(CNN) The extreme weather that comes with climate change is becoming the new normal, so normal that people aren't talking about it as much -- and that could make them less motivated to take steps to fight global warming, according to new research.

Researchers analyzed more than 2 billion social media posts between 2014 and 2016. What they found was that, when temperatures were unusual for a particular time of year, people would comment on it at first. But if the temperature trend continued and there were unusual temperatures again at that time the following year, people stopped commenting as much.

The authors of the study, published in Monday's Proceedings of the National Academy of Sciences , believe that this is a sign that because of memory limitations and their own expectations and biases, humans may not be the best judges of temperature change. The experience of weather in recent years, rather than over longer historical periods, determines the baseline that people use to evaluate the current weather.

It's the "boiling frog" effect, an urban legend about an experiment that involves putting a frog in a pot of boiling water, where it quickly jumps out. But if it's put in a pot of tepid water on a stove and the heat is gradually increased, the frog will stay in the pot until it dies, because it doesn't feel a difference until it's too late.

In other words, people may not recognize the signs of human-caused climate change until it's too late.

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