The Jan. 24 editorial “Keystone XL is coming back” was notable for not even mentioning climate change, the reason this project has become the biggest flashpoint for environmentalists in a generation. The Post is free to disagree with the 18 top climate scientists who sent the president a letter this month explaining that Keystone was a climate disaster, but not free, it seems to me, to simply ignore them.

Bill McKibben, Ripton, Vt.

The writer is co-founder and chairman of the board of the environmental group

Regarding the Jan. 23 news story “On climate, Obama makes a moral case”:

President Obama has been given the opportunity to choose immediate action to fight climate change after Nebraska’s decision last week to endorse the route of the Keystone XL pipeline. If approved by the Obama administration, the Keystone XL pipeline would contribute significantly to climate change by promoting the use of fossil fuels and producing carbon emissions. Rather than increase American dependence on dirty energy, President Obama can take bold action by rejecting the pipeline and commit federal investments in renewable energy, such as wind and solar.

Andrea Leigh, Culpeper

The writer is a member of the Sierra Club.