Some people continue to dismiss this notion and arguing that there is no real scientific evidence that the planet is heating up or that humans are causing it. The heating of the planet underway now cannot be reversed. Scientists expect the worldwide heating-up to continue for decades or centuries after the point that heat-trapping pollutants level off.
The planet had experienced the hottest wave of extreme weather. Enormous drought-driven forest fires, raging storms, torrential downpours and massive floods. The last two decades was considered the hottest decades of the history, in the first 11 months of 1998, the world saw almost $90 billion in weather-related damage, half-again more than the previous record set just two years before and more economic damage in a single year than in all the years of the 1980s combined. 1998 was the most destructive year in weather history and probably the hottest is 1200 years and was also the hottest since people began taking regular thermometer readings in 1860.
Put aside this question of human impact on global climate. The exponential increase in surface temperature of the earth and the global sea level in the last few decades is a major aspect of climate change that has attracted both researchers and policy makers in recent times.
Without the natural presence of heat trapping greenhouse gases in the atmosphere the Earth would be a frozen planet unable to sustain life as we know it. But greenhouse gases are accumulating beyond natural levels in the atmosphere and human activities, in particular fossil fuel burning, are responsible. The world’s top climate scientists working under the auspices of the United Nations-sponsored Intergovernmental Panel on Climate Change (IPCC) concluded that the surface of the Earth had warmed over the last century. The evidence was not clear enough, however, to conclude that this global warming was human-caused and not natural in origin, because the planet had never experienced this type of hot wave before as well as the human activities regarding the burning fuels has increased in this century. People has never worked to secure their environment.
The concentrations of greenhouse gases in the atmosphere is generated by a range of human activities, which include majorly the burning of fossil fuels, industrial activities and the cutting down of forest for agricultural purposes and urbanization, are substantially increasing, there by upsetting this atmospheric chemical balance. They are major sources contributing to the increasing concentration of carbon dioxide in the atmosphere.
The atmosphere experiences annually from the burning of fossil fuel About 5.4 billion metric tons of carbon. About 1.6 billion metric tons of carbon is in addition emitted into the atmosphere by deforestation for agricultural and other land use purposes.
On the other hand our ability to accurately quantify human influence on global climate change is therefore limited. That’s why, not everyone agrees that the surface temperature of the earth is on the increase. If global warming is real, not all accept the fact that human activities are mainly responsible to it. Evidences suggested that increasing atmospheric greenhouse gases concentrations due to human activities on earth is mainly responsible for global warming and climate change are presented.
The two most important greenhouse gases, carbon dioxide and methane, present in the atmosphere has swelled significantly higher than at any time in at least 220,000 years. Observations made from different sources like surface temperature measurements at weather stations, sea level rise and borehole temperature profiles showed that the earth’s surface has warmed significantly in the last century.
Encroachment in deserts, increased intensity of flooding and frequent drought, deforestation, more turbulent weather attributed to the global warming are being witnessed across the globe. The governments take appropriate measures that would control and stabilize global warming and reducing greenhouse gas emissions to a level that would prevent dangerous anthropogenic interference with the climate systems.
EVIDENCES OF GLOBAL WARMING FROM INDEPENDENT MEASUREMENTS
Surface air temperature measurements, sea level changes and temperature profiles in boreholes all shows that the surface temperature of the earth is on the increase there by warming up the globe
The daily temperature measurements are combined to produce mean weekly, monthly and annually temperatures. Thus, the averaged annual temperature change from year to year can easily be tracked. In the last two decades, the global mean temperature has increased by 0.1°C per decade, with 2005 being the warmest year on record (NASA, 2005; 2009).
Sea level rises
The volume of water in the oceans is increasing due to thermal expansion of water in the oceans, and the melting of glacier and polar ice, resulting from increasing warming of the earth. The mean sea level rose by about 18 cm in the last century (IPCC Report, 2007b) currently rising at the rate of about 3.4 mm per annum. The observed irregularity in sea level changes is another indication of the complexity and chaotic character of the interactions being witnessed by our planet resulting in climate change.
SATELLITES OBSERVATIONS OF EARTHLIGHTS
The solar radiation from the sun is balanced by the thermal radiations emanating from the earthThe presence of greenhouse gases, majorly water vapour, carbon dioxide and methane, in their natural abundance in the atmosphere would cause some of the outgoing thermal radiation to be trapped, thereby establishing a new energy balance with a surface temperature of about +15°C. This phenomenon, which amounts to 21°C of warming of the earth’s surface, is usually called natural or beneficial greenhouse effect. Most of the outgoing thermal radiation is absorbed by water vapour and carbon dioxide. But the change that occurs in the amount of water vapour in the atmosphere due to human activities is negligible.