**Author details**

throughout this chapter. First, the global warming is quantified with time to determine the moment when a prescribed UN climate target will be hit (in case of no climate mitigation), which is then used to explicitly determine the remaining CO2 budget; crucial parameter in emissions modelling. Naturally, an exponential pattern is proposed at first for its rapid decline and long-term stabilization slightly above zero. Then, by means of quadratic interpolations, a parametrized collection of flexible pathways *E<sup>γ</sup>* ð Þ 0<*γ* <1 is derived to ensure more feasibility by including a smooth transition to the exponential trend, which will help compensate a certain lack of nocarbon energy. It turns out that the no-transition (exponential) and no-mitigation (linear) models correspond to the limit values of the involved parameter *γ* introduced as an arbitrary fraction of the remaining CO2 budget expected to be used during the

exponential phase, which also gives an indication for the transition length.

ways by involving further greenhouse gases.

*Global Warming and Climate Change*

emissions by 2050 and 2040 respectively.

favourite colleagues, who helped resolve graphical issues.

The author declares no conflict of interest.

CDIAC carbon dioxide information analysis center

**Acknowledgements**

**Conflict of interest**

CO2 carbon dioxide

**Abbreviation**

**74**

Graphically, the *E<sup>γ</sup>* s are comparable to the corresponding IPCC pathways; similar to the RCP4.5, for targets between 1.5 and 2°C, and to the RCP2.6 and no- and low-overshoot, for the 1.5°C target. However, they have the advantage of predicting the nearly-zero emission (<0.01 GtCO2), e.g., by 2090 for *γ* <0*:*22*,* or even as early as 2050 for *γ* <0*:*03*,* with no need for CO2 removal. Such similarities could be improved by using the IPCC estimation for the remaining CO2 budget (though determined with high uncertainties), which may lead to more representative path-

Another virtue of the designed *E<sup>γ</sup>* s is their flexibility with regards to the constraints that would come with the climate target, which would provide climate policy makers with an uncountable set of ideal smooth pathways enlarging with decreasing target. For instance, whereas *E<sup>γ</sup>* s with 0*:*24<*γ* < 0*:*27 are recommended for the 1.5°C target, based on specific criteria including the peaking threshold, those with 0*:*01<*γ* <0*:*51 are recommended for a more binding target; the 1.4°C one. When it comes to the projection of the earliest feasible 'zero' emission, are recommended the *E<sup>γ</sup>* s with 0*:*017 <*γ* < 0*:*033 and 0 <*γ* <0*:*038*,* for the respective climate targets 1.5, and 1.4°C, which would result in the near extinction of CO2

I am grateful to my son Seyfen for his support and growing interest in my research on global warming and its mitigation. His relevant thoughts and questions on the environment and society have been a great source of motivation to conduct this work and further projects. I especially thank him for teaching me "*Nihongo*". Thanks also go to Yemad Mabrouk, an outstanding Math lecturer and one of my

I am also grateful to Rebekah Pribetic for her great availability as an Author Service Manager and to the whole team at IntechOpen for improving the English and editing.

Nizar Jaoua Department of Mathematics, College of Sciences and Human Studies, Prince Mohammad Bin Fahd University, Al Khobar, KSA

\*Address all correspondence to: nizar.jaoua@gmail.com

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
