**2. Climate change, a global challenge**

Climate Change is now considered the greatest threat to global health and security. Greenhouse effect, which propels global warming, has been identified as the main driver of Climate Change. The rising of global temperature is intricately linked with many other environmental concerns such as fragile ecosystem, melting glaciers, increasing sea level, acidification of sea water and increased flooding and droughts [1]. This climate challenge is also affecting the social community which can lead to immigration and conflicts over borders and natural resources such as water. More importantly, it could severely threaten food security that may affect about 3 billion of poor people in terms of access to food supply. These series of concerns are recognized as climate change and it is well accepted that to prevent its occurrence, greenhouse gas emission has to be reduced significantly over the twenty-first century [2]. The gases which are mainly responsible for the greenhouse effect include methane, carbon dioxide (CO2), nitrous oxide, water vapor, and fluorinated gases.

CO2 generated mainly from anthropogenic activities is the largest contributor to global warming. By 2020, the concentration of CO2 in the atmosphere had risen to 48% above its pre-industrial level [3, 4]. An increase of 2°C above pre-industrial average temperature could induce serious negative impacts on the natural environment and human health. The Paris Agreement, which is the biggest international treaty on Climate Change is determined to limit global warming to about 1.5°C, compared to pre-industrial levels, with an ambitious goal to reach NetZero CO2 emission by 2050 [5–7].

#### *CO2 Injectivity in Deep Saline Formations: The Impact of Salt Precipitation… DOI: http://dx.doi.org/10.5772/intechopen.104854*

The anthropogenic activities with highest carbon footprint include the burning of fossil fuel for power generation and the production of materials. Power generation from fossil fuels is responsible for over 70% of the global CO2 emissions [1]. Cumulatively, fossil fuel contributed about 84% of the World's primary energy consumption by 2019 and the world is expected to rely heavily on fossil fuels for its energy needs, at least within the short to medium term. Another major source of CO2 emission is the production of materials with high carbon and energy footprint. The notable of such materials is Portland cement which is the main building material used in most countries in the world. Portland cement production is responsible for about 5% of global CO2 emission [8]. About 2% of the total global energy consumption is used to produce Portland cement. Widespread use of energy efficient power generators, investing in renewable energy, Carbon Capture, Utilization and Storage (CCUS) remains the best options for reducing CO2 emission from burning of fossil fuels and achieving a faster transition to green energy.
