Is CO₂ Still the Most Maligned Gas in History? — Eight Years On

In the middle of August homes were destroyed as wildfires brought devastation to parts of Britain. The apocalyptic vision of the world on fire, with wildfires raging across Europe and the UK, prompted me to look again at a post I wrote eight years ago, Is CO₂ the Most Maligned Gas in History?. I wrote it in December 2018 when I was sceptical of the evidence attributing most recent climate change to human activity. Eight years later, I think some of the questions I raised remain worth asking, but the scientific answers have become considerably clearer.

The post is still relevant as a historical account of the debate, and some of its points remain valid. CO₂ is essential to life, it is quite different from conventional air pollutants, and mining will be essential to any large-scale transition away from fossil fuels. But its central scientific position, that climate change was probably mainly natural and that the contribution from human activity was uncertain, is no longer supported by the evidence.

In the 2018 article I wrote: “An increase in 40% [of CO₂] seems a lot, but in absolute terms this is an increase in concentration from just under 0.03% to the present level of just over 0.04%. Can this small increase have such a profound effect?” 

The science can now provide a much better answer to that question.

We can also now be much more precise about where the additional CO₂ is coming from. Scientists can distinguish fossil-fuel carbon from naturally circulating carbon by examining the isotopic “fingerprint” of atmospheric CO₂. Fossil fuels contain virtually no radioactive carbon-14, because it has decayed away over the millions of years that they have been underground. They are also relatively depleted in carbon-13. By measuring these isotopes in atmospheric CO₂, scientists can identify the contribution from fossil fuels and distinguish it from carbon being exchanged naturally between the atmosphere, oceans and living organisms.

This provides an important independent line of evidence. We are not simply assuming that the additional CO₂ is coming from burning coal, oil and gas because fossil-fuel use has increased at the same time as atmospheric CO₂. The chemical and isotopic fingerprints show that the extra carbon has the characteristics expected of ancient plant material,  precisely what we would expect from fossil fuels. The National Oceanic and Atmospheric Administration notes that these measurements can be used to determine what proportion of CO₂ in an atmospheric sample is derived from fossil fuels.

The important thing is not simply the percentage of the atmosphere occupied by CO₂, but the physical properties of the molecule and its effect on the Earth's radiative balance. CO₂ absorbs infrared radiation at specific wavelengths. Increasing its concentration makes it more difficult for the Earth to radiate energy back into space. The climate system then warms until outgoing radiation once again balances incoming energy. CO₂ does not have to make up a large proportion of the atmosphere to have a significant climatic effect.

Furthermore, we are no longer relying simply on correlations between CO₂ concentrations and temperature. The radiative effect of increasing greenhouse gases can be observed directly. NASA explains that its climate instruments measure how greenhouse gases affect the movement of infrared radiation through the atmosphere, and a 2024 NASA and Jet Propulsion Laboratory study directly measured how increasing atmospheric CO₂ reduces the Earth's ability to emit infrared radiation into space.

Looking back at my 2018 post, I would therefore no longer argue that the human contribution to recent warming is fundamentally uncertain. The evidence is now much stronger that the current rise in atmospheric CO₂ is overwhelmingly the result of human activity, principally the burning of fossil fuels, and that this increase is the dominant cause of the warming observed since the pre-industrial period.

But that does not make CO₂ a “villain” in the conventional sense. It remains an essential gas for life, occurs naturally, and has played an important role in regulating Earth's climate throughout geological history. Nor does recognising the importance of CO₂ mean that all environmental problems can be reduced to carbon dioxide. Conventional air pollutants such as particulate matter, sulphur dioxide and nitrogen oxides remain important threats to human health.

What has perhaps become even more relevant since I wrote the original article is the other side of the argument. If we accept the need to reduce greenhouse-gas emissions, then mining, a major emitter of CO₂, is not the enemy of the green revolution,  it is one of its essential foundations. Wind turbines, solar panels, electricity networks, batteries and electric vehicles all require large quantities of metals and minerals. The energy transition will therefore require more mining, not less (see posting of 10 April 2023).

The scale of the challenge is illustrated by the graphic below. In 2023, the world was still consuming enormous quantities of coal, oil and natural gas, with China and the United States among the largest consumers. Replacing an energy system of this scale is clearly going to be a very substantial undertaking.

Source: elements.visualcapitalist.com

This brings us back to the paradox at the heart of this article. If we accept the need to reduce greenhouse-gas emissions, mining is not the enemy of the green revolution, it is one of its essential foundations. The challenge is not simply to “stop mining”, but to produce the minerals needed for decarbonisation while reducing the environmental footprint and carbon intensity of their extraction and processing.

In that sense, my 2018 article is worth revisiting not because its scepticism about human-caused climate change has been vindicated, but because its underlying question has become even more important: how do we reconcile our environmental ambitions with the enormous material requirements of a modern, low-carbon society?

This is the paradox we should be discussing now. The route to a lower-carbon world runs, at least for the foreseeable future, through a mining industry that itself has to become substantially lower carbon.

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August Cornish Mining Sundowner, and Cornwall's next Industrial Chapter?

A cool evening, a rare occurrence this long hot summer. It was a pleasant 17C last night in Falmouth for the Cornish Mining Sundowner at the Chain Locker, with a modest attendance of around a dozen.

The Chain Locker sits by Falmouth's inner harbour, the more sheltered, upstream section around the town quays, while the wider Falmouth Harbour extends out towards Carrick Roads (the Fal estuary) and the sea, so there was something rather appropriate about discussing Cornwall’s industrial future from the Chain Locker last night.

The Inner Harbour and the Chain Locker

Look across Falmouth Harbour and you see centuries of working history, ships, quays, docks and warehouses. But the harbour may also have a role in Cornwall’s next industrial chapter.

A proposed £150 million redevelopment of Falmouth Docks aims to modernise the ageing infrastructure, increase cargo capacity and support the emerging floating offshore wind industry in the Celtic Sea. Importantly for Cornwall’s renewed interest in critical minerals, the plans could also create new import and export facilities supporting Cornish lithium and battery manufacturing.

Cornwall once exported copper and tin through its ports to markets around the world. Could Falmouth once again become part of a supply chain built around Cornwall’s natural resources, this time alongside renewable energy and modern marine engineering?

There is, however, another side to the story. The redevelopment has attracted opposition from oyster fishermen and environmental campaigners, particularly over proposed dredging and its potential impact on the Fal estuary and its habitats. So the question isn't simply whether Cornwall can bring industry back, it is what sort of industry we want, and how we balance economic opportunity with the environment and communities that make Cornwall special.

Join us at the Chain Locker for the next sundowner, which will be on Thursday September 17th, from 5.30pm.

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Eriez is the latest sponsor of Flotation '27

We are pleased to welcome Eriez as the latest sponsor of next year’s Flotation ’27. In fact, we are delighted to welcome them back, as Eriez has sponsored every MEI flotation conference since Flotation ’19, held just before the pandemic.

The Eriez booth at Flotation '19, the company's first year as a sponsor

The Eriez Flotation Division (EFD) delivers advanced flotation solutions designed to boost recovery while reducing operating costs. With more than 1,000 flotation systems designed, supplied and commissioned worldwide, Eriez offers a range of technologies aimed at achieving step-change improvements in mineral processing.

The strategic theme behind EFD is essentially more mineral recovery with less energy, water, equipment and grinding, using its broad range of flotation technologies. These include HydroFloat for coarse-particle recovery, CavTube Column Flotation, StackCell mechanical flotation and advanced sparging systems.

President and CEO Jaisen Kohmuench and Mining and Minerals Head Todd Burchett discussed step-change technologies at the SME Annual Meeting in Salt Lake City in February, highlighting integrated flowsheets incorporating HydroFloat Coarse Particle Flotation and StackCell systems.

Through technologies such as the HydroFloat separator, Eriez continues to advance coarse-particle recovery, with the potential to significantly reduce grinding energy, conserve water and enable safer tailings management. This work is often carried out in partnership with other equipment providers, including Comminution '27 sponsor Weir Minerals. In 2022 Weir Minerals announced a cooperative agreement with Eriez to design and develop coarse-particle flotation systems, allowing the two companies to better integrate Eriez flotation equipment with Weir Minerals’ expertise in slurry classification and conveying.

The commissioning of a HydroFloat installation at BHP’s Carrapateena copper mine in Australia is one of the more significant recent commercial references for Eriez’s HydroFloat technology.

Eriez is also addressing both ends of the particle-size challenge in mineral flotation: HydroFloat for coarse particles and CavTube for ultrafine particles. The current growth story for CavTube appears to be strongly linked to fine-particle and slimes recovery, as well as applications in phosphate and potash, with potential for other challenging ultrafine applications.

EFD is also participating in the University of Queensland’s Collaborative Consortium for Coarse Particle Processing Research, alongside major mining companies including BHP, Rio Tinto, Vale and Codelco. The second five-year phase of the programme, running from 2025 to 2030, is investigating coarse-particle and fluidised-bed flotation as potential routes to reducing grinding energy and improving mineral-processing efficiency.

There is clearly much happening within EFD, and with Flotation ’27 still 15 months away, we can look forward to hearing much more from Eriez next year, both in the conference room and at the Eriez exhibition booth.

#Flotation27
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$3 Billion for Mining: The West’s Critical Minerals Wake-Up Call

On August 7th US President Donald Trump announced a mining/critical minerals  investment package of roughly $3 billion. The announcement came during a mining industry round-table at the State Department. Trump said the administration was backing a series of projects intended to expand U.S. production of critical minerals.

Trump’s investment in mining and critical minerals is about much more than securing new sources of ore. It is about reducing the West’s dependence on China for processing the minerals it needs.

For decades, China has built a dominant position in the critical minerals supply chain, particularly in processing, separation and refining. This means that even when minerals are mined elsewhere, they may still depend on Chinese processing capacity before they can be turned into materials suitable for advanced manufacturing, energy technologies and defence applications. That dependence has become a strategic vulnerability.

The US investment signals a growing determination to bring critical-mineral processing capacity back to the West and develop more resilient supply chains. Crucially, this requires investment not just in mines, but in the technologies, pilot plants, research programmes and skilled people needed to process increasingly complex resources economically.

The emphasis on universities and research is therefore particularly significant. More than $180 million is being directed towards mining education and workforce development, including support for U.S. mining schools to train the next generation of engineers, geologists, technicians and other specialists needed to expand domestic capacity. This reflects a wider concern about the shortage of skilled workers across the mining sector, at a time when the U.S. is seeking to bring more critical mineral production and processing onshore. Alongside workforce development, other programmes are supporting research into critical mineral processing, recycling and recovery from unconventional resources. This is important because securing supply is not simply a question of finding new deposits: it also depends on developing more efficient ways to extract, separate and recover minerals from existing ores, waste streams and alternative sources, helping to reduce reliance on overseas processing and build more resilient domestic supply chains.

This is directly relevant to MEI’s Critical Minerals ’26. The conference will focus on the technologies needed to process and recycle critical minerals from primary and secondary resources - precisely the capabilities that the West needs to develop if it is to build supply chains that are less dependent on China.

The strategic objective is becoming increasingly clear: the West needs not only its own mines, but its own processing expertise and capacity. The coming years could therefore see a major shift in where critical minerals are processed; from a supply chain heavily centred on China towards more geographically diverse capacity in the US, Europe and other allied nations.

For the minerals processing community, this represents both a major challenge and a major opportunity. The technologies developed today could determine where the critical minerals supply chains of tomorrow are built.

That makes the forthcoming agenda at Critical Minerals ’26 in Cape Town especially timely.

#CriticalMinerals26
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Developments in Heap Leaching as a Technology Choice for Value Extraction from Primary and Secondary Resources

Heap leaching is part of the group of “percolation leaching” processes that selectively remove metal values from an ore into a suitable aqueous leaching agent that seeps through a pile or mass of the ore. It has become well-established technology choice for the treatment of low-grade copper and gold ores and is also practiced for uranium ores and REE recovery from ion adsorption clays. Various other applications (Zn, Ni, PGMs) have been explored but not reached commercial significance as yet. 

Apart from the different chemistries and mineralogies, all these applications operate on very similar principles, which will be laid out in some detail in a keynote from Prof. Jochen Petersen, of the University of Cape Town, at Hydrometallurgy '27.

Selection of heap leaching as process technology is primarily driven by its ability to extract value from low-grade materials, as the need for high capital and operating expenditures, especially for intensive comminution processes to produce a concentrate material for further processing, is avoided. However, the relatively long time required to recover the metal value from larger particles, with overall poorer metal extraction achieved, imposes certain economic penalties which have resulted in heap leaching remaining limited to low-grade ores.

Nonetheless, ever-increasing energy costs and awareness of the associated carbon footprint have recently led to a re-evaluation of the technology for primary ores. At the same time the drive towards resource efficiency and the attainment of circular economies for many metals has also opened significant opportunities for the heap leaching of tailings and waste materials and thus a re-evaluation of the technology. Some examples of these developments will be discussed in Jochen's presentation.

Jochen holds a PhD in Chemical Engineering from the University of Cape Town, where he is now Full Professor after a research career spanning close on 30 years in hydrometallurgy. His research covers leaching and recovery of Cu, Ni, Zn, PGMs, Au and REEs from both primary minerals and secondary resources such as e-waste. His key field of expertise is heap leaching.

Jochen has co-authored over 150 peer-reviewed journal and conference papers and supervised 15 PhDs and 60 MScs to graduation. He was the Editor-in-Chief of the journal Hydrometallurgy 2011-2021 and held a prestigious South African Research Chair 2018-2022.

Jochen at Biohydrometallurgy '10 in Cape Town after
being appointed the new co-editor of Hydrometallurgy.
 He is with Dean Eastbury, his publishing manager at Elsevier

Hydrometallurgy27
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Close encounters with a wild dolphin

August is always a quieter time, particularly in the Northern Hemisphere, where many families are away on holiday. So, today's blog is something a little different from the usual- a look back at a magical couple of months in Cornwall almost half a century ago.

This summer has been unusually hot, and thousands of visitors have taken to the sea. Many have joined wildlife safari trips along the Cornish coast, where the relatively warm waters, influenced by the Gulf Stream, attract an abundance of marine life. Seals are a familiar sight, while basking sharks, the world's second-largest fish, are regular seasonal visitors. Dolphins, however, are always the favourites, delighting passengers and photographers alike.

Dolphins are usually seen in pods, but in early 1978 a solitary male bottlenose dolphin made Falmouth his home. Soon affectionately known by locals as "Beaky", he became something of a celebrity, enchanting residents and visitors alike. For a remarkable period, he chose the harbour and surrounding waters as his territory, creating unforgettable encounters for those lucky enough to meet him. 

The safe waters of the harbour were a favoured location for Camborne School of Mines (CSM) divers to undertake their open water training and it must have been an unforgettable experience for them to share the water with a 350 kg dolphin.

Novice CSM diver and Beaky in Falmouth Harbour

One novice CSM diver, however, probably wished he could forget his first meeting with Beaky.

As Diving Officer for both the CSM and Falmouth branches of the British Sub-Aqua Club, I spent many Sunday mornings supervising students on their first shallow open-water dives. One such dive took place in the rocky gullies off Pendennis Headland, at the mouth of the Fal Estuary.

Beaky and CSM divers off Pendennis Headland

Keeping a close eye on the stream of bubbles from a novice and his experienced Falmouth club buddy, I noticed a familiar dorsal fin approaching. Moments later the fin disappeared beneath the surface, only to be replaced by an explosion of bubbles and the student bursting from the water shouting, "Shark! Shark!"

Still visibly shaken, he later explained what had happened. He had felt a firm nudge in the middle of his back and, turning round, found himself face to face with a large dark shape, a towering dorsal fin and two beady eyes. It was hardly surprising that his imagination ran wild, this was only two years after the release of the movie Jaws!

For the more experienced divers, deeper dives were made in Falmouth Bay from the 24-foot Pisces, skippered by local fisherman Ken Dunstan. Ken had recently been one of the four-man team to make the first deep dive on the wreck of the Rinovia (see post of 22 February 2024).

Beaky soon became familiar with the sound of Pisces and regularly accompanied us on our dives. He would even join us on deep wreck dives for five minutes or so before returning to the surface for air, only to reappear and continue swimming alongside us. 

Word of these remarkable encounters inevitably spread, and in early 1978 we were contacted by the BBC's Blue Peter, then at the height of its popularity as the world's longest-running children's television programme. The production team wanted to see whether Beaky might feature in the programme, so they sent a young researcher to spend a day aboard Pisces in search of Cornwall's famous dolphin.

The search proved remarkably short. Just minutes after leaving Falmouth Harbour, Beaky appeared. We dropped anchor and slipped into the water, where he immediately treated us to one of his wonderful displays, much to the delight of our visitor.

Bottlenose dolphins can reach speeds of up to 25 mph (40 km/h), and one of Beaky's favourite antics was as exhilarating as it was startling. He would charge towards you at full speed before suddenly slamming on the brakes just a few feet away, sending a wall of water crashing over your head. The first time it happened it was impossible not to flinch,until you realised he seemed to take as much pleasure in the surprise as we did.

At one point Ken and his seven-year-old daughter, Nicola, entered the water together. Beaky gently approached them before allowing Nicola to hold his dorsal fin as he slowly carried her in a small circle. It was one of those magical moments that none of us present would ever forget.

Nicola is introduced to Beaky....

Before holding on for a memorable ride

It was February, however, and before long the cold drove us back towards the boat. Beaky, though, clearly hadn't finished playing.

He disappeared beneath the surface and reappeared a minute later with the anchor line draped around his beak. Then, to everyone's amusement, he gently towed Pisces just beyond our reach. After several more minutes of his playful antics, we eventually managed to climb aboard. Our Blue Peter researcher was completely captivated by both Beaky and her first visit to Cornwall, promising that the full production team would soon be returning.

Towing the boat out of reach!

I wish there was a happy end to this story, but that was the last we ever saw of Beaky. Shortly after this episode a series of major winter storms hit the area and Beaky was never seen again. No one knows what became of him. He may simply have moved on, died naturally, or perhaps fallen victim to human activity. There has never been any definitive explanation.

Whatever his fate, those few magical months remain one of my most treasured memories of life beneath the waters of Cornwall. Everyone who encountered Beaky carried away a story to tell, and nearly fifty years later, he is still remembered with great affection by those fortunate enough to have shared his extraordinary world.

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