During the past decades, the worldwide spread of the human immuno-deficiency virus (HIV) has created one of the deadliest epidemics in history. In 2006, a total of 39.5 million people were living with HIV. Sub-Saharan Africa is clearly the most affected area of the world with more than 24...

The destruction of the Amazon is a major global environmental issue, not only because of greenhouse gas emissions or direct impacts on biodiversity and livelihoods, but also due to the forest’s role as a tipping element of the Earth System. It means that after crossing a biophysical threshold,...