A growing number of people are reluctant to bring a child into a world that’s set to be ravaged by climate change in the coming decades. 

Analysts at Morgan Stanley said in a note to investors last month that the “movement to not have children owing to fears over climate change is growing and impacting fertility rates quicker than any preceding trend in the field of fertility decline.”

To support their argument, they pointed to surveys, academic research and Google data that shows climate change is directly and indirectly accelerating the decline in fertility rates. UCLA researchers showed that the number of births in the U.S. fell in the nine months after an extreme heat event while a study of 18,000 couples in China last year showed that climate change, and particulate pollution in particular, was associated with a 20% increased likelihood of infertility.

Some people are choosing not to have children because they fear that that doing so will amplify global warming.

“Having a child is 7-times worse for the climate in CO2 emissions annually than the next 10 most discussed mitigants that individuals can do,” analysts at Morgan Stanley said.