Ok...
This question was started 6 years ago, so, I understand that some of the stuff is relating to 2008 and 2012 and I accept all that as relevantly true.
The previous 8 years were under a Democratic administration who seemed to take at least the idea of Climate Sciences at face value -- and seemed to value the global consensus that climate change was happening (whether it was GW or AGW, that was an internal debate) and that something aught to be done about it -- so thus sprung up the Paris accords where all but one country decided upon trying to set up voluntary plans for reducing emissions.
Given those as all good lets add the last few years to the list and see what a successful conservative Republican administration has done.
I can't get into President Trump's head, so I can't say exactly WHY he's doing everything..but, first off he's playing to his base -- and promising deregulations of everything and bringing back coal. Additionally, it seems he wants to dismantle anything President Obama created or touched.
I can only list WHAT he's done to deny global warming -- and say that it didn't happen when it was more liberal.
Now, fast forward to at least 2016...President Trump gets elected president, and very shortly after that almost ALL references to Climate Sciences on governmental websites gets deleted and/or removed. Climate and Earth Science research was potentially defunded or deemed not a priority.
The Paris Climate Accords are denounced by the President and he promptly, to the dismay of many people in Congress, decides to remove the US from those provisions -- being one of the only two non-signatures to it.
When asked about it, President Trump denies it's significance -- even when global and even domestic reports seem to rank it highly significant and a global threat. And his quotes that it's a "Chinese Hoax"
President Trump's push to elevate and promote Coal...even though, for the most part, there was a general consensus that perhaps Natural Gas was a better, cheaper alternative. Plus, all of the environmental roll-backs for stuff like Clean Air/Clean Water provisions and MPG regulations.
The Trump Administration's efforts to push for "Red Team" vs "Blue Team" climate science model. And, now that a new Climate Report is due for 2020 or 2021, their push that the new report eliminate the "worst case model" and only model out to 2040 as opposed to currently going to 2050 and beyond.