The negative effects of climate change on crop production are more pronounced in Sub-Saharan Africa than in other parts of the world. Thus, severe and prolonged droughts, flooding and loss of arable land leading to reduced agricultural yields through such avenues as crop failure and loss of livestock which provide draught power and household income is still probable. As a result of climate change, there is an observed 10% decline in maize yield, 15% decline in rice yield and 34% decline in wheat yield in Sub-Saharan Africa in previous years. Yield projections indicate that by the year 2021, yields from rain-fed agriculture in some African countries could be reduced by up to 50% which would to a great extent affect food security and worsen the malnutrition situation. In Zambia under the worst-case scenario, maize yields will decrease by 25% driven mainly by temperature increases offsetting the gains from increased rainfall. Decline in water availability in Zambia by 13% by the end of the century in 2100 at national level as a result of climate change which poses a much greater risk to field crops such as maize.
Africa’s inability to cope with the physical, human and socioeconomic consequences of the extremes of climate makes it the most susceptible to climate change. What also adds weight to the incumbent problem is that majority of maize agricultural producers in Sub-Saharan Africa reside in rural areas. For example, out of 83% of the 1.4 million smallholder households in Zambia grow maize—which is a huge number. But the rural poor are more vulnerable to these changes in climate and consequently, hunger, poverty and malnutrition levels will more likely continue to rise which means that the severity of climate change will increase keeping other factors constant. Because of this evidence, there is need to diversify from maize production as dependence on maize production in most Sub-Saharan African countries is a worry for food and nutritional security, especially when alternative supplements for dietary diversity are limited.
Although maize is usually considered as a warm season crop, it is actually more sensitive to high temperature stress as compared to other crops. At higher temperatures, maize yields will reduce but at the same time production or multiplication of some weeds and pests will be encouraged. At a high temperature of 35°C, maize yield reduces by 9% with a one-inch reduction in rainfall. Thus, even if plant breeders have developed maize varieties that grow well under different biophysical environments, sound maize productivity is still under threat by climate change effects.
Adaptation to Climate Change
Research on maize has a very important role to play when it comes to adaptation to climate change in vulnerable areas. Africa has been projected to be affected the most by climate change due to limited institutional, financial and technological capacity, adaptation to climate change will be difficult and complex. It is expected that research and plant breeding will mitigate many of the detrimental effects but the negative effects of climate change are what is expected if farmers continued to plant the same varieties in the same way in the same areas. Some autonomous adaptations that will help offset some negative impacts of climate change include shifting of planting dates, modifying crop rotations or an uptake of pre-existing crop varieties.
To ensure food security for a growing population of Sub-Saharan Africa, it is very critical to adapt agricultural systems to climate change. Important steps towards designing and implementing measures that are appropriate are to identify hotspots of climate change and understand associated socioeconomic impacts at different spatial scales. Continued investment in maize productivity remains crucial to the growth of agriculture and food security even if there has been success in the past, which includes policies that favour maize production and productivity as well as development and adoption of new and improved maize seed and fertilizer.
For instance, the maize area covered by improved varieties in Ethiopia grew from 14% in 2004 to 40% in 2013. There is need to invest in research to produce a new generation of improved varieties that are tolerant to drought, resistant to pests, and nutrition-efficient. Therefore, if appropriate actions are not put in place to reduce the negative effects of climate change, the danger of food insecurity is expected to increase. To manage the current climate change and for future adaptation to these variations, there is need for maize varieties that are tolerant to drought, heat and water logging and are resistant to diseases and pests and insects, and to effectively contribute to mitigating climate change, practicing conservation agriculture and precision agriculture would be helpful.
Relative Importance of Temperature and Rainfall
Even if temperature is an important factor in the year-to-year production, it is not as important as rainfall in determining agricultural production. In Sub-Saharan Africa, there has been some countries which had too much rainfall which led to severe flooding and unfavourable livelihood consequences. These countries included Burkina Faso in 2007 and 2009, Mozambique in 2000 and 2001, Ethiopia in 2006 and Ghana in 2007 and 2010 and in the year 2017 Niger, Nigeria, Burkina Faso, Guinea, Mali, Sierra Leone, Ghana, and Central African Republic experienced floods that destroyed lives and the agricultural sector . These rainfall-related disasters are more common in some countries. For example, Malawi has had 40 weather related disasters between 1976 and 2009. Floods are very destructive and their impact, which includes deaths and injuries of people and exposing people to toxic substances, are instant. Flooding is world over but the difference is the degree of the impact which is dependent on the adaptive capacity of a country. Poor countries suffer more from the impacts of flooding as compared to developed countries which have high capacity to adapt. Increases in temperature and variation in rainfall therefore make it less conducive for maize production in almost three quarters of countries in the world and results in yields declining.
However, the extreme opposite of too little rainfall, drought, is also a reality. Due to increased frequency of droughts, yields of grains and other crops could decrease substantially across the continent. The drought conditions could lead to maize being no longer grown in some areas. In southern Africa, the 2002–2003 drought experience resulted in a food deficit with an estimation of 14 million people who were at a risk of starvation and in eastern Africa in 2005–2006 and 2009, maize fields were struck by severe droughts. In the coming decades, so much droughts will be experienced in most of Sub-Saharan Africa. More than 100 million people were affected by drought in Africa, for example over the period 1991–2008, Kenya was affected by drought about seven times which affected about 35 million people and Ethiopia was affected by drought about six times in 25 years (1983–2008).
Climatic change impact on crop productivity greatly varies from region to region and climate change will also affect crops differently, that is, crops like maize, rice, wheat, beans and potatoes will be highly affected and crops like millet may be less affected since they are able to resist high temperatures and low water levels. However, smallholder farmers in developing countries are the most vulnerable and disadvantaged people as they entirely depend on rain-fed agriculture. In Sub-Saharan Africa and Latin America, a greater proportion of the variation in maize yields are associated with climate change. Hence, change in climate has the potential to hinder sustainable development of nations by reducing production in yield which consequently leads to food insecurity. However, Sub-Saharan Africa has a huge potential for expanding maize production. About 88 million hectares (88 M ha), excluding protected and forested areas, which has not yet been planted, is suited to maize production. For as long as farmers replace seed every season, advantages in yield can be significant. The adoption of improved open-pollinated varieties and hybrids was at 44% of maize area in Eastern and Southern Africa in 2006–2007 minus South Africa, and it was at 60% in West and Central Africa. This statistic was a suggestion of a significant increase in adopting improved varieties more so in West and Central Africa.
Climate change potentially threatens productivity and production of maize, a field crop that depends on water availability. Climate change effects on maize production and productivity are serious and if proper adaptation strategies to negative effects of climate change are not followed, these impacts would deepen in the near future. Governments and international agencies need to boost efforts to minimize effects of droughts, floods or in fact ensure that climate change effects are minimized. While we believe these efforts are in place, taking a longer step at improving adaption may mitigate these negative effects. For example, more competent irrigation technologies, increased research and development of drought-tolerant maize varieties, increased adoption of climate-smart adaption strategies, and call for world leaders to reconsider the negative effects of human activities on the ecosystems are highly encouraged.