When is Global Warming Significant?

In summary: Celsius temperature increase. That's still much slower than the 10+ degrees Celsius increase we've been experiencing. 2) The article goes on to say that we're already seeing some effects of global warming, such as an increase in the severity of hurricanes. Even if we stopped emitting greenhouse gases tomorrow, the Earth would continue to warm for many years to come due to the long-term accumulation of greenhouse gases in the atmosphere. In summary, the article discusses the findings of scientists that there is more energy being absorbed from the sun then emitted back to space, which is causing the Earth to warm. Even if we stopped emitting greenhouse gases tomorrow, the Earth would continue to warm for many years to come.
  • #1
Ivan Seeking
Staff Emeritus
Science Advisor
Gold Member
8,142
1,756
This number came up regarding the Permian mass extinction

... The combined temperature rise of 10°C is generally accepted as a figure able to cause truly mass extinction...
http://www.bbc.co.uk/science/horizon/2002/da yearthdied.shtml

I never realized that the threshold was so low.

The rapid rate of warming since 1976, approximately 0.2*C per decade, is consistent with the projected rate of warming based on human-induced effects.

...PETER D. EWINS; CEO, UK Meteorological Office

DR. JAMES BAKER; Under Secretary, US National Oceanic and Atmospheric Administration"
http://www.solcomhouse.com/metnoaa.htm

This also ignores any potential tipping points which could come much sooner.
 
Last edited by a moderator:
Earth sciences news on Phys.org
  • #2
Ivan Seeking said:
I never realized that the threshold was so low.

I've not read the links yet, but I shall shortly. I just thought I'd add something about this figure. When they state figures like these, they generally refer to a global average, where as a more detailed look may see changes much greater than that in some places than others. It is also averaged over the course of a year, and much greater seasonal variability may occur, with more pronounced temperature change between summer and winter for example. The figure of course does not mention the affects it has on the weather- such a temperature change could have numverous and far reaching knock on effects to atmospheric circulation patterns, leading to drought in some places, and flood in others.

I'd also venture that its a bit speculative to simply say that a rise of Xdegrees could cause mass extinction. It would be hard to gague the effects without putting a timescale on it, as species would be capable to some degree at least to adapt to climate change if it happened slowly enough
 
Last edited:
  • #3
Before it will appear significant to the doubters, it will be too late to do anything about it.

juju
 
  • #4
From a PBS program this weekend entitled: "National Geographic's Strange Days on Planet Earth" (The One Degree Factor)
...An entire population of caribou is declining, while other species are pushed to the limits of their physical survival in the oceans.
Even a slight change in temperature is affecting certain species, which in turn effect other species as a part of the food chain.
 
  • #5
juju said:
Before it will appear significant to the doubters, it will be too late to do anything about it.

juju

I think it's going to end up being like the evolution/creation debate. Half of Florida could be underwater and they'll still be going on about how nothing's conclusive.
 
  • #7
So let's keep the discussion on topic by discussing which criteria need to be met in order to speak of global warming. Some suggestions:

Are there local geographical areas that are of particular importance; for instance areas that normally have a very stable temperature profile, where a small deviation can be deemed significant.

Can a defined increase in temperature be used to define global warming, or are the temperatures too variable to draw conclusions.

Is there a certain time frame over which temperatures need to measured, after which conclusions can be drawn.

What would be the design of statistical tests to define significant increases in temperature.
 
  • #8
Climate Warming and Disease Risks for Terrestrial and Marine Biota

Infectious diseases can cause rapid population declines or species extinctions. Many pathogens of terrestrial and marine taxa are sensitive to temperature, rainfall, and humidity, creating synergisms that could affect biodiversity. Climate warming can increase pathogen development and survival rates, disease transmission, and host susceptibility. Although most host-parasite systems are predicted to experience more frequent or severe disease impacts with warming, a subset of pathogens might decline with warming, releasing hosts from disease. Recently, changes in El Nino -Southern Oscillation events have had a detectable inßuence on marine and terrestrial pathogens, including coral diseases, oyster pathogens, crop pathogens, Rift Valley fever, and human cholera. To improve our ability to predict epidemics in wild populations, it will be necessary to separate the independent and interactive effects of multiple climate drivers on disease impact. [continued]
http://www.conservationmedicine.org/papers/Harvell%20et%20al.%202002.pdf
 
Last edited by a moderator:
  • #9
When is Global Warming Significant?

when YOUR HOME IS UNDER WATER

here in south Fla we are low and sinking FIRST
avg elevation under 10 feet [my home is on a ridge at 12+ and that's rare]
 
  • #10
http://www.nasa.gov/vision/earth/environment/earth_energy.html
"Scientists have concluded more energy is being absorbed from the sun than is emitted back to space, throwing the Earth's energy "out of balance" and warming the globe."

When it comes to the original question, all changes are significant. How significant is extremely difficult to decide.
 
  • #11
If anything, I find this extremely encouraging. Why? Two reasons:

1) The discovery of fusion will almost certainly lead to a drop and hopefully an eventual halt to human-induced global warming rates. Even if I were to be extremely pessimistic and say that it's going to take us 100 years to get it working, your quoted rate leads only to a 2 degree rise in temperature, well below the quoted mass extinction level.

2) From what I've heard, humans have already induced a large number of extinctions by way of habitat destruction, hunting, etc. Although I'm never one to celebrate the loss of any life, it seems as if the combined effects of global warming might pale in comparison.

Of course, point 1 assumes that warming rates remain constant, something which is hard to be sure of from either the climatological or sociological standpoint. Even so, however, it seems like there's still quite a lot of breathing room.
 
  • #12
SpaceTiger said:
1) The discovery of fusion will almost certainly lead to a drop and hopefully an eventual halt to human-induced global warming rates.
How about the discovery of fission?
 
  • #13
hitssquad said:
How about the discovery of fission?

Are you nitpicking my wording or being serious? In any case, for those who aren't sure, I'm referring to the use of fusion for power generation, not its discovery as a phenomenon.
 
Last edited:
  • #14
SpaceTiger said:
I'm referring to the use of fusion for power generation
What advantages might it have over fission?
 
  • #15
hitssquad said:
What advantages might it have over fission?

I think http://www.pppl.gov/fusion_basics/pages/fusion_advantages.html sums it up pretty well.
 
Last edited by a moderator:
  • #16
No High-level Nuclear Waste
Similarly, there will be no fission products formed to present a handling and disposal problem. Radioactivity will be produced by neutrons interacting with the reactor structure, but careful materials selection is expected to minimize the handling and ultimate disposal of activated materials.
Remember the caveat!

First of all, we do not yet have a feasible commercial reactor design, so one cannot for now minimize this issue.

As for an accident, the radiological inventory of a fusion reactor certainly appears much less than a typical commercial reactor. On the other hand, after 20 years in the nuclear industry, I hesitate to minimize the issue.

===============================

But this thread is about global warming, specifically "When is Global Warming Significant?". Well it could be significant now - given all the weather related disasters like hurricanes, tornadoes, floods etc that have happened during the last decade. Then consider the droughts and continued desertification in various parts of the world.

Warm weather also allows for more undesirable insects like mosquitos to thrive. I think Ivan's last post is particularly relevant and disconcerting.
 
  • #17
Astronuc said:
As for an accident, the radiological inventory of a fusion reactor certainly appears much less than a typical commercial reactor. On the other hand, after 20 years in the nuclear industry, I hesitate to minimize the issue.

Perhaps this should be a separate thread, but I'm curious about your viewpoint on the safety of nuclear power. Do you think the public is being overly paranoid or do you think the concerns are well justified? I'm not familiar enough with the current safety standards to have a strong opinion on it.
 
  • #18
SpaceTiger said:
Perhaps this should be a separate thread, but I'm curious about your viewpoint on the safety of nuclear power. Do you think the public is being overly paranoid or do you think the concerns are well justified? I'm not familiar enough with the current safety standards to have a strong opinion on it.
It would appear so far that commercial nuclear power is generally safe, with the exception of Chernobyl.

I don't think the general public really understands nuclear power, and for that matter, the general public does really understand most technology.

I simply hesitate to minimize the safety issue. Not long ago, the folks at Davis Besse found that some of the carbon steel pressure vessel head had corroded away, and only a 3/8" stainless steel liner was holding back 2230 psi of reactor coolant water. Had that failed, then we would have had a LOCA event, and then we would have found out how well the safety systems would perform, how well the training prepared everyone involved, and how well the containment would have confined the problem.

http://www.nrc.gov/reactors/operating/ops-experience/vessel-head-degradation.html

I should point out that the plant personnel were aware of a leak and had planned to inpsect the head. Ideally, they should have inspected more thoroughly during the previous refueling outage, but there was a lot of pressure to get the plant back online.

As for fusion reactors, I am not sure how to assess the radiological hazard or an accident scenario. I was trying to think back a couple of decades to the concepts that were proposed and what type of accidents might be of concern, such as a confinement magnet failing and the consequences of such a failure.

I had ordered two books on Fusion Research, but the order was canceled so I will have to look elsewhere for some system designs.

Current nuclear plants have safety systems, such as Emergency Core Cooling Systems (ECCS). Then there are the structure like the containment building, which is designed to withstand postulated accidents.

Then as part of the operation, there is training of personnel, and there are periodic inspections and testing of various systems, much more than was the case when TMI happened, and all as a result of TMI.

Is that enough? Probably. Nevertheless, I simply hesitate to dismiss safety concerns.
 
Last edited by a moderator:
  • #19
Astronuc said:
Is that enough? Probably. Nevertheless, I simply hesitate to dismiss safety concerns.

Oh yes, that was very interesting, thank you.
 
  • #20
Oops. SpaceTiger, please excuse me, but when I wrote, "It that enough?", I was referring to the steps taken to ensure safety in commercial nuclear plants:

Current nuclear plants have safety systems, such as Emergency Core Cooling Systems (ECCS). Then there are the structure like the containment building, which is designed to withstand postulated accidents.

Then as part of the operation, there is training of personnel, and there are periodic inspections and testing of various systems, much more than was the case when TMI happened, and all as a result of TMI.

Otherwise, I would have addressed you directly with something like, "Have I answered your question to your satisfaction?"

The key question is - "Has the nuclear industry, specifically the operating utilities, suppliers of the technology and regulators done enough to ensure the safe operation of nuclear power plants?". Obviously, those opposed to nuclear will power will summarily argue, NO. Proponents will argue, YES.

If one argues, YES, then one can ask, "How do know that operating power plants are safe?" Simply saying the event at TMI-2 did not result in harm to the public (other than severe emotional distress for a lot of folks) is not enough to prove that nuclear power is inherently safe, or that other plants are not at risk for a catastrophic event that may compromise the safety of the plant personnel or public.

We demonstrate safety by a sustained program of inspection and training, and monitoring the performance of materials and systems during operation.

Take for example the steam generators (SGs) in many PWRs. The principal material for SG tubing was Inconel 600. The SGs and the tubes were designed with the intent of operating for the lifetime of the plant (40 yrs). However, in the mid 1980's, the rate of failure of SG tubing started to increase, particularly in high temperature PWRs (Thot > ~ 320°C). The Inconel 600 tubing was failing after about 15-20 years, and many PWRs have had to replace the SGs, at costs on the order of $50-100 million/SG. The safety issue was related to the reactor coolant (with some level of radioactivity) escaping from the primary system and entering the secondary system.

On the BWR side, cracks were found in certain internal structures that were supposed to operate for the life of the plant. The cracks were caused by Intergranular Stress Corrosion Cracking (IGSCC), which was related to the electrochemical potential (ECP) and oxygen potential of the reactor coolant environment in which the stainless steel components were operating. Remedial steps have been taken to address this issue.

Many plants still have years, and in some cases decades of operation, even without the industry trend to 'extend' operation of many plants to 60 years. The major issue is "can we ensure 'safe' and reliable operation?"

I am hopeful, but cautious.

========================

Now, the question of this thread, is when is Global Warming Significant? Well, if Global Warming is now the cause of more floods and storms that cause an increase in destruction of property and loss of life, and drought, then it would seem that it is significant now.

There are two questions however:

1) What is the precise cause of global warming - a) is it a natural process? or b) is it due to man-made greenhouse gases?

2) If global warming is a 'significant' problem, what steps 'must' be taken to mitigate / remediate the problem.
 
  • #21
Astronuc said:
Oops. SpaceTiger, please excuse me, but when I wrote, "It that enough?", I was referring to the steps taken to ensure safety in commercial nuclear plants

Ah yes, sorry. I'm a bit sleep deprived. :tongue2:
 
  • #22
With that diversion, come back on topic.
Bjørn Bæverfjord said:
When it comes to the original question, all changes are significant. How significant is extremely difficult to decide.
I don't see how all changes are significant: you first need to establish what range is normal.
 
  • #23
What about now? Well consider -

http://news.yahoo.com/s/usatoday/20050505/ts_usatoday/fruitfarmswitheringinnorthwestdrought
By John Ritter, USA TODAY
Thu May 5, 6:15 AM ET

To farmers like Ric Valicoff, the economics of drought are depressingly familiar. Four dry years in the past 13 have scorched their balance sheets and got them wondering whether there's something to the global warming hype.

Growers here in apple country are scrambling to find alternative water supplies as a drought that has eased in much of the West lingers in the Pacific Northwest. Even Seattle, capital of wet, urged residents last month to conserve water in case of summer shortages.

"We're all making tough decisions," Valicoff says. "There won't be much of a bottom line this year if you've been following apple prices." He and 1,400 other farmers in the Yakima Valley's Roza Irrigation District will get about a third of their normal water quota.
Is this due to Global Warming? Maybe, maybe not. Is it just random?
 
Last edited by a moderator:
  • #24
Astronuc said:
What about now? Well consider -

http://news.yahoo.com/s/usatoday/20050505/ts_usatoday/fruitfarmswitheringinnorthwestdrought
By John Ritter, USA TODAY
Thu May 5, 6:15 AM ET

Is this due to Global Warming? Maybe, maybe not. Is it just random?

That's the problem. AFAIK, there is no way to tell; and there won't be. We can only say whether or not observations are consisted with the weather models; and apparently they are so far. I also heard recent reports of signficant reductions in the flow of the deep ocean currents. I don't know yet if this is an early unsubstantiated report, or an established fact. But this is certainly one thing to watch.
http://www.firstscience.com/site/articles/gribbin.asp
http://www.sciencedaily.com/releases/1998/08/980814064519.htm
http://www.whoi.edu/institutes/occi/currenttopics/climatechange_wef.html
 
Last edited by a moderator:
  • #25
Ivan Seeking said:
I also heard recent reports of signficant reductions in the flow of the deep ocean currents.
Since when have they been measuring deep ocean currents?
 
  • #26
I don't know.

I don't know yet if this is an early unsubstantiated report, or an established fact. But this is certainly one thing to watch.

This may be related to some recent ocean surveys, but I only know for now what I heard as a news report. I will post anything that I find. Maybe someone else knows about this?
 
  • #27
Ivan Seeking said:
I don't know.
So how significant is the finding, I would take the guess that technology has not been around too long to be able to measure such currents. If you don't know what the background is, you can't interpret the data.
 
  • #28
Monique, I mentioned it as something to look into. You are debunking a clam that hasn't even been made. Your bias is painfully obvious.
 
  • #29
I also suggest that the US Navy [Submarines] probably know quite a bit about deep ocean currents.
 
  • #30
Ivan Seeking said:
Monique, I mentioned it as something to look into. You are debunking a clam that hasn't even been made. Your bias is painfully obvious.
The topic of discussion is about what is significant, excuse me for addressing it.
 
  • #31


Lamont's Broecker Warns Gases Could Alter Climate
Oceans' Circulation Could Collapse
Columbia University Record - VOL. 23, NO. 11 DECEMBER 5, 1997

On the eve of the international meeting on global warming that opened Dec. 1 in Kyoto, Japan, one of the world's leading climate experts warned of an underestimated threat posed by the buildup of greenhouse gases—an abrupt collapse of the oceans' prevailing circulation system that could send temperatures across Europe plummeting in a span of 10 years.

If that system shut down today, winter temperatures in the North Atlantic region would fall by 20 or more degrees Fahrenheit within 10 years. Dublin would acquire the climate of Spitsbergen, 600 miles north of the Arctic Circle.

"The consequences could be devastating," said Wallace S. Broecker, Newberry Professor of Earth and Environmental Sciences at Columbia's Lamont-Doherty Earth Observatory, and author of the new research, which appeared in the Nov. 28 issue of the magazine Science.

A complex of globally interconnected ocean currents, collectively known as the Conveyor, governs our climate by transporting heat and moisture around the planet. But the Conveyor is delicately balanced and vulnerable, and it has shut down or changed direction many times in Earth's history, Broecker reports. Each time the Conveyor has shifted gears, it has caused significant global temperature changes within decades, as well as large-scale wind shifts, dramatic fluctuations in atmospheric dust levels, glacial advances or retreats and other changes over many regions of the Earth, he said.
Some background -
Ocean Currents and Climate

Deep Water Circulation

Presumably some institutions (e.g. Columbia, USC, Scripps, etc) are measuring the variables such as temperature, salinity, flow, etc in order to determine if the Conveyor system is being undermined (?)
 
  • #32
About ocean currents, the notion of a slowing conveyor belt is not that new. Another idea is the heat storage capacity of the oceans and the long delay caused by the deep circulation in which case the current warming of the ocean is all about natural cycles and nothing about human influence. But whatever the cause of warming is, there may or may not be some significant impact.

Incidentely, someone said:
Your bias is painfully obvious.

I assume that it is an 'ad hominem' to point out that this is an 'ad hominem'. So I'll limit myself to the observation that it appears to be difficult to see any significance of this statement to the current topic.
 
Last edited:
  • #33
But then again, how much have the oceans warmed?

http://www.nodc.noaa.gov/OC5/PDF/PAPERS/grlheat05.pdf

During 1955–1998 world ocean heat content (0–3000 m) increased 14.5 10^22 J corresponding to a mean temperature increase of 0.037C.

That's a staggering ~0,1C per century. That way it takes another ten millenia (linear extrapolation) before global warming is getting significant.

I wonder why I'm debunking the 7-10 degrees warming-per-decade myth of the ice ages in the other thread.
 
Last edited by a moderator:
  • #34
If global temperature(s) continues to rise, does that mean that the troposphere will contain more water vapor?
 
  • #35
I'm afraid that this question is off topic in this thread. But if you start another one we could analyse the different assessments of the role of water vapor on the climate.
 

Similar threads

Replies
2
Views
4K
Replies
58
Views
11K
Replies
9
Views
27K
  • General Discussion
Replies
2
Views
4K
  • General Discussion
Replies
29
Views
9K
Back
Top