Climate change will increase the number of malnourished children in Africa by 10 million to 52 million  in the next 40 years, and the continent needs new agricultural investment of U.S. $2.9 billion a year to offset the adverse effects, says a new report.

The report, "Climate Change: Impact on Agriculture and Costs of Adaptation," is billed by its authors from the International Food Policy Research Institute (IFPRI), as the most comprehensive assessment of the impact of climate change on agriculture to date.

After comparing predictions of the numbers of malnourished children in 2050 with and without climate change, it concludes that climate change will produce 25 million more malnourished children around the world than would otherwise have been the case.

A fact sheet issued with the report says the number of malnourished children in Africa is expected to rise from 33 million in 2000 to 42 million in 2050 – without taking into account the effects of climate change.

"Climate change will further increase this number by over 10 million, resulting in 52 million malnourished children in 2050," the sheet says.

However, this outcome could be averted with a global investment of an extra U.S. $7 billion a year to boost agricultural productivity, said Gerald Nelson, the lead author of the report.

Sub-Saharan Africa needs 40 percent of the estimated $7 billion, most for rural roads, the report added.

Other key points from the report, issued in conjunction with international climate change meetings in Bangkok:

• The negative effects of climate change on crop production are especially pronounced in sub-Saharan Africa, as agriculture accounts for a large share of GDP, export earnings and employment in most African countries.

• In 2050 average rice, wheat, and maize yields will decline by up to 14 percent, 22 percent, and five percent, respectively, as a result of climate change.

• Climate change is expected to produce a 21 percent decline in calories by 2050, an average 500 calories fewer per person.