Climate variability and vulnerability to climate change: a review

Abstract

The focus of the great majority of climate change impact studies is on changes in mean climate. In terms of climate model output, these changes are more robust than changes in climate variability. By concentrating on changes in climate means, the full impacts of climate change on biological and human systems are probably being seriously underestimated. Here, we briefly review the possible impacts of changes in climate variability and the frequency of extreme events on biological and food systems, with a focus on the developing world. We present new analysis that tentatively links increases in climate variability with increasing food insecurity in the future. We consider the ways in which people deal with climate variability and extremes and how they may adapt in the future. Key knowledge and data gaps are highlighted. These include the timing and interactions of different climatic stresses on plant growth and development, particularly at higher temperatures, and the impacts on crops, livestock and farming systems of changes in climate variability and extreme events on pest-weed-disease complexes. We highlight the need to reframe research questions in such a way that they can provide decision makers throughout the food system with actionable answers, and the need for investment in climate and environmental monitoring. Improved understanding of the full range of impacts of climate change on biological and food systems is a critical step in being able to address effectively the effects of climate variability and extreme events on human vulnerability and food security, particularly in agriculturally based developing countries facing the challenge of having to feed rapidly growing populations in the coming decades.

Keywords: agriculture; climate variability; development; food system; poverty; uncertainty; vulnerability.

Fig 1

The effect of changes in temperature distribution on extremes. Different changes of temperature distributions between present and future climate and their effects on extreme values of the distributions: (a) Effects of a simple shift of the entire distribution towards a warmer climate; (b) effects of an increase in temperature variability with no shift of the mean; (c) effects of an altered shape of the distribution, in this example a change in asymmetry towards the hotter part of the distribution. From IPCC (2012).

Fig 2

The relationship between rainfall variability expressed as the 12-month Weighted Anomaly of Standardized Precipitation (WASP) and growth in GDP and agricultural GDP in three countries in sub-Saharan Africa: (a) Ethiopia, (b) Niger, (c) Mozambique. Data sources: World Bank, data.worldbank.org/indicator and the IRI data library, iridl.ldeo.columbia.edu/.

Fig 3

The differential impacts of across-the-board changes in rainfall CV of −1%, +1% and +2% on population distribution by rainfall variability in developing (a) and developed (b) countries.