11) What is the timing relationship between rice irrigation and atmospheric CHa
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11) What is the timing relationship between rice irrigation and atmospheric CHa concentrations? 12) How does rice farming generate CH 13) What is Ruddiman's explanation for an increase in atmospheric CO2 approximately 8000 yrs ago? 14) How do geologists (not historians) date when European crop farming and associated deforestation began? 15) The present population of England is approximately 50 million, how many people lived there in ~1100 A.D.? 16) If Ruddiman's interpretations are correct, how much temperature change can be attributed to these early farming practices? 17) Is this temperature change greater or lesser than warming recorded in the past century? 18) In the absence of this warming effect, what would the global climate be like today? 19) Describe how Ruddiman explains the brief drops in CO2 during the last 500 yrs?Explanation / Answer
11) There ane many method of rice irrigation according to water flooding level by which methan emission varies ,normal permanent flood for46 days post planting, normal flood with mid? season drainage aeration, normal flood with multiple drainage aeration, and late flood for 76 days post planting. Methane emission rates varied markedly with water regime, showing the lowest seasonal total emission (1.2 g m?2) with a multiple?aeration treatment and the highest (14.9 g m?2) with a late flood. Although the multiple? aeration water management treatment emitted 88% less methane than the normal irrigation treatment.
12)Methane in rice paddies is produced by microscopic organism that repair CO2. More CO2 on the atmosphere makes rice plant grow faster, and the extra plant growth supplies soil microorganism with extra energy,pumping up their metabolism. Increasing CO2 level will also boost rice yields but to a smaller extent then CH4 emission .
17)We know about past climates because of evidence left in tree rings, layers of ice in glaciers, ocean sediments, coral reefs, and layers of sedimentary rocks. For example, bubbles of air in glacial ice trap tiny samples of Earth’s atmosphere, giving scientists a history of greenhouse gases that stretches back more than 800,000 years. The chemical make-up of the ice provides clues to the average global temperature.As the Earth moved out of ice ages over the past million years, the global temperature rose a total of 4 to 7 degrees Celsius over about 5,000 years. In the past century alone, the temperature has climbed 0.7 degrees Celsius, roughly ten times faster than the average rate of ice-age-recovery warming.Models predict that Earth will warm between 2 and 6 degrees Celsius in the next century. When global warming has happened at various times in the past two million years, it has taken the planet about 5,000 years to warm 5 degrees. The predicted rate of warming for the next century is at least 20 times faster.
18)After ice age the global temperature begain to increase and got stable but begain to increase after industrial revolution around the world as consumption of fossil fuels (coal, crude oil) has increased drasically. and in around 5000 years there is recorded increase of 2 to 7 degree calsius and can even increase upto 10 degree calsius, so in the absence of this warming effect the earth atmosphere would have been cool by 5 to 6 degree calsius but will not be as cold as it was during ice age.
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