State of Knowledge | Science | Climate Change | U.S. EPA
What's Known
What's Likely
What's Uncertain
Yes, there is a lot of uncertainty about where this all leads.
There is an equal amount of uncertainty as to what is actually known. Lets take a look at your bit of scripture. Lets start with what they claim is known.
Human activities are changing the composition of Earth's atmosphere. Increasing levels of greenhouse gases like carbon dioxide (CO2) in the atmosphere since pre-industrial times are well-documented and understood.
Is that true? What is the residence time of a given CO2 molecule in the atmosphere? I have a couple of dozen peer reviewed studies stating it is less than 10 years but the IPCC and those closely associated state with certainty that it is from hundreds of years to thousands of years. And what is the natural variability of the earth's own CO2 making machienry? Do you know? Have you ever considered finding out? Would it surprise you to learn that humans don't produce enough CO2 to overcome the natural variability in the earth's own CO2 making aparatus from year to year? In light of those facts, it becomes questionable as to whether or not we are altering the atmosphere as it relates to so called greenhouse gasses. Couple that to the fact that paleohistory tells us that the atmospheric CO2 concentration has been in the thousands of PPM and the statement that we know that we are altering the atmopsphere as it relates to so called GHG's becomes highly questionable.
The atmospheric buildup of CO2 and other greenhouse gases is largely the result of human activities such as the burning of fossil fuels.
Again, explain the long periods of earth history where CO2 and other so called GHG's were in the thousands of parts per million and the bulk of earth history where the atmospheric concentrations were considerably higher than today and that certainty becomes questionable. Again, what is the natural variability in the earth's own CO2 making aparatus and do we produce enough so called GHG's to overcome that natural variability?
An “unequivocal” warming trend of about 1.0 to 1.7°F occurred from 1906-2005. Warming occurred in both the Northern and Southern Hemispheres, and over the oceans
That "unequivocal" warming trend is part of a warming trend that has been going on now for about 14,000 years. We are in an interglacial that has been punctuated by multiple periods including the Roman warming period and the Medieval warming period in which the temperatures rose higher and faster than anything we have seen in the past several hundred years without the benefit of man. For the past 14,000 years temperatures have fluctuated from warm to cold very often at rates more rapid than the present. In that light, the claim of knowledge about "unequivocal" warming being tied to the activities of man becomes highly suspect and takes on the aspect of a claim manufactured in an attempt to support a pretty shabby hypothesis.
The major greenhouse gases emitted by human activities remain in the atmosphere for periods ranging from decades to centuries. It is therefore virtually certain that atmospheric concentrations of greenhouse gases will continue to rise over the next few decades.
Really? Here is a list of peer reviewed studies and their findings with respect to the residence time of so called GHG's in the atmosphere.
There are 37 studies; 7 of them state that CO2 resides in the atmosphere for more than 10 years. Of those 7, two find that CO2 resides in the atmosphere for more than 20 years.
In light of the number of studies that find CO2 residence time to be less than 10 years and the completely outrageous claim made by the IPCC and AGW alarmists, that is another claim of knowledge that becomes highly suspect.
Increasing greenhouse gas concentrations tend to warm the planet.
Really? Describe a mechanism by which that might happen without breaking the second law of thermodynamics or the law of conservation of energy. I have been asking that question for a long time and to date, have never got a rational answer and I doubt that you are likely to give me one either. Explain how it might be that the warming has stopped for the past decade with ever increasing atmospheric concentrations of GHG's if increasing those gasses warm the planet?
Your state of knowledge isn't. Not a shred of it is proven by observable, testable, repeatable science and is in fact, little more than the output of computer models being presented as if it were actual data. Your scripture describes a false religion and you, my friend, are just another acolyte.