THIS POST IS A CRITICAL REVIEW OF AN ONLINE ARTICLE BY THE CONVERSATION THAT A CO2 GREENHOUSE HORROR KILLED VENUS AND THAT IS THE FATE OF OUR PLANET IF WE CONTINUE TO USE FOSSIL FUELS. LINK TO SOURCE: https://theconversation.com/venus-was-once-more-earth-like-but-climate-change-made-it-uninhabitable-150445

PART-1: WHAT THE SOURCE ARTICLE SAYS

We can learn a lot about climate change from Venus, our sister planet. Venus currently has a surface temperature of 450℃ (the temperature of an oven’s self-cleaning cycle) and an atmosphere with 96% CO2 with a density 90 times that of Earth’s. Venus is a very strange place, totally uninhabitable, except perhaps in the clouds some 60 kilometers up where the recent discovery of phosphine may suggest floating microbial life. But the surface is totally inhospitable.

However, Venus once a lot like our earth with an Earth-like climate. According to recent climate modelling, for much of its history Venus had surface temperatures similar to present day Earth. It likely also had oceans, rain, perhaps snow, maybe continents and plate tectonics, and even more speculatively, perhaps even surface life.

Less than one billion years ago, the climate dramatically changed due to a runaway greenhouse effect. It can be speculated that an intensive period of volcanism pumped enough carbon dioxide into the atmosphere to cause this great climate change event that evaporated the oceans and caused the end of the water cycle.

This hypothesis from the climate modellers inspired Sara Khawja, a master’s student in my group (co-supervised with geoscientist Claire Samson), to look for evidence in Venusian rocks for this proposed climatic change event. Since the early 1990s, my Carleton University research team — and more recently my Siberian team at Tomsk State University — have been mapping and interpreting the geological and tectonic history of Earth’s remarkable sister planet Venus.

Soviet Venera and Vega missions of the 1970s and 1980s landed on Venus and took pictures and evaluated the composition of the rocks, before the landers failed due to the high temperature and pressure. However, our most comprehensive view of the surface of Venus has been provided by NASA’s Magellan spacecraft in the early 1990s, which used radar to see through the dense cloud layer and produce detailed images of more than 98 per cent of Venus’s surface.

Our search for geological evidence of the great climate change event led us to focus on the oldest type of rocks on Venus, called tesserae, which have a complex appearance suggestive of a long, complicated geological history. We thought that these oldest rocks had the best chance of preserving evidence of water erosion, which is a such an important process on Earth and should have occurred on Venus prior to the great climate change event. Given poor resolution altitude data, we used an indirect technique to try to recognize ancient river valleys. We demonstrated that younger lava flows from the surrounding volcanic plains had filled valleys in the margins of tesserae.. To our astonishment these tesserae valley patterns were very similar to river flow patterns on Earth, leading to our suggestion that these tesserae valleys were formed by river erosion during a time with Earth-like climatic conditions. My Venus research groups at Carleton and Tomsk State universities are studying the post-tesserae lava flows for any geological evidence of the transition to extremely hot conditions.

EARTH ANALOGIES: In order to understand how volcanism on Venus could produce such a change in climate, we can look to Earth history for analogues. We can find analogies in super-eruptions like the last eruption at Yellowstone that occurred 630,000 years. But such volcanism is small compared to large igneous provinces, LIP, that occur approximately every 20-30 million years. These eruption events can release enough carbon dioxide to cause catastrophic climate change on Earth, including mass extinctions. To give you a sense of scale, consider that the smallest LIPs produce enough magma to cover all of Canada to a depth of about 10 metres. The largest known LIP produced enough magma that would have covered an area the size of Canada to a depth of nearly eight km. The LIP analogues on Venus include individual volcanoes that are up to 500 km across, extensive lava channels that reach up to 7,000 km long, and there are also associated rift systems — where the crust is pulling apart — up to 10,000 km long.

If LIP-style volcanism was the cause of the great climate change event on Venus, then could similar climate change happen on Earth?

We can imagine a scenario many millions of years in the future when multiple LIPs randomly occurring at the same time could cause Earth to have such runaway climate change leading to conditions like present-day Venus.

PART-2: CRITICAL COMMENTARYLarge Igneous Province:

(1) LIP is a form of near surface magmatism that can cause significant changes to the surface of the planets including Earth and Venus but this mechanism of planetary surface changes is rare and episodic at million year time scales and it does not account for a significant fraction of the geological magmatic CO2 transfer to the atmosphere. Most of that comes from more frequent geological magmatic transfers in the more mundane geology of seafloor spreading, mantle plumes, and volcanism. The LIP mechanism, though dramatic when they do occur, account for no more than 10% of the geological transfers from the mantle at billion year time scales. The argument that the greater CO2 release of LIP events explains the fate of Venus is inconsistent with the role of LIP in the overall CO2 transfers from the mantle to the atmosphere at the relevant time scales.

(2) Geological CO2: The geological source of CO2 as a driver of climate change inserted into the climate change dialog by The Conversation has interesting implications noted in related posts on this site linked below. There we show that the climate science assumption that observed changes in atmospheric CO2 must be understood in terms of fossil fuel emissions is inconsistent with the data. The statistical analysis of the data presented in LINK#2 shows that atmospheric composition is not responsive to fossil fuel emissions and implies that the observed rise in atmospheric CO2 may have an explanation in terms of geological sources of such emissions. The claim by climate science that the absence of carbon isotopes in atmospheric CO2 proves its fossil fuel source is not responsive to the argument for geological sources because geological carbon, like fossil fuel emissions, has no 14C or 13C isotopes.

LINK#1: https://tambonthongchai.com/2019/08/27/carbonflows/

LINK#2: https://tambonthongchai.com/2020/11/21/the-case-against-fossil-fuels/

LINK#3: https://tambonthongchai.com/2019/02/10/14c/

LINK#4: https://tambonthongchai.com/2019/04/28/13c/

(3) TIME SCALE: The current era of warming is one of many warming and cooling cycles at millennial and centennial time scales found in the 8,000-year history of the Holocene described in a related post: LINK: https://tambonthongchai.com/2019/06/11/chaoticholocene/ where climate science, claiming to know the science of Holocene temperature cycles has selected only the current warming period to explain. This kind of empirical research suffers from a data selection bias as noted in a related post: LINK: https://tambonthongchai.com/2020/10/09/a-data-selection-bias/ where we note that {IF THE GREENHOUSE EFFECT OF ATMOSPHERIC CO2 EXPLAINS THESE HOLOCENE TEMPERATURE DYNAMICS, IT SHOULD EXPLAIN ALL OF THE WARMING AND COOLING CYCLES AND NOT JUST ONE OF THEM}. But the greater issue here in the context of the Conversation article’s comparison with Venus is time scale.

Whereas, the current warming period, and in fact all of the Holocene temperature departure cycles, are understood at millennial and centennial time scales, the claim that the death of Venus caused by climate change at time scales of “billions and billions of years” has some correspondence to and provides an understanding of the current warm period and the future of the planet earth implied by the current warm period, is not credible. This is because the Venus story has no relevance to AGW because the time scales of the two events being compared do not match.

HUMAN CAUSE: THE REAL ISSUE HERE IS HUMAN CAUSE BECAUSE WITHOUT EVIDENCE OF HUMAN CAUSE OF THE WARMING TREND, WHATEVER IMPACTS THE WARMING MAY HAVE ARE ALL NATURAL.

LINK: https://tambonthongchai.com/2021/11/09/the-issue-is-human-cause/