Positive+Feedback+1

**// increased thawing ( melting) of permafrost, leading to an increase in methane levels, which increases the man global temperature //** 1. ** What scientific evidence is there to show that your feedback mechanism is occurring right now? ** •Change in duration of snow-covered ground north of 50°N. The number of days in a year in which the ground is snow covered has decreased by an estimated average of 7.5 days from 1970 to 2000. Source: Euskirchen and others 2007, image courtesy of UNEP (terranature) •Trees that have placed their roots in the permafrost are now beginning to tip over because the ground no longer supports them, known as drunken trees.(sciencedirect) •New plant species are now being found in the tundra and arctic because the permafrost is melting and now new competitor plant species can be supported. (mongabay)
 * -Positive feedback- **

• The research team found the expansion of the lakes between 1974 and 2000, increased methane emissions by 58 percent at two thawing lakes in northern Siberia (terranature) • in the past 800,000 years methane had never tipped 750 parts per billion (ppb), but is now 1,780 ppb (mongabay) • Water runoff from permafrost to the ocean has increased by 7% since the 1930s • Boreholes in Svalbard, Norway, for example, indicate that ground temperatures rose 0.4C over the past decade (sciencedirect) • It showed that surface soil temperature in the Tibetan Plateau has increased at an average rate of 0.6 °C per decade between 1980 and 2005, the thawing days on the surface have increased by 60 days from 1983 to 2001. • Researchers have seen areas of sea foaming with gas bubbling up through "methane chimneys" rising from the sea floor. They believe that the sub-sea layer of permafrost, which has acted like a "lid" to prevent the gas from escaping, has melted away to allow methane to rise from underground deposits formed before the last ice age. (Independent) •Releasing methane is very dangerous because it is 21 times more effective at trapping solar heat respectively than carbon dioxide, but it has a shorter life of about a decade. Ultimately it oxidizes to become carbon dioxide which then stays in the atmosphere for more than a hundred years. (mongabay) •The balance of evidence suggests that Arctic feedbacks that amplify warming, globally and regionally, will dominate during the next 50 to 100 years. ( mongabay ) •Methane that is locked in the deep sea and in the frozen soils of Siberia, Northern Europe, and North America release as the ice continue and melt, it would release billions of tons into the atmosphere. • An estimated 500 gigatons of carbon have been flash frozen in yedoma regions, and 900 gigatons in permafrost worldwide (terranature) • Results for the mid-21st century climate indicated up to 50% increase in the volume of organic substrate in the northernmost locations along the Arctic coast and in East Siberia, where wetlands are sparse, and a relatively small increase by 10%–15% in West Siberia, where wetlands occupy 50%–80% of the land. • increase the overall content of methane in the atmosphere by approximately 100 Mt, or 0.04 ppm, and lead to 0.012 °C global temperature rise. [] [] [] [] []
 * 2.Relatively speaking, what will the scale of the effect of your feedback mechanism be in the context of climate change? **