Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased by 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century. Most of the observed temperature increase since the middle of the 20th century has been caused by increasing concentrations of greenhouse gases, which result from human activities such as the burning of fossil fuel and deforestation.
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts. Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects include more frequent and intense extreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional changes is uncertain. As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic, a result that is predicted to continue.
The scientific consensus is that anthropogenic global warming is occurring. Nevertheless, skepticism amongst the wider public remains. The Kyoto Protocol is aimed at stabilizing greenhouse gas concentration to prevent a "dangerous anthropogenic interference". As of November 2009, 187 states had signed and ratified the protocol. Proposed responses to global warming include mitigation to reduce emissions, adaptation to the effects of global warming, and geoengineering to remove greenhouse gases from the atmosphere.
Global Surface Temperature
Since about 1950, the Earth’s global surface temperature has risen by just more than .6 degrees Celsius or just over 1 degree Fahrenheit.
Arctic Sea Ice
Using data reported from the National Snow and Ice Data Center, we can track the decline of Arctic sea ice. The image below shows the month of September with the 1978 – 1981 averages on the left, and Arctic sea ice from September 2007 on the right, which produced the smallest area of Arctic sea ice to date. This equates to a decline of nearly 32% in the Arctic sea ice. While the sea ice area has since increased from the record low of 2007, the level remains far below the those recorded since 1979.
The image on the left shows the average ice cover at the end of the summers of 1979 – 1981. The image on the right shows the ice cover at the end of summer in 2007. Ref: http://www.nasa.gov/topics/earth/sea_ice_nsidc.html
Sea Level Rise
As we all know, when water warms it expands. Add this to water melting from glaciers and the arctic and you will see a measurable amount of sea level rise. While sea level rise by all accounts has been occurring for as long as we can tell, what is of particular interest is the rate of change that has been occurring. From 1870 to 1992, the average sea level rise has been 1.7 mm. As the chart below indicates, those rates have nearly doubled starting in 1993.
Carbon Dioxide Levels
Carbon dioxide (CO2) in our atmosphere has been around longer than mankind. As we all know, CO2 is part of a natural process involving plants and animals as well as volcanic eruptions. Manmade CO2 comes from the burning of fossil fuels used in energy plants, manufacturing plants and the various modes of transportation we use. The chart below shows the levels of CO2 measured in the Earth’s atmosphere over the past 400,000 years. Everything appears quite normal up until about 1950 where instead of following the cycle of upward and downward trends, the levels increased beyond any point in history and continued upward. April 2010 set yet another record of atmospheric CO2 at 392 ppm.
Now we have four factual indicators of warming. The issue is really with last one, the CO2. What is causing the increase in CO2? That is the center of the debate as to whether we are causing the rising CO2 levels or is nature doing this?
As we all know by now, CO2 comes from nature and from man. If the Earth warms, CO2 from nature increases as well. When there is less ice in the arctic regions, the Earth will absorb more of the Sun’s energy, which will create more warming since the oceans will release more CO2 . This cycle is known as a positive feedback. As permafrost regions on the Earth begin to melt, more greenhouse gases including methane which is known to have even a bigger impact on the greenhouse effect, are released from the soil that was once frozen, again this is positive feedback.
Scientists are tracking solar output from the sun to determine if changes in the sun’s output, known as solar irradiance, is a contributing factor to global warming and the subsequent climate change. These studies are important as they may help us understand the influence the sun’s energy has in creating the recent warming. While there has been no conclusive evidence to date, it merits closer observation and study.
So, what is causing CO2 levels to continue to rise? We know that we are definitely putting more CO2 into the atmosphere than we ever have. As countries like China and India go through their new found industrial growth, we continue to release more CO2, while it would make sense to point at these man made increases as the primary culprit, it is simply not that easy. Unfortunately regulating CO2 levels across the globe is a daunting task. What agency will monitor what countries and businesses are doing? In an already poor global economy, what is the cost of making these changes? Will the changes even have an impact on reducing CO2 levels? While we continue to debate, what will the cost be of doing nothing? Should we act now and wait for science to prove definitively that nature or man causing the global warming? Do we wait until we know for sure?
Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts. Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers, permafrost and sea ice. Other likely effects include more frequent and intense extreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional changes is uncertain. As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic, a result that is predicted to continue.
The scientific consensus is that anthropogenic global warming is occurring. Nevertheless, skepticism amongst the wider public remains. The Kyoto Protocol is aimed at stabilizing greenhouse gas concentration to prevent a "dangerous anthropogenic interference". As of November 2009, 187 states had signed and ratified the protocol. Proposed responses to global warming include mitigation to reduce emissions, adaptation to the effects of global warming, and geoengineering to remove greenhouse gases from the atmosphere.
Statistics of the global warming trend
As the debate rages over global warming, it is important to understand what exactly is being debated. Nearly every scientist will support the fact that in the last 30 – 40 years, the Earth has gotten warmer. What continues to be debated, and rightfully so, is the reason for the warming trend. Are we seeing a natural trend or is the warming something anthropogenic (caused by humans). Below are the four primary data points that clearly show that warming is occurring.Global Surface Temperature
Since about 1950, the Earth’s global surface temperature has risen by just more than .6 degrees Celsius or just over 1 degree Fahrenheit.
Arctic Sea Ice
Using data reported from the National Snow and Ice Data Center, we can track the decline of Arctic sea ice. The image below shows the month of September with the 1978 – 1981 averages on the left, and Arctic sea ice from September 2007 on the right, which produced the smallest area of Arctic sea ice to date. This equates to a decline of nearly 32% in the Arctic sea ice. While the sea ice area has since increased from the record low of 2007, the level remains far below the those recorded since 1979.
The image on the left shows the average ice cover at the end of the summers of 1979 – 1981. The image on the right shows the ice cover at the end of summer in 2007. Ref: http://www.nasa.gov/topics/earth/sea_ice_nsidc.html
Sea Level Rise
As we all know, when water warms it expands. Add this to water melting from glaciers and the arctic and you will see a measurable amount of sea level rise. While sea level rise by all accounts has been occurring for as long as we can tell, what is of particular interest is the rate of change that has been occurring. From 1870 to 1992, the average sea level rise has been 1.7 mm. As the chart below indicates, those rates have nearly doubled starting in 1993.
Carbon Dioxide Levels
Carbon dioxide (CO2) in our atmosphere has been around longer than mankind. As we all know, CO2 is part of a natural process involving plants and animals as well as volcanic eruptions. Manmade CO2 comes from the burning of fossil fuels used in energy plants, manufacturing plants and the various modes of transportation we use. The chart below shows the levels of CO2 measured in the Earth’s atmosphere over the past 400,000 years. Everything appears quite normal up until about 1950 where instead of following the cycle of upward and downward trends, the levels increased beyond any point in history and continued upward. April 2010 set yet another record of atmospheric CO2 at 392 ppm.
As we all know by now, CO2 comes from nature and from man. If the Earth warms, CO2 from nature increases as well. When there is less ice in the arctic regions, the Earth will absorb more of the Sun’s energy, which will create more warming since the oceans will release more CO2 . This cycle is known as a positive feedback. As permafrost regions on the Earth begin to melt, more greenhouse gases including methane which is known to have even a bigger impact on the greenhouse effect, are released from the soil that was once frozen, again this is positive feedback.
Scientists are tracking solar output from the sun to determine if changes in the sun’s output, known as solar irradiance, is a contributing factor to global warming and the subsequent climate change. These studies are important as they may help us understand the influence the sun’s energy has in creating the recent warming. While there has been no conclusive evidence to date, it merits closer observation and study.
So, what is causing CO2 levels to continue to rise? We know that we are definitely putting more CO2 into the atmosphere than we ever have. As countries like China and India go through their new found industrial growth, we continue to release more CO2, while it would make sense to point at these man made increases as the primary culprit, it is simply not that easy. Unfortunately regulating CO2 levels across the globe is a daunting task. What agency will monitor what countries and businesses are doing? In an already poor global economy, what is the cost of making these changes? Will the changes even have an impact on reducing CO2 levels? While we continue to debate, what will the cost be of doing nothing? Should we act now and wait for science to prove definitively that nature or man causing the global warming? Do we wait until we know for sure?
At this point, we have more questions than answers and anyone who says otherwise is doing so for reasons outside of getting to the scientific truth. We know the Earth is warming. The factual evidence cannot be disputed. If you had the power today to decide what path we should take, what would you choose? Do nothing until science has been proven, or begin a program that reduces the amounts of CO2 that man is putting into the atmosphere?
