2015 Global Temperatures

[frontranger8]

It's interesting that some places have seen huge increases in temperature of 5-7 degrees over the past 50-100 years due in part to increased UHI, and yet people in those areas have adapted just fine. And the majority of warming from UHI is at night, just like with AGW.

 

Not to say that the globe could so easily adapt to 5-7 degrees of warming, but it's interesting when you consider all of those dire predictions of Chicago's climate turning into Dallas' in a few decades, etc. As it is, many people are already living in a local climate that has been massively altered for the warmer.

[A-L-E-K]

It's interesting that some places have seen huge increases in temperature of 5-7 degrees over the past 50-100 years due in part to increased UHI, and yet people in those areas have adapted just fine. And the majority of warming from UHI is at night, just like with AGW.

 

Not to say that the globe could so easily adapt to 5-7 degrees of warming, but it's interesting when you consider all of those dire predictions of Chicago's climate turning into Dallas' in a few decades, etc. As it is, many people are already living in a local climate that has been massively altered for the warmer.

 

 

what a hot take

[FloridaJohn]

Most papers I have seen claim that UHI is adjusted for, but then say that the UHI effect is actually insignificant when comparing urban and rural trends. I can point to dozens of stations that demonstrate this is simply not true. 

 

Fact 1: Over the past 100 years, not only have urban areas grown, but overall land surfaces have become much more covered by concrete/asphalt, which absorb and hold heat extremely well. Logically, this dictates that many areas have seen increased surface warming not related to climate trends. I have yet to see a paper that really quantifies how much warming has been generated by the changes to land surfaces in the vast majority of areas where people keep temperature records.

 

Fact 2: If you compare stations that have seen increased urbanization/concrete/lighting over the past 50-100 years to nearby stations that have remained relatively unchanged, the difference is often massive. But there is little to no mention of this in studies I have seen. Yet they point to much rarer situations like NYC moving their station to Central Park (right, cause every city has a giant park where the weather records are kept). Why is that?

 

Perhaps you haven't seen Jones et al 2008? The paper, called "Urbanization effects in large-scale temperature records, with an emphasis on China," investigates the exact scenarios you point out above.

 

First they compared urban and rural temperature records in England. The brown and dark blue lines are urban, the green ones are rural. Notice that the temperature is warmer in the urban areas, but the temperature trend is the same in both rural and urban areas.

 

 

Next, they looked at weather stations in Vienna, Austria. The brown is a urban location, and the green is a rural location. Notice, once again, that although the urban location is warmer, the trend of the two temperatures are nearly identical.

 

 

Finally, they looked at temperature records in China, where there has been a massive amount of urbanization and industrialization duirng a more recent time frame than in Europe. Here are the results of that investigation:

 

 

So, as you can see, urban heat islands are a real phenomenon, but they react to the overall global warming trend the same as the rural stations do. By comparing the temperature records between these types of stations allows for the global temperature record to take them into account.

[FreeRain]

Perhaps you haven't seen Jones et al 2008? The paper, called "Urbanization effects in large-scale temperature records, with an emphasis on China," investigates the exact scenarios you point out above.

 

First they compared urban and rural temperature records in England. The brown and dark blue lines are urban, the green ones are rural. Notice that the temperature is warmer in the urban areas, but the temperature trend is the same in both rural and urban areas.

 

 

Next, they looked at weather stations in Vienna, Austria. The brown is a urban location, and the green is a rural location. Notice, once again, that although the urban location is warmer, the trend of the two temperatures are nearly identical.

 

 

Finally, they looked at temperature records in China, where there has been a massive amount of urbanization and industrialization duirng a more recent time frame than in Europe. Here are the results of that investigation:

 

 

So, as you can see, urban heat islands are a real phenomenon, but they react to the overall global warming trend the same as the rural stations do. By comparing the temperature records between these types of stations allows for the global temperature record to take them into account.

 

Are you suggesting that there is no increasing UHI effect and that whatever UHI differences there are between urban and countryside occurred before 1960 or even before 1900?

[nflwxman]

Great Post Florida John.  You also can't forget that urban stations are actually a very small portion of the GHCN-v3 network used by GISS.  Hence, making a very small dent in the global trend.

 

This argument has been case closed for a while.  There are plenty of things that skeptics can latch on to (modeling, ECS, TCR), but this isn't one of them.

[ORH_wxman]

Are you suggesting that there is no increasing UHI effect and that whatever UHI differences there are between urban and countryside occurred before 1960 or even before 1900?

 

No, they already accounted for UHI...it's saying that once the adjustment is put in there, then the trends are the same.

[FreeRain]

No, they already accounted for UHI...it's saying that once the adjustment is put in there, then the trends are the same.

 

Certainly stands to reason that if you remove the effect of UHI in urban areas that global temperatures and trends would be the same in urban and rural areas.

 

Not sure why we need Jones et al 2008 to tell us that...if that was their point.

[Isotherm]

It's interesting that some places have seen huge increases in temperature of 5-7 degrees over the past 50-100 years due in part to increased UHI, and yet people in those areas have adapted just fine. And the majority of warming from UHI is at night, just like with AGW.

 

Not to say that the globe could so easily adapt to 5-7 degrees of warming, but it's interesting when you consider all of those dire predictions of Chicago's climate turning into Dallas' in a few decades, etc. As it is, many people are already living in a local climate that has been massively altered for the warmer.

 

 

It's interesting, but the implications of a 5-7F global temperature increase are far, far more significant than a localized increase of similar magnitude. Global scale temperature increases of that amount would affect the overall dynamics of the atmosphere, likely causing more severe flooding in some regions while others experience more extreme droughts; not to mention the profound effect on sea level rise and current ecosystems. The entire energy budget of the Earth is impacted when we translate those numbers to a global scale. Could it be adaptable, sure - that's possible, but the road to that point would probably be quite a rough one.

[ORH_wxman]

Certainly stands to reason that if you remove the effect of UHI in urban areas that global temperatures and trends would be the same in urban and rural areas.

 

Not sure why we need Jones et al 2008 to tell us that...if that was their point.

 

 

Well I think it was mostly to show that the adjustments are pretty solid when they are needed.

 

The specific examples for London though weren't even adjusted because the London station hadn't been really affected by UHI over the past century (it was already very urbanized that far back)...the adjusted comparison was in China where UHI is significant over the past 6 decades.

 

 

The U.S. also has far more UHI cases than Europe. But these trends have been accounted for pretty well in the homogenized datasets. You can nitpick them and probably find reasons to believe they are in error...but these errors are pretty small. (probably 10% of the trend or less)

[FloridaJohn]

Certainly stands to reason that if you remove the effect of UHI in urban areas that global temperatures and trends would be the same in urban and rural areas.

 

Not sure why we need Jones et al 2008 to tell us that...if that was their point.

 

Well, that wasn't really their point. I included a link the the actual paper (it's not behind a paywall) so you can read it and find out exactly what their point is, if you are really interested.

 

What this study points out, is that although UHI is a real and measurable effect, it doesn't have much of an influence on global temperature records due to the small amount of UHI area on the globe. A quick Google search reveals that only about 2.7% of the earth's land area is "urbanized", and the land areas only accounts for about 30% of the total surface area of the earth. That means less than 1% of the surface area of the earth could be considered a "UHI." One can then see that the UHI effect has very little influence on global warmng in general and on the global temperature record specifically.

 

If you read the paper, they also point out that in certain areas, the UHI portions are warming at a faster rate than the global temperature. But because this is such a small amount of land area, it doesn't have any influence to the global temperature record. Also, since it can be quantified, it can be accounted for in the temperature record, removing a very small amount of uncertainty in the global temperature record. So, scientists are aware of UHI and take it into account, but even if they didn't, it has a very small influence on overall trends.

[AvantHiatus]

ENSO poofed in 3.4 but other regions taking up the slack. Southern Hemisphere is not radiating enough ocean heat, SSTA is enormous there. Will probably end up like 2014 with more red...and 2014 was torch city over the oceans.

 

[The_Global_Warmer]

I agree with that. Modern humans would have been a better descriptor. Regardless of the source material, a global temperature jump does appear likely with the onset of long lasting ENSO + conditions.

Of course it's speculative, as predicting global temperature often is. There is solid reasoning on why it will happen, but noone can say for sure what we come to pass in the next 5 years with any modicum of certainty.

I can tell you with certainty that 2015-2019 will be much warmer than 2010-2014.

2015 is gonna blow the doors off this thing.

[The_Global_Warmer]

That's very warm and large.

Even tho positive wind anomalies are weak they are over a very large area and over enso 3 which is the staging point to get that big warmth to surface and be sustained.

[The_Global_Warmer]

It's interesting that some places have seen huge increases in temperature of 5-7 degrees over the past 50-100 years due in part to increased UHI, and yet people in those areas have adapted just fine. And the majority of warming from UHI is at night, just like with AGW.

Not to say that the globe could so easily adapt to 5-7 degrees of warming, but it's interesting when you consider all of those dire predictions of Chicago's climate turning into Dallas' in a few decades, etc. As it is, many people are already living in a local climate that has been massively altered for the warmer.

The Earth would become inhospitable if it warmed 5-7c.

[frontranger8]

Perhaps you haven't seen Jones et al 2008? The paper, called "Urbanization effects in large-scale temperature records, with an emphasis on China," investigates the exact scenarios you point out above.

 

First they compared urban and rural temperature records in England. The brown and dark blue lines are urban, the green ones are rural. Notice that the temperature is warmer in the urban areas, but the temperature trend is the same in both rural and urban areas.

 

 

 

Next, they looked at weather stations in Vienna, Austria. The brown is a urban location, and the green is a rural location. Notice, once again, that although the urban location is warmer, the trend of the two temperatures are nearly identical.

 

 

 

Finally, they looked at temperature records in China, where there has been a massive amount of urbanization and industrialization duirng a more recent time frame than in Europe. Here are the results of that investigation:

 

 

 

So, as you can see, urban heat islands are a real phenomenon, but they react to the overall global warming trend the same as the rural stations do. By comparing the temperature records between these types of stations allows for the global temperature record to take them into account.

 

The question isn't whether urban and rural stations have similar trends. It's whether the increased UHI effect in many stations near urban areas is being properly accounted for. This is quite often airports in the U.S.

 

There are so many examples in the western U.S.: Phoenix, Vegas, Salt Lake City, Portland, Seattle, LA, for starters. Compare the longterm temperature trends of these airports to nearby stations that have either remained rural or remained urban the whole time, and you'll see a marked difference.

[frontranger8]

It's interesting, but the implications of a 5-7F global temperature increase are far, far more significant than a localized increase of similar magnitude. Global scale temperature increases of that amount would affect the overall dynamics of the atmosphere, likely causing more severe flooding in some regions while others experience more extreme droughts; not to mention the profound effect on sea level rise and current ecosystems. The entire energy budget of the Earth is impacted when we translate those numbers to a global scale. Could it be adaptable, sure - that's possible, but the road to that point would probably be quite a rough one.

 

Yup, which is why I said "not to say the globe could adapt...".

 

But it's worth considering when people talk about heatwaves becoming much worse because of AGW...in many areas people live, they already have become much worse, primarily because of lack of cooling at night with UHI. Yet it's not like people are dying by the thousands because of this.

[frontranger8]

Well, that wasn't really their point. I included a link the the actual paper (it's not behind a paywall) so you can read it and find out exactly what their point is, if you are really interested.

 

What this study points out, is that although UHI is a real and measurable effect, it doesn't have much of an influence on global temperature records due to the small amount of UHI area on the globe. A quick Google search reveals that only about 2.7% of the earth's land area is "urbanized", and the land areas only accounts for about 30% of the total surface area of the earth. That means less than 1% of the surface area of the earth could be considered a "UHI." One can then see that the UHI effect has very little influence on global warmng in general and on the global temperature record specifically.

 

This is faulty logic, as there are far more long term stations near cities than away from cities. Increasing UHI has very little influence on the actual global temperature, but the temperature record and trends is very much connected to where people live.

[frontranger8]

The Earth would become inhospitable if it warmed 5-7c.

 

5-7F. That is what has already occurred in some areas that have seen increased UHI over the past 50-100 years.

[FloridaJohn]

The question isn't whether urban and rural stations have similar trends. It's whether the increased UHI effect in many stations near urban areas is being properly accounted for. This is quite often airports in the U.S.

 

There are so many examples in the western U.S.: Phoenix, Vegas, Salt Lake City, Portland, Seattle, LA, for starters. Compare the longterm temperature trends of these airports to nearby stations that have either remained rural or remained urban the whole time, and you'll see a marked difference.

What is the significance of this difference you are so concerned about? I can't figure out what your trying to get at here. Help me understand your position.

Are scientists taking UHI into account regarding the temperature record? Answer: Yes.

Does the UHI effect have a significant effect on global temperatures? Answer: No.

The global temperature record would be more or less the same if we completely ignored UHI effects or if we only used UHI weather stations. Both the rural and urban areas are being affected the same way. A rising tide lifts all boats, as the saying goes.

[The_Global_Warmer]

5-7F. That is what has already occurred in some areas that have seen increased UHI over the past 50-100 years.

Which is totally isolated from the Earths ecosystem.

2-3.5C would be enough to guarantee Greenland completely melting out

[frontranger8]

What is the significance of this difference you are so concerned about? I can't figure out what your trying to get at here. Help me understand your position.

Are scientists taking UHI into account regarding the temperature record? Answer: Yes.

Does the UHI effect have a significant effect on global temperatures? Answer: No.

The global temperature record would be more or less the same if we completely ignored UHI effects or if we only used UHI weather stations. Both the rural and urban areas are being affected the same way. A rising tide lifts all boats, as the saying goes.

 

1. Just because those that manage the temperature record take UHI into account does not necessarily mean it is accounted for accurately. If someone can point me to a study that shows exactly how much heat is attributable to human land use changes in places where we actually measure the temperature, that would be helpful.

 

2. The problem I see is that not every station over it's period of record remains either "urban" or "rural". The general trend over the past 100 years has been massive expansion of concrete/asphalt, electrical lighting, and other changes to the landscape that generally favor heat. With so many stations out there that clearly show a huge impact from increased UHI, I'd like to see a more complete logical explanation of how this has no impact on the overall temp trend. Just dividing stations into rural and urban data sets without real analysis of the actual physical changes that have occurred around these stations seems like incomplete science to me.

[frontranger8]

Which is totally isolated from the Earths ecosystem.

2-3.5C would be enough to guarantee Greenland completely melting out

 

See my post above on heatwaves. That was more the point.

[ORH_wxman]

1. Just because those that manage the temperature record take UHI into account does not necessarily mean it is accounted for accurately. If someone can point me to a study that shows exactly how much heat is attributable to human land use changes in places where we actually measure the temperature, that would be helpful.

 

2. The problem I see is that not every station over it's period of record remains either "urban" or "rural". The general trend over the past 100 years has been massive expansion of concrete/asphalt, electrical lighting, and other changes to the landscape that generally favor heat. With so many stations out there that clearly show a huge impact from increased UHI, I'd like to see a more complete logical explanation of how this has no impact on the overall temp trend. Just dividing stations into rural and urban data sets without real analysis of the actual physical changes that have occurred around these stations seems like incomplete science to me.

 

 

UHI doesn't affect the globe that much as a whole...it is more regional. USHCN has roughly 0.10-0.15C adjustment over the period from 1895 to account for UHI because the United States had a lot of growing urban regions during that time. But the global adjustment is literally something like 0.01C over a 100 year period...which is way smaller than the margin of error of any trend in that period. GISS error bars for one single year are + or - 0.05C.

 

 

This paper is a good read on the global insignificance of UHI: http://scitechnol.com/2327-4581/2327-4581-1-104.pdf

[Sophisticated Skeptic]

The Earth would become inhospitable if it warmed 5-7c.

 

 

2-3.5C would be enough to guarantee Greenland completely melting out

 

 

 

 

Interestingly, bold statements...

[skierinvermont]

Interestingly, bold statements...

 

Many studies indicated that Greenland would melt out completely with just 2C of additional warming. That's 30 feet of sea level rise. 5-7C would probably be enough to melt much of Antarctica, which would mean an additional 50-100 feet of sea level rise.

 

Places like Phoenix which now reach 120+ regularly would now see temperatures of 135+ regularly. Droughts and floods and ecosystems would all be radically altered.

[A-L-E-K]

you can still buy cheap lakefront land in the future Tropical Savannah climate of northern Michigan on the cheap, you're great, great, great, great, great grand kids will thank you

[FloridaJohn]

UHI doesn't affect the globe that much as a whole...it is more regional. USHCN has roughly 0.10-0.15C adjustment over the period from 1895 to account for UHI because the United States had a lot of growing urban regions during that time. But the global adjustment is literally something like 0.01C over a 100 year period...which is way smaller than the margin of error of any trend in that period. GISS error bars for one single year are + or - 0.05C.

 

 

This paper is a good read on the global insignificance of UHI: http://scitechnol.com/2327-4581/2327-4581-1-104.pdf

 

That is an excellent paper that very clearly shows the effects of UHI. To your point about the size of the UHI error, the paper has this to say:

 

"Our results are in line with previous results on global averages despite differences in methodology. Parker concluded that the effect of urban heating on the global trends is minor, HadCRU use a bias error of 0.05°C per century, and NOAA estimate residual urban heating of 0.06°C per century for the USA and GISS applies a correction to their data of 0.01°C per century. All are small on the scale of global warming.

 

The huge effects seen in prominent locations such as Tokyo have caused concern that the Tavg estimates might be unduly affected by the urban heat effect. It did not have a strong effect on our estimate– which is not surprising given that urban areas are only 0.5% of the land area"

[nflwxman]

The newer model that takes hiatus periods into account is dialing down some of the previous

extreme temperature projections for this century. But a 1-2 C temperature rise would still be

very significant.

 

https://www2.ucar.edu/atmosnews/news/5364/deep-oceans-can-mask-global-warming-decade-long-periods

 

To track where the heat was going, Meehl and colleagues used a powerful software tool known as the Community Climate System Model, which was developed by scientists at NCAR and the Department of Energy with colleagues at other organizations. Using the model’s ability to portray complex interactions between the atmosphere, land, oceans, and sea ice, they performed five simulations of global temperatures.

The simulations, which were based on projections of future greenhouse gas emissions from human activities, indicated that temperatures would rise by several degrees during this century. But each simulation also showed periods in which temperatures would stabilize for about a decade before climbing again. For example, one simulation showed the global average rising by about 2.5 degrees Fahrenheit (1.4 degrees Celsius) between 2000 and 2100, but with two decade-long hiatus periods during the century.

Nice find.  This kind of is counter to the paper that came out later last year that determined "hiatus" periods were very unlikely moving forward due to ever increasing forcing.  The difference between 1 and 2C is quite significant for a century time period.  Thinking about this in a more zoomed out picture, we warmed 0.7C in the 20th century.  The only way we are close to 1C in the 21st century is if emissions are cut drastically.

 

CO2 in 1960 was 310 versus 2000 at 367 (growth rate 14.25 ppm/decade)

 

CO2 is 2000 was 367 versus 2014 at 397 (growth rate 20 ppm/decade)

 

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2013/sep/03/global-warming-pacific-ocean-puzzle-piece

 

Small critique of the Meehl paper is that it actually only includes CO2 forcing increasing and resulting atmospheric water vapor feedback.  There is really no inclusion of smaller feedbacks like Methane, permafrost melting, aerosol, and albedo changes.

 

The recent pause was caused combination of slumping Solar and a tanking PDO.  The two variables conspired only enough to reduce warming to approximately 0.02C/decade from 2003-2012.  I struggle to think that will happen again (but anything is possible) without a major volcanic event.

[ORH_wxman]

Nice find.  This kind of is counter to the paper that came out later last year that determined "hiatus" periods were very unlikely moving forward due to ever increasing forcing.  The difference between 1 and 2C is quite significant for a century time period.  Thinking about this in a more zoomed out picture, we warmed 0.7C in the 20th century.  The only way we are close to 1C in the 21st century is if emissions are cut drastically.

 

CO2 in 1960 was 310 versus 2000 at 367 (growth rate 14.25 ppm/decade)

 

CO2 is 2000 was 367 versus 2014 at 397 (growth rate 20 ppm/decade)

 

http://www.theguardian.com/environment/climate-consensus-97-per-cent/2013/sep/03/global-warming-pacific-ocean-puzzle-piece

 

Small critique of the Meehl paper is that it actually only includes CO2 forcing increasing and resulting atmospheric water vapor feedback.  There is really no inclusion of smaller feedbacks like Methane, permafrost melting, aerosol, and albedo changes.

 

The recent pause was caused combination of slumping Solar and a tanking PDO.  The two variables conspired only enough to reduce warming to approximately 0.02C/decade from 2003-2012.  I struggle to think that will happen again (but anything is possible) without a major volcanic event.

 

 

In Meehl's simulations, the lower warming scenario models results were the ones that had multiple hiatus decades. Which makes sense...the less dominant GHG forcing is (and more influential natural variability is), the more likely a hiatus is to occur. Very strong GHG forcing will undoubtedly make a hiatus much much less likely the further you go out in time. If you are assuming a path more like RCP 8.5, then a hiatus decade is almost impossible.

 

The average of the model simulations in the 2011 paper was about 1.3C of warming in the 21st century.

[nflwxman]

My best guess for the next century would probably be 1-2 C of warming. But the wildcards are the unknowns of how fast

 we can transition from a fossil fuels economy and whether a major volcanic event occurs. So we have to respect the

uncertainty factor when attempting to forecast global temperatures that far out in time. Plus we probably won't have

many posters around to bump this thread in a 100 years to see how things actually turn out.

 

Haha fair point.  I'd guess 2-2.5C myself, but there's is a lot of time to hash that out with emissions, ect.  I'm pretty sure through the next PDO cycle, say in 2030, we should know quite a bit more about how ocean cycles effect TCR.  Hopefully, most of us are alive then.