Charles Krauthammer [“The myth of ‘settled science,’ ” op-ed, Feb. 21] is right in that “[no] science is settled, static, impervious to challenge.” However, enough of the science of global warming has been established as fact that those of us who look at the likely implications of these facts are very concerned about the Earth’s future climate. The fact that adding carbon dioxide to the atmosphere will increase the Earth’s temperature was established long ago by looking at basic scientific principles. Although climate scientists will never be able to predict exactly how much the Earth will warm for a specific amount of carbon dioxide, they can provide a range of likely values. Their best estimate at this time is that a doubling of atmospheric carbon dioxide — which will happen this century if we continue burning fossil fuels at the current rate — will very likely raise global average temperatures at least 5.4 degrees in the short run and possibly more than 11 degrees in the long run.

The resulting climate could be inhospitable to civilization as we know it, so I do not want my two granddaughters to inherit a significantly warmer world. It is imperative that we start reducing fossil-fuel emissions as soon as possible, and imposing a fee on carbon is the best way to get started.

Bruce Parker, Alexandria

The writer is a volunteer with the Citizens Climate Lobby.

I’m not a Democrat or a Republican. I worry about smart people being captured by their ideologies when analyzing important issues such as climate change. Just in case, after reading Charles Krauthammer’s op-ed column, I threw a few stones upward, and they all came back down. I guess that means that some facts can be settled by science. As with polluters, when intelligent people play ideological games with serious issues, we all lose.

Armando Morales, Cabin John