Why? Because there is no such thing. They pluck that "consensus" out of thin air. On the other hand the climate realists, like me, can produce a list of about 32,000 scientists, who disagree, including names and qualifications. This can be found under "Oregon Petition".
I can also read history books which show that the Mediaeval Warm period was warmer than today, when they write about the Viking settlers in Greenland. To confirm that are 912 scientists, in 542 separate institutions in 43 different countries. They can be found in CO2Science.org. I have also read the graph of the latest analyses of the Greenland ice cores for the past 8,000 years.
These show six periods in that time which were warmer than today. They also show that each warm period was cooler than the previous one, and each cool period colder than the previous one, culminating in the Little Ice Age.
I have also read some of the Climategate e-mails. What a disgusting load of chicanery! The jookery-pokery was rampant, and, as for their behaviour regarding the early death of John Daly, it was absolutely scunnersome. I have also read the summarised returns of over 60,000 measurements of CO2 density in the atmosphere which show that the 1940s had densities up to 60 parts per million greater than today.