.
I. Orbital eccentricity of the Earth changes with time
The eccentricity (e) tells you how elliptical an orbit is. An eccentricity of 0.000 means the orbit is perfectly circular. A typical comet’s orbit, on the other hand, is very elongated, with an eccentricity of 0.999 not at all uncommon. Right now, the Earth’s orbital eccentricity is 0.017, which means that it is 1.7% closer to the Sun at perihelion than its semimajor axis distance (a), and 1.7% further from the Sun at aphelion than its semimajor axis distance.
The greater the eccentricity the greater the variation in the amount of solar radiation the Earth receives throughout the year. Over a period of roughly 100,000 years, the Earth’s orbital eccentricity changes from close to circular (e = 0.000055) to about e = 0.0679 and back to circular again. At present, the Earth’s orbital eccentricity is 0.017 and decreasing. We now know the Earth’s orbital eccentricity changes with periods of 413,000, 95,000, and 125,000 years, making for a slightly more complicated variation than a simple sinusoid, as shown below.
II. Tilt of the Earth’s axis changes with time
The tilt of the Earth’s polar axis with respect to the plane of the Earth’s orbit around the Sun—called the obliquity to the ecliptic—changes with time. The Earth’s current axial tilt is 23.4°, but it ranges between about 22.1° and 24.5° over a period of about 41,000 years. Greater axial tilt means winter and summer become more extreme. Presently, the axial tilt is decreasing, and will reach a minimum around 11,800 A.D.
III. Orientation of the Earth’s axis changes with time
The Earth’s axis precesses or “wobbles” with a period of around 26,000 years about the north and south ecliptic poles. This changes what latitude of the Earth is most directly facing the Sun when the Earth is closest to the Sun each year. Currently, the southern hemisphere has summer when the Earth is at perihelion.
Milanković used these three cycles to predict climate change. His ideas were largely ignored until 1976, when a paper by James Hays, John Imbrie, and Nicholas Shackleton in the journal Science showed that Milanković’s mathematical model of climate change was able to predict major changes in climate that have occurred during the past 450,000 years.
These Milankovitch cycles are important to our understanding of climate change over much longer periods than the climate change currently being induced by human activity. Note the extremely rapid increase of greenhouse gas concentrations (CO2, CH4, and N2O) in our atmosphere over the past few decades in the graphs below.
The world population has increased by 93% since 1975. In 1975, it was about 4 billion and by 2020 it is expected to be 7.8 billion.
The Intergovernmental Panel on Climate Change (IPCC) issued an important special report yesterday on climate change. In the accompanying press release, they state the following:
Limiting global warming to 1.5°C would require “rapid and far-reaching” transitions in land, energy, industry, buildings, transport, and cities. Global net human-caused emissions of carbon dioxide (CO2) would need to fall by about 45 percent from 2010 levels by 2030, reaching ‘net zero’ around 2050. This means that any remaining emissions would need to be balanced by removing CO2 from the air.
This report will be a key scientific input into the Katowice Climate Change Conference in Poland in December, when governments review the Paris Agreement to tackle climate change.
We are already seeing the consequences of 1°C of global warming through more extreme weather, rising sea levels and diminishing Arctic sea ice.
Warming of 1.5ºC or higher increases the risk associated with long-lasting or irreversible changes, such as the loss of some ecosystems.
In the Summary for Policymakers, the IPCC states that “warming from anthropogenic emissions from the pre-industrial period to the present will persist for centuries to millennia and will continue to cause further long-term changes in the climate system, such as sea level rise, with associated impacts.”
This last point is very important. Even if humanity disappeared from the face of the Earth tomorrow, it will take centuries to millennia for greenhouse gases in our atmosphere to return to pre-industrial levels.
Richard Wolfson, Professor of Physics at Middlebury College in Middlebury, Vermont, states in his excellent 2007 video course, “Earth’s Changing Climate” (The Great Courses, Course No. 1219),
The atmosphere, living things, soils, and surface ocean waters all represent short-term carbon reservoirs. Cycling among these reservoirs occurs mostly on relatively short time scales. In particular, a typical carbon dioxide molecule remains in the atmosphere only about five years. But the rapid cycling of carbon through the atmosphere-biosphere-surface ocean system means that any carbon added to that system remains there much longer—for hundreds to thousands of years. Because the added carbon cycles through the atmosphere, the level of atmospheric carbon dioxide goes up and stays up for a long time.
We’ve known about this aspect of climate change for a long time. It is based on solid science. Any action we take now, either positive or negative, will affect Earth’s environment many generations into the future.
I know of no better introduction to climate science than Richard Wolfson’s video course. Even though it was produced 11 years ago, it is still completely relevant.