we would still be in the Little Ice Age if not for human use of fossil fuel. I have a hard time believing that – the Little Ice Age was a phenomenon restricted to northern temperate regions. But for the 40% increase in CO2 concentrations, global temperatures would be about 1.5°C lower than they are, but there is no reason to think that local climate variations would not have been substantial.

It is hard to believe that humans caused that early retreat of glaciers – why? Basic physics tells us that an increase in CO2 leads to an increase in temperature. CO2 began rising in the late 18th century.

It seems far more plausible that our understanding of climate drivers has high degree of uncertainty than to say that variations in climate since 1750 has been human driven – why? It is not plausible at all to suggest that you can increase the concentration of a major IR absorber by 40% and not raise the temperature.

As you indicated, the IPCC goes back to 1750 to note human influences on climate — the impact did not start with Phase II of 20th Century warming. However, the more I looked at this Figure 2, the more suspicious I have become. The Figure is stating that since 1750, human and natural changes have increased radiative forcing (thereby the temperature, of the Earth) by about 1.6 Watts per square meter, with about 95% of this coming from human activities. That seems to be saying that if not for human activities, we still would be in the Little Ice Age. Something seems to be amiss with a theory that says that climate change is driven by radiative forcing, for the last 260 years it has been humans in the driver’s seat. I come from four generations of farmers, and we have a good handle on what has been the climate we have faced — how that climate has oscillated over the decades, not a monotonic trend accompanied by small variations. Of course, one anecdotal farm does not disprove global trends. But our anecdotes can be repeated thousands — indeed, millions of times. A theory should make sense in light of anecdotes and in light of the global experiences. By saying that 260 years of climate change has been vitually all human-induced, credibility is threatened.

I just want to make sure there is no misunderstanding.

ANY temperature chance greater than +0.000001C can cause a glacier to recede, and since CO2 can lead to a temperature increase and has gone up since the beginning of the 19th century , all glacier losses since 1800 have to be due to CO2.

Thanks for the education.

I thought this whole discussion was relative to whether CO2 could account for glaciers starting to recede in mid 19th century. If CO2 only led to about 0.2C temperature rise 1900 – 1950, how much could it have increased temperature when glaciers started to recede?

I’m not arguing that there NO effect from CO2. I don’t see how 0.2C can lead to any large climate changes, including glaciers starting to decrease.