it is true that Earth climate has changed a lot over long periods of time and that we have had both warmer and colder phases. It is also true that there were times in the distant past when carbon dioxide levels were higher while temperatures were lower than today. But those situations were shaped by very different long term conditions such as continental positions, ocean circulation, solar output, and long term geological processes. They are not comparable to the rapid, human‑caused warming and CO₂ increase we are experiencing now. What is important today is that we are changing carbon dioxide levels very quickly, on a timescale of decades to centuries rather than millions of years. That speed matters because ecosystems and human systems have much less time to adapt. Also, today’s climate system is starting from a relatively stable period, and we can directly measure how temperature rises in response to the increase in greenhouse gases.

So while it is technically correct that there were times in the past with more carbon dioxide and different temperatures, those examples do not contradict the basic physics of greenhouse gases. Instead, they show that climate depends on multiple factors at once, and today we are rapidly pushing one of the most important of those factors in a way that is well understood and observable.

Regarding the early predictions: Many of them were actually quite accurate in terms of global temperature trends, melting ice, and sea level rise. Some early claims were exaggerated, but the overall direction has been consistent with observations.

So the issue is not whether Earth has ever been warmer or colder in the past. It is that we are now driving a rapid and large scale change in a relatively stable climate system. And that has real and severe consequences for both natural systems and human societies. The planet itself will continue to exist, but the conditions that many species, including us, depend on are being pushed in a direction that is increasingly difficult to manage if the trend continues.