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Author Topic: Global Warming  (Read 66365 times)

Bla

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Re: Global Warming
« Reply #240 on: January 02, 2017, 10:01:11 AM »
Whether we're actually causing climate change or not, is it possible that the ultimate result of it will actually be beneficial to us?
Global warming has a huge number of different effects so of course some will be positive, but the evidence points to the negative ones being far more dominant than the positive ones, hence the many times we've been warned about the problems by the scientific community.

The obvious issue that people are concerned about are the poles melting and sea levels rising. However, unlike other fluids, water expands when frozen due to the way it forms the crystalline structures of ice. As it melts, it takes up less area than it did when frozen. Does this mean that the flooding wouldn't be as bad as people think?
Yes, but much of that volume was bound above sea level, and when it melts it becomes a part of the sea instead of some stable glacier/etc., so even if the total volume is smaller after melting, the sea gains volume and thus sea level rises.

More moisture in the air also means more severe weather, but it also means more water getting to land. Will arid areas become less arid as a result?
We can't just take the extra water and average it out over the entire globe. Any extra moisture won't be distributed like that. The reason why many arid lands are arid are due to the Hadley cell. Higher temperature also means any water can evaporate faster in arid lands if the air is dry (as it tends to due to the Hadley cell).

With higher levels of CO2, our atmosphere becomes thicker, which means the average temperature will rise. However, does it also mean the temperature will become more constant across the Earth? The Earth's average temperature is about 16 degrees Celsius, so if global temperatures rise but become more constant regardless of location on Earth, will the end result be that the global climate equalizes and ends up more habitable than before?
Why would it become noticeably more constant? The extra CO2 is on the scale of 0.1% of the atmosphere, and in the process of making this, oxygen from the atmosphere has been used. The thickening is tiny if anything and the main reason why CO2 heats the Earth is because it absorbs infrared radiation.

A thicker atmosphere also means more for the plants to turn into oxygen, and thus more for us to breathe. Will we be healthier as a result of the thicker atmosphere?
So far the level of oxygen appears to be constant as far as I know, however the processes that create CO2 by combustion use oxygen in the process. In addition we're destroying many forest areas which you might expect to decrease the oxygen production. However the many processes that create CO2 by combustion also produce countless other harmful gases which cause e.g. smog in cities. Certainly our polluting industries and forms of travel that cause part of the global warming problems are at the same time making the atmosphere more unhealthy.

JMBuilder

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Re: Global Warming
« Reply #241 on: January 02, 2017, 01:43:52 PM »
Hmm... MOAR questions are brewing...

Does climate change mean an increase in the thickness of the cloud layers?

If this is the case, what effect will this have on Earth's albedo?

Darvince

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Re: Global Warming
« Reply #242 on: January 02, 2017, 01:47:04 PM »
Whether we're actually causing climate change or not,
We are causing climate change. Here is a simple explainer on it: https://www.skepticalscience.com/print.php?r=109

I know that this doesn't link rising global temperatures to the rise in ancient carbon expelled from the ground, but keep reading if you want to engage thoughtfully. What it does show, however, is that the ancient carbon we are digging out of the ground and burning is indeed causing the rise in carbon dioxide concentrations in the atmosphere, as the Earth is largely a closed system with the only effective input being solar energy and the only output being radiation loss to space, largely moderated by greenhouse gases, mostly water vapor and carbon dioxide.

You may have heard that the carbon dioxide doesn't matter because the amount of water vapor in the atmosphere is so much greater, but this is simply the first of many different spiralling feedbacks which amplify the amount of warming the planet experiences due to the increase in carbon dioxide concentrations, which is directly caused by coal, oil, and gas burning, when these materials were extracted from ancient rock layers anyway. The amount of water vapor in the atmosphere is largely determined by the carbon dioxide content, meaning that if carbon dioxide is added to the atmosphere, then water vapor will evaporate and increase the global temperature further.

Here is a graphic showing the trend of increasing water vapor in the atmosphere (which is far more noisy than the carbon dioxide signal due to other factors determining how much water vapor is in the atmosphere as well):


is it possible that the ultimate result of it will actually be beneficial to us?
Overall? No. Our society depends on a stable global climate system to continue to function, and moving biomes along with the disappearance of areas along the coastline does not bode well for the future. Some areas will "benefit" in some sick way, for example the taigas of the world, mainly in Canada and Siberia. They will benefit because the taigas will burn up as the areas they are in become too warm to support the high water demand of coniferous trees and the forest stands are replaced with grasslands in drier regions or deciduous forests in wetter regions. These types of land are more easily exploitable and their warmer climate will be more livable for humans.

The obvious issue that people are concerned about are the poles melting and sea levels rising. However, unlike other fluids, water expands when frozen due to the way it forms the crystalline structures of ice. As it melts, it takes up less area than it did when frozen. Does this mean that the flooding wouldn't be as bad as people think?
Water does expand when frozen, however for ice that is sitting on top of the ocean such as ice shelves and sea ice, this is compensated for by the top bit of the ice being above the water when frozen, resulting in no net change in sea levels.

The issue here is all of the water which resides on land. Much of the bedrocks of Greenland and Antarctica rest above sea level, or just below sea level. If more than roughly 10% of the water locked in ice in the column is above sea level, it will raise global sea levels when it melts and joins the ocean. Here are maps of the bedrock of Greenland, and the bedrock of Antarctica.

Since the Antarctic bedrock map does not have a scale, for reference the deepest parts of what are currently West Antarctica are about 2000 meters below sea level, and the highest points beneath the ice are around 3500 meters above sea level.

I am very worried about the glaciers which have their bases resting below sea level, because the mechanics of glaciers which have their bases resting in sea water are much more vulnerable to warming than the mechanics of glaciers whose fronts rest on land. The reason for this is because water carries an enormously larger amount of heat than air, as raising a 1kg parcel of water's temperature to 1C (34F) from the freezing point is the equivalent of raising a 1kg parcel of air's temperature to 36C (97F). Additionally, glaciers resting in water can calve icebergs which melt much faster, whereas glaciers resting on land can only have boulders of ice tumble down their slope or fall apart at the end of the glacier, which is a far slower process. Many of the glaciers which we are presently concentrating on, including Jakobshavn Glacier in Greenland, Petermann Glacier in Greenland, Pine Island Glacier and Thwaites Glacier, an interconnected complex of two massive glaciers in West Antarctica, are resting on bedrock that is below sea level and can therefore calve immense amounts of ice in a short period of time, raising global sea levels much faster than they otherwise would be able to do. There is one more feature to explain the worry: cliff faces. Glacial ice is not held together very strongly, so when there is a tall cliff face on the ocean, say, 500 feet tall, then it will likely collapse very rapidly until it re-achieves stability. The continued warming of the planet means that this point of stability continues to recede into the mountains, and in many cases, disappear entirely.

More moisture in the air also means more severe weather, but it also means more water getting to land. Will arid areas become less arid as a result?
This depends on which arid area you are talking about. In general, yes, they will receive more rainfall, but the rising temperatures will in many cases compensate entirely or overcompensate for this increase in precipitation. There are also arid regions where the amount of rainfall they will receive will decrease, notably the Great Basin and California. The main area which will benefit from increased rainfall is the Outback of Australia, where there are largely two stable states for the continent: a very arid one where the only regions with significant rainfall are around the edges, as it used to be; it is transitioning to a state where the Outback receives copious amounts of summer rainfall from tropical lows and other various thunderstorm activity.

Most water vapor in the atmosphere is evaporated from the ocean, but a significant contributor as well is plant life. Because of plant life, over the short term areas are much more susceptible to irreversible rapid drying than they are to irreversible rapid wetting.

With higher levels of CO2, our atmosphere becomes thicker, which means the average temperature will rise.
The atmosphere does not become thicker, as in increased air pressure, it becomes more opaque in the infrared, causing temperature to rise as more infrared photons are deflected back to Earth than continue out into space.

However, does it also mean the temperature will become more constant across the Earth? The Earth's average temperature is about 13* degrees Celsius, so if global temperatures rise but become more constant regardless of location on Earth, will the end result be that the global climate equalizes and ends up more habitable than before?
Yes! The global temperature will become more constant across the Earth. We can already see this in the Arctic with Arctic amplification this year going off the charts:

And it may become more habitable, but the climate system due to our massive pulse of carbon is trying to reach a new point of stability, which involves lots of melting of land ice, which takes a long time and therefore the instability of the system will continue to increase for the foreseeable future, causing weather to become more variable from year-to-year, not necessarily unpredictable. Also, the climate in the Northern Hemisphere may equalize, however the transition from our current Hadley, Ferrel, and Polar cells to a single Hadley cell is so messy and catastrophic that I and civilization would really prefer if it was avoided, as it is one of those things that could happen that is full of scary unknowns that may make regions that currently hold hundreds of millions of people uninhabitable deserts.

A thicker atmosphere also means more for the plants to turn into oxygen, and thus more for us to breathe. Will we be healthier as a result of the thicker atmosphere?
Again, the atmosphere will not be thicker, it will be more opaque. And yes, plants are and have been converting more and more carbon dioxide to oxygen, giving us a somewhat slower warming than we would otherwise be experiencing. Unfortunately, the form that it is immediately emitted in is carbon monoxide, which uses this chemical equation to turn into carbon dioxide:
2 CO + O2 → 2 CO2
Pure carbon and wasted hydrocarbons are also emitted, resulting in four times the rate of oxygen loss as carbon dioxide gain:
http://scrippso2.ucsd.edu/
There is also a very large unknown over whether phytoplankton in the ocean, which produce over 50% of global O2 content, will continue to decline. In the Pacific Ocean, they have already declined by 30% and show no signs of slowing down.

Finally, the opposite is true. The difficulties in ventilating offices and other buildings will continue to grow as the maximum carbon dioxide level that humans tolerate will not increase while the carbon dioxide level of the atmosphere will continue to increase:
https://www.skepticalscience.com/print.php?n=2724

Darvince

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Re: Global Warming
« Reply #243 on: January 03, 2017, 04:19:06 PM »
Does climate change mean an increase in the thickness of the cloud layers?
The response of clouds to global warming is the least settled part of climate science, and drives almost all of the variability in climate sensitivity models and is the reason for the huge range of outcomes for temperature rise over the rest of the 21st century (for example, AR5 IPCC reported a range of between a temperature increase of +1.1C to +7.2C for the highest path of fossil fuel burning). However, recent research has become available that shows that clouds, mainly stratocumulus over subtropical oceans underneath the great Hadley cell high pressures, will decrease with climate change and result in another spiralling feedback.

Additionally, Arctic and Antarctic cloud cover during polar night traps heat very effectively, increasing with thickness. This is the main driver of Arctic amplification and may be the key to achieving an equable climate with only one atmospheric circulation cell in the Northern Hemisphere. However, thicker cumulonimbus thunderstorm clouds in the tropical latitudes may keep the tropics from heating up too massively, helping along any possible switch to an equable climate.
« Last Edit: January 03, 2017, 04:23:22 PM by Darvince »

JMBuilder

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Re: Global Warming
« Reply #244 on: January 03, 2017, 04:46:05 PM »
Does climate change mean an increase in the thickness of the cloud layers?
The response of clouds to global warming is the least settled part of climate science, and drives almost all of the variability in climate sensitivity models and is the reason for the huge range of outcomes for temperature rise over the rest of the 21st century (for example, AR5 IPCC reported a range of between a temperature increase of +1.1C to +7.2C for the highest path of fossil fuel burning). However, recent research has become available that shows that clouds, mainly stratocumulus over subtropical oceans underneath the great Hadley cell high pressures, will decrease with climate change and result in another spiralling feedback.

Additionally, Arctic and Antarctic cloud cover during polar night traps heat very effectively, increasing with thickness. This is the main driver of Arctic amplification and may be the key to achieving an equable climate with only one atmospheric circulation cell in the Northern Hemisphere. However, thicker cumulonimbus thunderstorm clouds in the tropical latitudes may keep the tropics from heating up too massively, helping along any possible switch to an equable climate.

So we're looking at an overall decrease in Earth's albedo?

Darvince

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Re: Global Warming
« Reply #245 on: January 03, 2017, 06:00:20 PM »
So we're looking at an overall decrease in Earth's albedo?
Yes. I don't remember the magnitude of how much from the abstract (i.e. on the level of a complete loss of Arctic sea ice or the complete loss of the Antarctic ice sheet), but here it is:

http://www.nature.com/nature/journal/v536/n7614/full/nature18273.html

Unforunately it's behind a paywall, so I can't access the full paper.

Darvince

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Re: Global Warming
« Reply #246 on: January 03, 2017, 06:45:10 PM »

blotz

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