I think that the current US conservative government do believe that climate change exists, though they currently deny it. Most members of that government have large shareholdings in industries that have caused global warming, and don’t want to make admissions that one day could help lawsuits prove their culpability. They are still making money from those industries. They are mostly getting old. So the climate and flowon effects wont affect them directly, so they think. That’s my theory.
I think, the reason they really want a wall is because, when the countries near the Equator heat up, flood, or otherwise become inhospitable, the US don’t want the resulting refugees yet to come. See on this map where the Equator is, cutting through Colombia and Brazil. Then see the land route from there to the USA.
1996. Courtesy of the University of Texas Libraries, The University of Texas at Austin.
Parts of Europe have been putting up security fences to keep out hordes of immigrants. I believe these are, at heart, climate refugees, however, their numbers are nothing to what is going to occur in the future, as climate change gets worse. I believe all countries in temperate zones are aware of the inrush of immigrants yet to come, whether their governments admit to climate change or not.
Do countries have the right to protect their borders with walls? Well, yes, I think they do, actually. It’s literally a stopgap measure though. We need to address the causes. As a planet, we have to urgently reduce our carbon output, stop deforestation, our pollution production generally needs to go down to almost nil. We need to drastically reduce our population growth.