Greenhouse gases let solar radiation through the atmosphere, but trap outgoing earth radiation
By Dr. John J. Hidore
October 18,2014—Planet Earth is now in a period of rapid change. The first years of the 21st century serve to indicate how fast it is changing. A fundamental driving force in many of these recent changes is the growth of the human population. From the time of its origin until now the population has been growing faster and faster. It took modern humans some 200,000 years to reach a total of one billion individuals. We have added another billion in less than 15 years since the start of the century.
A major element in change is now global warming and its associated changes. The warming is largely due to the accumulation of greenhouse gasses in the atmosphere. Greenhouse gases let solar radiation through the atmosphere, but trap outgoing earth radiation. Heat thus accumulates in the earth system.
Carbon Dioxide and Methane
The major greenhouse gases are carbon dioxide and methane. Both of these gases have been accumulating for the last several centuries. Since the start of the industrial revolution, the burning of organic fuels has released more than 500 billion tons of carbon dioxide into the atmosphere. The concentration in the atmosphere is now the highest it has been in the past 800,000 years. The gases are at their highest levels in historic times and have now passed 400 parts per million.
Four countries contribute most of the carbon dioxide. They are China, India, The United States, and Russia. In the past year, each of these countries increased their emissions of carbon dioxide. The United States, which had been stabilizing emissions, increased its contributions. At a recent conference on climate change and greenhouse gas emissions, China, India, and Russia did not attend. Globally an estimated 39.8 billion English tons (36.1 billion metric tons) of carbon dioxide were contributed to the atmosphere in the last year. That is 2.3 % more than the previous year. Almost all carbon dioxide comes from burning fossil fuels. .
Methane levels are also at record levels. It forms in the natural world largely from the decomposition of organic matter. It has begun to accumulate during the past two centuries. Since 1750, the level of methane in our atmosphere has more than doubled, from about 700 to 1800 parts per billion (ppb) in 2013. The current level is the highest in at least the last 650,000 years. About half of the increase has occurred since 1960. Methane comes from a variety of sources including agriculture, mining, and manufacturing, and fracking
Increasing Greenhouse Gases
Global temperatures have increased accompanying the increase in greenhouse gasses. In the months of May and June of this year (2014) the highest average global atmospheric temperatures, since records began, were recorded. In 2012, worldwide land-surface temperatures for the months of June through August were the hottest ever. Australia recorded its warmest year of record in 2013. Not all of the planet experienced unusually warm conditions at this time, but overall, earth’s temperature has increased.
Parts of the arctic region are now the warmest they has been in 44,000 years. The warming is taking place around the North Pole including the Arctic Ocean and the surrounding land masses. Most of the ice shelves in the Canadian Arctic broke away from land during the past 14 years. Every summer, for the last ten years, the area of sea ice has been below the average of the previous 20 years. Sea ice in the Arctic sea reached is lowest level ever on September 16, 2012.
2012: Records Broken in the U.S.
2003-2012 The warmest decade ever recorded in the United States.
2011-2012 The winter (Dec, Jan, Feb) was the fourth warmest since records began in the 1890s. It was about four degrees Fahrenheit above the average and the warmest since the year 2000. Twenty seven states had one of the 10 warmest of record.
2011-2012 Warmest records in U.S. History.
2012 Warmest year ever recorded in the United States. The year averaged 3.2F above the average of the 20th century.
2012 March sets record high temperatures. More than 7700 U.S daily-high temperature records were set.
2012 In March more than 90 cities set record highs for the month.
2012 The six warmest 12 month periods so far in the U.S. ran through 2012.
2012 Global land surface temperatures in the months from June to August were the warmest ever.
2012 September tied for the warmest ever in the United States,
2011-2012 The 12 months from August 2011 to July 2012 were the warmest ever in the United States.
2012 In July of this year all 50 states in the Unites States set record highs. During the summer of 2012, ninety degree temperatures forced the Tennessee Valley Authority to shut down three nuclear power reactors.
2012 Drought affected as much as 65% of the lower 48 states.