Global Warming/Climate Change Discussion Thread

[Famine]

So... just to get this right... The report says that if Climate Change happens, the climate will change?

 

[Sureboss]

I've found a way to stop climate change and recycle old freezers...

 

[Alfaholic]

For the UK, one of the most worrying possibilities is the collapse of the Atlantic circulation system - the water-driven heat conveyor belt which transports warm water into the Northern Hemisphere. Without it, Britain's climate would be more akin to Newfoundland in Canada, or other frozen places along a similar latitude.

So if England gets colder due to a change in Atlantic currents, why would Greenland be getting warmer? That's also North Atlantic isn't it?

Also, as has been pointed out more than once on this thread, Greenland was not always half covered in ice (hence the name) in the past, and there's been no great change in coastlines that I am aware of. Also, the melting artic sea ice should have no effect on sea level.

 

[Touring Mars]

So if England gets colder due to a change in Atlantic currents, why would Greenland be getting warmer? That's also North Atlantic isn't it?

Such cooling as experienced by the UK would be a local effect. It's already very well established that a global increase in mean temperature doesn't mean that every point on Earth will experience the same warming. Greenland getting warmer and ice melting there would cause the UK to experience colder conditions because it was cause the Gulf Stream to shift. So it's perfectly possible for one place to experience warming at the same time as another faces cooling - especially if one causes the other.

Also, as has been pointed out more than once on this thread, Greenland was not always half covered in ice (hence the name) in the past, and there's been no great change in coastlines that I am aware of.

The fact that Greenland was once 'greener' than it is today is debatable, and it certainly doesn't mean that Greenland was once completely green... the ice there is up to 110,000 years old - hence the name 'Greenland' has always been something of a misnomer.

Also, the melting artic sea ice should have no effect on sea level.

This is true, but melting arctic sea ice is contributing to global warming by decreasing the amount of radiation being reflected away from the Earth and being absorbed by the sea water instead.

 

[Sureboss]

I thought Greenland was called as such to fool potential invaders?

 

[Touring Mars]

Ironically, the truth is probably the opposite - it was probably called Greenland by some bright spark wanting to attract visitors! It's a bit like Scotland changing it's name to Dryland...

 

[Danoff]

Ironically, the truth is probably the opposite - it was probably called Greenland by some bright spark wanting to attract visitors! It's a bit like Scotland changing it's name to Dryland...

At one point, parts of Greenland were truly habitable. You can still visit the towns that the ice eventually reclaimed.

 

[Alfaholic]

Cheers TM. 👍 I stand corrected.

 

[KSaiyu]

China has worst winter in over 50 years

This made me think about the whole climate change issue - surely if they had the hottest winter since the '50s it would be covered in all the papers and blamed on manmade actions.

So instead of watching another one of those EDF energy ads (I really hate those....) and believing all the hype, I'm trying to find some definitive proof to back up why we're being told non stop to "bank green" or reduce our "carbon footy-print" and I'm struggling. Points raised in this thread supporting the theory have been either disproven scientifically or historically, or at best remain inconclusive. I read facts such as

"solar scientists discovered that solar flares appear to have ceased just over a year ago and have predicted a period of global cooling as a result."

and

"Planetary scientists have established that during the same period in which the earth has shown a small increase in its average mean temperature most of the planets in our solar system have shown similar increases." (from http://http://canadafreepress.com/index.php/article/1782

and it opens my eyes but confuses me at the same time. Why are our lives becoming increasingly affected by something that is no where near being proven yet? If I'm wrong, please give me some concrete facts to read over without dictating to me that my classic car is Satan and that it shouldn't be allowed in Central London anymore (I can see us heading that way).

 

[Sureboss]

Well for a start you are from the UK, we put out about 2% of the worlds emissions (iirc, from a Famine post). So we as a nation can do very little, pointless if you like when India and China 'grow' more than that a year.

I think we should try to use less energy and more efficient cars, simply because it'll give the world longer to find alternative fuels, something we will have to do. And in all probability we will have to cut energy usage when that time comes, as I understand it, the 'green' fuels aren't going to meet our demands even if we did all we could as of now.

I think that we have an impact upon our environment, however, I couldn't tell you that with 100% confidence. You and your classic car do little. Ships, Planes and Industry are the big polluters. I will make more sacrifices (baring in mind I don't drive I put out very low CO2) when the government does. When they are more interested in making the far more efficient fuel cheaper then I will be interested in doing more. Btw, I try and buy British produce. That helps, it tastes better too, often pay more though.

 

[Thiele]

This is wierd, the world is supposed to be getting warmer, but we're having temperatures as low as 20c in the middle of summer. We haven't had anywhere near 40 for ages.

 

[Sureboss]

That's not true though. The average global temperature is increasing, but climate change will mean more unpredictable weather, Cooler summers, hotter winters. It'd be fair to say there is no really way of knowing how it'll affect different areas. We've had a mild winter for instance (us Southerners anyway, the North is always different).

 

[Famine]

That's not true though. The average global temperature is supposed to be increasing, but climate change will mean more unpredictable weather, Cooler summers, hotter winters. It'd be fair to say there is no really way of knowing how it'll affect different areas. We've had a mild winter for instance (us Southerners anyway, the North is always different).

Edited for truth.

One of the theoretical results of an increase in global mean temperature is a shifting southwards of the Gulf Stream which warms the UK - resulting in a colder climate in the UK... So "global warming" might make the UK colder.

 

[Danoff]

I don't think the average temperature has been going up as predicted over the last few years. Not only that, but an increase in temperature should actually result in a more stable temperature, not an increase in temperature variance. And I've never seen an explanation for why global warming should result in cooler summers or warmer winters unless you're talking about highly localized phenomenon like the one Famine just mentioned.

 

[KSaiyu]

The average global temperature is increasing

I swear I read that the average temp since 2002 globally hasn't increased. Lemme see if I can find it....

 

[Sureboss]

I think you're right, iirc from what I've learnt is that the big rises happened during the 60s/70s/80s. The early Noughties were quite hot too, haven't 7 of our hottest summers been in the last decade? Or something like that. If someone could research that, it'd be good. I've got College in 15 so can't...

 

[KSaiyu]

Well it wasn't this article, but it says more or less the same thing (this one says from 1998):

http://www.telegraph.co.uk/opinion/main.jhtml?xml=/opinion/2006/04/09/do0907.xml

About the hottest summers thing, I'd have to look that up.

 

[Sage]

http://crackle.com/c/Penn_Says/Penn_Says_-_Weather_Opportunists/2140387#ml=fpl=264776&fx=&o=12

 

[Touring Mars]

I swear I read that the average temp since 2002 globally hasn't increased. Lemme see if I can find it....

According to NASA's Goddard Institute for Space Studies (GISS), the 5 warmest years since 1890 have all occured since 1998... 1) 2005, 2) 1998, 3) 2002, 4) 2003, 5) 2006 ... ref

Couple the global surface mean temperature anomaly as reported by NASA GISS:

​

..with the direct observation from satellites measuring the activity of the sun for the past 30 years... (as reported in Nature, Sept. 2006) showing that the sun has not shown any significant change in activity over this period in time (other than the normal 11-year cycle)...

 

[KSaiyu]

And this brings me to my earlier post - something must be wrong with one side's arguments/evidence.

 

[Danoff]

According to NASA's Goddard Institute for Space Studies (GISS), the 5 warmest years since 1890 have all occured since 1998... 1) 2005, 2) 1998, 3) 2002, 4) 2003, 5) 2005 ... ref

Couple the global surface mean temperature anomaly as reported by NASA GISS:

​

This confuses me greatly. If 5 of the years between 1998 and 2008 are the warmest of all time, that means that the other 5 are presumably cooler than 1998. But that chart seems to disagree with you.

Edit: Maybe I see. 1998 is super hot, then 1999 and 2000 are cooler than '01, '02, and '03. Nope, that's not it either.

 

[Famine]

It's worth a note that the margin for error with Global Mean Temperature measurements is +/- 0.2 degrees. And that we took no direct measurements before 1880 (the end of the Little Ice Age).

It also looks like 1944 was warmer than all but 18 years in the last 64...

 

[Touring Mars]

And this brings me to my earlier post - something must be wrong with one side's arguments/evidence.

It does mean that you have to be very careful about the claims you make for any single piece of 'evidence' that you care to cite. It's perfectly plausible that the same graph can be used to support two opposing arguments. The solar variance graph I posted yesterday can support the argument that global warming isn't happening - if you believe that global warming is completely due to solar radiation, then this graph (which shows that solar radiation hasn't changed significantly in the last 30 years) would support that claim. But that claim is flawed as it is preloaded with the assumption (the incorrect assumption) that solar radiation is always the principle driving force behind all periods of known global warming. (It would also require ignorance of the many other lines of evidence that show that global warming is indeed happening). The same graph supports a completely different argument - one based on an acceptance that global warming is happening - and that is that solar variance alone cannot explain the current trend in global warming, since global temperatures have continued to increase (at a higher rate) since 1978, yet solar radiation hasn't changed (if anything there is a slight downward trend). So the evidence itself hasn't changed - but the way it is used to support a viewpoint preloaded with assumptions (or acceptance of other 'evidence') is different - hence the confusion. Similarly, the article you posted by Bob Carter is largely based on a fairly controversial take on some pretty interesting data:

Consider the simple fact, drawn from the official temperature records of the Climate Research Unit at the University of East Anglia, that for the years 1998-2005 global average temperature did not increase (there was actually a slight decrease, though not at a rate that differs significantly from zero).

That'll be this data then... (from the exact source he cites)

So, what he is saying is not wrong - just very misleading... The trend for the short period he talks about is skewed by the fact that 1998 was abnormally high - since 1998 saw a particularly powerful El Nino event... but the general gist of his point, that global warming has stopped, or has even gone into reverse, is seriously questionable. The fact that the average appears to have leveled off is also somewhat misleading - try ending the graph at 1995 and redraw the black line - that, too, would look like warming had 'stopped' - the next 10-12 years worth of data, however, radically changes the path of that line... in other words, the "leveling off" appearance is infact an artefact created by the fact that the data stops at 2006...

This confuses me greatly. If 5 of the years between 1998 and 2008 are the warmest of all time, that means that the other 5 are presumably cooler than 1998. But that chart seems to disagree with you.

Edit: Maybe I see. 1998 is super hot, then 1999 and 2000 are cooler than '01, '02, and '03. Nope, that's not it either.

A closer look, perhaps...

​

Apart from anything else, the individual 'years' do not matter a jot - it's the overall trend and the rate of warming that is significant. Couple this with the evidence which suggests strongly that solar irradiance alone cannot explain the observed current pattern and magnitude of global warming...

Incidentally, this blow-up also (faintly) shows the error bar (in light blue) which spans 0.1 dec C (or +/- 0.05 deg C)... the error is larger the further back you go (since data is more accurate in recent years)...

By the way, the full article that this graph came from is Hansen et al., Proceedings of the National Academy of Sciences (PNAS), 103 (39): 14288 (2006)

 

[Danoff]

I've got a question for you there TM. Why did they put 0 where they chose it to be? It appears to me based on that chart that the global warming situation is no more dire than the global cooling situation was in 1910. Or, really, more like 1860 or 1890.

 

[Touring Mars]

The zero line on that graph should not be interpreted as the 'normal' value for the whole time period shown on that graph... the 'temperature anomaly' is relative to a specific period, in this case approx. 1961-1990...

Here is a similar graph with similar data, but this time using the full range (1901-2000) as the baseline, to illustrate my point...

 

[Danoff]

The zero line on that graph should not be interpreted as the 'normal' value for the whole time period shown on that graph... the 'temperature anomaly' is relative to a specific period, in this case approx. 1961-1990...

That's what I was afraid of. So we have to determine what an appropriate "normal" value is so that we can determine whether this is an issue, if we've been in a cold spell for the last hundred years, or what. I think no matter what, 100 years is wholly insufficient for this discussion.

 

[Touring Mars]

True... although these graphs show that the recent trend in warming is unusual in the context of the last ~150 years, it has to be put in a broader perspective... Interestingly, a new paper published only last week in the journal PNAS addresses a key point which I have always thought has been largely overlooked in this thread - the fact that the rate of change (increase) in global temperature as witnessed in the 20th Century, is without precedent in the last 20,000 years...

"Rates of change in natural and anthropogenic radiative forcing over the past 20,000 years"
Joos et al., PNAS 105 (5), 1425-1430 (2008)

In summary, the rate of change in anthropogenic greenhouse gas forcing is unique in the context of the past. The 20th century rise in anthropogenic forcing occurs faster than changes in the combined radiative forcing from CO2, CH4, and N2O during the past 20,000 years. Decadal-scale rates of change in CO2, CH4, and N2O and in their forcing are several times larger during the Industrial Era than the last 2,000 years. In addition, the multidecadal scale rate of change in anthropogenic forcing is also very high in the context of the known natural forcing variations of the past millennium. For recent years, the analysis by (7) shows that CO2 emission from fossil and industrial sources, the primary driver of anthropogenic climate forcing, have been accelerating over the past few years compared with the 1990s.

Regarding climate change, the cause-effect chain from anthropogenic emissions to atmospheric concentrations to radiative forcing to climate change (13) implies that the ongoing anthropogenic climate change very likely proceeds with a high speed compared with naturally forced decadal-to-century scale global climate variations of the past millennia. Data and models show that the global warming of 4 to 7°C since the Last Glacial Maximum occurred at an average rate {approx}10 times slower than the warming of the 20th century (5). An increase in global mean temperature of up to 6°C is projected for business-as-usual scenarios over this century (29). This is comparable in magnitude to the millennial-scale increase from the last ice age to the current interglacial, but is projected to occur within 100 years only. Our analysis of forcing supports the conclusion that human society and the socioeconomic and natural systems are confronted with global climate change progressing rapidly.

Full article (may require subscription)

 

[Sureboss]

Interesting how the graph rises during the second World War.

 

[Danoff]

True... although these graphs show that the recent trend in warming is unusual in the context of the last ~150 years, it has to be put in a broader perspective... Interestingly, a new paper published only last week in the journal PNAS addresses a key point which I have always thought has been largely overlooked in this thread - the fact that the rate of change (increase) in global temperature as witnessed in the 20th Century, is without precedent in the last 20,000 years...

I wonder if there isn't a decrease in the last 20,000 years that occurred with the same rate of the increase we're seeing now. Certainly some of the early 1900's data indicates that fast changes can occur.

I think what your plot shows is that the temperature fluctuations that we've seen even in the last 150 years are not so unusual or out of family of what is plausible naturally.

Interesting how the graph rises during the second World War.

Are you suggesting that carbon output increased during WWII, caused the temperature to rise, and then decreased afterward causing the temperature to fail?? On such a short timeline?

Or are you suggesting (as they are) that we had a global mean temperature determined to within 0.2 degrees?

 

[Sureboss]

I was suggesting nothing, I just said it was interesting.