All global warming scientists will fully admit that they are not sure of everything. Yet despite this, they are sure that anthropogenic global warming is occurring - and there is compelling evidence of this based on the last 50 years. Your quibble is marginal really.
One of the things the professional contrarians like to do is exploit the uncertainty inherent in the science, along with a few outright lies about what actually is uncertain, to create the illusion that it's *all* uncertain.
The science predicting the ‘greenhouse effect’ has been around a long time and is not in doubt (I’m going to take the phrase ‘among qualified scientists writing in peer reviewed journals … ‘ etc. as read here to save repeating it every paragraph) That we humans have significantly changed the quantities of greenhouse gasses in the atmosphere is not in doubt. We also understand pretty well the additional amount of solar energy these gasses trap in the climate system. We know that the Earth’s surface temperature has warmed significantly since we started burning fossil fuels and destroying forests etc. We can model the recent historical data with enough accuracy to be pretty damn sure that more emissions mean more warming. There is uncertainty to be sure, but not about any of that stuff.
The uncertainty starts to creep in when we try to project the models forward because we're constantly refining the estimates of how sensitive the climate is and when we try to predict consequences. We know we'll cause some warming and we've got an approximate idea how much for any given emissions scenario, but things get fuzzier as you project further forward and as you add more variables (like what we do to control emissions, interactions with other issues like resource depletion, soil erosion etc.)
There are some consequences that are fairly straightforward to predict, for a given rise in temperature. For example, a 0.5-1.5m rise in sea level for the emission scenarios considered by the IPCC is pretty straightforward to predict and hence can be considered high-probability, which also means a couple of hundred million refugees from places like Bangladesh and Egypt are also high probability.
Other changes are triggered at some hard to determine threshold though. For example the irreversable melting of major ice sheets adding several more metres to sea level and the switching off of the Atlantic Thermohaline Circulation are predicted to happen at some point if greenhouse gas levels continue to rise, but we’re not really sure a) what that point is and b) how much more emissions will actually rise given that we don’t yet know the outcome of the struggle between those who want to mitigate the effects now and those who want to keep emitting
The thing is, the science does prove this is happening, but it’s harder to show exactly what the effects will be. Some of them are regional for a start. So it’s not just a matter of uniform warming. It’s also a matter of changes in weather patterns and knock on effects like the extinction of species providing valuable ecosystem services or the wider spread of disease causing species.
So there is a sort of cascade of uncertainty. The basic climate models have some uncertainty in them but we pretty much understand how much. There are questions about how big the effect is, but we already know enough to say that it's going to cause a lot of problems. There are also limitations in computing power that mean the models have to work in units rather larger than Belgium and you need to model much smaller units to get an accurate idea of what effect a given mountain or forest has on local conditions. Once you get down to knock-on effects, like where and when crop failures will occur, or just when Wales becomes malarial, the uncertainty is also magnified by the inherent uncertainty of predicting behaviour in complex natural systems.
In addition, we have some potential problems with very grave impacts (like the major ice sheets melting or some big natural carbon sink turning into a carbon source) where the problem occurs at some undetermined threshold. One might use smoking as a metaphor here. We know it can cause cancer, but we can’t say with confidence just exactly how many cigarettes a given individual needs to smoke to get sick. We can say with confidence that smoking is a bad idea though.