These aren't models of climate sensitivity, they are complex models of the global climate, and climate sensitivity can be derived from them. I am skeptical of these results because the climate
sensitivity derived from studying the palaeoclimate is much less than what we get from these latest models and the amount of climate change observe since around 1900 is also consistent with
a lower climate sensitivity of about 3 degrees C. for a doubling of CO2. However, these new models also reproduce the 20th century warming and other aspects of the climate better than previous models. If the climate
sensitivity turns out to be around 3 degrees C. for a doubling of CO2 rather than 5 degrees C for a doubling of CO2, that still represents a good chance of catastrophic warming by the end of the 21st century.
The most significant finding from these new models is that the net cloud feedback could result in more warming than previously expected. The net cloud feedback is the biggest uncertainty in climate
science and it isn't known if the feedback is positive or negative but most of the evidence supports a positive feedback for clouds as the planet's surface warms. These new climate models support a
higher positive feedback from clouds that is caused primarily by less reflection of sunlight.