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Land Use Changes and Global Warming

Jack Hays

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Here's an area not often explored. Land use seems like a fruitful topic for environmental research. What do you think of the thesis?


A new paper from Richard Betts shows land use change is a significant component of global warming

From the Roger Pielke Sr. has been saying this for years department comes this paper where Dr. Richard Betts of the UK Met Office is a co-author. h/t/ to Betts Twitter feed today. It is published in Climate Dynamics. Unfortunately, it has a $40 price tag, since it is part of Springer publications, so I…
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The money quote from the new paper is this:
Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.
Effective radiative forcing from historical land use change

Timothy Andrews, Richard A. Betts, Ben B. B. Booth, Chris D. Jones, Gareth S. Jones
The effective radiative forcing (ERF) from the biogeophysical effects of historical land use change is quantified using the atmospheric component of the Met Office Hadley Centre Earth System model HadGEM2-ES. The global ERF at 2005 relative to 1860 (1700) is −0.4 (−0.5) Wm−2, making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. The land use ERF is found to be dominated by increases in the land surface albedo, particularly in North America and Eurasia, and occurs most strongly in the northern hemisphere winter and spring when the effect of unmasking underlying snow, as well as increasing the amount of snow, is at its largest. Increased bare soil fraction enhances the seasonal cycle of atmospheric dust and further enhances the ERF. Clouds are shown to substantially mask the radiative effect of changes in the underlying surface albedo. Coupled atmosphere–ocean simulations forced only with time-varying historical land use change shows substantial global cooling (dT = −0.35 K by 2005) and the climate resistance (ERF/dT = 1.2 Wm−2 K−1) is consistent with the response of the model to increases in CO2 alone. The regional variation in land surface temperature change, in both fixed-SST and coupled atmosphere–ocean simulations, is found to be well correlated with the spatial pattern of the forced change in surface albedo. The forcing-response concept is found to work well for historical land use forcing—at least in our model and when the forcing is quantified by ERF. Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.
Andrews, T., Betts, R.A., Booth, B.B.B. et al. Clim Dyn (2016). doi:10.1007/s00382-016-3280-7

 

ALiberalModerate

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This has been known for decades and a lot of research has been done on it. We have developed roughly half the land surface on earth. The changes in albedo, rainfall patterns, and even dust being blown onto snowfields creates a significant impact on climate. For example, a study several years ago found that dust resulting from poor land use in Africa settles onto snow pack in the Southern Rockies and accelerates spring melting.
 

Jack Hays

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This has been known for decades and a lot of research has been done on it. We have developed roughly half the land surface on earth. The changes in albedo, rainfall patterns, and even dust being blown onto snowfields creates a significant impact on climate. For example, a study several years ago found that dust resulting from poor land use in Africa settles onto snow pack in the Southern Rockies and accelerates spring melting.

If truly "known for decades" then we might have expected some mention in climate forecasts.
 

Jack Hays

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And yet:

Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.
Andrews, T., Betts, R.A., Booth, B.B.B. et al. Clim Dyn (2016). doi:10.1007/s00382-016-3280-7
 

ALiberalModerate

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And yet:

Our results suggest that land-use changes over the past century may represent a more important driver of historical climate change then previously recognised and an underappreciated source of uncertainty in global forcings and temperature trends over the historical period.
Andrews, T., Betts, R.A., Booth, B.B.B. et al. Clim Dyn (2016). doi:10.1007/s00382-016-3280-7

Right, well that is one study. Surely you are not so ignorant of science to think that one study refutes all before it? The majority of single studies both in science and in medicine are shown to be wrong or erroneous. This is the whole point of meta-analysis.

Not to mention, you guys need to get your story straight. Its not really warming.... We are on the cusp of a mini ice age.... Its warmed but not very much....It's warmed but its not co2 (insert alternate explanation here).... Now, let's say that land use changes are the primary driver behind AGW. Is that what you really want to hang your hat on? Reason being is that mitigating climate change will then require global regulation of land use which is a lot bigger deal than even reducing carbon emissions.
 
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Jack Hays

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Right, well that is one study. Surely you are not so ignorant of science to think that one study refutes all before it? The majority of single studies both in science and in medicine are shown to be wrong or erroneous. This is the whole point of meta-analysis.

Not to mention, you guys need to get your story straight. Its not really warming.... We are on the cusp of a mini ice age.... Its warmed but not very much....It's warmed but its not co2 (insert alternate explanation here).... Now, let's say that land use changes are the primary driver behind AGW. Is that what you really want to hang your hat on? Reason being is that mitigating climate change will then require global regulation of land use which is a lot bigger deal than even reducing carbon emissions.

Stop whining. I don't have a "story" in this case and you need to stop dodging the data. This particular paper concludes land use is more important than has been recognized. My guess is the authors were fully aware of previous work. If you want to claim they were not then you risk looking both silly and desperate.
 

ALiberalModerate

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Stop whining. I don't have a "story" in this case and you need to stop dodging the data. This particular paper concludes land use is more important than has been recognized. My guess is the authors were fully aware of previous work. If you want to claim they were not then you risk looking both silly and desperate.

There are at least dozens of studies on this. Do you ever understand how meta-analysis works?
 

Jack Hays

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There are at least dozens of studies on this. Do you ever understand how meta-analysis works?

I know you believe there are many. And yet reputable scientists published in a peer reviewed journal their conclusion that land use had not been fully appreciated as a driver. Perhaps you should try to understand why.
 

ALiberalModerate

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I know you believe there are many. And yet reputable scientists published in a peer reviewed journal their conclusion that land use had not been fully appreciated as a driver. Perhaps you should try to understand why.

Even a quick glance at Richard Betts' twitter feed would tell you he doesn't share the same views on this paper as you do. https://twitter.com/richardabetts

Moreover in the abstract you posted, its quote "making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. " So what he is saying is that land use drivers are a big driver in climate - which is exactly what others have said for decades. He is not saying that CO2 is not the biggest driver in our current warming. So I am not even sure what your point is. This guy is not in anyway a skeptic.
 

Lord of Planar

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I know you believe there are many. And yet reputable scientists published in a peer reviewed journal their conclusion that land use had not been fully appreciated as a driver. Perhaps you should try to understand why.

Almost everything I have seen on land use doesn't mention the loss of transpiration. Just straight up albedo changes.
 

Jack Hays

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Even a quick glance at Richard Betts' twitter feed would tell you he doesn't share the same views on this paper as you do. https://twitter.com/richardabetts

Moreover in the abstract you posted, its quote "making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. " So what he is saying is that land use drivers are a big driver in climate - which is exactly what others have said for decades. He is not saying that CO2 is not the biggest driver in our current warming. So I am not even sure what your point is. This guy is not in anyway a skeptic.

And where have I made any claim about CO2?
 

ALiberalModerate

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Almost everything I have seen on land use doesn't mention the loss of transpiration. Just straight up albedo changes.

Practically everything I have ever read on deforestation and other land use changes talked about transpiration. For example, humidity increases substantially in the midwest during the late summer because of corn sweats. Droughts are exacerbated in the Amazon due to deforestation. Hell in the 30s they tried planting a national forest in Western Kansas because they thought it would increase rainfall out there.
 

Jack Hays

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Even a quick glance at Richard Betts' twitter feed would tell you he doesn't share the same views on this paper as you do. https://twitter.com/richardabetts

Moreover in the abstract you posted, its quote "making it the fourth most important anthropogenic driver of climate change over the historical period (1860–2005) in this model and larger than most other published values. " So what he is saying is that land use drivers are a big driver in climate - which is exactly what others have said for decades. He is not saying that CO2 is not the biggest driver in our current warming. So I am not even sure what your point is. This guy is not in anyway a skeptic.

Why must you go into a defensive crouch every time a topic is set out for discussion? Can you not simply enjoy the exchange?
 

ALiberalModerate

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Why must you go into a defensive crouch every time a topic is set out for discussion? Can you not simply enjoy the exchange?

We come at this from 2 different directions. You are looking for anything and everything that you think disproves AGW, specifically AGW resulting from carbon emissions. I look at it as science is constantly being built upon. In this case, we have decades of study into land use and its impact on climate. We now have a paper from a highly respected researcher that looked at past work on land use and its impact on climate further clarified its role in our current warming. That is how science works. Models are refined as more research is done. In this case, what will likely happen is predicted warming will be revised upwards over this century as the impacts of land use will amplify warming that is already occurring due to increased carbon emissions.

Just the same, as Richard Betts is easily one of the most vocal scientists on earth in defending the science behind AGW - specifically the need to curb carbon emissions, I don't think the actual author of this paper is drawing the same conclusions from it that you seem to be.
 

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If truly "known for decades" then we might have expected some mention in climate forecasts.

Maybe it's just not that important.
From your citation...
"... the fourth most important anthropogenic driver of climate change"
What would the three more important ones be?
 

Jack Hays

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We come at this from 2 different directions. You are looking for anything and everything that you think disproves AGW, specifically AGW resulting from carbon emissions. I look at it as science is constantly being built upon. In this case, we have decades of study into land use and its impact on climate. We now have a paper from a highly respected researcher that looked at past work on land use and its impact on climate further clarified its role in our current warming. That is how science works. Models are refined as more research is done. In this case, what will likely happen is predicted warming will be revised upwards over this century as the impacts of land use will amplify warming that is already occurring due to increased carbon emissions.

Just the same, as Richard Betts is easily one of the most vocal scientists on earth in defending the science behind AGW - specifically the need to curb carbon emissions, I don't think the actual author of this paper is drawing the same conclusions from it that you seem to be.

My post had nothing to do with carbon emissions AGW, positive or negative. You and you alone brought that topic to the party. Thank you for illustrating my point.
 

Jack Hays

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Maybe it's just not that important.
From your citation...
"... the fourth most important anthropogenic driver of climate change"
What would the three more important ones be?

Maybe so, but then why produce a paper? And why publish that paper?
 

Grand Mal

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Maybe so, but then why produce a paper? And why publish that paper?

Don't know. Scientists study and report on lots of stuff that looks meaningless to anyone outside their field. I think the idea is that all information has value.
 

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Practically everything I have ever read on deforestation and other land use changes talked about transpiration. For example, humidity increases substantially in the midwest during the late summer because of corn sweats. Droughts are exacerbated in the Amazon due to deforestation. Hell in the 30s they tried planting a national forest in Western Kansas because they thought it would increase rainfall out there.

True. That would be the theme in agricultural usage. I should have elaborated I was referring to urban and suburban areas, where the transpiration is dramatically reduced rather than increased due to concrete, asphalt, and building occupying what once was plant life.
 

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We come at this from 2 different directions. You are looking for anything and everything that you think disproves AGW, specifically AGW resulting from carbon emissions. I look at it as science is constantly being built upon. In this case, we have decades of study into land use and its impact on climate. We now have a paper from a highly respected researcher that looked at past work on land use and its impact on climate further clarified its role in our current warming. That is how science works. Models are refined as more research is done. In this case, what will likely happen is predicted warming will be revised upwards over this century as the impacts of land use will amplify warming that is already occurring due to increased carbon emissions.

Just the same, as Richard Betts is easily one of the most vocal scientists on earth in defending the science behind AGW - specifically the need to curb carbon emissions, I don't think the actual author of this paper is drawing the same conclusions from it that you seem to be.

Given that you say that science is constantly being built upon, how have you revised your expectation of warming during this century given the lack of warming since the IPCC/M.Mann came out with the hockey stick in 1998? Do you expect it to be at the top of their range or lower than that?
 

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Given that you say that science is constantly being built upon, how have you revised your expectation of warming during this century given the lack of warming since the IPCC/M.Mann came out with the hockey stick in 1998? Do you expect it to be at the top of their range or lower than that?

Being that almost every model is on about a 30 year resolution, I don't know how one could draw such conclusions yet. Moreover, 2015 was the warmest year on record and 2016 is on track to top it.
 

Jack Hays

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Moreover, 2015 was the warmest year on record and 2016 is on track to top it.

Increasingly unlikely.

https://wattsupwiththat.com/2016/08/...and-july-data/

moyhu.blogspot.ca – Nick Stokes – Click the pic to view at source

The above bar graph shows the RSS bar heights for 2016 in blue and the corresponding heights for 1998 in red. For January, February and March, the blue bar is higher than the red bar indicating that for these three months, 2016 was warmer than 1998. However since April, the blue bar is lower than the red bar indicating that for these months, 2016 was colder than 1998. Note that the July 2016 anomaly is already lower than that of several later months in 1998. In this respect, RSS is the same as UAH6.0beta5 which, among other data sets, can also be viewed on Nick Stokes’ site.
 

ALiberalModerate

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Increasingly unlikely.

https://wattsupwiththat.com/2016/08/...and-july-data/

moyhu.blogspot.ca – Nick Stokes – Click the pic to view at source

The above bar graph shows the RSS bar heights for 2016 in blue and the corresponding heights for 1998 in red. For January, February and March, the blue bar is higher than the red bar indicating that for these three months, 2016 was warmer than 1998. However since April, the blue bar is lower than the red bar indicating that for these months, 2016 was colder than 1998. Note that the July 2016 anomaly is already lower than that of several later months in 1998. In this respect, RSS is the same as UAH6.0beta5 which, among other data sets, can also be viewed on Nick Stokes’ site.

Seems the actual scientists disagree with you: UN: 2016 on track to be hottest year on record

Then again, they don't cherry pick their datasets.

980x.jpg
 

Jack Hays

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Seems the actual scientists disagree with you: UN: 2016 on track to be hottest year on record

Then again, they don't cherry pick their datasets.

On the contrary, that's just what they're doing. From the #23 link:

The above bar graph shows the RSS bar heights for 2016 in blue and the corresponding heights for 1998 in red. For January, February and March, the blue bar is higher than the red bar indicating that for these three months, 2016 was warmer than 1998. However since April, the blue bar is lower than the red bar indicating that for these months, 2016 was colder than 1998. Note that the July 2016 anomaly is already lower than that of several later months in 1998. In this respect, RSS is the same as UAH6.0beta5 which, among other data sets, can also be viewed on Nick Stokes’ site.
 
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