Have We Immanentized the Eschaton?

About 20 years ago, I became convinced that several things are true:

• Carbon dioxide, water, and methane are all greenhouse gasses.
• Greenhouse gasses reflect infrared energy (heat) back to the Earth.
• An increase of greenhouse gasses will, in the absence of other factors, increase the average temperature of the earth.
• If the average temperature increases, the amount of water that evaporates will increase, further increasing the amount of greenhouse gasses in the atmosphere.
• Various measurements have shown recent increases in greenhouse gasses including carbon dioxide, both near human activity and also distant from it.
• A number of human activities generate carbon dioxide (e.g. burning fossil fuels) while a number of other human activities reduce the amount of plant life capable of removing carbon dioxide (e.g. development and improper land management).

My conclusion: human activity demonstrably increases the amount of greenhouse gasses, and this will (in the absence of other factors) lead to changes in climate. I don't have enough training or knowledge to predict exactly what those changes will be or how quickly they will occur, however there are those who claim to have such training and knowledge who have published their projections. I have no basis to dispute their claims.

However, I have issues. In no particular order:

• I find it difficult to comprehend that someone really has developed a method to determine the average temperature of the earth based on local weather readings that is demonstrably accurate to a tenth of a degree Celsius, and that this method has been demonstrated to be consistent for the last hundred or hundred and fifty years.
• It amazes me that people are able to extract a trend line for this data that shows an upward trend of a degree every few decades, given that the instantaneous temperature at any point in the planet can change 5 degrees Celsius in less than an hour. A huge amount of noise has been processed to extract a very quiet signal.
• While the computer models have made a number of predictions, it's not clear to me that different models show the same predictions nor that these have been confirmed by observation.
• When the weather is colder than average or storms are less intense than predicted, people are very quick to point out that weather is not climate, and that local effects in no way are representative of the planet as a whole. When extreme weather hits or there is a local heat wave, people are quick to say that this is exactly the kind of thing we should expect as the planet heats. Now, granted, both may well be true because weather is highly variable both day to day and year to year, and perhaps we would be seeing more heat waves, droughts, and severe storms (depending on your location) on a hotter Earth. However, this ends up sounding very much like the financial analyst who blames all losses on the market but takes credit for all gains.
• The magnitude of what will really need to be done to reduce human greenhouse gas emissions to a pre-industrial level - given that the human population more than doubled in the last 50 years - is rarely fully discussed.