One example he gave in the report was the aftermath of the 2012 Hurricane Sandy in New York City. While thousands of low-income people were left without power and healthcare for days, the Goldman Sachs HQ on Manhattan was kept safe by tens of thousands of sandbags and powered by a private generator.

But extreme weather events fueled by climate change are also deepening disparities within countries.

Poor communities and women are more vulnerable, because they tend to be more reliant on agriculture.

The livelihoods of the world's poorest are most exposed to climate change disasters, because poverty makes it impossible to escape, says the research. When extreme weather hits, the poorest lack the resources necessary to recover, and become even poorer, creating a vicious circle.

"Perversely, while people in poverty are responsible for just a fraction of global emissions, they will bear the brunt of climate change, and have the least capacity to protect themselves," Alston said.

The UN has also warned that just slowing down the rise in temperature as outline by the 2015 Paris Agreement won't be enough to save millions of people who are already suffering.

"Even the unrealistic best-case scenario of 1.5 (degrees Celsius, or 2.7 degrees Fahrenheit) of warming by 2100 will see extreme temperatures in many regions and leave disadvantaged populations with food insecurity, lost incomes, and worse health," the report said.

Tuesday's UN report has again highlighted the need for nations to recognize that basic human rights -- to life, food, housing, and water -- will be dramatically affected by climate change, especially if they fail to take action.