Biochar is a new term, denoting char made from BIOmass for the purpose to 
be returned into BIOsphere, by applying the char to soils to increase 
their fertility. Biochar has been used thousands of years in various parts 
of the world, with amazing results, unnoticed by science.

Its recently recognised additional virtue is a reliable long-term storage 
of carbon in a form which is order(s) of magnitude more stable than 
uncharred biomass carbon on/in soils. Turning a part of dead biomass into 
char instead of letting it decompose completely by biological processes or 
burning it "to ash" is the most promising way of taking carbon away from 
quick natural cycles.

Char in general can be made even from polymers produced in factories. And, 
technologically, there is no large difference between production of char 
to be used as a fuel -- called charcoal -- and to be used as a soil 
amendment. Large final particles are desirable for charcoal, small ones 
are needed for biochar application. Small-grained biomass is the best raw 
material for producing biochar.

UN wants biochar to become a part of carbon trading. It will be a part of 
Copenhagen agenda in December.

http://en.wikipedia.org/wiki/Biochar gives a good overview. A recent 
Economist article on biochar it mentions the Boulder/Colorado conference 
held in August, see
  http://www.economist.com/sciencetechnology/displaystory.cfm?story_id=14302001
  -- the website http://biochar-international.org of the International 
Biochar Initiative points to it and to all relevant information on biochar 
in general, especially to the 2009 book "Biochar for Environmental 
management: science and technology". From the Colorado conference, video 
files are available already, see
  http://biochar-international.org/north/american/conference
and the link from there.

Restructuring biomass utilisation on a global scale to achieve maximum carbon 
storage will demand more research and huge effort. At the end, it could 
produce a steady carbon flux away FROM the atmosphere amounting to about 
1 Gt/a, one tenth of the present man-made flux TO the atmosphere.

Meanwhile, it is desirable to process at least all existing bio-waste 
fluxes this way, instead of composting (with almost all carbon escaping 
to the atmosphere soon, some in the form of methane) or burning them 
completely. And, in many cases, current thermal efficiency of using 
precious biomass is so low (cooking in developing countries being a prime 
example) and the accompanying pollution so large (soot -- a strong 
greenhouse agent, respiratory diseases from smoke), that 
biochar-producing stoves may actually improve the situation tremendously, 
in spite of leaving the char unused thermally. Portable or stationary 
charring stoves are a technology which should spread globally within a 
decade, with rich countries taking a lead.

The future of Earth depends on stopping the use of coal and other fossil 
fuels soon enough. And then, on being content with at most two thirds of 
energy content of biomass from forestry and agriculture -- the remaining 
part is to be brought back to the sediments as char to remain there for 
centuries and millenia. An atmosphere compatible with our civilisation 
and nature as it existed during its evolution can be restored this way -- 
maybe only this way.