From Watts Up With That?

By Anthony Watts

[editor’s note. there was a layout issue when published a few hours previously. now resolved]

I often get asked this question on social media, so I decided to provide the answer as a simple primer.

1. The Basics: Climate Does Change

First, let’s be clear — climate change is real in the literal sense. The Earth’s climate has been changing for billions of years. We have geological records showing periods that were much warmer (like the Eocene, with crocodiles in the Arctic), and much colder (like the Ice Ages that covered North America in glaciers).

Even more recently, we have the Holocene Climate Optimum, significantly warmer than present day:

So, yes — the climate changes, and it always has. The debate isn’t about whether it changes, but why, how fast, and how much humans are influencing it today. The debate is also about how accurately we are able to detect temperature change, plus the overreliance on climate models to predict the future rather than actual data.

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2. What the “Consensus” Says — and Where It Falls Short

The mainstream position (IPCC, NOAA, NASA, etc.) holds that recent warming — roughly 1.1°C since the late 1800s — is largely due to increased CO₂ from human activity, mainly fossil fuels.

But here’s the rub: this view is heavily dependent on climate models, which are notoriously uncertain. As someone with a meteorology background, I can tell you models struggle with cloud feedbacks, ocean cycles, solar variability, and regional forecasts — all of which are crucial to understanding climate.

When models are run backward, they often fail to replicate past climate variability accurately — like the Medieval Warm Period or the Little Ice Age — unless they’re tuned heavily. That calls into question their reliability for long-term projections.

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3. Natural Variability: The Elephant in the Room

A lot of warming in the 20th century happened before CO₂ rose sharply post-WWII. For example:

• The warming from 1910 to 1940 occurred with much lower CO₂ levels.
• Then there was a cooling trend from the 1940s to 1970s, despite rising CO₂ emissions during that time period.

Clearly, natural factors — like solar cycles, ocean oscillations (PDO, AMO), volcanic activity, and cloud dynamics — are still in play and possibly underestimated in mainstream assessments.

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4. The CO₂ Connection: Overstated?

CO₂ is a greenhouse gas, no question. But its effect on temperature is logarithmic — meaning, the more CO₂ you add, the less warming you get per unit. The first 100 ppm has the biggest impact, and we’re well past that as seen in the figure below.

Moreover, satellite data from UAH and RSS shows a slower warming trend than surface datasets like HadCRUT or GISS. That discrepancy raises questions about data adjustments, urban heat island effects, and instrument biases.

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5. Are We in a Crisis?

Even if we accept that humans are influencing climate, the notion that we’re in an “existential crisis” is unproven. Extreme weather trends (hurricanes, tornadoes, droughts) don’t show clear worsening patterns once you account for improved detection and population growth in vulnerable areas such as coastal developments.

The Intergovernmental Panel on Climate Change (IPCC) agrees, suggesting a “low confidence” in many current and future weather events being affected by climate change. The “existential crisis” view is heavily dependent on climate model projections, which are notoriously uncertain and refuted by data.

Sea level is rising — but at a slow, linear pace of about 3 mm/year. That’s about 12 inches per century, similar to what’s been observed since before industrial CO₂ emissions.

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Bottom Line

Yes, the climate is changing. It always has. The idea that global climate must be unchanging is simply wrongheaded. The real issue is how much of today’s change is due to human activity, how reliable our predictions are, and whether proposed policy responses are justified — or likely to do more harm than good.

At Watts Up With That, we’ve been pointing out for years that this issue is riddled with confirmation bias, model overconfidence, and selective reporting. There is no justification for shutting down economies or reshaping civilization based on the incomplete science of climate change.

So yes, climate change is real, but no, it’s not a crisis.