BOOM: Global land use change responsible for a significant portion of global warming says study

From the EUROPEAN COMMISSION JOINT RESEARCH CENTRE and the “Dr. Roger Pielke Sr. was right” department. I suspect a whole bunch of climate models that don’t take this into consideration, and think CO2 is the dominant climate driver, are going to need to be revised.

Land use change has warmed the Earth’s surface

Natural ecosystems play a crucial role in helping combat climate change, air pollution and soil erosion. A new study by a team of researchers from the Joint Research Centre, the European Commission’s science and knowledge service, sheds light on another, less well-known aspect of how these ecosystems, and forests in particular, can protect our planet against global warming.

The research team used satellite data to analyse changes in global vegetation cover from 2000 to 2015 and link these to changes in the surface energy balance. Modifying the vegetation cover alters the surface properties – such as the amount of heat dissipated by water evaporation and the level of radiation reflected back into space – which has a knock-on effect on local surface temperature. Their analysis reveals how recent land cover changes have ultimately made the planet warmer.

“We knew that forests have a role in regulating surface temperatures and that deforestation affects the climate, but this is the first global data-driven assessment that has enabled us to systematically map the biophysical mechanisms behind these processes”, explains Gregory Duveiller, lead author of the study.

The study also looked beyond deforestation, analysing changes between different types of vegetation, from evergreen forests to savannas, shrublands, grasslands, croplands and wetlands. However, they found that the removal of tropical evergreen forest for agricultural expansion is the vegetation cover transition most responsible for local increases in surface temperature.

From a greenhouse gas perspective, the cutting of forests might only affect the global climate in the mid-to-long term. However, the scientists point out that local communities living in areas where the trees are cut will immediately be exposed to rising temperatures.

###

The study was published in Nature Communications and the datasets behind are fully described in Scientific Data.

The mark of vegetation change on Earth’s surface energy balance

Abstract

Changing vegetation cover alters the radiative and non-radiative properties of the surface. The result of competing biophysical processes on Earth’s surface energy balance varies spatially and seasonally, and can lead to warming or cooling depending on the specific vegetation change and background climate. Here we provide the first data-driven assessment of the potential effect on the full surface energy balance of multiple vegetation transitions at global scale. For this purpose we developed a novel methodology that is optimized to disentangle the effect of mixed vegetation cover on the surface climate. We show that perturbations in the surface energy balance generated by vegetation change from 2000 to 2015 have led to an average increase of 0.23 ± 0.03 °C in local surface temperature where those vegetation changes occurred. Vegetation transitions behind this warming effect mainly relate to agricultural expansion in the tropics, where surface brightening and consequent reduction of net radiation does not counter-balance the increase in temperature associated with reduction in transpiration. This assessment will help the evaluation of land-based climate change mitigation plans.

Figure 1: Potential changes to surface temperatures caused by deforestation. Panels describe the expected average annual change of a day-time and b night-time clear sky land surface temperature (LST), of c mean LST (defined as the average between a and b) and of d LST diurnal amplitude (defined as the difference between a and b)

Introduction

Our novel approach adopts the space-for-time logic to multi-scale remote sensing products to quantify the potential effect that a complete transition from one vegetation class to another would have on the individual components of the surface energy balance and on the resultant change in land surface temperature. This information is spatially and temporally explicit, enabling us to draw a comprehensive picture of the geographic and seasonal patterns of these potential changes. The resulting data set is freely available and fully described in an accompanying data description publication30. We use this global data set to quantify the total effect on the surface energy balance resulting from all vegetation changes that have occurred during the period 2000–2015, and then translate this effect into a change of 0.23 ± 0.03 °C over the concerned land.

Discussion

This study makes the first global scale data-driven assessment of how different vegetation changes can influence the surface energy balance. Altogether, our results quantify these influences across different geographic regions and biomes, confirming the need to jointly assess both radiative and non-radiative processes in order to estimate the changes in surface climate induced by land cover change. In particular, this assessment shows that in ecosystems where vegetation growth is limited by water availability the climate impacts of a vegetation cover transition are dominated by changes in evapotranspiration, whereas in ecosystems where vegetation growth is limited by energy, such as boreal shrublands, the perturbation of the surface temperature is dominated by changes in the radiative and aerodynamic properties of those ecosystems. The origin of actual vegetation cover change in the recent past is divided along the same lines, with direct anthropogenic changes (such as agricultural intensification) occurring mostly where evaporation dominates, while changes within natural ecosystems have generally been confined to higher latitudes where radiative and aerodynamic effects prevail.

Our results show that vegetation cover change over the period 2000–2015 has produced on average a brighter but warmer land surface. This apparently contradictory signal is controlled by the three dominant transitions driven by agricultural expansion in mostly tropical regions (from evergreen broadleaf forests, shrublands or deciduous broadleaf forests to cropland, Fig. 5), which each lead to similar increases in albedo, and consequent reductions in absorbed radiation and turbulent energy fluxes. This perturbation of the surface energy balance ultimately produces a counter-intuitive warming of areas with higher albedo because of stronger plant-mediated constraints on evaporative cooling, in accordance with recent findings that prove the central role of non-radiative biophysical effects mediated by evapotranspiration18.

Figure 5: Cumulated changes in energy for each component of the surface energy balance resulting from recent major vegetation transitions. Transitions are sorted according to decreasing absolute change in the surface energy balance. The changed area per transition, calculated based on the ESA CCI land cover maps of 2015 and 2000, are reported in megahectares on the right of the bars. The transitions shown involve the following vegetation classes: evergreen broadleaf forests (EBF), deciduous broadleaf forests (DBF), savannas (SAV), shrublands (SHR) and croplands (CRO)

Full paper, open access: https://www.nature.com/articles/s41467-017-02810-8

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79 thoughts on “BOOM: Global land use change responsible for a significant portion of global warming says study

    • There was a prof from University of Minnesota (or Wisconsin) that said the same thing years ago, theorizing that land use had a large, but unquantified, role in warming. I don’t think he had a “side” in the debate. Obviously, however, he was attempting to swim against the current and was swept aside.

    • I presented a chapter “Ecological changes” in my book “Climate Change: Myths & Realities” in 2008. Earlier to it in my scientific articles. Used urban-heat-island effect and rural-cold-island effect.

      Dr. S. Jeevananda Reddy

  1. In addition to land use induced changes, we probably have to consider changes in the oceans. Plankton are extremely important and are likely to have been affected by human activities. My WAG is that the increase of atmospheric CO2 could be explainable by changes in plankton. They are poorly understood and it looks to me as if the people doing the CO2 budgets are crossing their fingers and assuming that the plankton will keep doing exactly what they have always done in an unchanging manner.

    • They actually assume that the plankton will produce less with an increase of atmospheric CO2, just look 5 articles down on WUWT for example.

    • The oceans are still the primary drivers of climate change. Land use changes can affect regional climate but are unlikely to have a major impact on global climate.

      I’m skeptical of studies like this which have lots of built in assumptions.

      • Almost all our temperature data sets showing a warming originated from land based weather stations. The impact is on what we think the global climate is, and this is more than significant. Adjustment time again?

      • In this case I am forced to agree with one of our trolls, that is a misleading map, because the roads, as displayed, are way bigger than they are in reality. If this portrayal was accurate, one could look down at the Earth from the ISS and easily see all of the roads.
        I’m not denying that roads have an impact, especially where there are a lot of them. But this portrayal makes it look like the US is much more heavily paved than it really is.

    • that is something that i have always believed. plankton varies by orders of magnitude in certain areas over various timescales ,a huge unquantified part of the system. quite possibly the most important.

    • People are concerned that there will be a drop in plankton due to ocean acidification and its effect on shell building.

      Interesting theory, but they can tell that much of the CO2 is from fossil fuels based on C-14 ratios. And the populations of plankton would have to be enormous. Nutrients and O2 would be limiting. No, I can’t see it. The ocean is a CO2 sink.

  2. However, the scientists point out that local communities living in areas where the trees are cut will immediately be exposed to rising temperatures.

    Which is where weather stations are more likely to be located, and so they show rising temps as a consequence. Duh.

    • In reality, the ‘uncertainty’ in evidence in the alarmist’s approach is such that they are in about the same position as shamans and witchdoctors were in millenia past and so any old scare campaign will likely resonate given the right theatrics and being useful to the right political players.

      Ignoring UHI or this sort of land use HI effect is par for the course when proper, scientific accounting for same would remove the uncertainty which is the essential element of any scare campaign.

    • Komrade Kuma” Ignoring UHI or this sort of land use HI effect is par for the course when proper, scientific accounting for same would remove the uncertainty which is the essential element of any scare campaign.”

      What are you talking about? Who is ignoring anything? Do you really believe that scientists want to retain uncertainty? Why do you say such things?

      Devidmhoffer “Which is where weather stations are more likely to be located, and so they show rising temps as a consequence. Duh.”

      It’s interesting that scientists’ intelligence, insight, thoroughness and especially integrity are so often underestimated or outright insulted. Do you really think they haven’t thought of the things you do? They haven’t taken these things into account? There are ways, you know.

      It’s really amazing that people on this site will look for any possible excuse to denigrate climate science and scientists. The arguments offered *seem* plausible – and there are so many ! – but they are based on assumption, speculation, accusation, simplification. I see it again and again and again. It must be because there is such a strong desire to find evidence to support the skeptic claims.

      • We don’t have to look for an excuse to denigrate climate science and climate scientists.
        They lay out the ammunition every time they post one of their pseudo studies.
        The truth remains that there is and never has been any science behind the CAGW movement. Models, especially models that fail every attempt to calibrate them, are not science.

      • Kristi Silbir
        Do you really think they haven’t thought of the things you do?

        Appeal to authority in all its glory. They’re scientists, how dare I challenge them, right? News flash Kristi, I’ve been part of this debate for over a decade, I’ve read the papers, and the IPCC reports, I’ve looked at the data and the physics. I’m going to burst your bubble.

        My problem with the science is NOT that the scientists haven’t thought of these things. It is that the have, and they chose to ignore them. They have, and instead of discussing the problems in their data and science, they chose to instead obfuscate. Hence we have “hide the decline” and “Mike’s Nature trick” and computer programs that selectively weight tiny amounts of hockey stick shaped data over the majority of the data, and paper after paper predicated on RCP scenarios that are not remotely possible, minuscule changes in temperature magnified hundreds of times to make it look like a large change… I could go on for pages.

        So yes, Kristi. I do think they’ve thought of the things I have. In fact, evidence abounds that they have. The crime is that they have ignored the very things they have thought of in order to justify alarmist claims that have no basis in science. They used to come here to argue their position, and they got crushed so many times, they no longer show up. They spend their time making up excuses for the failure of their predictions instead. D*mn right they’ve though about it. But the gravy train ends for them if they admit it.

      • Kristi
        It must be because there is such a strong desire to find evidence to support the skeptic claims.

        The skeptic evidence can be drawn directly from the IPCC reports themselves. Read them some day.

      • If this is the picture I’ve seen elsewhere the left side is Haiti and the right side is the Dominican Republic.

    • This represents what people do to the environment when they are POOR. Expensive and unreliable energy makes people POOR! We will all cut and degrade whatever we have to to feed our kids.

  3. If the ‘carbon-tax movement’ were instead the ‘plant-more-trees movement’, I think we’d all have common ground.

  4. Some years before this, Freeman Dyson concluded that planting more trees would be a good approach. Instead we are cutting down forests in North Carolina, Georgia, etc. to feed the insatiable maw of the DRAX plant in the UK.

    • Only because they cut down all the trees in Scotland, and now maintain them as beautiful ‘natural’ Heather habitats. Maintained by the wealthy with annual burning so their grouse shooting goes uninterrupted.

      How very effing natural!

  5. Global reconstruction of temperatures in the early 70 s had everybody convinced the globe had cooled by half a degree. Most the data was for land and that now shows less than 0.2 degrees of cooling. More recent adjustments seemed have added another 0.4 since 1979. It appears that half of that was from adjustment of SST.
    http://woodfortrees.org/graph/crutem4vgl/from:1940/mean:60/plot/uah6-land/mean:60/offset:0.3/plot/crutem3vgl/from:1940/mean:60
    So rather than a degree of warming when emissions were significant, it could be as low as 0.3 with a significant amount of that further clearing and building – and error.

  6. “are going to need to be revised.”

    Need to be revised, definitely.
    Will they be revised, highly unlikely.

  7. Sorry but land use and deforestation were demoted by advocacy groups in order to focus on the singular wrong thing molecule.

  8. Land-use changes could certainly cause some local warming, however it’s a stretch to say they have been responsible for warming on a global scale, or at least any that might be measurable.

    • That would be true except that the land that is being changed is where almost all of the ground based temperature sensors are.
      Then these contaminated sensors are extrapolated to cover the vast majority of the planets surface that isn’t covered by any sensors.

      • MarkW

        Good point.

        But a question from a layman. When measuring land surface temperatures in forested regions, is that done at canopy level or in the dank recesses of the forest at ground level? Or perhaps in a clearing? Which would seem artificial as it’s representative of neither.

      • PS

        It’s a question I didn’t think to ask my late father in law who was a UN forester. He despised the interfering green movement as he was a scientist and knew intimately what we were all headed for, especially the destitute Africans, if the greens had their way.

      • Except that the claim is that it has actually caused warming, not that it has skewed the measurements higher, which I do believe.

      • Mark W “…. land that is being changed is where almost all of the ground based temperature sensors are.”
        Reference?

      • Just look at up the co-ordinates for any sensor in the US or Europe.
        It really is amazing how much you don’t know about your own religion.

      • For a trivial example. Until automated sensors were deployed, all sensors had to be close enough to a home or place of business so that someone could visit it once a day to take a reading.
        That meant the sensors had to be in developed areas. A small number of sensors might be near say a ranger station that was out in the middle of the woods, but such stations were a tiny fraction of the total number of stations.
        And let’s not even talk about the many stations that are at airports.

      • MarkW said: “Just look at up the co-ordinates for any sensor in the US or Europe.
        It really is amazing how much you don’t know about your own religion.”

        Another assertion by MarkW without supporting links. And when asked to back it up, he punts and blames it on the questioner. What’re we up to now, Mark, 25,000 posts without a supporting link provided?

    • Local warming is all that is measured by instruments on the ground. Or do you think a thermometer is somehow actually measuring the temperature for 250km around it?

    • At one time a got one of the alarmists to admit that there were a lot of problems with the ground based network, especially as one goes back in time.
      The problem was that they were forced to work with it since it was all they had.

      My response is that if the data doesn’t exist to analyze you either wait till the data does exist, or you find something else to do with your time.
      Inventing data to fill in the gaps is not and never will be science.

  9. ” agricultural expansion in mostly tropical regions”….

    I thought the tropics has the smallest GW fingerprint?

  10. Whether warming is caused by deforestation or rising GHGs, it is still “anthropogenic”. And the forcing due to land use change is already on the IPCC’s books as a forcing. Perhaps the IPCCs consensus values for the forcing from land use change will need to be changed, but this publication didn’t make any suggestions about this subject, The word forcing only appears once.

    • That is true. At the same time that they are adjusting upwards the land use change forcing, they are going to have to adjust downwards the CO2 forcing.

      • Upward adjustment of the land use forcing does not require downward adjustment of the CO2 forcing. Forcing is measured in W/m2 – from space in this land use paper (although some quantities appear to be derived from other sources). CO2 forcing begins with measurements made in the lab and applied to radiative fluxes in out atmosphere. The spectra of OLR we measure from space and DLR from the ground agree closely with the radiative fluxes we expect to see.

        When we add up all of the forcing (dF) and compare it with warming (dT) we calculate TCR. TCR is usually reported in units of dT/doubling rather than dT/dF. If we add ocean heat uptake (dQ), we can calculate ECS (aka energy balance model). When we do so, we assume that all climate change is forced, something we know isn’t true (but is the best we can do.)

        IF you ASSUME that all climate change is forced and that ECS is a known quantity, then a changing forcing for land use APPEARS to be inconsistent with the forcing for CO2. In reality, a larger forcing for land use means that TCR and ECS from EBMs needs to be revised downward.

      • If they don’t adjust downward the CO2 forcing at the same time they are adjusting upwards the land use forcing, then the models will run even hotter than they already are.

  11. Land use changes will continue to drive “warming”.

    As water becomes more scarce due to aquifer depletion and population increases, GM crops what require less water will come into use. Also farming practices will become more efficient. This means less water to evaporate over large areas (crop lands) and therefore more heat near the surface.

    As forests are cut, they also will result in higher surface temperatures.

    As cities grow and more roads are built, again high surface temperatures.

    Most of these are local changes, but you get enough local changes caught on land temperature measurements, they go into the data and come out as rising global temperatures.

    This doesn’t even touch upon air pollution (I mean real air pollution, not the fake kind the activists worry about). Soot will darken areas, especially when it settles on ice. Other pollutants may have positive or negative effects – but in generally as Africa, India, and China develop the air is going to become more polluted at least for a while.

    All of this while activists wring their hands about CO2, and point to rising global temperature (most of which is manufactured in tampering with the data) as proof of CO2’s role.

  12. Without even reading past the headline of the article, I thought, “How interesting: just two days ago, my thoughts went exactly to land use as an oft unspoken factor in “warming”. I don’t know why I started thinking about this, but it’s just eerie how a WUWT article appears shortly thereafter. [spooky music soundbite]

    Now I’ll go back up and read the article.

    • I noticed the same thing except that I had made that connection long ago but just brought it into a conversation in some comment section a day or two ago.

  13. Deforestation, mentioned, re-mentioned, blah, blah, blah. Thousands acres of federal lands were deforested, because of gross mismanagement. Fires have been huge the last several years. We need a forest management plan, that includes logging, to provide for a healthy forest and not a ‘natural’ deforestation by mismanagement.
    Some times the left is so blinded by ideology that can’t approach rational and logical approaches to our problems. Their ideology thus mutates into an idiot-ology.

  14. “We obviously change the albedo of a large proportion of the land area through agricultural practices, roads, parking lots and buildings.
    We change the reflective quality of seasonal snow and of the cryosphere through snow clearing, tracking and by spreading dark particles.”
    The above is a direct quote from an essay on climate available here. https://goo.gl/9Ns3ux

  15. So, how does this number get incorporated into a “global temperature” average, or is to early to expect this to be done? What is the likelihood of this measure being accepted as a legitimate component?

  16. scraft1 — I don’t a number from this study comes into the global temp avg. I think the method may fit into a model at some point to add information at the landscape scale. That’s as I understand it, anyway.

    From the article in full: “It is worth noting that our approach addresses exclusively the direct biophysical impact of land cover change at local scales, since climate feedbacks and large-scale teleconnections cannot be assessed with this method of local space-for-time substitution.”

  17. Dear god

    The are talking about LST, not SAT!
    Also you should know that they dont actually measure LST. and the accuracy of LST is around 1K.
    so over a 15 year period, using physics model that estimates LST from the reflected surface light ( and emissivity guesses based on land type) the estimate a change (.23C) in LST that is less than the accuracy of the sensors.

    Psst. we already know land use change is repsonsible for some of the warming in SAT.

    • Does not matter if accuracy is 1K, precision and linearity is what matters when you compare two temperatures. If the real temperature is 20C and increases to 20.23 the instrument might measure 21C and 21.23C due to an error offset. The absolute accuracy is bad, but any error offset will be removed when you subtract the temperatures, 21.23-21=0.23. The uncertainty will depend on precision and linearity.

  18. Actually

    I am not sure they got it right.

    My results show it is cooling where they chopped the trees (e.g. Tandil, ARG)
    and it is warming where they turned a desert into an oasis (e.g. Las Vegas, USA)..

    • John
      Your report gives the wrong impression that vegetation helps cool the world.
      Obviously, looking at the shade a tree provides, yes it does cool the spot below.
      However, overall vegetation traps heat. I believe the reaction at night when it converts the CO2 (to sugar) is exothermic? Anyway, e.g. note the development of the minimum T over the past 40 years in Tandil (ARG) where they chopped the trees.and compare it with that of Las Vegas (USA) , where they turned a desert into an oasis.

  19. Here is a report of Pielke’s findings as originally published on NASA’s web site as it appeared on Science Direct https://www.sciencedaily.com/releases/2002/10/021002070639.htm
    Landcover Changes May Rival Greenhouse Gases As Cause Of Climate Change

    Date:
    October 2, 2002
    Source:
    NASA/Goddard Space Flight Center
    Summary:
    While many scientists and policy makers have focused only on how heat-trapping gases like carbon dioxide are altering our global climate, a new NASA-funded study points to the importance of also including human-caused land-use changes as a major factor contributing to climate change.
    Share:

    FULL STORY

    While many scientists and policy makers have focused only on how heat-trapping gases like carbon dioxide are altering our global climate, a new NASA-funded study points to the importance of also including human-caused land-use changes as a major factor contributing to climate change.

    Land surface changes, like urban sprawl, deforestation and reforestation, and agricultural and irrigation practices strongly affect regional surface temperatures, precipitation and larger-scale atmospheric circulation. The study argues that human-caused land surface changes in places like North America, Europe, and southeast Asia, redistribute heat regionally and globally within the atmosphere and may actually have a greater impact on climate than that due to anthropogenic greenhouse gases combined.

    The study also proposes a new method for comparing different human-influenced agents of climate change in terms of the redistribution of heat over land and in the atmosphere. Using a single unit of measurement may open the door to future work that more accurately represents human-caused climate change.

    “Our work suggests that the impacts of human-caused landcover changes on climate are at least as important, and quite possibly more important than those of carbon dioxide,” said Roger Pielke, Sr., an atmospheric scientist at Colorado State University, Fort Collins, Colo., and lead author of the study. “Through landcover changes over the last 300 years, we may have already altered the climate more than would occur associated with the radiative effect of a doubling of carbon dioxide.” If carbon dioxide (CO2) emissions continue at current rates, atmospheric CO2 concentrations are expected to double by 2050. Land surface changes will also continue to occur.

    Types of land surface strongly influence how the Sun’s energy is distributed back to the atmosphere. For example, if a rainforest is removed and replaced with crops, there is less transpiration, or evaporation of water from leaves. Less transpiration leads to warmer temperatures in that area. On the other hand, if farmland is irrigated, more water is transpired and also evaporated from moist soils, which cools and moistens the atmosphere, and can affect precipitation and cloudiness.

    Similarly, forests may influence the climate in more complicated ways than previously thought. For example, in regions with heavy snowfall, reforestation or afforestation would cause the land to reflect less sunlight, and more heat would be absorbed, resulting in a net warming effect despite the removal of CO2 from the atmosphere through photosynthesis during the growing season. Further, reforestation could increase transpiration in an area, putting more water vapor in the air. Water vapor in the troposphere is the biggest contributor to greenhouse gas warming.

    Local land surface changes can also influence the atmosphere in far-reaching ways, much like regional warming of tropical eastern and central Pacific Ocean waters known as El Niño. El Niño events create moist rising air, thunderstorms and cumulus clouds, which in turn alter atmospheric circulations that export heat, moisture, and energy to higher latitudes. Tropical land surface changes should be expected to play a greater role on global climate than El Niño, given that thunderstorms prefer to form over land, and the fact that the large area of tropical land-use changes far exceeds the relatively small area of water responsible for El Niño. Impacts of land use changes are harder to detect because they are permanent, as opposed to El Niño, which comes and goes.

    Pielke Sr., and colleagues propose a new method for measuring the impacts of both greenhouse gases and landcover changes by using a formula that quantifies all the various anthropogenic climate change factors in terms of the amount of heat that is redistributed from one area to another. This heat redistribution is stated in terms of watts per meter squared, or the amount of heat associated with a square meter area. For example, if a flashlight generated heat of one watt that covers a square meter, then the heat energy emitted would be one watt per meter squared.

    By using a measure based on the spatial redistribution of heat to quantify the different human influences on climate, including landcover changes and greenhouse gases, the researchers hope to achieve a more accurate portrayal of all of the anthropogenic influences on climate change in future research.

    The paper was published in a recent issue of the Philosophical Transactions of the Royal Society of London. The research was funded by grants from NASA and the National Science Foundation.

    Story Source:

    Materials provided by NASA/Goddard Space Flight Center. Note: Content may be edited for style and length.

    https://www.gsfc.nasa.gov/topstory/20020926landcover.html

    And if you follow the link to the article shown above, this is what you would see for the last decade
    “404 page not found”

  20. While atop an 18+ thousand foot mountain in Mexico, I observed a great deal of dirt embedded in the glacial ice of what was reported to me as a shrinking ice cap. I would imagine, via the albedo effect, the suspended dust is contributing to melting. I suspect that nearby volcanic activity would explain some of the particulates and I am also aware of negative impacts of dust from Arizona and New Mexico on the snowpack in Southern Colorado.

    The author points to an increase in warming due to a reduction in the evaporative cooling effect of forest cover. Is there a further issue with an increase in atmospheric dust when forests are cleared for farmland that has been measured?

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