Climate change looks to be an unmitigated disaster that is going to cause a very large amount of pain and suffering. This disaster will have been caused completely by us and we will have to put the work in to both deal with its effects and fix the damage in someway.
That some people, including some very powerful people (such as George W. Bush), do not accept there is a problem makes it extremely difficult to get started at dealing with it.
The scale of the problem is such that having people deny it seems criminally irresponsible and neglectful to the utmost degree.
Let me explain the scale of the disaster. There are already places in the Pacific that are starting to be inundated with salt water. The people of Carterets Island (near Papua New Guinea) are moving to Bougainville. The island nation of Tuvalu has sea water coming up through the middle of the island and ruining crops. Now one might argue that it is the land sinking and not sea level rising - this doesn't help the people who are removed from their homes and their country.
Bangladesh, with its 150 million people living on what is basically one very large river delta, is likely to be the country with the biggest problem. The country already has floods seemingly every other year during typhoon season. It would not take a lot of sea level rise before Bangladesh is uninhabitable. So where do those 150 million people go?
There's India to the west. Overcrowded and the (mostly Hindu) Indians aren't going to be exactly charitable to the (mostly Muslim) Bangladeshis. They haven't been in the past - that's why Bangladesh exists. Do they go north to Tibet? China would be distinctly unhappy about that. How about east - Myanmar/Burma. The backwards military junta there will not help.
Can you imagine the chaos if even 10% of the 150 million have to move somewhere?
The next problem is what it will do to the plants and animals on this world. The plants and animals we utterly rely on to live but never seem to acknowledge. A species lives in a certain place because it's found a niche there. It has a temperature it likes, food it likes and a place to live. As the temperature changes these species are going to have to move or they will die. Yet many of them probably can't move quickly enough to match the temperature change. It takes quite a long time for plants to reproduce and grow and many animals will require certain plants to be there. Secondly, as species move up mountain ranges to find cool enough temperatures, the species at the top will simply be pushed off - and become extinct.
Why do we care? Do you like breathing? Do you pay anything to create the oxygen to breathe? The biology of this planet is kind enough to do this for you. The planet is an incredibly detailed web. We do not know how it all fits together. We haven't even named and described all of the species. So how can we go changing the way the world lives if we have no way of predicting the outcome?
So, in the light of this massive problem, why shouldn't the world express exasperation at people who would rather ignore it?