[mntlblok]

Originally Posted by biker1

The evidence of anthropogenic warming is both extensive and pervasive. Unfortunately, most people fail to understand the basics. As a retired research meteorologist with undergraduate and graduate degrees in meteorology and as a developer of atmospheric models at NASA and the National Weather Service, I will try to explain the basics to you. You start with a theory and collect evidence to either support or disprove the theory. In the case of anthropogenic warming from the release of CO2, the theory has been around for some time. I think Manabe's 1967 paper is perhaps the best place to start. Essentially, if anthropogenic CO2 is going to have an impact you will see the lower troposphere warm and the stratosphere cool. Increasing CO2 impacts the net long wave radiation budget. A more detailed explanation is beyond the scope of this post. Again, there is extensive observational data that shows this effect. You can do literature searches fairly easily but the best place to start is AR6. Roy Spencer has a 40+ year tropospheric satellite dataset that shows significant warming (and he is not a doom and gloomer by any stretch of the imagination). What most people get wrong is the impact and time scale. It is about 1C for the global surface temperature anomaly. This is in the last 100 years. The issue is time scale. Climatic changes driven by the three Milankovitch cycles have much longer time scales: 20,000 to 100,000 years. The concern is not what will happen in 40,000 years but what will happen by the end of the century. Predictions for the remainder of the century come from coupled climate modeling, which is still an area of research. Retrospective integrations seem to be a bit warm. The biggest issue, IMO, is that the press and politicians appear to have chosen to focus on the most pessimistic 8.5 scenario that shows the global surface temperature anomaly as high as 10C. That would be a big problem. I don't think there is much doubt that the temperature anomaly will grow to 2C or more. I believe that negative feedbacks in the atmospheric/oceanic/land surface system reduce the probability of a 10C temperature anomaly by the end of the century. Modeling these systems is difficult and getting all the positive and negative feedback correct is a challenge (which is why it is still an area of research). However, a couple of degrees will have geopolitical consequences which is what many Governments may be worried about. The other issue is that I just don't believe we (the world) can do anything to substantially cut CO2 emissions for the next 50 years. For example, the US emits about 11% of the global CO2. Even if we dropped to zero tomorrow, it would not have much of an impact. Doing what we can within practical limits is a good idea. I would put most efforts into remediating coastal regions for the continued rise in ocean levels. The world is not going to end but it will continue to get warmer and the impact varies geographically.

Was it you who posted a few months back about the feedback loops? I recall that the poster had a similar sounding background.