At least 10 million people are now believed to be in need of humanitarian assistance in east Africa as a result of severe drought, failed harvests, unpredictable weather patterns, rising food prices and conflict.

Parts of Kenya, Ethiopia, Somalia and South Sudan are experiencing their worst drought in 60 years. The Disasters Emergency Committee has launched a fundraising appeal, which has so far raised £9m, along with individual non governmental organisations (NGOs), to provide emergency relief.

The situation is particularly acute in Somalia. The UN says the number of malnourished children in affected areas has doubled since January. Estimates show that one in three children in south and central Somalia, and almost a quarter of all children in Bosaso (the main port in the north) are now malnourished.

In recent weeks, thousands of refugees from Somalia have been arriving in Dadaab refugee complex in Kenya, putting pressure on a camp already declared full. A meeting between the head of the UN refugee agency, António Guterres, and the Kenyan government about opening another camp at the complex scheduled for Monday was cancelled.

Droughts in the regions experiencing the food crisis are not uncommon, so why are things so bad this time? Could governments and international donors have acted more quickly to avert this crisis? What needs to be done in Dadaab?

Between 4pm and 5pm On Wednesday 13 July, Mike Sunderland, Africa emergencies manager with Save the Children, and David Throp, Plan International's country director in Ethiopia, will be live online to answer your questions about the drought and the food crisis.

Sunderland is in Kenya and has recently visited Dadaab, while Throp is leading Plan's response to what has been termed a "green drought" in southern Ethiopia. Throp says the term green drought relates to the fact that the landscape looks lush and green, but people don't have food to eat. "To outsiders it seems incredible," he says. "This year, the rains that allow seeds to germinate and crops to start to grow did not come. As a result, families were not able to harvest crops when they normally do. The later rains did arrive in some measure, but now the crops are only half-grown, and are not ready to eat until at least September. In the meantime, people are facing a serious food shortage, even though they're surrounded by greenery."

Post your questions now and come back to see how Sunderland and Throp answer them at 4pm on Wednesday. If you have any problems posting, or if you would prefer to comment anonymously, email us at development@theguardian.com and we'll add your question.