Global warming caused mostly by humans

In a new study, as reported by USA Today:

NASA researchers updated calculations of the Earth's energy imbalance, which is the difference between the amount of solar energy absorbed by the Earth's surface and the amount returned to space as heat. They found that despite unusually low solar activity from 2005 to 2010, the planet continued to absorb more energy (half a watt more per square meter) than it returned to space during that time period.

In other words, it's not the sun.

In fact, a growing body of research suggests that humans may be causing more than 100% of global warming, because without human influences on Earth's climate, the planet would actually be cooling.  See What Amount of Global Warming is Human-Caused?

Why is human-induced warming so potentially dangerous? Because when tipping points are reached, warming will accelerate due to feedback effects.  For example, as Arctic ice melts, more solar heat is trapped with less sunlight reflected back into space.  See Climate Change in Arctic could Trigger Domino Effect Around the World.