Biomass burning is widespread in sub-Saharan Africa, which harbors more than half of global biomass burning activity. These African open fires are mostly induced by humans for various purposes, ranging from agricultural land clearing and residue burning to deforestation. They affect a wide variety of land ecosystems, including forests, woodlands, shrublands, savannas, grasslands, and croplands. Satellite observations show that fires are distributed almost equally between the northern and southern hemispheres of sub-Saharan Africa, with a dipole-type annual distribution pattern, peaking during the dry (winter) season of either hemisphere. The widespread nature of African biomass burning and the tremendous amounts of particulate and gas-phase emissions the fires produce have been shown to affect a variety of processes that ultimately impact the earth’s atmospheric composition and chemistry, air quality, water cycle, and climate in a significant manner. However, there is still a high level of uncertainty in the quantitative characterization of biomass burning, and its emissions and impacts in Africa and globally. These uncertainties can be potentially alleviated through improvements in the spatial and temporal resolutions of satellite observations, numerical modeling and data assimilation, complemented by occasional field campaigns. In addition, there is great need for the general public, policy makers, and funding organizations within Africa to recognize the seriousness of uncontrolled biomass burning and its potential consequences, in order to bring the necessary human and financial resources to bear on essential policies and scientific research activities that can effectively address the threats posed by the combined adverse influences of the changing climate, biomass burning, and other environmental challenges in sub-Saharan Africa.
Benjamin F. Zaitchik
Humans have understood the importance of climate to human health since ancient times. In some cases, the connections appear to be obvious: a flood can cause drownings, a drought can lead to crop failure and hunger, and temperature extremes pose a risk of exposure. In other cases, the connections are veiled by complex or unobserved processes, such that the influence of climate on a disease epidemic or a conflict can be difficult to diagnose. In reality, however, all climate impacts on health are mediated by some combination of natural and human dynamics that cause individuals or populations to be vulnerable to the effects of a variable or changing climate. Understanding and managing negative health impacts of climate is a global challenge. The challenge is greater in regions with high poverty and weak institutions, however, and Africa is a continent where the health burden of climate is particularly acute. Observed climate variability in the modern era has been associated with widespread food insecurity, significant epidemics of infectious disease, and loss of life and livelihoods to climate extremes. Anthropogenic climate change is a further stress that has the potential to increase malnutrition, alter the distribution of diseases, and bring more frequent hydrological and temperature extremes to many regions across the continent. Skillful early warning systems and informed climate change adaptation strategies have the potential to enhance resilience to short-term climate variability and to buffer against negative impacts of climate change. But effective warnings and projections require both scientific and institutional capacity to address complex processes that are mediated by physical, ecological, and societal systems. Here the state of understanding climate impacts on health in Africa is summarized through a selective review that focuses on food security, infectious disease, and extreme events. The potential to apply scientific understanding to early warning and climate change projection is also considered.