A tale of two planets

Just as we discover tree may be life in Venus’s toxic atmosphere, we take another step on the path to making our own planet uninhabitable.

Scientists engaged in the endless, fascinating quest to find extra-terrestrial life are agog at what might be their most significant discovery yet: evidence of life in the atmosphere of Venus.

A paper published last week in Nature Astronomy revealed that floating in clouds 50 km above Venus’s hellishly hot surface is an unusually high concentration of phosphine, a compound of phosphorus and hydrogen, which as far as anyone knows occurs naturally only where there is life.

The UK-led international team that made the observation, using advanced detecting equipment at observatories on Hawaii and in the Chilean Andes, says there is a high level of certainty the phosphine is present in Venus’s atmosphere. The question is, how did it get there?

A year ago, NASA modellers found that Venus probably had a stable, temperate, well-watered climate for three billion years – plenty of time for life to evolve – before a massive release of carbon dioxide, probably from volcanoes, over thousands of years, pushed Venus’s carbon dioxide levels to 96 per cent of the atmosphere.

The resulting greenhouse effect raised the planet’s surface temperature to a baking 450C. But 50 km up it’s around 30C, cool enough for organisms to survive.

The team could identify no other possible cause of the phosphine but living organisms able to function in Venus’s air. But there’s a catch: Venus’s clouds are not made of water droplets like ours but of sulphuric acid, and science knows of no way that life can survive in such an environment.

With the team’s intriguing findings out in the scientific domain, some day we will learn either that microbes can survive in acid or that phosphine can come from a non-biotic source. Either way, in the search for extra-terrestrial life Venus is back on the radar.

Here on Earth we have started an experiment which, like the Venus research, is testing how species manage hostile conditions. It’s a simple one; we just keep polluting air, ground, streams and oceans until greenhouse heat, broad-scale pollution and habitat loss push species beyond breaking point.

Our experiment has been identified by science as the Anthropocene, an extinction event of the same global scale as past events that destroyed as much as 90 per cent of life on Earth. The main differences with past events is that this one is exceptionally rapid, and was instigated by us.

Besides being burned for energy, the coal, oil and gas we have removed from safe underground storages have yielded any number of chemicals for agricultural, industrial, medical and personal use, plus the plastics now found in Earth’s every niche. Fossil carbon powered our civilisation; now it’s smothering the life out of our planet.

A leader in this planetary experiment is Australia, which has the highest rate of terrestrial species extinction anywhere on Earth, largely due to our special fondness for activities that are key drivers of the Anthropocene, clearing land and burning fossil fuels.

Throwing off our damaging addictions is proving frustratingly hard. Last week prime minister Scott Morrison and energy minister Angus Taylor revealed that a fossil fuel, natural gas, will be a centrepiece of the nation’s plans to recover from recession.

Specifically, the government claims we need gas to provide dispatchable power after the ageing Liddell coal plant in NSW is closed in 2023, and says it will build a gas-fired plant itself if the industry can’t bring itself to do so.

But gas costs money to extract, and plants are not cheap to run. There are now much more cost-effective ways of managing electricity for rapid dispatch. Smart network technology evens out demand spikes, and storages for hydro (including pumped hydro) and large battery arrays store wind and solar power.

Both the government and the Labor opposition, singing from the clean gas songsheet, point out that natural gas when burned produces much less carbon dioxide than coal. But that is only part of the story. Leakage of natural gas before burning, in extraction and processing, amounts to many millions of tonnes a year in Australia alone.

An analysis of methane traces in Greenland ice cores, published in Nature early this year, indicates that even those calculations underestimate emissions from oil and gas extraction many times over. When all the sums are done, gas may turn out to be every bit as polluting as coal.

The gas-led recovery is yet another victory for ideology over science, which will only deepen the government’s energy policy woes. More to the point, it is one more fateful step along the path to an uninhabitable planet.

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