--- title: "Meaning & Key Takeaway of: The principal energy sources of our…" description: "\"“The principal energy sources of our present industrial civilization are the so-called fossil fuels. We burn wood and oil, coal and natural gas, and, i..." image: "https://sms4smile.com/quotes/i/da3/carl-sagan-160_blue-planet_the-principal-energy-sources-of-our-pres_1126507.jpg" --- # The principal energy sources of our present industrial… ![“The principal energy sources of our present industrial civilization are the so-called fossil fuels. We burn wood and oil, coal and natural gas, and, in the process, release waste gases, principally CO2, into the air. Consequently, the carbon dioxide content of the Earth’s atmosphere is increasing…” quote by Carl Sagan](https://sms4smile.com/quotes/i/da3/carl-sagan-160_blue-planet_the-principal-energy-sources-of-our-pres_1126507.jpg) [Download](https://sms4smile.com/quotes/i/da3/carl-sagan-160_blue-planet_the-principal-energy-sources-of-our-pres_1126507.jpg) [Open image](https://sms4smile.com/quotes/i/da3/carl-sagan-160_blue-planet_the-principal-energy-sources-of-our-pres_1126507.jpg) > ““The principal energy sources of our present industrial civilization are the so-called fossil fuels. We burn wood and oil, coal and natural gas, and, in the process, release waste gases, principally CO2, into the air. Consequently, the carbon dioxide content of the Earth’s atmosphere is increasing dramatically. The possibility of a runaway greenhouse effect suggests that we have to be careful: Even a one- or two-degree rise in the global temperature can have catastrophic consequences. In the burning of coal and oil and gasoline, we are also putting sulfuric acid into the atmosphere. Like Venus, our stratosphere even now has a substantial mist of tiny sulfuric acid droplets. Our major cities are polluted with noxious molecules. We do not understand the long-term effects of our course of action. But we have also been perturbing the climate in the opposite sense. For hundreds of thousands of years human beings have been burning and cutting down forests and encouraging domestic animals to graze on and destroy grasslands. Slash-and-burn agriculture, industrial tropical deforestation and overgrazing are rampant today. But forests are darker than grasslands, and grasslands are darker than deserts. As a consequence, the amount of sunlight that is absorbed by the ground has been declining, and by changes in the land use we are lowering the surface temperature of our planet. Might this cooling increase the size of the polar ice cap, which, because it is bright, will reflect still more sunlight from the Earth, further cooling the planet, driving a runaway albedo\* effect? Our lovely blue planet, the Earth, is the only home we know. Venus is too hot. Mars is too cold. But the Earth is just right, a heaven for humans. After all, we evolved here. But our congenial climate may be unstable. We are perturbing our poor planet in serious and contradictory ways. Is there any danger of driving the environment of the Earth toward the planetary Hell of Venus or the global ice age of Mars? The simple answer is that nobody knows. The study of the global climate, the comparison of the Earth with other worlds, are subjects in their earliest stages of development. They are fields that are poorly and grudgingly funded. In our ignorance, we continue to push and pull, to pollute the atmosphere and brighten the land, oblivious of the fact that the long-term consequences are largely unknown.”” [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) ## About This Quote This interpretation was drafted with AI assistance. It is one reading of the quote, not the author's own explanation. Human activity releases greenhouse gases and aerosols, causing both warming and cooling forces that destabilize Earth’s climate and risk extreme planetary states. **In simple terms:** Human actions change climate, risking dangerous warming or cooling. Key Takeaway Recognize and mitigate both emissions and land‑use impacts. Themes environment climate change science risk policy Mood concerned urgent reflective Type scientific warning When to use this quote - energy policy - urban planning - agricultural reform - forestry management - public education Key Concepts greenhouse effect albedo feedback deforestation acid rain planetary habitability Questions to Reflect On - What balance of emission cuts and land‑use changes best stabilizes climate? - How can societies act now without harming economies? A Different Perspective Mitigation is complex; trade‑offs exist between reducing warming and avoiding over‑cooling. ★ ★ ★ ★ ★ No ratings yet [Blue planet](https://sms4smile.com/quotes/about/blue-planet/) [Carbon dioxide](https://sms4smile.com/quotes/about/carbon-dioxide/) [Climate](https://sms4smile.com/quotes/about/climate/) [Environment](https://sms4smile.com/quotes/about/environment/) [Fossil fuel](https://sms4smile.com/quotes/about/fossil-fuel/) [Fossil fuels](https://sms4smile.com/quotes/about/fossil-fuels/) [Ice age](https://sms4smile.com/quotes/about/ice-age/) [Natural gas](https://sms4smile.com/quotes/about/natural-gas/) ## Related quotes > [“To understand how the first tree appeared on Earth, we must look back more than 3 billion years to Earth’s cooling off and changing…](https://sms4smile.com/quotes/richard-m-ketchum/to-understand-how-the-first-tree-appeared-on-earth-we-must-look-back/) [Richard M. Ketchum](https://sms4smile.com/quotes/author/richard-m-ketchum/) > [“Thus, 99 percent of the Earth’s atmosphere is of biological origin. The sky is made by life.”](https://sms4smile.com/quotes/carl-sagan/thus-99-percent-of-the-earth-s-atmosphere-is-of-biological-origin-the/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [“Another glorious feature of many modern science museums is a movie theater showing IMAX or OMNIMAX films. In some cases the screen is ten…](https://sms4smile.com/quotes/carl-sagan/another-glorious-feature-of-many-modern-science-museums-is-a-movie/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [If the greenhouse effect is a blanket in which we wrap ourselves to keep warm, nuclear winter kicks the blanket off.](https://sms4smile.com/quotes/carl-sagan/if-the-greenhouse-effect-is-a-blanket-in-which-we-wrap-ourselves-to/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [What a splendid perspective contact with a profoundly different civilization might provide! In a cosmic setting vast and old beyond ordinary human understanding we…](https://sms4smile.com/quotes/carl-sagan/what-a-splendid-perspective-contact-with-a-profoundly-different/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Our posturings, our imagined self-importance , the delusion that we have some privileged position in the universe are challenged by this point of pale light.](https://sms4smile.com/quotes/carl-sagan/our-posturings-our-imagined-self-importance-the-delusion-that-we-have-2/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [A sound Physics of the Earth should include all the primary considerations of the earth's atmosphere, of the characteristics and continual changes of the…](https://sms4smile.com/quotes/jean-baptiste-lamarck/a-sound-physics-of-the-earth-should-include-all-the-primary/) [Jean-Baptiste Lamarck](https://sms4smile.com/quotes/author/jean-baptiste-lamarck/) > [The entire range of living matter on Earth from whales to viruses and from oaks to algae could be regarded as constituting a single…](https://sms4smile.com/quotes/james-lovelock/the-entire-range-of-living-matter-on-earth-from-whales-to-viruses-and/) [James Lovelock](https://sms4smile.com/quotes/author/james-lovelock/) > [Above me I saw something I did not believe at first. Well above the haze layer of the earth's atmosphere were additonal faint thin…](https://sms4smile.com/quotes/david-g-simons/above-me-i-saw-something-i-did-not-believe-at-first-well-above-the/) David G. 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But others pop up…](https://sms4smile.com/quotes/neil-degrasse-tyson/some-molecules-ammonia-carbon-dioxide-water-show-up-everywhere-in-the/) [Neil deGrasse Tyson](https://sms4smile.com/quotes/author/neil-degrasse-tyson/) > [“The Earth is bathed in a flood of sunlight. A fierce inundation of photons—on average, 342 joules per second per square meter. 4185 joules…](https://sms4smile.com/quotes/kim-stanley-robinson/the-earth-is-bathed-in-a-flood-of-sunlight-a-fierce-inundation-of/) [Kim Stanley Robinson](https://sms4smile.com/quotes/author/kim-stanley-robinson/) > [Between earth and earth's atmosphere, the amount of water remains constant; there is never a drop more, never a drop less. This is a…](https://sms4smile.com/quotes/linda-hogan/between-earth-and-earth-s-atmosphere-the-amount-of-water-remains/) [Linda Hogan](https://sms4smile.com/quotes/author/linda-hogan/) ## More by Carl Sagan > [It is sometimes said that scientists are unromantic, that their passion to figure out robs the world of beauty and mystery. But is it…](https://sms4smile.com/quotes/carl-sagan/it-is-sometimes-said-that-scientists-are-unromantic-that-their/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [The prediction of nuclear winter is drawn not, of course, from any direct experience with the consequences of global nuclear war, but rather from…](https://sms4smile.com/quotes/carl-sagan/the-prediction-of-nuclear-winter-is-drawn-not-of-course-from-any/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [The suppression of uncomfortable ideas may be common in religion or in politics, but it is not the path to knowledge; it has no…](https://sms4smile.com/quotes/carl-sagan/the-suppression-of-uncomfortable-ideas-may-be-common-in-religion-or/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [“Telepathy’ literally means to feel at a distance, just as ‘telephone’ is to hear at a distance and ‘television’ is to see at a…](https://sms4smile.com/quotes/carl-sagan/telepathy-literally-means-to-feel-at-a-distance-just-as-telephone-is/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [“On the scale of worlds—to say nothing of stars or galaxies—humans are inconsequential, a thin film of life on an obscure and solitary lump…](https://sms4smile.com/quotes/carl-sagan/on-the-scale-of-worlds-to-say-nothing-of-stars-or-galaxies-humans-are/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Every one of us is, in the cosmic perspective, precious. If a human disagrees with you, let him live. In a hundred billion galaxies,…](https://sms4smile.com/quotes/carl-sagan/every-one-of-us-is-in-the-cosmic-perspective-precious-if-a-human/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [In our time, we have sifted the sands of Mars, we have established a presence there, we have fulfilled a century of dreams!](https://sms4smile.com/quotes/carl-sagan/in-our-time-we-have-sifted-the-sands-of-mars-we-have-established-a/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [ “\[ When a religious couple wrote to Sagan about fulfilled prophecies, he wrote back in May 1996 :\] If ‘fulfilled prophecy’ is your criterion,… ](https://sms4smile.com/quotes/carl-sagan/when-a-religious-couple-wrote-to-sagan-about-fulfilled-prophecies-he/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Don't judge everyone else by your own limited experience.](https://sms4smile.com/quotes/carl-sagan/don-t-judge-everyone-else-by-your-own-limited-experience/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [“Books permit us to voyage through time, to tap the wisdom of our ancestors. The library connects us with the insight and knowledge, painfully…](https://sms4smile.com/quotes/carl-sagan/books-permit-us-to-voyage-through-time-to-tap-the-wisdom-of-our/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [We live on a hunk of rock and metal that circles a humdrum star that is one of 400 billion other stars that make…](https://sms4smile.com/quotes/carl-sagan/we-live-on-a-hunk-of-rock-and-metal-that-circles-a-humdrum-star-that/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [A tiny blue dot set in a sunbeam. Here it is. That's where we live. That's home. We humans are one species and this…](https://sms4smile.com/quotes/carl-sagan/a-tiny-blue-dot-set-in-a-sunbeam-here-it-is-that-s-where-we-live-that/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Any sufficiently crisp question can be answered by a single binary digit-0 or 1, yes or no.](https://sms4smile.com/quotes/carl-sagan/any-sufficiently-crisp-question-can-be-answered-by-a-single-binary/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Humans — who enslave, castrate, experiment on, and fillet other animals — have had an understandable penchant for pretending animals do not feel pain.…](https://sms4smile.com/quotes/carl-sagan/humans-who-enslave-castrate-experiment-on-and-fillet-other-animals/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Every star may be a sun to someone.](https://sms4smile.com/quotes/carl-sagan/every-star-may-be-a-sun-to-someone/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) [Explore all 1,043 Carl Sagan quotes ](https://sms4smile.com/quotes/author/carl-sagan/) ## More Blue planet quotes > [With respect to the ocean being the heart of our blue planet: We are often asked, 'How much protection is enough?' We can only…](https://sms4smile.com/quotes/sylvia-earle/with-respect-to-the-ocean-being-the-heart-of-our-blue-planet-we-are/) [Sylvia Earle](https://sms4smile.com/quotes/author/sylvia-earle/) > [“It was floating. Waiting. It had no sense of how long It had been in this state. Its awareness had retreated into a tiny…](https://sms4smile.com/quotes/j-valor/it-was-floating-waiting-it-had-no-sense-of-how-long-it-had-been-in/) [J. Valor](https://sms4smile.com/quotes/author/j-valor/) > [“You'll get over it...' It's the cliches that cause the trouble. To lose someone you love is to alter your life for ever. You…](https://sms4smile.com/quotes/jeanette-winterson/you-ll-get-over-it-it-s-the-cliches-that-cause-the-trouble-to-lose/) [Jeanette Winterson](https://sms4smile.com/quotes/author/jeanette-winterson/) > [“This blue planet contains oceans, lands, forests, deserts, rivers, ice, rich and poor people, different beliefs and religions, birth and death, satisfaction and hunger…](https://sms4smile.com/quotes/mohamad-shaban-alayoubi/this-blue-planet-contains-oceans-lands-forests-deserts-rivers-ice/) Mohamad Shaban Alayoubi > [Whenever I gaze up at the moon, I feel like I'm on a time machine. I am back to that precious pinpoint of time,…](https://sms4smile.com/quotes/buzz-aldrin/whenever-i-gaze-up-at-the-moon-i-feel-like-i-m-on-a-time-machine-i-am/) [Buzz Aldrin](https://sms4smile.com/quotes/author/buzz-aldrin/) > [We can all be heroes, joining together in a grand mission to save those living on this little blue planet.](https://sms4smile.com/quotes/jay-inslee/we-can-all-be-heroes-joining-together-in-a-grand-mission-to-save/) [Jay Inslee](https://sms4smile.com/quotes/author/jay-inslee/) > [I couldn't watch 'BP' for a long time, until I started doing this job, because I knew in my heart that 'Blue Planet,' as…](https://sms4smile.com/quotes/clive-lewis/i-couldn-t-watch-bp-for-a-long-time-until-i-started-doing-this-job/) [Clive Lewis](https://sms4smile.com/quotes/author/clive-lewis/) > [When seen from outer space, our beautiful blue planet has no national boundaries.](https://sms4smile.com/quotes/dalai-lama/when-seen-from-outer-space-our-beautiful-blue-planet-has-no-national/) [Dalai Lama](https://sms4smile.com/quotes/author/dalai-lama/) > [We B Rollin Ya'll Somewhere in the infinite vastness of the universe, there is a small rotating Galaxy called the Milky-way. Its moving through…](https://sms4smile.com/quotes/jay-mathews/we-b-rollin-ya-ll-somewhere-in-the-infinite-vastness-of-the-universe/) Jay Mathews > [“We are each of us like our little blue planet, hung in black space, upheld by nothing but our mutual reassurances, our loving lies.”](https://sms4smile.com/quotes/john-updike/we-are-each-of-us-like-our-little-blue-planet-hung-in-black-space/) [John Updike](https://sms4smile.com/quotes/author/john-updike/) > [Fragile creatures of a small blue planet, surrounded by light years of silent space.](https://sms4smile.com/quotes/jeanette-winterson/fragile-creatures-of-a-small-blue-planet-surrounded-by-light-years-of/) [Jeanette Winterson](https://sms4smile.com/quotes/author/jeanette-winterson/) > [“I saw Sonora before me, so otherworldly, so desolate, some cast-out mistress on the pale blue planet, and longed suddenly to stay.”](https://sms4smile.com/quotes/hannah-lillith-assadi/i-saw-sonora-before-me-so-otherworldly-so-desolate-some-cast-out/) [Hannah Lillith Assadi](https://sms4smile.com/quotes/author/hannah-lillith-assadi/) > [Our posturings, our imagined self-importance , the delusion that we have some privileged position in the universe are challenged by this point of pale light.](https://sms4smile.com/quotes/carl-sagan/our-posturings-our-imagined-self-importance-the-delusion-that-we-have-2/) [Carl Sagan](https://sms4smile.com/quotes/author/carl-sagan/) > [Thanks to David Attenborough and 'Blue Planet 2,' we've become aware of the damage to our oceans from plastic pollution. We now know to…](https://sms4smile.com/quotes/barry-gardiner/thanks-to-david-attenborough-and-blue-planet-2-we-ve-become-aware-of/) [Barry Gardiner](https://sms4smile.com/quotes/author/barry-gardiner/) > [The attempts to command the climate and decide about the temperature on our planet are wrong and arrogant. I wrote a book about it…](https://sms4smile.com/quotes/vaclav-klaus/the-attempts-to-command-the-climate-and-decide-about-the-temperature/) [Vaclav Klaus](https://sms4smile.com/quotes/author/vaclav-klaus/) [Browse all 36 Blue planet quotes ](https://sms4smile.com/quotes/about/blue-planet/) ```json { "@context": "https://schema.org", "@graph": [ { "@type": "Quotation", "text": "“The principal energy sources of our present industrial civilization are the so-called fossil fuels. We burn wood and oil, coal and natural gas, and, in the process, release waste gases, principally CO2, into the air. Consequently, the carbon dioxide content of the Earth’s atmosphere is increasing dramatically. The possibility of a runaway greenhouse effect suggests that we have to be careful: Even a one- or two-degree rise in the global temperature can have catastrophic consequences. In the burning of coal and oil and gasoline, we are also putting sulfuric acid into the atmosphere. Like Venus, our stratosphere even now has a substantial mist of tiny sulfuric acid droplets. Our major cities are polluted with noxious molecules. We do not understand the long-term effects of our course of action. But we have also been perturbing the climate in the opposite sense. For hundreds of thousands of years human beings have been burning and cutting down forests and encouraging domestic animals to graze on and destroy grasslands. Slash-and-burn agriculture, industrial tropical deforestation and overgrazing are rampant today. But forests are darker than grasslands, and grasslands are darker than deserts. As a consequence, the amount of sunlight that is absorbed by the ground has been declining, and by changes in the land use we are lowering the surface temperature of our planet. Might this cooling increase the size of the polar ice cap, which, because it is bright, will reflect still more sunlight from the Earth, further cooling the planet, driving a runaway albedo* effect? Our lovely blue planet, the Earth, is the only home we know. Venus is too hot. Mars is too cold. But the Earth is just right, a heaven for humans. After all, we evolved here. But our congenial climate may be unstable. We are perturbing our poor planet in serious and contradictory ways. Is there any danger of driving the environment of the Earth toward the planetary Hell of Venus or the global ice age of Mars? The simple answer is that nobody knows. The study of the global climate, the comparison of the Earth with other worlds, are subjects in their earliest stages of development. 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