Global warming is the excess greenhouse effect caused by various factors that rise earth’s temperature beyond an optimum level, causing adverse impacts to the biosphere. Earth’s temperature is determined by the amount of solar radiation received from sun, radiation reflected or absorbed by various gases in the atmosphere as well as various surface features such as snow, water bodies, built environment etc. (US Environmental Protection Agency, 2016). Natural as well as anthropogenic factors contribute to global warming and associated climate change.
Natural Vs. Anthropogenic Causes of Climate Change
Global surface temperature increases occur due to natural causes such as sunspots and Milankovitch cycles. Milankovitch cycles include the earth’s orbit around the sun, tilt in earth’s rotational axis, as well as rotation of earth’s spinning axis (perpendicular to the orbit) known as precession. Earth’s orbit around the sun is elliptical, and there are times when earth is very close to sun, and the temperature is very high. Due to the tilt on earth’s axis of rotation that keeps changing there are extremes in winter and summer, when the tilt is maximum. Finally, due the precession Milankovitch cycle, the northern hemisphere becomes warmer than the southern hemisphere, especially when earth is closer to the sun in its orbit. The three Milankovitch cycles are the reason for glacial-interglacial periods spanning a time period of 100,000 years (Hilderman, 2011). Sunspots and solar flares lead to sudden increases in radiation output from sun, and they occur rarely in millions of years (Conserve Energy Future, 2013). However, in the last 4 decades of 20th and 21st century there were very less sunspots. Thus, if global warming is attributed to sunspots or solar radiation output alone, the earth must be cooling since 2004 (Hilderman, 2011). Thus anthropogenic factors are the major causes for climate change.
Deforestation and Burning of fossil fuels are two major reasons for climate change. Greenhouse gases (GHGs) such as carbon dioxide, methane, water vapor, nitrogen oxides, etc. absorb incoming solar shortwave infrared (IR) radiation, and reflect long wave IR emitted by earth back to its surface. Thus the GHGs entrap heat radiation and increase earth’s temperature. Trees are natural sinks for carbon dioxide (CO2), and they help in reducing its concentration in the atmosphere for several years during the entire lifetime of the plant. Thus deforestation to create more space for supporting a growing population is a major cause for global warming (Conserve Energy Future, 2013). Also, fossil fuels such as coal and petroleum release high concentration of GHGs (Conserve Energy Future, 2013). Fossil fuels are used excessively for power generation and transportation. Anthropogenic GHG emissions will only increase with growing population and development.
It is established beyond doubt that global warming is happening by the increase in surface temperature of earth in spite of reduction in solar output, especially with the fact that earth’s warmest 10 years occurred within the past 12 years (NASA, 2016). Shrinking icecaps, rising sea level (there has been 17cm rise in the last century), decreased snow cover, retreating glaciers, extreme weathers and ocean acidification, all prove that global warming is happening, and the rate has increased only after industrialization (NASA, 2016). Further, atmospheric CO2 concentration trend is itself proves that anthropological GHG emission is the main reason for global warming. CO2 concentration has increased from 300ppm in 1950 to a current level of 400ppm, which is the highest recorded level since earth formed 400,000 years ago (NASA, 2016). Increase in concentration of GHG implies global warming, because the gases would surely absorb more solar heat.
Mitigation Strategies
Two current mitigation strategies for controlling global warming are increasing carbon sinks, i.e. improving land area under forest cover, and switching to cleaner energy resources such as solar, wind or hydropower. Forest degradation is occurring at a rate of 30 million hectares a year, and more than one billion people (belonging to developing or underdeveloped nations) in earth depend only on forests for their livelihood (United Nations Environment Programme [UNEP], 2016). About 40 billion USD investment a year towards reforestation, conservation, and payment to landowners from year 2010 to 2050 can increase carbon storage capacity of the natural sinks by 28% (UNEP, 2016). The funds are also used to derive sustainable income forest products and increase their value. However, attracting a stable funding form governments or corporates for this type of mitigation is a challenge (UNEP, 2016). Switching to renewable energy sources can reduce GHG emissions from fossil fuels, but there is reluctance in adopting new technology and challenges such as need for ample sunlight, wind or water resource, backup facility, training in use of new technology, etc. For instance even in regions with ample sunlight 300 days a year, land availability could be a constraint for a solar power project. However, clean technologies are being implemented at a faster rate even in developing economies, and about 211 billion USD investment has already been made in this sector (UNEP, 2016).
Policy Change Suggestions
Though there are several mitigation options, implementing them is proving difficult. Often climate change policies are proposed at a global scale. For example, emission limits for different countries are agreed in an International panel according to some accord such as the Kyoto protocol. But, the actual reduction in GHG can occur only if individual industries or corporates accept, and implement emission reduction strategies. A strong commitment at a local level is thus essential, in all countries across the globe. Climate change policies should clearly identify and designate local leadership agencies, strengthen and support them through financial as well as knowledge resources. Developed countries funding renewable projects in developing ones, and externally offsetting their GHG emissions will not suffice. Policies should become practical and stringent, i.e. big emitters must be brought under law, and provisions to prohibit business activities of emitters who do not show any reduction within a defined period of time must be included. Highly polluting process industries such as mining, fertilizers, petroleum refining, etc., must be monitored, and the climate change policy must set clear standards for emissions, and mandatory emission control methods for these sectors. On the whole, the climate change policy should go beyond setting just time frames for emission reduction, and provide industry specific targets that must be achieved.
Conclusion
Thus global warming is happening for sure, and there is enormous evidence to support that anthropological activities post industrialization are the main cause for climate change. Mitigation measures being adopted by governments are not sufficient and there is a need for more localization of emission reduction goals. With greater community participation climate impacts can be managed efficiently.
References
Conserve Energy Future. (2013). Natural and Man-Made Causes of Global Warming –
Conserve Energy Future. Retrieved June 18, 2016, from http://www.conserve-energy-future.com/GlobalWarmingCauses.php
Hilderman, R. (2011, January 17). Role of Milankovitch Cycles and Sunspots in Climate
Change. Retrieved June 18, 2016, from http://www.motherearthnews.com/nature-and-environment/role-of-milankovitch-cycles-and-sunspots-in-climate-change.aspx
NASA. (2016, June 17). Climate change evidence: How do we know? Retrieved June 18,
2016, from http://climate.nasa.gov/evidence/
US Environmental Protection Agency. (2016, February 23). Causes of Climate Change.
Retrieved June 18, 2016, from https://www3.epa.gov/climatechange/science/
causes.html
United Nations Environment Programme. (2016). Retrieved June 18, 2016, from
http://www.unep.org/climatechange/mitigation/Forests/tabid/104338/Default.aspx
