Carl Sagan (1934 – 1996), a renowned American-born astronomer, first defined and explained the phenomenon of nuclear winter in 1983 . In the article Nuclear Winter, based on the scientific article "Global Atmospheric Consequences of Nuclear War", Sagan explained and analyzed an unintended consequence, a drastic drop in global temperature, of nuclear war. In a historical context, the potential use of nuclear warheads during the Cold War (1947-1991) prompted the author to emphasize the consequences of nuclear war. Sagan succeeds in conveying his message through coherent structure, strong support, effective tone, and careful word selection; however, the essay's exaggerated pessimism and ineffectiveness in a modern context weaken its argument. The writer provides a series of facts to inform the public and policy makers about the catastrophic consequences of thermonuclear war. The most serious of these consequences is a drastic drop in global temperature. Based on their extensive research, Sagan and his fellow scientists developed the phenomenon of nuclear winter. They say particles heated after the nuclear explosion will rise to form a layer around the earth that will absorb incoming sunlight. The Earth, deprived of sunlight, will experience a sharp drop in temperature. This will interrupt photosynthesis and kill livestock, leading to a global food shortage. The author has maintained the coherence of the text by organizing his ideas in a logical order. The consequences of nuclear war are listed first, followed by a scientific explanation of the causes of these consequences and finally a valuable conclusion drawn from his arguments. In the first paragraphs, the author lists various results of ...... middle of article ......rs, well-supported arguments helped to convince readers and skillful selection of words and the Use of tone increased the effectiveness of the test. Even though its inapplicability in the modern political context diminishes the effectiveness of the argument, such awareness was felt in the 1980s. Therefore, the article achieved its objective in raising awareness among the public and policy makers policies. Works Cited “Anti-nuclear movement”. Pollution problems. Internet. April 12, 2011. .Sagan, Carl. “Nuclear winter”. Readings for writers. Ed. McCuen, Jo Ray and Anthony Winkler. Fort Worth: Harcourt Brace College, 1995. Print. "Treaties and Agreements | Arms Control Association." Arms Control Association | The authoritative source on arms control since 1971. Web. April 12. 2011. .