The idea with these, is that if humans give global warming a kick-start, larger
ID: 107437 • Letter: T
Question
The idea with these, is that if humans give global warming a kick-start, larger changes like the melting of the boreal permafrost and release of methane could set positive feedback loops in motion that could dramatically alter the global climate far beyond the effect that human emission of greenhouse gases would have had on their own.
Describe the positive feedback loop that could occur with the melting of Greenland ice sheet and resulting changes in sea level (# feet?) and albedo. Would humans still need to keep adding greenhouse gases in order for this feedback loop to continue?
Explanation / Answer
Ice-albedo feedback is a positive feedback climate process where a change in the area of snow-covered land, ice caps, glaciers or sea icealters the albedo. This change in albedo acts to reinforce the initial alteration in ice area. Cooling tends to increase ice cover and hence the albedo, reducing the amount of solar energy absorbed and leading to more cooling. Conversely, warming tends to decrease ice cover and hence the albedo, increasing the amount of solar energy absorbed, leading to more warming.
The effect also applies on the small scale to snow-covered surfaces. A small amount of snow melt exposes darker ground which absorbs more radiation, leading to more snowmelt.
The effect has mostly been discussed in terms of the recent trend of declining Arctic sea ice.
Internal feedback processes may also potentially occur, as land ice melts and causes eustatic sea level rise, and also potentially induces earthquakes as a result ofisostatic rebound, which further acts to disrupt glaciers, ice shelves, etc.
Once we stop adding greenhouse gases that is the release of carbon dioxide stored in the fossil fuels we burn, it accumulates in and moves amongst the atmosphere, the oceans, the land, and the plants and animals of the biosphere. The released carbon dioxide will remain in the atmosphere for thousands of years. Only after many millennia will it return to rocks, for example, through the formation of calcium carbonate – limestone – as marine organisms' shells settle to the bottom of the ocean. But on time spans relevant to humans, once released the carbon dioxide is in our environment essentially forever. It does not go away, unless we, ourselves, remove it.
If we stop emitting today, it’s not the end of the story for global warming. There’s a delay in temperature increase as the climate catches up with all the carbon that’s in the atmosphere. After maybe 40 more years, the climate will stabilize at a temperature higher than what was normal for previous generations.
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