The reality is that we don't actually have the answers people imagine we have. Temperature records have been kept since about the 1850s and data from before that time is based on proxies from which we make inferences.

https://en.wikipedia.org/wiki/Global_temperature_record

First actual recording of temperature in Seattle, Washington dates to 16 February 1870.

https://mrcc.illinois.edu/FORTS/histories/WA_Seattle_Conner....

I am not readily finding a similar document for Portland, Oregon.

In the US, we sometimes have oral histories from Indigenous populations that help clue us. In Southern California, there were Native stories about their ancestors being aware of a lake in what is now the Salton Sea and was dry land when White settlers or explorers were first going into that area.

We have data models. We have oral histories. We think we know what the weather was like for thousands of years but actual recorded weather goes back less than two hundred years.

So the reality is that we know for certain less than our stories in popular media might lead you to believe. Please keep in mind that our awareness of a hole in the ozone was delayed due to an algorithm that dropped readings of "zero" from the data on the assumption that it was some kind of error.

If you think our data models are perfect and humans make no mistakes, you can believe what our news stories tell you. If you don't believe that, then the answer is that "We don't actually know as much as we like to pretend we do."

(insert references to The Incredibles and Edna asking "Do you know where he is?" https://www.youtube.com/watch?v=OqMxPw6MVzY)