Global Climate Change Report
Global Climate Change
Global climate change is the result of the externality associated with greenhouse gasses; it includes a number of terrestrial consequences, such as global temperature variations and heatwaves, rising sea levels, rising acidity in the ocean and melting of ice caps and glaciers…. etc. The fact that global climate change involves causes of both natural process and human activities has triggered arguments, making it a controversial topic among scientists and NGOs. This report will discuss the causes of climate change, including natural external forcings and ones that are human-induced, and scientific predictions of it.
Changes in climate can be forced by natural processes outside the atmosphere, such as changes in solar radiation, and inside, such as changes in ocean atmospheric composition and ocean circulation. First of all, the amount of insolation reaches the earth’s surface varies according to its tilted orbit. Orbital oscillations vary the amount of insolation different parts of the world receives. Moreover, the amount of radiation emitted by sun is based on the “solar cycle”, which occurs every eleven years, where sunspot activity takes place and changes in amount. Sunspots are bubbles that cool down sun’s radiation and therefore increase its output. However, it is controversial to what extent this activity affects climate change. Figure 1 shows the changes in sunspot activity in the New Scientist, which concludes that there is no correlation between the activity and the severe warming in the past 40 years. In fact, the Intergovernmental Panel on Climate Change halved the maximum possible influence of solar activity on global warming from 40% to 20%. Secondly, changes in albedo is largely believed to have an impact on surface temperature. The lower the albedo of the earth, the greater the amount of insolation it absorbs; the greater the albedo, the greater the amount of insolation is reflected back into space. Snow has the highest albedo of 80% to 90%, therefore, the melting of ice sheets and glaciers leads to larger amount of solar radiation being absorbed by the earth. For instance, the parts of the Artic where ice is lost is replaced by sea water, which has a lower albedo. Sand has the third highest albedo of 30-35%. Ironically, desertification in Sahel in Africa during the 20th century has led to an increase of albedo from 14% to 35%. Last but the least, the changing composition of the atmosphere, including greenhouse gases and aerosol content, has a large impact on the longwave radiation reflected back to space. However, this is caused by both natural and anthropogenic factors.
Even though it is a fact that global climate changed before humankind large-scale economic activities, the present rate of change is the highest ever in history. Figure 2 shows that the global average temperature increased by 0.6 in the 20th century – an exponential growth.
Most climate experts believe that human activity has increased greenhouse gases in a significant amount. The main greenhouse gases are carbon dioxide, methane, nitrous oxides, chlorofluorocarbons and ozone. Deforestation and burning of rainforests releases carbon dioxide. Methane is released from decaying plants and animal remains, especially from cattle and rice padi fields. Cattle emit 100 million tons of methane annually as they convert 10% of what they consume into methane. On the other hand, the main sources of chlorofluorocarbons are aerosols, refrigerators, foam packaging and air conditioning, while those of of nitrous oxide and ozone are vehicle emissions and power plant emissions.
As the economies of China, India and other NICs grow, the amount of greenhouse gases will continue to increase. Most climate models anticipate that the doubling of pre-industrial levels of greenhouse gases will lead to an increase of 2 to 5 in global mean temperatures, which can be reached between 2030 to 2060. If no effort is put in reducing greenhouse gas emissions, the concentration of greenhouse gases will be larger than treble pre-industrial by 2100. Global warming alters water patterns, and increases the droughts and floods in occurrence; projections suggest that the portion of land in extreme drought will increase from 1% to 30 % by the end of this century. Apart from these regions, warmer air and ocean will increase the risk of typhoons and hurricanes.
in 2007, the Intergovernmental Panel on Climate Change warned that the world has until 2020 to avoid the most severe consequences of climate change. Practices to combat climate change have been implemented on different parts of the world in various levels. For instance, by 2014, Iceland has 85% of its primary energy use coming from indigenous renewable resources, from which 66% come from geothermal energy – making it extremely effective in contributing to reduction of greenhouse gas emissions. On the other hand, in 2007, the British government stated its aim to reduce its carbon dioxide emissions by 60% by 2050. Apart from increasing green taxes, the British government has put out proposals to become a low-carbon economy; this include establishing a ten-year program to convert taxis to electric or hybrid power, stopping the expansion of all airports, and investing a more complete public transportation. Eventually, governments of MEDCs should communicate and cooperate with those of NICs to sort out ways to reduce greenhouse gas emissions in on-going industrializations in NICs.