Introductory Chapter: Climate Change

1. Introduction

Global evidence of climate change is unequivocal. This conclusion is based on recurrent observations of variations in numerous climatic variables. This phenomenon is further characterised by a paradox as both the direction of the changes in climate variables and effects often move towards opposite directions [1, 2, 3]. This is seen as while precipitation is increasing in some parts of the world, climate change is at the same time driving declining precipitation in other parts of the world. Across Africa, for example, the recent Intergovernmental Panel on Climate Change (IPCC) AR6 argues that for various global warming scenarios (1.5° C, 2° C and 4° C), northern and southern Africa will continue to witness declining precipitation and increasing temperature while west, middle and east Africa will witness increasing temperatures and increasing, sporadic but unreliable precipitation [4].

As can be seen in the scenarios above, various global warming scenarios are driving climate change. Even though the evidence of climate change is unequivocal, the scientific literature has been somehow divided on the causes of climate change [5]. In this case, three major schools of thought emerged. The first school of thought argues that global warming, for example, is driven by mainly climatic or biophysical drivers and while the second posits that non-climatic drivers are mainly responsible for global warming [6]. The third school of thought argues that both climatic and non-climatic drivers have a role to play in the occurrence of global warming and, consequently, climate change. Whichever direction the debate is going, both climatic and non-climatic forcing have a critical role to play, as discussed by [6, 7]. If the global rise in temperature is at the centre of global warming, which in turn is driving climate change, then it is obvious that human or anthropogenic drivers (energy, agriculture, industrial processes, and land-use change/forestry) that are spewing up greenhouse gases are at the centre of the loop [5] while non-anthropogenic drivers are reinforcing the feedback loop [8].

Globally, the need for climate change mitigation strategies, actions, technologies and innovations has never been so urgent than during the current decade. The IPCC AR6 report argues that for most parts of the world and for various representative concentration pathways (RCP 4.5. 8.8), temperatures will continue to rise while precipitation will decline [4], creating important water deficits in many countries. Also, various economic sectors continue to spew out huge amounts of greenhouse gases (GHG). For example, the US Environmental Protection Agency (EPA) [9] presents the following global GHG emission levels for various economic sectors; electricity (25%), agriculture and forestry (24%), transportation (14%), other energy (10%) and building (6%). From these statistics, at the global scale, agriculture is the second major contributor to the global GHG budget. However, over the last three decades, worldwide GHG emissions from the energy sector has increased four times than agriculture. In fact, though the contribution of various sectors may vary, the role of global greenhouse gas emissions in driving global warming and climate change has been established [8].

It has been agreed that global temperature rise caused by increased greenhouse gases is driving global warming and, consequently, climate change. These changes are impacting agriculture, forests, and water levels at groundwater and river levels, while in other regions, they are shifting the frontiers of established climate zones. In many parts of the world, droughts, floods, and sandstorms are frequent, and livelihoods are negatively impacted [9]. It can be said that while rising temperatures are causing droughts in Africa, they are melting Arctic ice in Canada, and this is negatively impacting other livelihoods that are Arctic ice dependent but also creating more favourable conditions for greenhouse crop production in the Arctic [10], and field crops production in countries. In other parts of the world, climate change has been of immense benefit to agriculture as the growing season of some crops has increased while that of others has been shortened due to prolonged droughts [11]. Increased carbon dioxide concentration, for example, has been argued to increase photosynthesis and therefore yield, particularly C4 plant species. Several studies across the Sahel, for example, have shown that the latter region is getting greener and wetter due to NDVI-based evidence; a change that is partly attributed to increased carbon dioxide emissions and increased photosynthesis [10, 11, 12]. Notwithstanding these recent observations, the question that comes to mind is, why is the region still facing acute food security challenges despite these gains in greening and rainfall? This invariably shows that, besides climate change, systems of land use are evidently playing an important role in the Sahel, for example, because, on the one hand, the current recovery in terms of rainfall is not readily available for agriculture due to duration and timing while on the other hand, the rainfall gains are weathered by poorly managed land use systems.

Evidently, most of the reports on the effects of climate change on livelihoods are often from the global south, with Africa being the least responsible for emitting greenhouse gases yet the most vulnerable. This is explained by high levels of vulnerability, which are often anchored on the low adaptive capacity of the people [13, 14]. The adaptive capacity will therefore continue to play an important role in determining how societies will build resilience to climate change. This is seen as the issue at stake now, and in the years to come will no longer be the magnanimity of the climate forcing but, most importantly on, key proxies of adaptive capacity such as poverty and literacy rates, which will evidently determine the ability of a society to access the resources needed to build resilience against such climate shocks [1, 2, 3, 15, 16]. Even in the developed north, communities with lower adaptive capacities have been found to be more vulnerable to the effects of climate change due mainly to limited access to resilience-building schemes which are mainly determined by adaptive capacity. The Arctic of Canada, for example, is disproportionately impacted by the effects of climate change mainly due to the extremely low levels of adaptive capacity recorded in such regions when compared to the southern communities in Canada [17].

Therefore, apart from the need to enhance adaptive capacities across most of the south and in the more remote and less developed parts of the world in general that are more vulnerable to climate change, there is equally a strong need for research in these regions or communities. The research will help enhance our understanding of climate change in these regions and therefore help frame how adaptations can be structured. A major bulwark that is often associated with the south, especially in the context of climate change, is the availability of climate data which is often relevant to better understanding climate change to elaborate robust adaptations. Across Africa, for example, there are inadequate observed weather stations to monitor various climatic variables such as precipitation and temperature. Additionally, in the face of food security, it is not clear how crop yields have evolved over time. This hampers effort at understanding the effects of climate on crop yields and water resources. This phenomenon is more acute in Africa due to inadequate funding to increase the number of weather stations and comprehensive yield accounting.

2. Conclusion

To grapple with these research challenges, scientists can now compare satellite-based precipitation, temperature and crop yield data with existing observed precipitation, temperature and yield data. This process will establish a relationship between satellite-based precipitation, temperature and crop yield with the limited observed data. It becomes feasible to determine which satellite products simulate the limited observed data best. This will yield new knowledge on which satellite product(s) are closest to or best simulate the existing observed data. Such products can now be used as a proxy for precipitation, temperature or yield at any given scale. In the Tensift basin of Morocco for example, among several satellite precipitation products (PERSIANN, PERSIANN CDR, TRMM3B42, ARC2, RFE2, CHIRPS and ERA5), the PERSIANN CDR product is the most representative product as it simulates observed precipitation better than the other products [18]. In agriculture, observed time series yield data from FAOSTAT, and Global Yield Gap Atlas can be compared with crop yield satellite products such as MODIS, Copernicus Sentinel 1 and 2 to determine a proxy for yield. This approach is highly recommended to bridge the wide gap between inadequate observed data and satellite-based data for elements of climate such as precipitation.

Therefore, there is no doubt therefore why, in this book, ‘Climate change: Recent Observations,’ the range of chapters varies as does the scope of the book itself, creating room and inclusivity for topics that reflect the great diversity of climate change and its challenges. With a wide range of topics covered, this work will become a key compendium for most enthusiasts of climate change. The major advantage being it covers observations of climate change across the world.