Here, via MSNBC, is what most scientists say is certain:
And here's more of what they say.
"This heat wave and other extreme events we've seen in recent years are completely consistent with what we expect to become more common as a result of global warming, even though we can't be definitive on any single event," says Jay Gulledge with Pew Climate Change. [...]
"So far, we've had about 80 daily high temperature records broken and in the month of July there were about 50 all-time records for the month of July broken -- that's phenomenal for any air mass, any heat wave that's going on right now," says Dennis Feltgen, a meteorologist with the National Oceanic and Atmospheric Administration.