The climatic conditions of Venus can be compared with Earth’s climate in one aspect: it varied over time, probably because of correlation between geologic activity and atmospheric dynamics. Indeed, both planets have climates that are influenced by the interaction between geologic and atmospheric processes. Few trustworthy facts have been known about geology of Venus until recently, but the invaluable discoveries made by the Magellan mission in 1990-1994 makes the consideration of this issue a high priority. Careful interpretation of the discovered facts can shed light on the dynamic interplay of geology and climate change. This analysis can help to gain a deeper understanding of some processes taking place on our planet as well.
The paper itself is divided into three parts, the first one being this abstract, the second one featuring main information on the issue in the body paragraphs, ending with a conclusion with a student perspective. References to a variety of different sources dealing with this issue, including books, journal articles, scientific and popular websites are available at the end as a separate page.
Venus: Geology and Climate
Although often referred to as Earth’s “sister planet”, Venus is totally different from Earth in terms of climate. No life exists there, no water either. The surface air pressure is approximately 100 times that on Earth, and the temperature is about 460 degrees Celsius. “Venus is the hottest planet in the solar system, its surface hot enough to melt some metals.” (Space.com, 200, “Climate and structure”, para.1) The climate of Venus is also characterized by globally encircling clouds of sulfuric acid. It’s atmospheric composition includes Carbon dioxide (96%); nitrogen (3+%); trace amounts of sulfur dioxide, water vapor, carbon monoxide, argon, helium, neon, hydrogen chloride, hydrogen fluoride. (NASA, N/d., “Venus”)
Recently there was no sufficient information about the existence of volcanic activity there, but it was discovered that Venus has undergone massive volcanic eruptions in the past and is almost surely active today. After receiving this information scientists felt the need to find answers, and the past billion years of Venus’s climate history was attempted to be reconstructed with the help of computer simulations. The result was as follows: scientists arrived at the conclusion that intense volcanic activity has driven large-scale climate change. So, Venus, just like Earth, has a complex and continuously evolving climate.
Bullock ; Grinspoon (1999) suggests that their simulations showed that the clouds gradually won out, and the surface cooled by about 100 degrees C. After it the clouds slowly disappeared, water diffused higher in the atmosphere and dissociated by solar ultraviolet radiation. The hydrogen left into space, and the sulfur dioxide reacted with carbonate rocks. This formed the climate observed on Venus nowadays. “Slow heating and cooling globally could have formed large areas of cracks on Venus’ surface. A major episode of resurfacing occurred on Venus roughly 700 million years ago, in which water and sulfur levels in the atmosphere rose.” (Sciencedaily.com, 2003, para.8)
Comparison with Mars isn’t so helpful, for the ample reason that the planet is too cool now for volcanism to be active, and the surface rests in a deep freeze. But the climate change on Venus is worth in-depth analysis. What is really astonishing is how forces similar to those on Earth have had such a dissimilar outcome on our “sister planet”. And there is no consensus in the academic community about this issue, as well as a number of other.
These issues include, for instance, the question of craters. There are two approaches to explaining the phenomenon of craters. To some scientists, the random distribution of the observed and the small number of partially modified craters mean that a geologic event of global proportions unexpectedly wiped out all the old craters around 800 million years ago. An alternative model was suggested by Roger J. Phillips of Washington University, and it’s known under the name of equilibrium resurfacing. This theory argues that steady geologic processes gradually eradicate craters in small patches, preserving an overall global distribution that is inherently random. Those who oppose this concept show that some geologic features on Venus are immense and geologic activity could not wipe craters out cleanly and randomly in every place.
There are other controversial issues, surrounded by enigmas and ambiguities. For instance, some striking lineaments resemble water-carved landforms. As it was mentioned before, the climate of Venus doesn’t allow for liquid water. These landforms look like meandering rivers and floodplains on Earth. The possible explanation is that calcium sulfate and other salts carved these forms.
Moreover, the mysterious tesserae should be mentioned here, and it also indicates that the planet had higher temperatures many years ago. Mysterious tesserae are intensely crinkled landscapes, situated on continentlike plateaus rising a few kilometers above the lowland lava plains. “[O]n Venus, where the thick, C02-rich atmosphere produced a runaway greenhouse effect that gives Venus its abnormally high surface temperature.” (Schneider, 2002, p.23)
Perturbations to the atmospheric inventory of radiatively active species may have a significant impact on the climate of Venus and upon the stability of the greenhouse effect. (Bullock & Grinspoon, 1999).
Finally, cracks and folds crisscross the planet. All these suggest that temporal variations in climate could happen on Venus. And we are lucky that the climate of our planet has not undergone similar extremes in the geologically recent past.
Conclusions: Student Perspective
From the student (and my personal) perspective, the topicality of this issue is obvious. Now it’s high time to pose ourselves groundbreaking questions about the uniqueness of Earth’s climate, as well as its stability.
Indeed, “our two neighbour planets, Mars and Venus, conveniently provide us with natural greenhouse ‘experiments.’” (Schneider, 2002, p.10) The processes happening on these planets shouldn’t be left without the attention of leading scientists and scientific institutes, because the outcomes of this research can become a basis of quality long-term prognosis of the climate change on the Earth in the 21st century or even further. I believe that climate change will be the most burning issue for the new generation of researchers in the domain of natural science.
Today we are holding a massive and nearly uncontrolled experiment on the terrestrial climate produced by technological society. The reasons that influence the climate change on neighbouring planets is important to understanding how natural and anthropogenic forces affect the climate on our own planet.
Bullock, M.A., and Grinspoon, D.H. (1999). Global Climate Change on Venus. Scientific American, 280, # 3 50-7.
Bullock, M. A, and Grinspoon, D.H. (1996). The Stability of Climate on Venus. Journal of Geophysical Research, Volume 101, Issue E3.
Schneider, S.H. (2002). Climate Change Policy: A Survey. Washington DC: Island Press.
Scienedaily.com. Math Program Cracks Cause Of Venus Climate Change. March 19, 2001. Retrieved October 17, 2005, from http://www.sciencedaily.com/releases/2001/03/010313074923.htm
Space.com. Venus: The Fire-Drenched Goddess. July 7, 2005. Retrieved October 17, 2005, from http://www.space.com/reference/venus/climate.html
NASA. Magellan Mission at a Glance: Mission Summary. N/d. Retrieved October 17, 2005, from http://www2.jpl.nasa.gov/magellan/fact.html