Study: Earth hottest in 400 years

[CFLarsen]

The Earth is the hottest it has been in at least 400 years, probably even longer. (http://www.cnn.com/2006/TECH/science/06/22/global.warming.ap/index.html)

The National Academy of Sciences, reaching that conclusion in a broad review of scientific work requested by Congress, reported Thursday that the "recent warmth is unprecedented for at least the last 400 years and potentially the last several millennia."

A panel of top climate scientists told lawmakers that the Earth is running a fever and that "human activities are responsible for much of the recent warming." Their 155-page report said average global surface temperatures in the Northern Hemisphere rose about 1 degree during the 20th century.

The report was requested in November by the chairman of the House Science Committee, Rep. Sherwood Boehlert, R-New York, to address naysayers who question whether global warming is a major threat.

Quousque tandem....?

[Rustle]

Clearly its a 401 year cycle. Its fine. CO2 is life.

[TV's Frank]

I've been monitoring your body temperature recently. It is the hottest it's been in the last few seconds, and maybe even an hour. This spells doom.

[casebro]

SOoo, it was hotter than this 400 years ago, without any AGW. It was hotter than this 2,000 years ago, without AGW (but with the heat from a bright star over Bethlehem?). The past couple years show a cooling trend...

[Jimbo07]

I've been monitoring your body temperature recently. It is the hottest it's been in the last few seconds, and maybe even an hour. This spells doom.

Nope...

... but it could be the onset of a fever.

[Overman]

Nope...

... but it could be the onset of a fever.


which could be the symptom of a much more serious virus or diease...

[Aepervius]

SOoo, it was hotter than this 400 years ago, without any AGW. It was hotter than this 2,000 years ago, without AGW (but with the heat from a bright star over Bethlehem?). The past couple years show a cooling trend...

Firstly you have to look over average and over period of time. In absolut this is terribly incorrect to look at a year. There will always be variation up and down from a year to the next. Secondly the reliable data if you read the article only goes back to 400 years. Thirdly it might have been gotten hotter 2000 years ago, but temperature changed slowly over a long period of time. In the last 100 years it changed very quickly only in one direction (for the trend). And that is what make everybody afraid. Especially if the trend continue for, say, 100 years.

Every climatologue say the global warnming is a reality. What is disputed, and nobody has a definitive say on it, is whether this warming is anthropomorphic or not.

[Stellafane]

Studies apparently show that the earth has gone through periodic warming and cooling trends for far longer than humans have been around. Thus there's no definite proof yet that this latest trend is necessarily due to us (or more precisely, the effect our civilization has on the atmosphere).

What is not in dispute, however, is that (1) the CO2 content in the atmosphere is currently at its highest known level in the history of the planet (over 400 parts per million according to the latest measurements); (2) this level has risen dramatically since the Industrial Revolution (over 100 PPM); (3) no known natural sources of this increased CO2 (such as a global rise in volcanic activity) exists; and (4) in the past, whenever the CO2 level has been elevated near this level (as happened during the Mesozoic), the earth has undergone dramatic warming (no polar ice caps, etc.).

Given 1, 2, 3, and 4, I have a very difficult time not accepting that we're responsible for this latest warming trend, and that this trend will continue to warm the planet significantly for the foreseeable future, resulting in dramatic changes to the weather, climate, and environment. Other possibilities can't be ruled out of course -- it would probably require the proverbial proving of a negative to do so, not to mention more climatological predictive power than we possess at the moment -- but given the potential risks involved, I just can't see how any prudent and knowledgable individual would advocate for any other conclusion.

[Overman]

Given 1, 2, 3, and 4, I have a very difficult time not accepting that we're responsible for this latest warming trend, and that this trend will continue to warm the planet significantly for the foreseeable future, resulting in dramatic changes to the weather, climate, and environment.


I don't know about responsible for the latest warming trend....much more likely we are major contributers.

Either way something has to be done. I started digging my hole yesterday.:o

[TV's Frank]

What is not in dispute, however, is that ...

I dispute that those statements are not disputed.

[Red Siegfried]

What is not in dispute, however, is that (1) the CO2 content in the atmosphere is currently at its highest known level in the history of the planet (over 400 parts per million according to the latest measurements); (2) this level has risen dramatically since the Industrial Revolution (over 100 PPM); (3) no known natural sources of this increased CO2 (such as a global rise in volcanic activity) exists; and (4) in the past, whenever the CO2 level has been elevated near this level (as happened during the Mesozoic), the earth has undergone dramatic warming (no polar ice caps, etc.).

Well, I would agree with you on at least the first three points, but I'm not sure that these high levels of CO2 are really making a big difference in the warming that is occurring.

Roger Pielke says in this study that of the current warming, only 26.5%-28% of it is attributable to atmospheric carbon dioxide.

So you take one of the commonly accepted estimates that says that we are getting a 0.6 ± 0.2 °C temp rise that would be 6/10 x 28/100 = ~0.17 ± ~0.06 °C. Not too much.

http://climatesci.atmos.colostate.edu/2006/04/27/what-fraction-of-global-warming-is-due-to-the-radiative-forcing-of-increased-atmospheric-concentrations-of-co2/

Of course, other studies may have different data. But regardless of how much global warming is going on and whether mankind is causing it, I would encourage people to find potential solutions that do not involve raising someone's taxes (the universal government solution to everything) or decreasing anyone's standard of living. I think we're smart enough to solve any potential global warming problem without resorting to that. Unfortunately, some people can't resist politicizing this possible problem.

And by "politicizing" I mean blaming America and looking for a solution that will hurt America the most.

It's sad that the quest for real knowledge is less important to some people than finding another way to punish those more fortunate than themselves.

[Stellafane]

I dispute that those statements are not disputed.

Really? Which one(s) do you think are open for dispute? The fact that the current level of CO2 in the atmosphere (over 400 PPM) is the highest ever recorded? The fact that this level has risen dramatically since the onset of the Industrial Revolution? The fact that there are no known natural sources for this CO2 increase? Or the fact that past high levels of CO2 in the atmospere generally coincide with warmer global temperatures?

Sorry, but I'm pretty certain all four statements are generally accepted as scientific fact. Whether or not they apply to the current warming trend, and whether or not they necessarily mean that humans are responsible for it (or whether "global warming" itself as currently defined is an entirely legitimate concept), is certainly a matter of debate. But I don't think the four facts I've cited are.

[Aepervius]

And by "politicizing" I mean blaming America and looking for a solution that will hurt America the most.

It's sad that the quest for real knowledge is less important to some people than finding another way to punish those more fortunate than themselves.

Blaming America for CO2 level is not that unfounded when you look at the CO2 quantity in absolute or per head. For the "past" in the very end it does not matter, because even if the cause of GW is anthropomorphic, it was "unknowingly" that it was done. So IMO the blame for the past is stupid. Now taking the blame for the unwillingness to change the future IS founded. The economical argument is a bloody short sighted one when half your coast will be submerged in a very short term (on a climat scale. Medium term on human scale).

As for limiting the Co2 level it is IMO a good things now to reduce the polution level of our city. And they are way to reduce the CO2 without damaging economy (coal electrical production central => something else like nuclear).

Finally just a word, I read recently in certain blog/article that climatologue says, that anyway, we should concentrate on solution for the side effect of GW, rather than limiting CO2 because it is quite too late. Which is more scarying in a certain way than any thing else.

Frankly by now I am so misanthrop and disappointed by humanity, that I do not care anymore as long as the effect of GW comes after my death of old age...

[Stellafane]

Well, I would agree with you on at least the first three points, but I'm not sure that these high levels of CO2 are really making a big difference in the warming that is occurring.

Roger Pielke says in this study that of the current warming, only 26.5%-28% of it is attributable to atmospheric carbon dioxide.

So you take one of the commonly accepted estimates that says that we are getting a 0.6 ± 0.2 °C temp rise that would be 6/10 x 28/100 = ~0.17 ± ~0.06 °C. Not too much.

http://climatesci.atmos.colostate.edu/2006/04/27/what-fraction-of-global-warming-is-due-to-the-radiative-forcing-of-increased-atmospheric-concentrations-of-co2/

Of course, other studies may have different data. But regardless of how much global warming is going on and whether mankind is causing it, I would encourage people to find potential solutions that do not involve raising someone's taxes (the universal government solution to everything) or decreasing anyone's standard of living. I think we're smart enough to solve any potential global warming problem without resorting to that. Unfortunately, some people can't resist politicizing this possible problem.

And by "politicizing" I mean blaming America and looking for a solution that will hurt America the most.

It's sad that the quest for real knowledge is less important to some people than finding another way to punish those more fortunate than themselves.

I hear what you're saying about "politicizing" the issue. But personally, I can't get my mind past the fact that everything I've ever read on the subject has indicated a very strong positive correlation between high carbon dioxide levels and high global temperatures. And the fact that the CO2 level is higher than it's ever been in the history of the Earth. And it's not just some bald coincidence; the mechanism for how a greenhouse gas like CO2 can trap solar heat and raise worldwide temperatures is very well understood and articulated.

In fact, I think it's too late. I think the damage is already done. We've injected ourselves with the drug, now we're just waiting to observe the consequences. The CO2 level is so high, I believe it must have an effect, even if we stopped cutting down trees and burning fossil fuels tomorrow. I think any measures we take now might mitigate further changes, but they are inevitably coming.

As to what those changes are, I have no idea. I've seen everything from Massachusetts becoming sub-tropical to a new ice age, depending on what model you want to believe. But I know just enough about climatological systems to be dangerous, and I think by stretching one value so far out of whack (CO2 content), the entire system becomes unstable and will break down, to be replaced by something else that can accommodate the heightened CO2. What that new system might be, who knows. It might benefit billions of people for all I know (more rain in the American deserts, milder winters in Canada and Russia). Or it might be catastrophic (although certainly nor "Day After Tomorrow" stuff).

I'm concerned that the very legitimate discussion about what this means and what if anything should be done about it will overwhelm the accepted scientific knowledge. Future ice ages and rising sea levels are matters of speculation and debate. Measurable CO2 levels and what they've historically meant to global temperatures are not.

*Edited to fix stupid typo.

[Red Siegfried]

Blaming America for CO2 level is not that unfounded when you look at the CO2 quantity in absolute or per head. For the "past" in the very end it does not matter, because even if the cause of GW is anthropomorphic, it was "unknowingly" that it was done. So IMO the blame for the past is stupid. Now taking the blame for the unwillingness to change the future IS founded. The economical argument is a bloody short sighted one when half your coast will be submerged in a very short term (on a climat scale. Medium term on human scale).

That's about as much circular reasoning and begging the question as I'm willing to take today. Now I remember why I usually avoid these debates.

[CFLarsen]

which could be the symptom of a much more serious virus or diease...
But is it?

We have a scientific theory, backed by a rapidly body of growing evidence.

What do you have?

[Red Siegfried]

I hear what you're saying about "politicizing" the issue. But personally, I can't get my mind past the fact that everything I've ever read on the subject has indicated a very strong positive correlation between high carbon dioxide levels and high global temperatures. And the fact that the CO2 level is higher than it's ever been in the history of the Earth. And it's not just some bald coincidence; the mechanism for how a greenhouse gas like CO2 can trap solar heat and raise worldwide temperatures is very well understood and articulated.

And I understand where you're coming from too. It's just that we disagree on which data are significant. I prefer to err on the side of not unduly setting back human progress or anyone's standard of living when the conclusions are uncertain. You think (I guess) that it's too big a chance not to take to do something about it, even if the consequences have some negative aspects, which is also reasonable.

The big questions as I see it and my opinions on them:

1. Is GW real? (I say yes).
2. Is it a problem? (I say no.)
3. Is it something we can change? (I say no.)
4. At what price? (I say it's not worth it at any price because it's not a problem.)

All of us have our own takes on these questions based on our knowledge about global warming as well as other factors (which would start a politics debate so I won't go there).

[Rob Lister]

I concur with the bionic bigfoot. confince me 1) it is a problem, 2) it is something we can change, and then I'll dicker on price. Is the cure worse than the supposed disease? Is the cure worse than than a disease than may not even be?

Guess I'm not in the running for UN funding.

[Stellafane]

The big questions as I see it and my opinions on them:

1. Is GW real? (I say yes).
2. Is it a problem? (I say no.)
3. Is it something we can change? (I say no.)
4. At what price? (I say it's not worth it at any price because it's not a problem.)


And for my part (whatever it's worth):

1. Is GW real? (I say yes).
2. Is it a problem? (I say it might be. It also might be beneficial. It also might be a problem for some, and beneficial to others. But it's not something we can ignore.)
3. Is it something we can change? (I say not in the short or intermediate term, but probably in the long term.)
4. At what price? (This is the question that I myself have no answer for. But again, I don't believe it can be safely ignored.)

[Rob Lister]

Well, so you seem to be in the same situation as me. It might be a problem, it might fixable, and we don't know if the cure is worse than the disease that may not exist and may not be curable anyway.

Let's throw some worthless CO2 credits at it and see if that helps.

[patnray]

I prefer to err on the side of not unduly setting back human progress or anyone's standard of living when the conclusions are uncertain.
I see you're a glass half empty kind of person. I see it as half full: mitigation of CO2 emissions is a huge economic opportunity. Your statement assumes (without justification) that people can not solve the problem without reducing their standard of living. I have faith in human ingenuity and ambition and believe we can reduce emissions and raise our standard of living at the same time. If we deny the problem and don't encourage development of solutions we will be left behind. I'd prefer that this country set a goal of becoming world leaders in new technolgies, otherwise we'll be buying those technologies from some one else.

Just this week I read that a company is planning a new factory to produce solar cells that will double the US capacity. Even so we'll still be behind Japan...

When the US sought to reduce chloroflurocarbon use via a stiff tax on CFCs, some companies took your approach and bemoaned the economic impact. They were soon scrambling to catch up because their competitors saw an opportunity and developed aqueous based cleaning solutions for electronic circuits (a major use of the CFCs) that worked BETTER than using CFCs and was cheaper (even before the tax).

I reject your assumption that mitigating emissions requires an economic penalty. We will suffer most if we fail to rise to the challenge.

[Interesting Ian]

But regardless of how much global warming is going on and whether mankind is causing it, I would encourage people to find potential solutions that do not involve raising someone's taxes (the universal government solution to everything) or decreasing anyone's standard of living.

Absolutely incredible. No we just do what it takes. The very last thing we should be concerned about is raising peoples' taxes.

[Ginarley]

Hey everyone - first post so Hi!

As for GW, I think it IS real, it IS going to be a problem (mid-long term) but the fact remains that the only potential solution is to cut GHG emission. It doesn't really matter whether GHGs are actually the cause of increased temperatures or not, it is the only anthropocentric cause we can see that is potentially avoidable so not doing anything about it doesn't make sense. If GHG emissions are not the cause and temperatures grow anyway we're still screwed, it is just not out fault lol.

However I think our motivation for doing something about it is going to come much sooner more urgently, and from an entirely different direction. Fossil fuels are all facing peaking production within the next 20-30 years, and while I doubt we will run out soon, prices are going to get very high, and keep climbing, and in the not to distant future. It is not just oil, gas faces a similar problem, and in fact outside the fossil fuels, Uranium also faces a similar problem. There are solutions to all these problems but there is no way that any Government in the world is realistically going to do anything meaningful about these problems. So the world faces a very real economic disaster in the not too distant future.

Therefore while global warming is an issue, and the only possible thing that humans can do is try and avoid emitting GHGs to prevent it, the motivation to do so perversely is going to come from an entirely different direction, and quite probably will cripple several most of the world powers in the process.

A lot of environmentalists try and discard the economy saying the environment matters more - that may be so but our biggest challenge of the 21st century is to avoid a massive economic disaster, not environmental or other issues which aren't going to hurt us until well after the economic disaster does.

Just my 2c

Cheers
Ian

[athon]

My opinion on GW:

As already stated, if the entire history of average global temperatures was laid out to see, there is little dispute that there would be a trend over the past few hundred years where the squiggly line would be kicking up. Yes, it is on average warmer now than it was before. And significantly I don't think any one cause can be to blame in a complicated system such as global temperature.

Could the actions of man (BTW, people, small nitpick here, but the word is 'anthropogenic', meaning 'man made') be responsible? Wrong question. It's 'how much effect has the behaviour of humanity over the past few centuries affected global temperatures?'. The answer is, we don't know. To say we are fully responsible for the earth's temperature rise is ignorant of a range of other influences. To say not at all is to ignore what we know about greenhouse gases. How all of this works together is hard to pin down at this point, although evidence is slowly gathering which makes the picture a little more clearer each year.

The actual temperature rise itself is of smaller concern than the admitted ignorance on what it could trigger in rapid environmental change. Evidence is scant here, and we can only speculate.

The truth is, environments do change. And they will, with or without human intervention. We need to understand how, and what we can do to minimise the negative impact of either gradual or rapid environmental changes. Therefore, one positive consequence of focussing on the GW issue is we bring attention to the need to understand how our global climate system changes.

The other issue is whether we should alter our behaviour to prevent possible negative rapid environmental changes. Again, I think we need to look at this in a slightly different way. Will changing out behaviour ultimately be beneficial regardless of rapid environmental change?

I believe so. Sustainable energy development is inargubaly superior to relying on sources that are being consumed faster than they are being created. For humanity to grow and develop, it needs to be aware of the existence of resources in the long term. Potentially making any form of development and lifestyle satisfaction difficult for future generations is irresponsible.

The debate is far from clear, but I cannot see why this should prevent us from progressing towards more sustainable resources and technology in the future.

Athon

[Soapy Sam]

http://en.wikipedia.org/wiki/Global_dimming

What's needed, obviously, are more Brights...

I can't get excited about learning the world is hotter than it has been since the start of the Little Ice Age.

[gumboot]

We know the earth has cycles of cold weather - in the form of ice ages. There seems to be enough regularity to these periods of cold to assume that they are a natural part of a circular system, rather than events that only occur because of outside forces.

Would it not be logical to assume that this pattern is some sort of S-curve? And that between each of these ice age troughs there is a "hot-age" crest?

Another question. How do we know the world's eco system is fragile? We have plenty of solid evidence of utterly devastating world events throughout its history. But I see no evidence that life was wiped out and had to start again at any point.

I would propose that the earth's eco system is incredibly robust. It will adapt to whatever changes - be they a natural cycle or caused by outside events.

The question, obviously, is which particular species' will survive with the earth? I am betting man will. Many others may not. Well, that's how life works, isn't?

We have evidence of "heating up" on earth dating back much further than any industrialisation. The Ancient Romans, for example, cultivated what is now the Sahara Desert. But no other regions the Romans cultivated turned into such arid desert. So was that a case of humans stripping the land clean? Or was it simply a natural result of a gradual change in climate?

Having said that. Even if there were absolute proof that humans were not having any affect on the environment, if we *can* reduce the toxins and what-have-you that we're putting into the system, we might as well...

-Andrew

[Soapy Sam]

We know the earth has cycles of cold weather - in the form of ice ages. There seems to be enough regularity to these periods of cold to assume that they are a natural part of a circular system, rather than events that only occur because of outside forces.

Some at least of the reasons for such fluctuations are known. Google Milankovitch Cycles. Not sure what you mean by "outside forces". Solar output fluctuation perhaps?

Would it not be logical to assume that this pattern is some sort of S-curve? And that between each of these ice age troughs there is a "hot-age" crest?
Only in very general terms. It really is a lot more complex than that, partly due to inertia in the system (hysteresis), partly because the mechanisms feed back into one another . eg the Younger Dryas glaciation was possibly caused by land ice melting during a warm phase, flooding the N.Atlantic with cold water and disrupting the N.Atlantic drift, causing a sudden plunge back into a cold phase.

Another question. How do we know the world's eco system is fragile? We have plenty of solid evidence of utterly devastating world events throughout its history. But I see no evidence that life was wiped out and had to start again at any point.

Well, the Permian extinction was pretty rough, for one. The reason the evidence is "solid" is because the climate change on land was global and lasted far longer than anything remotely human has existed. The ecosystem recovers, but on timescales that dwarf all human history. We really don't want to go that route.

I would propose that the earth's eco system is incredibly robust. It will adapt to whatever changes - be they a natural cycle or caused by outside events.

Yes, but said adaptation might include the extinction of Hom.sap. (This bothers some folk less than others.)

The question, obviously, is which particular species' will survive with the earth? I am betting man will. Many others may not. Well, that's how life works, isn't?

Yes indeed. I don't think anyone believes humanity could not survive - the concern is that faced with the need to adapt fast, some folk might decide they need someone else's lebensraum with all the usual consequences.

We have evidence of "heating up" on earth dating back much further than any industrialisation. The Ancient Romans, for example, cultivated what is now the Sahara Desert.
Really? I 'm not sure that's what Cato meant by "ploughing Carthage with salt."
But no other regions the Romans cultivated turned into such arid desert. So was that a case of humans stripping the land clean? Or was it simply a natural result of a gradual change in climate?

I think you have this one wrong. What's your source?
ETA- The Sahara was certainly much wetter in the past, but well pre-Roman times. I have several arrowheads I found deep in the Algerian Sahara. They were used for hunting waterfowl and lost in reeds surrounding a lake. Not sure of the age, but I think 3-4000 bp.

Having said that. Even if there were absolute proof that humans were not having any affect on the environment, if we *can* reduce the toxins and what-have-you that we're putting into the system, we might as well...

Absolutely. I am far from convinced that the present warming trend is a result of human action. (Though perhaps not so far as I used to be). Still, it makes sense not to be profligate with limited resources. Only a fool soils his own nest. China's "one child" program may have been the biggest positive step any country has taken towards true conservation, but those only children are now growing up and asking for a car.

-Andrew
. .

[Red Siegfried]

I see you're a glass half empty kind of person. I see it as half full: mitigation of CO2 emissions is a huge economic opportunity. Your statement assumes (without justification) that people can not solve the problem without reducing their standard of living. I have faith in human ingenuity and ambition and believe we can reduce emissions and raise our standard of living at the same time.

I hope you're right. Honestly, I do believe, like you, that we can reduce CO2 emissions and raise our standard of living at the same time. It's just that most of the solutions I hear proposed are nothing but punative, counterproductive and simply won't work when there's no reason why they have to be like that other than pure politics. I have great faith in human potential to solve any problem, I just don't have great faith in certain governments and the UN to get anything solved, nor am I entirely certain that global warming is a problem in the first place.

But if GW is a problem, whether it is caused by humans or not, I think we can solve it without hurting growth if we really want to. I just happen to think that GW is another stick that some people of the more socialist persuasion want to club others over the head with when, if it is a true problem, that is irresponsible and counterproductive. Let's solve the problem (if it's really a problem) then talk about redistributing wealth later, hmm?

Shuffling around money and resources so that everyone can suffer equally is not going to change the temperature of the atmosphere.

(I'm not implying that you think these things, just to be clear. It's nice to have a reasonable debate with someone without being accused of being a fascist, ignorant, evil racist just because I don't think GW is a problem.)