Some of the biggest flaws in the warmest advocates arguments are that current temps are much below historic temps over the eons.  Also the warmist's models are consistently overstating the actual temps occurring.  Two charts are below. 

Another of the warmist biggest failures are a series of predictions of the Arctic Ocean becoming ice free.  Add to that the list of their other statements which history shows to be false;  increasing forest fires-FALSE,  increasing tornadoes-FALSE, increasing hurricanes-FALSE. 

Then there's various times where leaders among the warmist groups have admitted -- its really about redistribution of wealth & power, changing the economic system, even alleging that over-population of the globe needs central planning.   Control, control.

Chart Title: Eons of warm earth temps 
Image Info: Chart of  four million years of Earth temperatures -- clearly show current levels are much cooler than the Earth's historic levels. 

Source -- Greg Wrightstone, Four million years of  temperature data,  Author: Inconvenient Facts --the science Al Gore doesn't want you to know

Image Info: Click Here  36 climate models overstate temps, on average nearly doubling the temps actually recorded.   

Official NOAA observations produce a 50-year summer temperature trend of +0.26 C/decade for the U.S., while the models range as high as +0.71 C/decade.