Impact on Climate Change
Within the next 50 years, the world population will have completed its demographic transition, moving from 2.5 billion people (in 1950) to more than 9 billion in 2050. Then, it will reach a plateau, after which it will slightly decrease. Meanwhile, globalization will have spread its benefits across new economies. New economies will have emerged and will have caught up with mature economies. A massive middle class will emerge, with needs and wishes that correspond to those of their counterpart in OECD countries. Consequently, the industry sector will adjust to provide for these needs, causing the associated energy consumption to rise by around 45 %, mostly in Asia. The living standards of the middle class will see much improvement, leading to a surge in energy consumption in buildings. If nothing is done, the increase of energy consumption in buildings in new economies should be three times faster than in mature economies, and increase overall by around 30 %. Finally, globalization will connect billions of people and give them the ability to integrate into the global economy. Consequently, the mobility of this emerging middle class will increase considerably. The total mobility in the world shall more than double in the next four decades. As a consequence the energy consumption associated with mobility is expected to grow by 40 %. In the end, if nothing is done, the world will consume 35 % more primary energy in 2035 than today, and up to 50 % more by 2050.
Scientists from the Intergovernmental Panel for Climate Change (IPCC) (2007) have measured the increase of temperature on Earth. They demonstrated that the temperature rose by 0.74 degrees on average between 1906 and 2005; the rise was only 0.6 degrees between 1901 and 2000. As well, sea levels have risen on average by 1.8 mm per year since 1960, and 3.1 mm per year since 1993. Their report confirms both the increase and the acceleration.
Many different factors can influence the increase of the temperature at the surface of the planet. First, astronomic evolutions have an important impact on the climate on Earth as they lead to evolutions in radiative emissions from the sun.
The Serbian climatologist Milutin Milankovitch (1920) identified three main astronomic origins of Earth’s climate evolution: orbit eccentricity, the regular evolution of the elliptic shape of Earth’s orbit around the sun; obliquity, the variation of the angle between the rotation axis of the planet and an axis perpendicular to its orbit; and precession, the evolution of the planet’s rotation itself. These astronomic variations are mainly linked to gravitational attraction evolutions between Earth and other planets. Beyond these evolutions, changes in solar activity and sun spots also have an important impact. On the planet, the movements of tectonic plates our continents sit on also contribute to climate change as they modify ocean currents. Volcanic activity also has a non-negligible impact.
Another factor in climate change is human activity and its impact on greenhouse gas emissions, also called “anthropogenic forcing”. Earth receives every second around 340 W/m2 of radiation from the sun. A part of this radiation remains trapped inside the atmosphere (around 100 W/m2). A higher greenhouse gas concentration in the atmosphere makes it more difficult for this trapped radiation to leave the atmosphere. A larger share remains trapped and contributes to an increase in Earth’s surface temperature. “Anthropogenic forcing” today stands at 2 W/m2, which corresponds to around 400 ppm of CO2 concentration (largest contributor before methane, around 75 % of total emissions), a level which never exceeded 280 ppm in the last 650,000 years (Durand 2007).
All these factors need to be taken into account when building a climate model. The vast majority of scientists today recognize that the recent acceleration of climate warming can only be explained by “anthropogenic forcing”. Many national science academies across the world have publicly acknowledged this (National Academies 2009). Now, a small group of experts continue to question this as they challenge the accuracy of current climate models. They however recognize unanimously that the increase of greenhouse gas concentration in the atmosphere will lead eventually to climate evolutions.
Greenhouse gases have different atmospheric lifetimes. Methane stays on average 10 years in the atmosphere; it takes 50-200 years for CO2 to disappear. Daily emissions of methane and CO2 thus accumulate in the atmosphere, accelerating the phenomenon. Greenhouse gas concentration has increased by more than 40 % in a century (OMM 2014) and the daily emissions have increased by more than 70 % between 1970 and 2004 (GIEC/IPCC 2007). The concentration phenomenon thus accelerates; it is a historical determinism.
If we focus on CO2 emissions, six regions represent more than 68 % of the world emissions, and three of them (North America, Europe and China) represent half of the total. The United States represents 25 % of the world’s CO2 emissions with only 4 % of the world population. Europe represents 14 % of total emissions (© OECD/ IEA CO2 2013). China and India still have lower emissions, but they are far from having realized their economic transition, and the volume of their emissions grows quickly. Their share shall increase significantly in the coming decades (Fig. 2.29).
A full 40 % of CO2 emissions come from the production of electricity, and a bit less than a quarter from transportation. Any ambition to stabilize the volume of emissions will then be related to efforts in those two domains (Fig. 2.30).
Fig. 2.29 CO2 emissions per region (GIEC/IPCC 2007; © OECD/IEA, CO2 2013)
Fig. 2.30 CO2 emissions by origin (GIEC/IPCC 2007; © OECD/IEA, CO2 2013)
The IPCC has come up with a number of scenarios to predict the evolution of greenhouse gas concentration and its impact on the planet’s climate. They do not measure any probability of occurrence but consolidate a vast array of indicators, such as world population growth, economic growth, evolution of multilateral government relationships, political stability, and possible energy supply choices. These different scenarios foresee an increase in Earth’s temperature of between two and four degrees by the end of the century. Even if greenhouse gas emissions were limited to their pre-industrial level (obviously impossible), the current concentration would lead to a temperature increase of at least 0.6 degrees by the end of the century.
A number of consequences are thus expected. The IPCC (2007) ranks them between “probable” and “highly probable”. The modifications of the structure of snowpack, the increase of the size of mountain lakes, and the intensification of runoffs would be among the primary observable consequences of temperature increase. Cyclonic activity, particularly in the Atlantic Ocean, should increase as well. Sea levels would rise and the oceans would become more acidic, modifying the cycles of rain. Wind and marine streams, linked to temperature gradients across regions, would also be modified. This would have an impact on the world’s climate as we know it. Rainfall should be more frequent at higher latitudes and rarer at lower latitudes. This would in turn bring about consequences on ecological balance in those regions as well as on the way people live. Seasons should be modified, as well as yearly migrations of a number of animal species.
Fragile ecological systems would first be threatened. The acceleration of climate evolution is indeed the major threat to these ecosystems because of the lack of time to adapt to these changes. Mountains, Mediterranean regions, tropical forests and marine systems such as coral reefs would be among the most impacted. Poor populations would also be impacted first, notably in central Africa, with the rise of water stress and the transformation of forests into savanna, or with the rise of sea level in some parts of Asia.
Finally, consequences could be more serious. Beyond a temperature rise of two degrees, 30 % of the living animal species could disappear, considerably modifying the food chain on Earth. Beyond four degrees, these extinctions could be massive. With a three-degree rise, 30 % of coastal areas could be submerged by oceans, and a number of pathogens could migrate from their original region to others.
The world seems to have acknowledged for a few years the terrible consequences on the climate of our way of living. This is partly thanks to the work and efforts of the IPCC. Still, despite numerous international climate summits, a global response has yet to be defined. The Kyoto protocol (not ratified by the United States) led to a number of improvements as many countries adopted specific policies and targets on their emissions, but the execution of those plans proved to be complex as it can impact the competitiveness of nations. More recently, the COP21 conference on climate change (December 2015), held in Paris, was an important step forward in the right direction, although the agreement remains to be ratified by all countries. As the world moves on, the historical catchup of new economies remains anyhow the primary objective, and international competitiveness continues to be the primary indicator. While this happens, energy consumption continues to rise and greenhouse gas emissions accumulate in the atmosphere. The impact of human activities thus continues to worsen.