New research suggests that the AIDS virus first emerged in human populations about 100 years ago. That seems a bit surprising, given the way in which the impacts have exploded in the last few decades. The explanation is simply to consider the lag times and exponential growth curves involved. In 2007, 2.1 million people died of AIDS, from among the 33.2 who were infected. Despite improved access to antiretroviral therapies, the sheer extent to which the disease has spread means that the deaths in any recent year probably far exceed the combined deaths from the first few decades of the disease’s existence.
Disturbing parallels exist in relation to climate change. Once again, there is a lag between the cause (contracting HIV or emitting greenhouse gases) and the effects (destruction of the immune system or climatic change). Once again, the rate of growth in the underlying cause has been exponential. Thankfully, there is reason to hope that we are still not too far along the path, when it comes to climate change. It is like having discovered AIDS decades before we actually did – it would have allowed more time to develop and deploy treatments and encourage changed behaviours. It would also have made the peak in number of infections lower and sooner to arrive, before crossing over to the long and difficult slide towards elimination.
Another parallel between AIDS and climate change is that some people deny the links between causes and effects, probably causing a great deal of trouble.
HIV/AIDS Deaths
Acquired Immunodeficiency Syndrome, or AIDS, was first identified in 1981 in Los Angeles in the United States. In 2002 nearly 80% of the 2.6 million deaths from AIDS occured in sub-Saharan Africa, where the disease, usually untreated, caused more than 6000 deaths every day and accounted for almost one in five of all deaths and half of the deaths of adults aged 15 to 59 years.