1. The Causes of Climate Change & Earth's Changing Climate
1.1. The Causes of Climate Change United Nations Framework Convention on Climate Change
1.1.1. Climate change refers to changes in climate that are caused directly or indirectly by human activities that change the composition of the global atmosphere and also to the variability of natural climates observed over a certain period of time.
1.2. Earth's Changing Climate: Intergovernmental Panel on Climate Change
1.2.1. The warming that occurs in the Earth's climate system is clearly felt, along with the abundant evidence from observations of rising air and sea temperatures, melting snow and ice in various parts of the world, and rising global sea levels.
2. Greenhouse Gas (GHG) Emissions
2.1. Fossil fuels that are formed from the bodies of plants and animals that have long died are the sole source of GHG from human activities. Burning coal, oil and natural gas releases billions of tons of carbon into the atmosphere every year (which should remain deep in the Earth's crust), as well as large amounts of methane and nitrous oxide. More carbon dioxide is released into the atmosphere when trees are cut down and not replanted.
2.2. Meanwhile, livestock in large numbers will emit methane, as well as agriculture and waste disposal, because the use of fertilizers can produce nitrous oxide. Gases with long life / residence times such as CFC, HFC and PFC, which are used in air conditioners and refrigerators (refrigerators) are also dangerous gases when in the atmosphere. Human activities that emit GHG into the atmosphere are currently very much done and very essential in the global economy and are part of today's human lifestyle.
3. Assessing Science: The Intergovernmental Panel on Climate Change
3.1. The United Nations, through the United Nations Environment program, The World Meteorological Program and Organization (WMO) formed The Intergovernmental Panel on Climate Change (IPCC) in 1988 to research and analyze emerging scientific issues. Since 1990 every five or six years the IPCC has issued reports related to science knowledge through observation and prediction to find out its future trends.
3.2. The IPCC does not conduct new research, but the task of the IPCC is to draft policies that are consistent with issues and literature around the world on the scientific, technical and socioeconomic aspects of climate change. IPCC reports are compiled by thousands of experts from all parts of the world.
3.3. The fourth research report (The Fourth Assessment Report) was released in 2007, in four sections, each of which was compiled by a different working group. In preparing the report, the draft manuscript is circulated to experts with different fields of expertise. Comments from these experts will then be accommodated by the authors at the IPCC who then prepare a second review for world governments and for all the authors and expert reviewers. Governments and expert reviewers can provide input but are limited to the accuracy and completeness of the scientific / technical / socioeconomic content and the balance of the overall draft report draft. The final document is a combination of the views of many parties, both scientific and technical.
3.4. Each report has an overview for policymakers, which is approved by the delegation of governments of IPCC member countries at the plenary session of the working group that prepared the report. The lead author of the report will be present ready to explain scientific facts that support the statements in the summary. Changes can only be made if there is agreement with the main author, to ensure consistency with the scientific and technical aspects. The summary also indicates agreement for the report content / findings: Statement from participating governments that there is sufficient scientific evidence from around the world to support the statements in the report document.
4. Quick Facts
4.1. The natural sheath of GHGs in the atmosphere keeps the earth warm enough to life - currently within a comfortable level of 15 ° C. GHG emissions caused by human activities have resulted in a thickening of the envelope, so that a lot of heat is trapped and triggers global warming. Fossil fuels are the largest source of GHG emissions from human activities.
4.2. Earth's average temperature has been fairly stable in the last 10,000 years and has varied from less than 1 ° C, so that human civilization was able to thrive until today with a comfortable temperature of 15 ° C. But the successful development of human civilization poses a risk to the balance of the earth's climate.
4.3. The naturally occurring GHG “envelope” in the troposphere - approximately 1% of the overall composition of the atmosphere - has a vital function for Earth's climate. When solar energy in the form of visible waves enters and warms the surface of the earth, the earth, which is much colder than the sun, then emits that energy back to space in the form of infrared or thermal, radiation waves. GHG will block the infrared radiation from returning to space. This "natural GHG effect" causes the earth's temperature to be 30 ° C warmer than the earth's temperature should be, this is of course very important for human life.
4.4. The problem currently facing humans is that since the start of the industrial revolution 250 years ago, GHG emissions have increased and thicken the GHG cap in the atmosphere at a significant rate of increase. This has resulted in the largest change in the composition of the atmosphere for 650,000 years. The global climate will continue to warm at a rapid rate in the coming decades unless efforts are made to reduce GHG emissions to the atmosphere.
5. Current Projections Indicate Acceleration of Heating
5.1. Continuous greenhouse gas (GHG) emissions at or above levels at its current speed will cause further heating and trigger other changes to the global climate system during the 21st century with a greater impact than that observed in the 20th century.
5.2. The rate of heating depends on the emission level: If the carbon dioxide concentration is stable at 550 ppm - double the pre-industrial period - the average warming is expected to be 2-4.5 ° C, with the best estimate being 3 ° C or 5.4 ° F. For the next two decades it is estimated that a warming rate of 0.2 ° C per decade does not include a reduction in GHG emissions.
5.3. Other GHGs also play a role in warming and if the combined impact of this GHG is equivalent to the impact of 650 ppm carbon dioxide, the global climate will warm by 3.6 ° C, while the figure of 750 ppm will result in a warming of 4.3 ° C. The projection depends on several factors such as economic growth, population, technological developments and other factors.
6. Climate change at a glance
6.1. Increasing warming:
6.1.1. Eleven of the last twelve years have been the warmest years of global surface temperature since 1850. The average rate of warming over the past fifty years has nearly doubled the average of the last hundred years. Global average temperatures rose by 0.74 ° C during the 20th century, with warming felt more on land than in oceans.
6.2. Greater amount of carbon dioxide in the atmosphere:
6.2.1. Carbon dioxide is the most dominant cause of climate change today and its concentration in the atmosphere has increased from pre-industrial times of 278ppm (parts-per million) to 379 ppm in 2005.
6.3. More water, but uneven distribution:
6.3.1. present Increases in precipitation in recent decades have been observed in the Eastern part of North and South America, Northern Europe, Asia, North and Central Asia. But in the Sahel, Mediterranean, South Africa and parts of South Asia experiencing reduced precipitation. Since 1970 there have been stronger and longer droughts.
6.4. Sea level rise:
6.4.1. Currently reported sea level rise from the 19th century to the 20th century, and the increase in the 20th century was 0.17 meters. Geological observations indicate that the sea level rise in the preceding 2000 years was much less than the sea level rise in the 20th century. Mean global sea temperatures have increased to a depth of at least 3000 meters.
6.5. Reduction of snow cover:
6.5.1. Snow cover is getting less and less in some areas, especially in spring. Since 1900, the maximum area covered by snow in winter / spring has decreased by about 7% in the Northern Hemisphere and rivers will freeze more slowly (5.8 days slower than a century ago) and melt faster by 6.5 days.
6.6. Melting glaciers:
6.6.1. Mountain glaciers and average snow cover reduced in both hemispheres and has contributed to sea level rise of 0.77 millimeters per year from 1993-2003. The reduction of ice sheets in Greenland and Antarctica contributed by. 0.4 mm per year for sea level rise (between 1993 - 2003).
6.7. Arctic Continent warms up:
6.7.1. The average temperature of the Arctic Continent has increased to double the average temperature of the last hundred years. Satellite data taken since 1978 show that the average area of sea ice in the Arctic has decreased by 2.7% per decade