NASA states that multiple studies that have been performed and published in peer-reviewed, and therefore reputable, scientific journals show that over 97% of scientists working in the climatology field agree that warming trends over the past century are more likely than not caused by human activities. Further, most of the leading scientific organizations globally have issued statements confirming that this is the case.
In short the current scientific consensus of climate change studies is that the earth has warmed to a statistically significant degree since the late 1800s (the advent of the industrial revolution). They also state that human activities that have resulted in greenhouse emissions are the primary cause of this warming. Further they attest that continuing human activities that cause these emissions at the current rate will increase the likelihood of severe global consequences evidenced in extreme weather patterns.