Human+Contribution

**Human Contribution to Climate Change**
Human activities that cause climate change primarily include the burning of fossil fuels such as coal, oil and natural gases, as well as deforestation, aerosols, and land use. The human changes are somewhat masked by the natural changes in climate. Studies attempt to separate these two factors and are usually two parts: detection of an unusual change and attribution of that change to a particular cause.

**Detection and attribution** of the climate are very similar to the diagnosing of an individual. Measurements of body temperature that are abnormal detect the presence of some abnormal condition, but the body temperature itself is not the cause, it is the symptom. To attribute a symptom to a cause, a doctor would have to perform more complex tests. Early work on climate change detection examined average global surface temp. Most of these studies observed an increase of about 0.5 degrees Celsius was larger than what would be expected as result of natural climate change. Over time, ways in which temperature is measured has grown more advanced and accurate. Unfortunately, an accurate measurement of the earth’s surface has only existed for 50 years, and is not a long enough time line to provide any definitive information about the extent of human influence. Therefore, we have to make use of **climate models** that attempt to recreate the past changes in the climate that we were not around to measure accurately. These models have been used to estimate the effects and rage of human contributions. The human factors include recent changes in the atmosphere greenhouse gases, as well as aerosols.

The basic idea underlying pattern-based approaches is that different potential causes of climate change have different characteristic patterns of climate response or fingerprints. Attribution studies seek to obtain a fingerprint match between the patterns of climate change predicted by models and those actually observed. So to answer the question: **“Do humans contribute to climate change?”** we need to examine some select possible causes, and see if what is happening now matches what we think would happen if said causes were attributed.
 * The changes in average global temperature** that have occurred recently are similar to those predicted in the climate models. To find out if human contributions are indeed making a significant change requires more powerful and complex methods, which go beyond the use of global averages alone. More recent studies focus on comparing maps or patterns of temperature change in observations and in models. Pattern analysis is the climatological equivalent to the aforementioned “more complex tests” described in the medical analyogy

**__What do humans do to contribute to climate change?__** Most commonly it is believed that the burning of coal, natural gas, and deforestation are caused a change in the composition of the atmosphere and contributing to climate change. These human activities have caused an increase in the concentrations of greenhouse gases such as carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons. The changes these gases cause is shown in the graph below



We can see from the above graph that carbon dioxide produced when coal, oil and natural gas is burned is by far the largest contributor to the warming effect. The human use of these fuels accounts for about 80% of the carbon dioxide being added to the atmosphere. Deforestation also contributes to carbon dioxide emissions. Vegetation contains carbon that is released as carbon dioxide when the vegetations decays or dies. In a natural world free of human interaction, these emissions would be canceled out by re-growth. However, deforestation over the past several hundred years has disrupted this natural balance. Currently land use changes are responsible for 20% of carbon dioxide emissions. The below graph shows the carbon dioxide emissions from burning coal, oil, and natural gas from 1860 to 1992 for three major countries. The trend is that carbon emissions are increasing almost exponentially.



From the previous graph we can see that methane of natural gas is the second most influential greenhouse gas resulting form human activities. Methane is produced by cultivation of rice, cattle, sheep, and other ranching, and the decaying material in landfills. Methane is also a by-product of mining coal and drilling for oil. It is estimated that human activities have increased the concentration of methane in the atmosphere about 145% Nitrous oxide is produced by various industrial and agricultural practices. Nitrous oxide is about 15% above what would be present naturally due to human activities. CFCs have been used in refrigeration, and air conditioning. Thankfully, the production of these gases is being eliminated due to new international legislation. Contrary to popular belief, the hole in the ozone layer that was partially caused by the CFCs does not contribute to global warming. In fact the hole over the artic has resulted in a small cooling effect.
 * Methane:**
 * Nitrous Oxide:**
 * Chlorofluorocarbons:**


 * __How do we know that the build-up of greenhouse gases is due to human activity?__**

The composition of carbon atoms is different when it is emitted by burning fossil fuels than when they are naturally occurring. They differ in the fact that the ones that occur naturally have slightly radioactive nuclei where as the ones emitted by the burning of fossil fuels do not have a radioactive nuclei. Scientist are able to differentiate between the two, and therefore can test the atmosphere and see what proportion of the carbon dioxide nuclei are radioactive, and subsequently cased by the human burning of fossil fuels. Scientists are able to see how this proportion has changed as far back as the 1800s by examining tree rings, as trees consume carbon dioxide. The data has conclusively shown that the concentration of carbon dioxide is due in large in human contributions. Another way to see how carbon dioxide, as well as other greenhouse gases, have changed in composition is to examine ice cores from the arctic. Scientist are able to drill deep into glaciers where air bubbles have been trapped for thousands of years. By testing the composition of the air trapped in these bubbles, scientists are able to see the carbon dioxide composition from many years ago.

Are human contributions even a factor? If so, how large of a role do we play in the earth's global temperature rise? [|Read on for a little blog on the subject...]

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Human Factors
Human contributions to climate change include CO2 emissions, aerosols, land use, water vapor, and dozens of other factors. etc etc etc etc elaborate

CO2
Recently, CO2 has been...