Increasing in population size, age and distribution is affecting climate by producing more green house gases, either in the form of automobile or in the form of thermal energy to meet increasing electricity demand. A larger global population means a larger demand for everything--most urgently, energy. The world population is growing by 75 million people each year. That’s almost the size of Germany. Today we are nearly 7 billion people. At this rate we will reach 9 billion people by 2040. According to other report, if current fertility rates continued, in 2050 the total world population would be 11 billion, with 169 million people added each year. Almost all growth will take place in the less developed regions, where today’s 5.3 billion population of underdeveloped countries is expected to increase to 7.8 billion in 2050.
More people means more food, and more methods of transportation. That means more carbon and methane because there will be more burning of fossil fuels. If we take the case of Jharkhand state of India, to meet the demand of electricity more and more coal mines are being opened which has thrust more carbon dioxide and methane to the atmosphere.
Life on Earth is dependent on carbon dioxide (CO2) to regulate the temperature of our planet, but too much can create a heat-trapping blanket over our atmosphere. In the last century, unsustainable population growth and excessive consumption have raised levels of CO2 so dramatically that the earth's climate has been altered in ways never experienced before. Agricultural expansion and forest depletion have multiplied emissions of greenhouse gases like CO2, but it is our dependence on fossil fuels that propels monumental atmospheric change. When we burn fossil fuels such as coal, oil, and gas, we release unsustainable levels of CO2—the primary global warming culprit. Those of us living in the developed world bear a majority of the responsibility for reversing this disturbing trend.
The relationships among humans, their activities and global temperature can be assessed by making the appropriate measurements and analyzing the data in a way that shows the connections and their magnitudes. Human population can be closely estimated and the consequences of their activities can be measured. For example, the volume of carbon dioxide, methane and nitrous oxide emissions is an indicator of human's energy and resource consumption.
Population does appear to be a vital factor in the increase in carbon dioxide emissions. According to an estimate, over a third of the doubling of fossil fuel emissions in developed countries between 1960 and 1988 was due to increased population. The significance of this change is its potential for raising the temperature of the earth through the process known as the Greenhouse Effect. Carbon dioxide in the atmosphere prevents the escape of outgoing long wave radiation from the earth to outer space. As more heat is produced and less escapes, the temperature of the earth increases.
The threat of climate change and global warming has therefore, been heavily influenced by population growth. As developing countries, with rapidly increasing populations follow the Western path of development, it is likely to add greatly to the problem. A country like China, for example, which has rapid industrialization and has the largest population in the world is projected to increase its population further, and is expected to become the leading source of global- warming gas emission by 2050.
Increasing population is decreasing forest cover, which happens to be major absorbent of carbon dioxide. Experts agree that population pressure contributes directly to the continuing loss of forest cover. Based on UN Food and Agriculture Organization (FAO) land use estimates, it would appear that in the past three decades or so 59% of the forests cleared in developing countries were for human settlements, roads and other non-agricultural developments- almost entirely related to population growth.
The act of cutting trees to generate farmland, has a great impact on global warming. The cutting of trees is mainly done for paper production, livestock farming etc. Deforestation is responsible for about 20% emission of global warming. Experts opine that deforestation has greater impact on global warming than emissions from factories and automobiles.
Each day the average person breathes in about 15,000 liters, or approximately 35 pounds, of air. (http://www2.envmed.rochester.edu/envmed/TOX/faculty/frampton.html) Since air is 21% oxygen (molecular weight 16) and 78% nitrogen (molecular weight 14) by volume, oxygen is 23.5% by weight and nitrogen is 76.5% by weight in air. So the amount of oxygen breathed in per day by the average person is about 35*0.235 = 8.2 lbs.
Humans breath out about 16% oxygen by volume, so about 5% of the air by volume is converted to CO2, which is about (5/21)x8.2 = about 2 lbs of CO2 every day.
The molecular weight of O2 is 32 and the molecular weight of CO2 is 12+32=44. Therefore, humans emit 44x2x/32 lbs = about 2.8 lbs of CO2 breathed out every day or about 1005 lbs = about 0.5 tons per person per year.
In 2005 the Earth population was about 6.66x109. So the emitted CO2 per year by their breathing was about 3.3x109 tons.
In 2002 CO2 emissions due to human activities were about 25x109 tonnes = 27.6x109 tons (http://www.unep.org/geo/yearbook/yb2006/077.asp). Breathing comprises about 3.3x109 tons of that amount, or about 12% of it.
Globally, annual average emissions of carbon dioxide per capita due to human activities (other than breathing) have been fairly stable since 1990. For 2002, this figure was up to 3.93 tonnes from 3.85 tonnes in 2001 (http://www.unep.org/geo/yearbook/yb2006/077.asp).
Scientists have predicted that the day is not far when nations would fight for drinking water and people would perish due to floods and climate changes. Population explosion, though undeniably the root cause of global warming, has so far been largely overlooked.
UN estimates forecast around 8 to 10 billion population on the planet by 2050 — a galloping 50 per cent increase from the present world population, which is estimated to be 6.5 billion. Scientists have proved that human activities do influence climatic conditions. Therefore, any long-term planning to combat the threat of climate change would not succeed without first finding solutions to rectify the demographic trends.
While industrial nations have been primarily responsible for high emissions levels in the recent past, the rapidly growing population of the developing world will be a major factor in future emissions levels. As we look to the developed world to curb and reduce emissions, many in developing countries need to increase their energy use to meet basic needs and improve their quality of life. Countries such as India and Brazil are looking for solutions to balance the needs of people and the planet. Therefore, all national policies and international agreements on global warming must take population growth into account.