# Carbon Dioxide Uptake by Cement-Based Materials: A Spanish Case Study
## 2 Effect of Emissions on Atmospheric CO2 and Global Temperature  
Figure 3 shows the trends in the world average temperatures on the surface, land, and oceans combined between 1850 and 2012 [1]. It is evident that from 1950 up to now, there is an increase in the world average temperatures on the surface, land, and oceans.  
Figure 3: Irregularity observed in the world average temperatures on the surface, land and oceans combined between 1850 and 2012 (Reproduced with permission from The Intergovernmental Panel on Climate Change, _IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change_; Figure SPM.1 (a) Observed global mean combined land and ocean surface temperature anomalies, from 1850 to 2012 from three data sets. annual mean values. published by Cambridge University Press [1]).  
The sea surface temperature is a climate change indicator that increased during the 20 th century and continues to rise. From 1901 through 2015, the temperature rose at an average rate of 0.07 \({}^{\circ}\)C per decade. Sea surface temperature has been particularly higher during the last 30 years than at any other period since 1880. Apparently, sea surface temperature appears to have cooled between 1880 and 1910. Nevertheless, it increased particularly between 1910 and 1940 and from 1970 to the present. Finally, it should be considered that changes in sea surface temperature vary regionally. Given that, some few areas have experienced cooling, whereas most of the world's oceans have reported temperature rise.  
In addition, global land temperature is considered as a climate change indicator. In this respect, 2015 was the warmest year, and 2006-2015 the warmest decade reported worldwide since 1880 (Figure 3). In addition, the global average surface temperature has risen at an average rate of 0.08 \({}^{\circ}\)C per decade since 1901.  
Carbon dioxide, CO\({}_{2}\), is a gas that exists in the air in a proportion of 0.03-0.04% in volume. Figure 4 shows the way that this gas has evolved historically in the atmosphere ranging from 280 ppm in the preindustrial era to 400 ppm at the present time. Therefore, the rate at which this gas increases in the atmosphere is around 1-2 ppm/year. The data to obtain such conclusions come from ice core studies and recent air monitoring measurements. In addition, global atmospheric concentrations of methane, nitrous oxide, and other manufactured greenhouse gases have risen over the last years. Obviously, the current global atmospheric concentrations of carbon dioxide are soared to unprecedented levels compared with the last years.  
It is well known that the carbon dioxide concentrations have increased significantly since the beginning of the industrial era. Carbon dioxide concentrations have risen from 280 ppm in the late 1700s to 401 ppm in 2015, as reported recently in some places. This huge increase (43%) is attributed mainly to human activities.  
The most abundant greenhouse gas (GHG) in the atmosphere is the water vapor. However, the human activities have a small direct influence on the water vapor atmospheric concentrations. On the contrary, the human activities have a clear indirect influence through irrigation and deforestation.