Alarmist Attenborough's Aspersion Abolished

In David Attenborough's series Africa, he made the outlandish claim:
Africa's climate is certainly changing. Some parts of the continent have become 3.5ºC hotter in the past 20 years.
As the Guardian points out:
I'd never heard this arresting claim before. If that rate of temperature rise continued over, say, a century, then those parts of Africa would see a deathly rise of 17.5ºC?! Could that claim really be true?
I also noticed some people on Twitter asking the same question. So the following morning I called the BBC press office and asked where this information about a 3.5ºC temperature rise over 20 years had come from.
Also reported by the UK Telegraph, Hayley Dixon writes:
Given that since 1850 global temperatures have risen by about 0.8ºC, causing widespread concern, it was seen as a shocking assertion. 
Bloggers and environmentalists expressed their surprise and questioned the scientific evidence behind the claim.
But the BBC initially defended it.............Unable to back up the assertion, the BBC last night deleted the words from the repeat of the episode.
David Attenborough has previously had problems with his Frozen Planet series in which he used fake footage and also had a propaganda episode dropped by the US.

See Also Donna Laframboise's The Workshop Presentation that Never Was