Thinking AI models like ChatGPT emit '50 times more CO2' but still give wrong answers
Artificial Intelligence is a tool being used by millions of people the world over. AI is when computer systems perform tasks that typically require human intelligence, such as learning, problem-solving, and decision-making.
From homeowners asking ChatGPT for renovation advice, to the software revealing what Scottish homes could look like in the next 25 years, engaging with AI can be helpful and eye-opening, but can also come with serious risks.
A recent study from MIT found that using ChatGPT for essay writing can negatively impact cognitive engagemen t and memory recall, compared to those who wrote purely from their own brain.
But it's not just the personal impact AI can have, it can also damage the environment. Another study analysing different types of AI found there was a marked difference in CO2 output depending on the model.
A query typed into a large language model (LLM), such as ChatGPT, requires energy and produces more CO2 emissions. Emissions, however, depend on the model, the subject matter, and the user.
Researchers compared 14 models and found that complex answers cause more emissions than simple answers. Meanwhile, models that provide more accurate answers also produce more emissions.
Wondering how asking AI a question produces CO2 emissions? Well, no matter which questions we ask an AI, the model will come up with an answer, the researchers in Germany explained.
To produce this information - regardless of whether that answer is correct or not - the model uses tokens. Tokens are words or parts of words that are converted into a string of numbers that can be processed by the LLM.
This conversion, as well as other computing processes, produce CO2 emissions. Many users, however, are unaware of the substantial carbon footprint associated with these technologies.
With that in mind, researchers measured and compared CO2 emissions of different, already trained, LLMs using a set of standardised questions.
"The environmental impact of questioning trained LLMs is strongly determined by their reasoning approach," explained first author Maximilian Dauner.
"Explicit reasoning processes significantly drive up energy consumption and carbon emissions. We found that reasoning-enabled models produced up to 50 times more CO2 emissions than concise response models."
'Thinking' AI causes the most emissions. Reasoning models, on average, created 543.5 'thinking' tokens per question, whereas concise models required just 37.7 tokens per question.
Thinking tokens are additional tokens that reasoning LLMs generate before producing an answer. A higher token footprint always means higher CO2 emissions.
It doesn't, however, mean the resulting answers are more correct. This is because elaborate detail does not always equal correctness.
Subject matter also resulted in significantly different levels of CO2 emissions. Questions that required lengthy reasoning processes, for example abstract algebra or philosophy, led to up to six times higher emissions than more straightforward subjects, like high school history.
The most accurate model was the Cogito model with 70 billion parameters, reaching 84.9 per cent accuracy. The model produced three times more CO2 emissions than similar sized models that generated concise answers.
All is not lost, though. If you are a tech enthusiast, but also climate-conscious, you can, to an extent, control the amount of CO2 emissions caused by AI by adjusting your personal use of the technology, the researchers said.
"Users can significantly reduce emissions by prompting AI to generate concise answers or limiting the use of high-capacity models to tasks that genuinely require that power," Dauner pointed out.
Choice of model can make a big difference in CO2 emissions. For example, having DeepSeek R1 answer 600,000 questions would create CO2 emissions equal to a round-trip flight from London to New York.
Meanwhile, OpenAI's ChatGPT consumes 500 ml of water for every five to 50 prompts it answers, according to Shaolei Ren, a researcher at the University of California, Riverside.
"If users know the exact CO2 cost of their AI-generated outputs, such as casually turning themselves into an action figure, they might be more selective about when and how they use these technologies," Dauner said.
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But after Siberia had been smouldering at the surface for countless generations, something far more menacing began to cook below. Colossal 1,000ft-thick sheets of magma, stymied in their ascent to the surface, instead started spreading sideways into the rock far underground, like incandescent rhizomes, baking through the underworld. This is when everything went to hell. These massive magma roots were burning through an old layer cake of Russian rock eight miles thick. The quarter-billion-year pile of strata had accumulated in the vast Tunguska basin: the remnants of bygone salt flats and sandstones, but more catastrophically, carbon-rich limestone and natural gas deposits from ancient seas, and coals from ages past. The magma cooked through all these fossil fuels and the carbon-rich rock underground on contact, and detonated spectacular gas explosions that shattered the rock far above, erupting at the surface as half-mile craters that spewed carbon dioxide and methane into the air by the gigaton. After hundreds of thousands of years of familiar surface eruptions, the volcanoes had suddenly started burning through the subterranean world on a massive scale and began acting like enormous coal-fired power plants, natural gas plants and cement factories. 'The burning of coal,' one scientist writes of the end-Permian extinction, 'would have represented an uncontrolled and catastrophic release of energy from Earth's planetary fuel cell.' The Siberian Traps suddenly started to emit far too much CO2, and far too quickly for the surface world to accommodate it. Here's a plausible sequence of events at the end of the Permian. First, and most simply: the excess CO2 trapped more energy from the sun on the surface of our planet – a simple physical process that was worked out by physicists more than 150 years ago. And so the world helplessly warmed – models and proxies both point to about 10C of warming over thousands of years – pushing animal and plant physiology alike to their limits. It's also a simple physical fact about our world that for every degree it warms, the atmosphere can hold about 7% more water, so, as the temperature climbed and the water cycle accelerated, storms began to take on a menacing, drowning intensity. As the ocean warms as well, it holds less oxygen. Unfortunately, living in hot water is hard work, so the luckless animals in it required more oxygen to live, not less. Thus, as the ocean got hotter and more stagnant, the creatures in it began to fall away, and the seas began to empty. Making matters worse, the carbon dioxide in the air diffused into these gasping seas as carbonic acid (H2CO3). The entire global ocean became more acidic as a result, and the water was robbed of the chalky carbonate dissolved in it, and which animals used to build their shells. In these souring seas, the creatures became brittle and sickly, or even failed to form shells in the first place. As this sea life was decimated, the global marine food web began to teeter and collapse. Meanwhile, the ecosystem on land was being destroyed by wildfire (themselves spewing even more CO2 into the air) and lashed by violent storms. Terrestrial wreckage washed into the ocean, blasting the coastal seas with decaying vegetation and minerals weathered out of the land, such as phosphorus, that acted as plant food, fuelling massive algae blooms offshore. The oceans, already wanting for oxygen from the heat, now began to suffocate in earnest as algae blooms died and decomposed. As the CO2 continued to issue from the Siberian Traps in massive and unrelenting belches, the planet became hotter still, and the oceans didn't have a chance in hell. CO2 was now pushing the planet outside the limits of complex life. And just as these lifeless, anoxic, hot seas began to spread, a spectre from the Earth's ancient past was renewed on this dying planet. Unlike most life on Earth with which we're familiar, primitive anaerobic bacteria, having evolved aeons ago on an all-but-breathless world, don't need oxygen to burn their food. For some, sulphate will do the trick. And on this rotting, suffocating world, this microbial life became ominously ascendant, breathing out hydrogen sulphide (H2S) as exhaust. Unfortunately, hydrogen sulphide is mercilessly toxic, instantly killing humans (and creatures like us), as it sometimes does today in manure pits, or around oil pads like those in Texas's Permian basin. And so this dark cloud of primeval life spread insidiously through the deep and even into the shallows. The world was now very, very hot, very stormy, almost totally denuded of vegetation, with acidifying, anoxic oceans that belched unsparingly poisonous gas from an ancient microbial metabolism that killed anything that came near it. On the other side of the planet from the eruptions, once-forested polar South Africa became so denuded of life that rivers that once happily curved and twisted – their banks anchored by living plant roots – now rushed straight over the scoured landscape in braided, sprawling arroyos. Unearthly hot and dry seasons razed the forests with fire, then alternated with apocalyptic superstorms that washed it all away. The animals that had stocked the now-vanished forests for millions of years vanished as well. In the rocks, fungal spores strangely appear in the fossil record all over the world, heralding the collapse of the biosphere. Even insects, whose sheer numbers usually cushion them against mass death, struggled to hold on. While the heat devastated life at the poles, the Earth's searing midsection had become plainly unearthly. As CO2 sent global temperatures soaring, the ocean in the tropics became as hot as 'very hot soup', perhaps sufficiently hot, even, to power outlandish 500mph 'hypercanes' that would have laid waste to the coasts. In the continental interiors, the temperature would have leaped even further off the charts. In the planet's most miserable hour, much of its surface came to resemble less Earth as we know it than the feed from a lander probe on some hopeless and barren exoplanetary outpost. Earth, in its darkest hour, was losing its Earthiness. In fact, the postapocalyptic ocean was so vacant that carbonate reefs all over the world came to be built again in the recovery not by animals such as the archaic corals and lamp shells that were driven extinct, but by calcified mounds of bacterial slime. Everywhere. Even a short hike from my apartment in Boulder, Colorado, brings me face-to-face with this stromatolite rock from the end of the world, left behind by foul microbial mats. In the Colorado Front Range, where Earth history has been lifted out of the ground, tilted sideways and ornamented with ponderosa pine, one encounters this hummocky red rock laid down, layer by layer, by microbes in a deathly sea 252m years ago. It is wedged between more prosaic sandstones from the Carboniferous before it, and the dinosaur-trampled beach sands of the Mesozoic after it, hogbacks of which loom like a backstop behind Denver – the geology of happier times. But the implications of this brief wedge of bacterial rock, and a global ocean momentarily dominated by mounds of calcifying slime, are truly frightening. Before long, almost every living thing on the planet was dead. The interiors of the continents were silent except for hot, howling winds that swept over the wastes – a dry desolation that alternated with punishing, unearthly storms that smelled like death. The oceans, whose open seas once flashed iridescent with shoals of bobbing spirals and tentacles, and whose nearshore reefs were once dappled fire-engine red to ultraviolet by life, were now putrid, asphyxiating, empty and covered in slime. Every gear of the grand, intricately interlocking biogeochemical machinery of this planet became jammed, decoupled or spun hopelessly out of control. Complex life, as a subset of this global geochemical churn, unravelled as well. All from adding too much CO2. If there is a geologic precedent for what industrial civilisation has been up to in the past few centuries, it is something like the volcanoes of the end-Permian mass extinction. Now let's pull back from the brink. However similar to this era our modern experiment on the planet might first appear, it's worth acknowledging, even stressing, that the end-Permian climate catastrophe was truly, surpassingly bad. And on a scale unlikely ever to be matched by humans. Upper estimates for how much carbon dioxide the fossil-fuel-burning Siberian Traps erupted, ranging up to 120,000 gigatons, defy belief. Even lower estimates, of say 30,000 gigatons, constitute volumes of CO2 so completely ridiculous that matching it would require humans to not only burn all the fossil fuel reserves in the world, but then keep putting ever more carbon into the atmosphere for thousands of years. Perhaps by burning limestone for fun on an industrial scale for generations, even as the biosphere disintegrates. As it is, industrial civilisation could theoretically generate about 18,000 gigatons of CO2 if the entire world pulled together on a nihilistic, multicentennial, international effort to burn all the accessible fossil fuels on Earth. But while the sheer volume of CO2 generated by the Siberian Traps dwarfs our present and future output, that total was achieved over tens of millennia. What is alarming, and why it's worth talking about the Siberian Traps in the same breath as industrial civilisation, is that even in comparison with those ancient continent-spanning eruptions, what we're doing now seems to be unique. It turns out that the focused, highly technological effort to find, extract and burn as much of the world's fossil-fuel reservoir as is economically feasible, as fast as possible, has been extremely prodigious at getting carbon out of the crust – even compared to the biggest Lips in Earth history. In fact, the best estimate is that we're emitting carbon perhaps 10 times faster than even the mindless, undirected Siberian volcanoes that brought about the worst mass extinction ever. This matters because it's all about the rate. There's almost no amount of carbon you can pump into the atmosphere that, given enough time, Earth couldn't buffer itself against. Volcanic CO2 is supposed to enter the system. Without it, none of this works: the climate wouldn't be habitable, life would run out of raw material, and oxygen would run out. But everything in moderation. To maintain its homeostasis, the planet continuously scrubs CO2 from the atmosphere and oceans so that it doesn't build up and cook the planet. But this process is very slow on a human timescale. It buries this CO2 in coals, oil and gas deposits, and, most importantly, ocean sediments that turn to carbonate rock over millions of years. When more modest-sized eruptions inject a massive slug of CO2 to the atmosphere, threatening to overwhelm this process, the Earth has several emergency handbrakes. The oceans absorb the excess carbon dioxide, becoming more acidic, but in their millennial overturn they bring these more acidic surface waters to the seafloor on the downdraft of the planet's great ocean currents. There they dissolve the seafloor's carbonate sediments – the massive carpeting of tiny seashells at the bottom of the ocean, laid down by life over millions of years – and buffer the seas in the exact same way that a Tums settles an upset, acidic stomach. This is the first line of defence in the carbon cycle, and it works to restore ocean chemistry over thousands of years. Eventually, these forces work to restore the carbon cycle and coax the Earth back from the edge. On a world without humans or especially catastrophic Lips, these feedbacks usually suffice to rescue the planet. The excess CO2 is removed and transmuted to rock; the temperature eventually falls; and the pH of the ocean is restored over hundreds of millennia. So it's not just the amount of CO2 that enters the system that matters, it's also the flux. Put a lot in over a very long time and the planet can manage. But put more than a lot in over a brief enough period of time and you can short-circuit the biosphere. Unfortunately, the rate at which humans are now injecting CO2 into the oceans and atmosphere today far surpasses the planet's ability to keep pace. We are now at the initial stages of a system failure. If we keep at it for much longer, we might see what actual failure really means. If you want to overwhelm the system in a shorter time frame and shove the carbon cycle dangerously out of equilibrium, you need a much more intense infusion of CO2 into the oceans and atmosphere – faster than biology or weathering can save you. The modern global industrial effort to find, retrieve and burn as much ancient carbon buried in the Earth's crust as possible in a matter of mere centuries might be up to the task. Adapted from The Story of CO2 Is the Story of Everything: A Planetary Experiment, published by Allen Lane on 26 August. To support the Guardian, order a copy from Guardian bookshop. Delivery charges may apply Listen to our podcasts here and sign up to the long read weekly email here.
