Are you discounting Greta Thunberg? According to her, we have but about 10 years to go and she is the most expert person on global warming on the planet. 
@rangerrebew @Gefn Greta's parents say she is autistic. Usually, an actual autistic child will center on one thing and stay with it to the exclusion of all other things. Spending time with Greta would determine if she cannot think of any other subject.
It is usually hard to get an autistic child to look at you since he/she is in another world mentally and won't let you in. I was called to test a young boy child about 4 yrs. old. He would not look at me. I had to bang my hand on the table, make a fairly loud noise before he would look my direction. I kept talking and showing him items, slamming my hand down again to get his attention and that continued through my time with him. Yes, he was autistic.
Parents brought a 5 or 6 year old to me (don't remember the age exactly), wanted to know if their son was autistic. Along with their son, they brought a very large phone book and gave it to me, then the parents went to the lounge to wait. I showed the phone book to the child, and he took it and with it closed, began to quote the phone book, name by name with address and phone number. At home, he did that all day long, every day, and if he did not have the phone book, he would repeat the ones he knew all day.
With all autistic children, I had to estimate IQ based on info. from parents from the time the child was born, any problems with the birth, and how the child had responded, or not, from that time. Can you memorize the phone book? What level of intelligence does it take to be able to do that?
