There's been a lot of debate among average people and in the political arena when it comes to the legitimacy (or not) of global warming and how dangerous (or not) it is to the world wide weather patterns, water levels, animal populations (such as insect swarms and fish schooling patterns), etc.
However whether or not global warming is legitimate or not is beside the point. Conservatives don't oppose global warming because the science is bad on it (or not). Conservatives would have different responses if it were legitimate and there really needed to be something done to make things better, but we don't even get a chance to have a say in how this apparent phenomenon is handled.
Let's say that the worst predictions of Al Gore and other prominent global warming promoters are true. Crops will fail, the Maldives will sink under the water, coastal cities will flood, mosquitoes and other vermin will thrive, diseases will spread, major hurricanes will form at a much higher rate, etc.
Now let's look at what liberals tell us we should do about this.
1. Global Warming believers make everything you buy and do more inconvenient and more expensive
The liberals believe that we can't even have a properly flushing toilet (have to have a low flow) because of "global warming", and we have to have dangerous squiggly light bulbs full of mercury that are more expensive rather than regular light bulbs. Businesses spend a lot of money to not create too much carbon due to increased regulation and they pass the costs down to the consumers. Land owners are told even more what they can and can't do with their own land. "Energy efficient" products are often sub-par, such as a washing machine that won't agitate properly like the older models did. These are just a few examples but the basic picture is that life is more expensive, more inconvenient, etc. because of all this global warming and extreme environmentalism stuff.
2. Global warming believers advocate killing lots of people
This is the real heart of why conservatives don't like this global warming stuff. Because of global warming nonsense, we've all been brainwashed that "There are too many people in the world", and that we need to "reduce the population".
What this comes to in real world terms are: Promoting homosexuality as a lifestyle (many people have the potential to have homosexual attraction, there are many more people that are actively homosexual today than there have been in the past), promoting abortion (to reduce the number of people on earth, liberals hope to abort as many babies as possible), and promoting euthanasia and assisted suicide (infants that the parents don't want to care for, old people, terminally ill, or people who just don't want to live).
There are also other aspects that tie into this such as some vaccines potentially being unsafe and the danger of GMO foods, etc.
Many food companies have been reducing calories in their food products. This might be good for people who have enough money to buy more than enough food to eat, but not so good for people who can't afford very much food. Imagine if you only had enough money for two small meals a day and the food company cut the calories in those products. That would be harming you, not helping you.
At any rate all this "sustainable development", "population control", etc. is why we are really against the global warming agenda.
Whether or not the science is valid is really irrelevant.
People reject the whole idea of global warming because it's tied in with the abortion, the euthanasia, the homosexual agenda, and other means of "population control" which are nefarious.