What's the deal with global warming?

[radioprius1]

Hi guys,

I'm trying to get a basic understanding of global warming. I've seen Al Gore's video but as I understand it's not accurate.

Basically, as I understand, global warming is occurring, but the debate is whether or not man is contributing to it? The people that say man is contributing to it are measuring CO2 levels, but the other side says that CO2 levels are just correlated but not causal of/with global warming.

Is this pretty accurate?

Thank you
RP1

[T-Dog]

Global warming does and has taken place over the history of earth in a cyclic nature. The difference now being is that since man has entered into the equation the rate of CO2 emission has increased exponentially. CO2 has well been documented, world-wide, and is widely accepted by the scientific community as a major contributor to the greenhouse effect. In the past the warming of the earth took place a result of catastrophic natural expulsions of gases from within the earth ie. volcanic activities of which CO2 was a more minor component. The problem most people have with accepting global warming as a recordable occurrence is that its damn cold in Chicago in October this year. Guess what the more accurate term as it relates to us mere human living in one spot on this earth is Climate Change. That, we can see and feel. Not too many of us have the ability to check overall globe temperature changes and must trust that those making the recordable and observable changes are doing so accurately. It is not some giant mythical leap to associate CO2, a known and growing contributor to the Greenhouse Effect, as a cause to the changes we see. And yes there are other contributing gases to this as well and yes we are contributing many of those as well, just not in the same astronomical rates. If you remember back to your basic Biology classes in high school, we know that plants need and remove CO2 from the atmosphere (unfortunately we seem to be removing those at an astronomical rate as well). So plant and hug a tree and keep driving your Prius.

[tochatihu]

RP1 you already know that this topic is very controversial in the media and across wide swaths of public opinion right? Therefore do not be surprised if what I write below is not accepted here as 'revealed truth' !!

I would start at wikipedia, for example:

Climate change - Wikipedia, the free encyclopedia

Climate_change

Not everyone thinks wikis are high accuracty and neutral, but one must start somewhere. Next there are issues about which we are more or less certain:

Certainly:
Carbon dioxide has increased, 1958 to now. Most of it came from fossil fuel combustion. Half of that stays in the atmosphere, and half is consumed by land and sea biota. Carbon dioxide absorbs infrared re-radiated from the earth. During this time a variety of direct and indirect measurements of temperature and terrestrial heat content have increased. 'How much' is controversial. Some people believe that some of these measurements have been modified, concealed, etc. in an effort to make the situation look more dire than it is. Interglacial is like now, glacial is like 25,000 years ago. CO2 is now 380 parts per million in the lower atmosphere.

Probably:
Prior to that CO2 measurements can only be made indirectly, from ice-core bubbles, isotopic ratios, and other techniques that not everyone accepts fully. But those indicate that CO2 was 180 to 280 parts per million for at least 800,000 years. Cyclic variations in Earth orbit around sun caused small variations in solar energy input, and the climate flipped from glacial to interglacial (8 times). Biospheric changes were thus externally forced and CO2 slightly lagged temperature changes. CO2 increases in the future will (further) alter the earth's energy balance and surface tempertures will rise, 2 to 6 degrees centigrade during the 21st century (this is the central tenent of the IPCC and a variety of agruments are raised against it). Some polar and continental ice will melt; we are not sure how much. Sea level will rise; we are not sure how much.

Maybe:
Even acting aggresively to limit CO2 emissions will not eliminate the possibility of some climate consequences that are outside the range of enviromnets experienced by humans throughout our evolutionary history. Decisions now will influence earth climate (especially second half of this century) but without wide agreement, what will those decisions be?

The above is far from an exhaustive list. After you read the wikis and the governmental agencies and the IPCC, then you can delve into the more or less partisan web sites that focus on these matters; realclimate, climateaudit, Roger Pielke's (not a complete list, others may add more selections).

At the end, you may be firmly convinced that action is critically required. Or that it is a world-domination hoax. Or something in between? Or you may just be thoroughly confused. Just don't expect the road to understanding to be simple! The primary scientific literature is not written for 'civilians'. People on both extremes employ emotional arguments and other tricks of the trade.

Author's opinion:
No way will the Copenhagen meeting (December 2009) lead to binding emissions limtations on any country. If it does, they will not be followed. There is too much money to be made from combustion. For the next decade or two CO2 emissions will continue to increase. We may spend money (lots of money) to increase biological uptake which can greatly reduce the airborne fraction. We will spend money (maybe lots of money) to develop low-carbon energy, but it will take much longer for those to displace fossil fuel combustion. If enough people are sufficiently inconvenienced, we may sped lots of money on geoengineering, which can await later discussion.

Anyway, those alive 20 years hence will be able to grade the current crop of decision makers, and the people who strive to influence them. I hope it turns out OK and I firmly believe that even 'climate sceptics' hope the same thing.

[Felt]

I thank both of the above writers for perhaps the best explanation I have read thus far on the subject. I regret that the issue has become so political ... the politicians really have gotten in the way, IMO. I fear congress is much more interested in increasing taxes (Cap & Tax) than addressing the real issue.

I am doing my part as best I can ... the purchase of a Prius is one contribution; I have certainly become much more aware of my "footprint," but honestly, I see the USA destroying our economy for naught until India and China join the effort.

I feel hyprocacy damages the effort too. It seem the public officials (and personalities) that talk the loudest, have carved out exception for their own excess.

Lastly ... I read that some "experts" claim the global temperature peaked several years ago. Like every (political) issue ... there is no consensus among the "experts."
What is to be believed?

[tochatihu]

I don't think you are obligated to believe either. Certainly not either extreme. Study the matter as far as inspiration takes you, and rest assured that will be much more than average citizen

The only thing that really rankles me is the assertion that carbon-cycle scientists and/or climatologists are in it for the money and they "know" (deep down inside) that it ain't so. I know some of these folks and they are honest, curious and concerned. It is entirely a good thing that research funding is available. I wish there were more (in this field among others).

If 450 ppm or 550 ppm (or pick your number) CO2 does not much alter ecosystem functions, that's great. The research will vastly improve our understanding of the earth and that is great to have if some other thing goes wrong.

On the other hand, if we do get some very uncomfortable climate-related changes, the research will represent our only hope to mitigate. This is a dandy planet for life and there is no good alternative in the general vicinity. We need to make things work here. Really tough to do that, without understanding how the system works.

[TonyPSchaefer]

Originally Posted by radioprius1

I'm trying to get a basic understanding of global warming. I've seen Al Gore's video but as I understand it's not accurate.

Which parts?
One of the best Global Climate Change discussions I've ever had was with a gentleman who had not only seen "An Inconvenient Truth" a few times but was able to discuss - in length - Al's movie and other sources of data, their interpretations, his interpretations, and the latest data. He had personally done his homework and checked each fact to his own satisfaction.

I say this because whenever I hear the phrase "but as I understand" I cringe. Mostly because that phrase is used by people who are quoting hearsay and false allegations to explain why they don't like the Prius.

I'm not trying to come down on you, but like tochatihu said, this is a touchy subject. Depending on the crowd, you will get wildly different answers. This could easily sway your opinions.

[drees]

Originally Posted by Felt

I am doing my part as best I can ... the purchase of a Prius is one contribution; I have certainly become much more aware of my "footprint," but honestly, I see the USA destroying our economy for naught until India and China join the effort.

You may see it that way, but until the population of India/China reaches a standard of living which matches the United States, Western Europe, Japan, and Australia and on a per capita basis starts to even approach the CO2 emissions of the western world on a per capita basis, you will find them very reluctant to do anything.

After all, it goes both ways - they look at the average American and say - "You burn 30x the resources per person that we do. We are entitled to to do the same!"

That is why it is important to lead by example. Not only that, but we can use our resources to develop technologies which benefit us and the world as a whole both in the near term and long term.

Driving the most fuel efficient vehicle you can is a good start - but there's a lot more to be done.

[chogan2]

There's no doubt that the increased atmospheric C02 is man-made. We've got receipts. From statistics of trade we know how much oil, gas, and coal gets sold and burned. Add in a bit for cement production (also well measured), a little for land-use changes (those have to be estimated). What you end up with, each year, is far more than than annual increase in atmospheric C02. Mother Nature remains a net sink for the time being. The carbon is definitely ours.

In addition to getting a grip on the basics, I think it's worthwhile to put a little time into understanding why climate scientists show so much concern about the arctic. It's a good endpoint to study.

Here's the shortcut: The Arctic isn't just a big frozen wasteland. It's a giant meatlocker fully of readily available carbon. If it thaws, it rots. As it rots it offgasses methane and C02. If that happens fast enough, emissions from the arctic would dwarf human emissions, and that that point, that positive feedback (thawing to GHG release to more thawing) would drive the climate to a fairly warm state in a fairly short period of time (read: mostly deserts, little food, population collapse).

Nobody can say for sure at what point, or whether, this will happen. But, interestingly, there are seemingly serious scientists who will hazard guesses like ... 4 to 6 degrees centigrade warmer than we are now. Here's the Secretary of Energy talking about it, about 6:30 in on this youtube video:

YouTube - greenman3610's Channel


If we don't change what we're doing, that level of temperature increase is pretty much a given, if not this century, then next.

So for me, this has gotten pretty simple. Yeah, we're going to have to reduce fossil fuel use drastically sometime. It's ugly, but the alternatives are uglier. It's probably smarter to get started on that sooner rather than later. Having America take the lead in creating clean energy technology beats the hell out of buying it from overseas. So we might as well start now.

[chogan2]

On the "global warming has stopped", the people who say that don't really understand basic statistics and/or they don't understand that many factors can affect one year's temperature and/or they are just out to spread disinformation.

Once again, there's several nice youtube videos on that. Just look 2:30 into the first one, you'll see what you need to see. At 4:00, he illustrates what you can "show" with short trend lines imposed on the temperature time series.

The others are informative as well.

YouTube - greenman3610's Channel

YouTube - greenman3610's Channel

YouTube - greenman3610's Channel

Bottom line: many factors affect one year's temperature. You need to grasp how SLOW the trend rate of warming is. Roughly speaking, call it 0.03 degrees Farenheit per year. Three-hundredths of a degree. But year-to-year random variation in global temperature is much larger than that. (Variation caused by, e.g., volcanic eruptions, or oscillation in the takeup of heat by the oceans, such as the El Nino).

The point is that you need to have a long time period to be able to pick the trend out from the noise -- 30 years is what is hear. I think the Brits may have said 15 years recently. Pick 10 years, being sure to start at a high-outlier year (as 1998 was) and you'll show no upward trend. But it's meaningless -- just noise.

Plus, if the NASA GISS is right, the development of a new El Nino means that 2010 is likely to break the 2005 record. At which point, all the "global warming has stopped" stuff should pretty much die off. It's always dicey to predict temperature in the short term, but the folks at NASA are pretty familiar with the underlying data.

Basically, you've got a slow trend and a lot of year-to-year variation. El Nino/La Nina cycle is a big piece of that variation. NASA seems to be saying that, all other things equal, the next El Nino ought to create a new record.

EDIT: Might as well go ahead and speculate. You can see the actual NASA monthy summary here:

http://data.giss.nasa.gov/gistemp/tabledata/GLB.Ts.txt

Trend has been up all year. If the September value were to hold for the rest of the year, 2009 would come in at 0.74 C above the 1951-1980 average. I think that would make it the second-warmest year on record. If, by contrast, the trend holds, it'll round out to 0.76, making it (tied for) the warmest year on record.

Of course that won't stop people from saying that global warming has stopped, but it should at least provide a ready response.

[darelldd]

This can't be said enough:

That is why it is important to lead by example. Not only that, but we can use our resources to develop technologies which benefit us and the world as a whole both in the near term and long term.

My 4th grader often assumes that if somebody else does something wrong, that she should be able to get away with it too. This is the same reasoning being used regarding India and China. If they get to pollute, then we should get to pollute! The idea that polluting is going to be *good* for our economy is at best rediculous, and at worst, deadly. Not everything that's good for business is good for America.