Carl Sagan Warns Congress about Climate Change (1985)

With­out cli­mate change, we could­n’t inhab­it the Earth as we do today. The green­house effect, by which gas­es in a plan­et’s atmos­phere increase the heat of that plan­et’s sur­face, “makes life on Earth pos­si­ble.” So says Carl Sagan in the video above. He adds that with­out it, the tem­per­a­ture would be about 30 degrees centi­grade cool­er: “That’s well below the freez­ing point of water every­where on the plan­et. The oceans would be sol­id.” A lit­tle of the cli­mate change induced by the green­house effect, then, is a good thing, but “here we are pour­ing enor­mous quan­ti­ties of CO2 and these oth­er gas­es into the atmos­phere every year, with hard­ly any con­cern about its long-term and glob­al con­se­quences.”

It’s fair to say that the lev­el of con­cern has increased since Sagan spoke these words in 1985, when “cli­mate change” was­n’t yet a house­hold term. But even then, his audi­ence was Con­gress, and his fif­teen-minute address, pre­served by C‑SPAN, remains a suc­cinct and per­sua­sive case for more research into the phe­nom­e­non as well as strate­gies and action to mit­i­gate it.

What audi­ence would expect less from Sagan, who just five years ear­li­er had host­ed the hit PBS tele­vi­sion series Cos­mos, based on his book of the same name. Its broad­cast made con­ta­gious his enthu­si­asm for sci­en­tif­ic inquiry in gen­er­al and the nature of the plan­ets in par­tic­u­lar. Who could for­get, for exam­ple, his intro­duc­tion to the “thor­ough­ly nasty place” that is Venus, research into whose atmos­phere Sagan had con­duct­ed in the ear­ly 1960s?

Venus is “the near­est plan­et — a plan­et of about the same mass, radius, den­si­ty, as the Earth,” Sagan tells Con­gress, but it has a “sur­face tem­per­a­ture about 470 degrees centi­grade, 900 Fahren­heit.” The rea­son? “A mas­sive green­house effect in which car­bon diox­ide plays the major role.” As for our plan­et, esti­mates then held that, with­out changes in the rates of fos­sil fuel-burn­ing and “infrared-absorb­ing” gas­es released into the atmos­phere, there will be “a sev­er­al-centi­grade-degree tem­per­a­ture increase” on aver­age “by the mid­dle to the end of the next cen­tu­ry.” Giv­en the poten­tial effects of such a rise, “if we don’t do the right thing now, there are very seri­ous prob­lems that our chil­dren and grand­chil­dren will have to face.” It’s impos­si­ble to know how many lis­ten­ers these words con­vinced at the time, though they cer­tain­ly seem to have stuck with a young sen­a­tor in the room by the name of Al Gore.

Relat­ed Con­tent:

A Cen­tu­ry of Glob­al Warm­ing Visu­al­ized in a 35 Sec­ond Video

Watch “Degrees of Uncer­tain­ty,” an Ani­mat­ed Doc­u­men­tary about Cli­mate Sci­ence, Uncer­tain­ty & Know­ing When to Trust the Experts

Bill Gates Lets Col­lege Stu­dents Down­load a Free Dig­i­tal Copy of His Book, How to Avoid a Cli­mate Dis­as­ter

Carl Sagan Pre­dicts the Decline of Amer­i­ca: Unable to Know “What’s True,” We Will Slide, “With­out Notic­ing, Back into Super­sti­tion & Dark­ness” (1995)

Based in Seoul, Col­in Mar­shall writes and broad­casts on cities, lan­guage, and cul­ture. His projects include the Sub­stack newslet­ter Books on Cities, the book The State­less City: a Walk through 21st-Cen­tu­ry Los Ange­les and the video series The City in Cin­e­ma. Fol­low him on Twit­ter at @colinmarshall or on Face­book.