If current TV coverage seems overladen with PBS shows, let me assure readers that the January batch of programming cooked up by the beleaguered Public Broadcasting programming is so diverse, informative, and stimulating that it deserves the almost undivided attention of both viewers and critics. That's you and me.
Example: ''Life on Earth'' (PBS, Tuesday, Jan. 12 and for 12 Tuesdays thereafter, 8-9 p.m., check local listings for premiere and repeats - many stations are repeating it on Sundays). Hosted and scripted by the delightfully erudite natural historian David Attenborough (who will be interviewed on these pages next week), ''Life On Earth'' is the most important series to emerge from the BBC since ''Civilisation'' and ''The Ascent of Man.'' It is filled with fascinating pictures and facts about the development of creatures on earth, from the first organisms in the ocean to today's unnerving mammals. Attenborough has verve, panache, and information as well as an incredible sense of theater. This is the nature series to end all nature series - its appeal to young and old is liable to start a whole new generation of zoology buffs among us.
But just as I find myself waxing enthusiastically about ''Life on Earth,'' I find I must put in an almost equally enthusiastic word for the first in the new National Geographic series ''The Sharks'' (PBS, Wednesday, 8-9 p.m.). It is the other side of the movie ''Sharks'' - sharks as victims. The film constitutes a much-needed counterbalance for the creatures, which are often thought of as vicious but who, according to this special, behave badly only when humans invade their environment and provoke them. Underwater cinematography is superb, with startling shots of sleeping sharks in their underwater Mexican grotto.
If you've been an admirer of National Public Radio's ''All Things Considered, '' you will be especially interested in an experimental TV version which airs on PBS on Wednesday, 9:30 p.m. Although only portions were available for screening at press time, ''ATC'' would seem to be short on graphics, heavy on words. ''All Things'' regulars Sanford Ungar, Cokie Roberts, and Susan Stamberg appear, and the highlight seems to be a segment on new immigrants and the problems of integrating them into the community.
The problem of integrating literate writing and legitimate action seems to have been solved by close-ups of the hosts on screen with action film clips behind them. If journalism is the major aim of ''All Things Considered,'' perhaps the producers had better consider whether newspapers or their old standby radio might suit the contents even better than TV. But the TV version is a good try, an experiment worth risking.