Viral Tweet Misrepresents Climate Science on CO2 and Global Warming

A viral tweet by Peter Clack, a frequent critic of climate science, claims that human contributions to greenhouse gases are negligible, possibly as low as 0.28%, and that the concept of greenhouse gases itself is questionable. He further argues that greenhouse-driven warming is a hoax because Earth is still in an ice age, framing climate change as a fabricated crisis designed to incite fear about the future. However, each of these claims misrepresents established scientific findings. 

Claim Post:

Human contributions to greenhouse gases may be as low as 0.28%? No one knows because it's all based on computer models designed to create hysteria. Do greenhouse gases even exist? Greenhouse warming ignores the ice age we're in to fake a global environmental crisis IN THE FUTURE. pic.twitter.com/OJQspOmnCJ

— Peter Clack (@PeterDClack) May 26, 2025

Claim 1: “Human contributions to greenhouse gases may be as low as 0.28%. It’s all based on computer models designed to create a sense of hysteria.

Fact 1: False. This figure is not grounded in any credible scientific source. The Intergovernmental Panel on Climate Change (IPCC) and NASA clearly state that human activities are responsible for more than 100% of observed global warming since 1950. That figure accounts for natural processes that would have slightly cooled the planet, independent of human influence.

The 0.28% claim confuses the human share of total atmospheric CO2 with its impact. Humans have increased atmospheric CO2 by over 50% since pre-industrial times, from 280 ppm to 420 ppm or higher. While natural sources, such as respiration and ocean release, contribute CO2, they are part of a balanced carbon cycle. What humans add through fossil fuel combustion and land-use change is extra, and it accumulates because natural sinks, such as forests and oceans, cannot absorb it quickly enough. This imbalance is what drives global warming.

As for computer models, they are not designed to produce hysteria. Climate models are physics-based tools that have been developed over decades, and their predictions have been extensively tested and refined against real-world data. Observed warming trends have matched model projections with high accuracy, confirming the reliability of these projections.

Claim 2: Do greenhouse gases even exist?

Fact 2: False. Greenhouse gases not only exist, but they are also measurable, observable, and scientifically well understood. Molecules like carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) trap heat in Earth’s atmosphere by absorbing and re-emitting infrared radiation. This property has been demonstrated through lab experiments and confirmed via satellite-based infrared spectroscopy.

The concept of greenhouse gases is not a modern invention. As early as the 1850s, physicist John Tyndall experimentally showed that gases like water vapour and CO2 absorb heat. Later, Swedish scientist Svante Arrhenius calculated that changes in CO₂ levels could affect Earth’s temperature—a hypothesis now validated by extensive observational data.

Today, global monitoring systems track greenhouse gas concentrations with precision. CO2 levels have increased from about 280 parts per million (ppm) before the Industrial Revolution to over 420 ppm today. The physical consequences of that rise are visible in melting glaciers, warming oceans, and shifting weather patterns—all of which follow the thermodynamic principles behind the greenhouse effect.

Claim 3: Greenhouse warming ignores the ice age we’re in. It’s a hypothetical future global environmental crisis.

Fact 3: Misleading. Earth is indeed in a Quaternary ice age, a geologic period that began around 2.6 million years ago and is characterised by alternating glacial and interglacial phases. We are currently in an interglacial period known as the Holocene, which began roughly 11,700 years ago. These natural cycles are well-understood and unfold over tens of thousands of years.

What makes the current warming unusual is its speed and cause. Natural interglacial warming is typically slow and tied to orbital variations, but the temperature spike observed over the past century has been rapid, far exceeding natural variability. This accelerated warming coincides with the dramatic rise in anthropogenic greenhouse gases, not orbital shifts.

Calling today’s climate crisis “fake” ignores overwhelming evidence from glacial ice cores, tree rings, satellite records, and ocean heat content data, all of which show that today’s climate trajectory is not part of a natural pattern. The impacts are not hypothetical or limited to the future; they are already happening in the form of heatwaves, rising sea levels, and more frequent extreme weather events.

Why Human-Driven Greenhouse Gas Emissions Are the Dominant Force Behind Current Warming

Although Earth remains within a Quaternary ice age in geological terms, we are presently in an interglacial period where natural warming is expected to be slow and gradual. What we are seeing now, however, is a sharp and accelerated rise in global temperatures that aligns directly with the increase in anthropogenic greenhouse gases, particularly CO2, CH4, and N2O, measured with high accuracy through spectroscopy and satellite data.

Climate models are not tools of hysteria; they are validated scientific instruments built on known physical laws, continuously refined with real-world data. These models, along with observational evidence, demonstrate that human activities have not only contributed to but have been the primary driver of more than 100% of the observed warming since 1950, offsetting even minor cooling influences, such as volcanic activity or solar variability. The science is precise, and this is not a natural fluctuation; it’s a human-forced climate shift.

References:

Analysis: Why scientists think 100% of global warming is due to humans

https://climate.nasa.gov/vital-signs/carbon-dioxide

https://www.epa.gov/ghgemissions/overview-greenhouse-gases

https://www.rigb.org/explore-science/explore/blog/who-discovered-greenhouse-effect

https://earthobservatory.nasa.gov/features/Arrhenius

https://www.nationalgeographic.com/science/article/quaternary

https://education.nationalgeographic.org/resource/anthropocene

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