Questions And Answers
How do we know climate change is linked to CO2 in the atmosphere? Over the last 650,000 years the natural range for CO2 concentrations in the atmosphere has been between 180 to 300 parts per million (ppm). This data has been found through ice core surveys, where air trapped as the ice froze hundreds of thousands of years ago, has been carefully analysed. The graph below shows the results of the ice core measurements along side temperature up until the year 1950. The graph shows that the amount of CO2 in the atmosphere up until 1950 had never exceeded 300ppm.
The atmospheric concentrations of CO2 in 2005 was 370ppm, this far exceeds the natural range over the last 650,000 years (180 to 300 ppm) as determined from ice core surveys. Over the last 10 years, we have seen the fastest annual growth rate in the carbon dioxide concentration, since the start of direct atmospheric measurements (1960).
How do we know that levels of CO2 don't just increase as temperature increases? Over the last several hundred thousand years the temperature has varied mainly due to changes in the Earth's orbit around the sun. Over this period changes in temperature did drive the levels of CO2 in the atmosphere. However, now the levels of CO2 are much higher and increasing much faster than at any time over the last 650 thousand years - meaning what is happening now is very different to anything that has happened over the last 650 thousand years.
How do we know that Solar activity isn't causing the warming? Changes in the Earth’s orbit around the sun have been the main driver for temperature change on the Earth over the past 650 thousand years. Up until the early 20th century, the models of temperature against solar, Earth orbit and volcanic activity were well aligned. However the recent warming we have seen over the last 50 years, does not fit within these models and can only be explained when the levels of CO2 from burning fossil fuels are included within the simulations. The link to solar activity and cosmic rays is purely speculative. Even if they do have an affect on the climate, the measurement of solar irradiance from satellite observations shows no real increase, and therefore does not explain the recent increases in CO2 and temperature.
Don't volcanic eruptions put out more CO2 than a decade of human activity? No. This is a common misconception. If this was true then the CO2 record would be full of spikes, one for each eruption. From analysing data from dozens of sample stations around the world, we do not see these spikes, instead the CO2 trend is very smooth. The total rate of CO2 emissions from all the volcanoes is about 1/150th that from human activities. Comparison of CO2 emissions from volcanoes vs. human activities
How do we know the amount of CO2 in the atmosphere is linked to Human Activity? The rise in CO2 in the atmosphere is very well established. One way we know this is linked to human activity is by looking at historical records of human activity. Fossil fuels have been burnt since the start of the industrial revolution, along with forested land being cleared at unprecedented rates. These process have been turning the organic compounds into Carbon Dioxide. Enough carbon dioxide has been produced to raise the atmospheric content to 500ppm. Fortunately, these levels haven't been reach because the oceans and biosphere have the ability to absorb some of this CO2. Unfortunately, because we are producing CO2 faster than the oceans and biosphere can absorb them, we see the increased levels. Another way, we know that the fossil fuels are causing CO2 increase in the atmosphere is by analysing the carbon isotopes, similar to carbon dating. More information can be found at Real Climate.
In the 1970's we were concerned about the coming Ice Age! This is partly true - in that there were some predictions about an imminent ice age. However, when you compare the warnings then to today's warnings on Global Warming you will find a massive difference. Today we have widespread scientific consensus that the world is warming, supported by national academies and all major scientific institutions, warning about rising temperatures and the link to CO2 by human activities. in the 1970's there was a book and a few articles in popular press, and a small amount of scientific speculation based on the recently discovered glacier cycles, and a slight cooling trend from "Global Dimming". No daily headlines. No avalanche of scientific papers. No UN treaties. No G8 summit. And nothing like an IPCC. For more information on the "1970's Ice Age warnings" try visiting the RealClimate.
What is the IPCC? The IPCC (Intergovernmental Panel on Climate Change), was set up in 1988 by the World Meteorological Organisation and the United Nations Environment Programme. The most recent assessment report issued by the IPCC on the 2 February 2007, concluded that global warming is "unequivocal" and gave the strongest warning yet that it is very likely (> 90%) caused by human activities.
Is research being funded to manufacture uncertainty about climate change? Britain's Royal Society in September 2006, found that the world's largest publicly traded corporation Exxon-Mobil contributed nearly 16 million dollars between 1998 and 2005 to a network of 43 advocacy groups that questioned the increasingly solid consensus that greenhouse gas emissions contribute to global warming. "ExxonMobil has manufactured uncertainty about the human causes of global warming just as tobacco companies denied their product caused lung cancer," said Alden Meyer, UCS's director of strategy and policy. The global oil and gas market generated total revenues of $3200.9 billion in 2005, representing an increase of 27.4% on the previous year’s value.
What is Ozone Depletion? Most people are well aware that the World's Ozone layer is being depleted. Until recent times , aerosol products have contained CFC propellant chemicals, now proven to destroy ozone in the upper atmosphere. Most countries have introduced regulations to ban / minimise use of CFCs. Why does this matter? Holes in the Ozone layer expose us to harmful UV light, linked strongly with skin cancer, cataracts and impaired immune systems. It is also thought to reduce crop yields and have deleterious effects on ocean and amphibious populations worldwide.
Common misconceptions about ozone depletion include:-
Even though the hole in the ozone layer doesn't contribute to global warming. We should still be concerned about the affects of increased UV light. What can I do? Some CFC products are still in use - most commonly in air conditioning units. Your car and maybe also your home have air conditioning units that feature ozone depleting refrigerant chemicals; if these are released into the atmosphere, they will cause harm. Make sure that you choose a reputable services company, who will safely recover the refrigerant chemicals when you have your equipment serviced... then you will avoid risk to the environment. |
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