Incoming radiative energy from the Sun is intercepted by the Earth’s surface. Part of this incoming radiation is reflected back to space. Absorbed solar energy is redistributed by atmospheric circulation and ocean currents. The energy absorbed warms up the Earth’s surface which in turns emits thermal radiation. Naturally occurring ‘greenhouse gases’ in the Earth’s atmosphere—water vapor (H2O), carbon dioxide (CO2), ozone (O3), methane (CH4) and nitrous oxide (N2O)—absorb some of this outgoing thermal radiation. This phenomenon known as the ‘greenhouse effect’ is a natural phenomenon that maintains a habitable climate on Earth. But it is increased today because of human activities changing the atmospheric composition.
CO2 concentration has increased by over 35% since the pre-industrial period. The primary human-related causes of CO2 release are fossil fuel combustion (mainly oil, coal and gas) and deforestation. Atmospheric methane concentration has also increased since the mid-1700s, largely due to livestock production, the decomposition of refuse in landfills, and fossil fuel production and use. Nitrous oxide concentration has increased by 16% since the mid-1700s with the major human-related sources including nitrogen fertilizer use, industrial activities, and livestock production.
For humanity, possible consequences are: modification of water resources, people displaced to avoid flooding of their cities or villages, loss of land and natural resources on coastline, impact on agriculture and fisheries (food security), impact on human health (expansion of diseases), damage or destruction of infrastructures built on the coastline (cities, industries, port installation, tourist accommodations…), increased pollution consequently to flooding and destruction of infrastructures. The social, economical and environmental consequences will be incalculable.
Management and Solutions
Meeting the challenge of global warming will require sustained effort over decades – on the part of governments, who must establish the rules and modify them as we learn more of the science, and as technological solutions begin to manifest themselves; on the part of industry, who must innovate, manufacture, and operate under a new paradigm where climate change will drive many decisions; and on the part of the public, who must also switch to a more climate-friendly path in their purchases and lifestyles, particularly as regards energy consumption. Research shows that mitigating climate change will require:
- a fundamental shift from an economy based on traditional burning of fossil fuels to one based on more efficient energy production, generation, and use
- an increased use of low-carbon energy
- capture and storage of carbon from fossil fuels
- as well as adaptation to the changes that are already taking place.