The Guardian, had an article on the futility of planting trees in non-tropical regions to offset global warming. The article reads: 

Planting trees to combat climate change is a waste of time, according to a study by ecologists who say that most forests do not have any overall effect on global temperature, while those furthest from the equator could actually be making global warming worse.

“The idea that you can go out and plant a tree and help reverse global warming is an appealing, feel-good thing,” said Ken Caldeira of the global ecology department at the Carnegie Institution of Washington in Stanford, California, a co-author of the study. “To plant forests to mitigate climate change outside of the tropics is a waste of time.” 

Professor Caldeira and his colleague Govindasamy Bala, of the Lawrence Livermore National Laboratory, also in California, said that outside a thin band around the equator, forests trap more heat than they help to get rid of by reducing CO2. More…

Caldeira and his colleagues ran a computer model to determine their assertions. Their premise is that boreal forests change the albedo, warming the air around the forest, grassy fields are cooler in their models. Apart from the observation that forests are cooler than open fields on hot days, and that soil in open fields traps heat whereas forest soils are cooler, their study overlooks, downplays really, the carbon sequestration represented by forests.
Chen et al, in a study called Effects of climatic variability on the annual carbon sequestration by a boreal aspen forest, found that massive amounts of carbon are sequestered in Canadian boreal areas to the extent of “40–60 Tg Carbon per year, which is 2–3% of the missing global carbon sink,” not an insignificant amount.

If the objective is to reduce carbon, then forests, boreal or tropical would still seem to be a viable alternative to many of the more technological solutions being put forward.

Caldeira found that tropical forests can reduce local air temperatures through evapo-transpiration. Given that we are cutting tropical forests at an alarming rate to plant biofuel stocks, would it not be more reasonable to plant more tropical trees as well, instead of soy beans, sugar cane and oil palms?

Caldeira also made an interesting statement, “Past 50 degrees, forests warmed the Earth by an average of 0.8C. But in the tropics forests helped cool the planet by an average of 0.7C.” This statement seems to be rather over the top, boreal forets alone have raised the GLOBAL temperature by 0.8 degrees C?

If we take the statement at face value, the net effect is 0.1 degree C, so the balance would still make boreal sequestration viable, as long as we maintain tropical forests.