Sentences with phrase «global cloud feedback»
One explanation for that correlation would be a moderately positive global cloud feedback.
http://www.realclimate.org/
The shortwave impact of changes in boundary - layer clouds, and to a lesser extent mid-level clouds, constitutes the largest contributor to inter-model differences in global cloud feedbacks.
Very recently, Ringer et al. (2014) and Brient et al. (2015) analyzed the CMIP5 fully coupled ocean — atmosphere models and their corresponding Cess experiments and confirmed again that the Cess experiments provide a good guide to the global cloud feedbacks determined from the coupled simulations, including the intermodel spread.
Not exact matches
«Our analysis confirmed that the Planck Response plays a dominant role in restoring global temperature stability, but to our surprise we found that it tends to be overwhelmed locally by heat - trapping positive energy feedbacks related to changes in clouds, water vapor, and snow and ice,» Brown said.
The climate sensitivity classically defined is the response of global mean temperature to a forcing once all the «fast feedbacks» have occurred (atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.), but before any of the «slow» feedbacks have kicked in (ice sheets, vegetation, carbon cycle etc.).
The variation in global climate sensitivity among GCMs is largely attributable to differences in cloud feedbacks, and feedbacks of low - level clouds in particular.
To investigate cloud — climate feedbacks in iRAM, the authors ran several global warming scenarios with boundary conditions appropriate for late twenty - first - century conditions (specifically, warming signals based on IPCC AR4 SRES A1B simulations).
This empirical fast - feedback climate sensitivity allows water vapor, clouds, aerosols, sea ice, and all other fast feedbacks that exist in the real world to respond naturally to global climate change.
The climate sensitivity classically defined is the response of global mean temperature to a forcing once all the «fast feedbacks» have occurred (atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.), but before any of the «slow» feedbacks have kicked in (ice sheets, vegetation, carbon cycle etc.).
You are welcome to try something similar with global radiative forcing fluctuation, but if you do it will be rather tricky to isolate the cloud effect, since you have the snow and ice albedo effect to deal with then, which are largely temperature - related feedbacks.
On the possibility of a changing cloud cover «forcing» global warming in recent times (assuming we can just ignore the CO2 physics and current literature on feedbacks, since I don't see a contradiction between an internal radiative forcing and positive feedbacks), one would have to explain a few things, like why the diurnal temperature gradient would decrease with a planet being warmed by decreased albedo... why the stratosphere should cool... why winters should warm faster than summers... essentially the same questions that come with the cosmic ray hypothesis.
There are other highly uncertain topics such as hurricanes and global warming and cloud / aerosol feedbacks, that are arguably more important for the global warming argument than the paleo reconstructions.
For instance, increasing cloud cover due to global warming may change the albedo, but this would be a feedback to a larger warming effect, rather than a cooling.
Increasing the negative feedback, as might happen in the atmosphere if global warming creates increased cloud cover (hence albedo), can increase the amplitude of the oscillations.
The physics underlying the lapse rate will insure dew point temperatures at some level in the atmospheric column, although the level will increase with global warming (the resulting high (er) clouds may give a positive feedback).
Re 9 wili — I know of a paper suggesting, as I recall, that enhanced «backradiation» (downward radiation reaching the surface emitted by the air / clouds) contributed more to Arctic amplification specifically in the cold part of the year (just to be clear, backradiation should generally increase with any warming (aside from greenhouse feedbacks) and more so with a warming due to an increase in the greenhouse effect (including feedbacks like water vapor and, if positive, clouds, though regional changes in water vapor and clouds can go against the global trend); otherwise it was always my understanding that the albedo feedback was key (while sea ice decreases so far have been more a summer phenomenon (when it would be warmer to begin with), the heat capacity of the sea prevents much temperature response, but there is a greater build up of heat from the albedo feedback, and this is released in the cold part of the year when ice forms later or would have formed or would have been thicker; the seasonal effect of reduced winter snow cover decreasing at those latitudes which still recieve sunlight in the winter would not be so delayed).
This is what I get out of it: the Arctic - ice - albedo situation is more complicated than earlier thought (due to clouds, sun - filled summers, dark winters, etc), but NET EFFECT, the ice loss and all these other related factors (some negative feedbacks) act as a positive feedback and enhance global warming.
Models indicate that cloud - feedback would not substantially slow global warming, but because of the uncertainty, it has been an area of significant scientific interest.
The iris hypothesis and the tropical upper tropospheric water vapor and cirrus cloud feedbacks, while arguably still open to debate, are not by any stretch of the imagination a major driver in global climate feedback.
(3) This cloud cover reaction is a rapid, positive feedback with respect to TSI, and a slow negative feedback with respect to global average surface temperature.
And because cloud cover gates the Sun on and off, it is the most powerful feedback in all of Earth's climate to amplify solar variations and to mitigate global warming from any cause.
Cloud variations are obviously an important element on a global scale, but the effects of Arctic ice melting are important locally and also a non-trivial fraction of global albedo feedbacks, which are a contributor to total feedback that is smaller than those from water vapor and probably from cloud feedbacks, but not insignifiCloud variations are obviously an important element on a global scale, but the effects of Arctic ice melting are important locally and also a non-trivial fraction of global albedo feedbacks, which are a contributor to total feedback that is smaller than those from water vapor and probably from cloud feedbacks, but not insignificloud feedbacks, but not insignificant.
Aside from continuing to misunderstand that the «missing heat» is about having an inadequate global climate observational network (mainly because we don't have good measurements of deep ocean heat), observational data have demonstrated that water vapor, and likely clouds, are indeed positive feedbacks.
ENSO involves feedbacks: wind, cloud, sea level pressure, surface temperature, Rossby waves — it is a complex and dynamic system in its own right — but only part of the wider global dynamic.
These data are used to research atmospheric radiation balance, cloud feedback processes, and to initialize and evaluate model performance, which are critical to the understanding of global climate change.
In an analysis of global warming cloud feedbacks, Dessler (2010) used short term (i.e., not climate) variations in surface temperature and CERES data to determine that cloud cover was negatively correlated with temperature.
The point is that in order for clouds to be an effective negative feedback to CO2 forcing there needs to be a gradual and persistent increase in global cloud coverage as the temperature of the earth rises.
How may low - cloud radiative properties simulated in the current climate influence low - cloud feedbacks under global warming?
The question as to whether ENSO can be used to determine cloud feedback from global warming seems answered in the negative.
Because it affects our ability to find the Holy Grail of climate research: cloud feedback... Sufficiently positive cloud feedback could cause a global warming Armageddon.
• biological aerosol seeding of clouds (phytoplankton and forests releasing isoprenes, Lovelock, Makarieva / Gorshkov), • and the «biotic pump hypothesis» (Makarieva / Gorshkov) •... among others... In addition, AGW - theory advocates systematically downplay the number and contribution of damping / stabilizing (or «negative») feedbacks (both of heat and CO2) in the global climate system — most implicated directly or indirectly with the activities of life, as illustrated in point # 3.
Re: «atmospheric water vapor acts as feedback magnifier» How do you quantify and validate the global magnitude of impacts (INCLUDING CLOUDS) or even whether they are positive or negative?
Perhaps the negative feedback of cloud cover has kicked in, dampening global warming, or the ocean absorption of atmospheric heat is playing a new and more decisive role.
Modelling how clouds, of many different charateristics and associated feedbacks, affect global climate is horrendously difficult.
He has published two papers stating that climate change is not serious: a 2001 paper hypothesizing that clouds would provide a negative feedback to cancel out global warming, and a 2009 paper claiming that climate sensitivity (the amount of warming caused by a doubling of carbon dioxide) was very low.
«To assess the models» cloud feedback and climate sensitivity, we follow the Cess approach by conducting a pair of present - day and global warming simulations for each model using prescribed SSTs and greenhouse gas (GHG) concentrations (Cess et al. 1990).
Unfortunately, establishing the reality of this cloud feedback requires a measurement of global cloudiness with an accuracy of a small fraction of a percent — a very difficult problem.
The results are collective feedbacks of cloud, snow, ice and MOC that produce the potential for «surprises on both the warm and cold ends of the spectrum due entirely to internal variability that lie well outside the envelope of a steadily increasing global mean temperature.»
I could say that the sun is weaker than it has been for a while in this cycle, yet global cloud cover is lower, which is evidence that the Svensmark theory is wrong, while this evidence consistent with AGW and positive cloud feedback.
It should be self - evident that clouds have to provide a negative feedback, or there would be regular runaway «global warming» events in the geological record.
A slight change of ocean temperature (after a delay caused by the high specific heat of water, the annual mixing of thermocline waters with deeper waters in storms) ensures that rising CO2 reduces infrared absorbing H2O vapour while slightly increasing cloud cover (thus Earth's albedo), as evidenced by the fact that the NOAA data from 1948 - 2008 shows a fall in global humidity (not the positive feedback rise presumed by NASA's models!)
His research focuses on the representation of clouds and convective storms in the GISS global climate model and their role in cloud feedbacks on climate change, as well as climate impacts associated with storms.
Existing climate models with a positive feedback from H2O are plain wrong, since they don't allow the heated water vapour to rise, forming clouds that contribute to global dimming, offsetting CO2 effects on temperature.
The uncertain effect of feedback between climate and clouds is one of the largest obstacles to producing more confident projections of global climate.
This bias may be explained by a misrepresentation of mixed - phase extratropical clouds, often pinpointed as playing a key role in driving global - cloud feedback and uncertainties in climate sensitivity estimates (e.g., Tan et.
Knowing that the spread in ECS is mostly related to uncertainties in low - cloud feedback, it seems obvious that constraining how low clouds respond to global warming can reduce the spread of climate sensitivity among models.
76) Dr Roy Spencer, a principal research scientist at the University of Alabama in Huntsville, has indicated that out of the 21 climate models tracked by the IPCC the differences in warming exhibited by those models is mostly the result of different strengths of positive cloud feedback — and that increasing CO2 is insufficient to explain global - average warming in the last 50 to 100 years.
In particular, anomalously high convection in ENSO and ENSO - related regional cloud changes can lead to negative feedbacks not seen with persistent forcings that operate over longer timescales on a more global basis.
«Evidence for climate change in the satellite cloud record» «Cloud feedback mechanisms and their representation in global climate models» «A net decrease in the Earth's cloud, aerosol, and surface 340 nm reflectivity during the past 33 yr (1979 — 2011)» «New observational evidence for a positive cloud feedback that amplifies the Atlantic Multidecadal Oscillation» «Impact of dataset choice on calculations of the short - term cloud feedback&rcloud record» «Cloud feedback mechanisms and their representation in global climate models» «A net decrease in the Earth's cloud, aerosol, and surface 340 nm reflectivity during the past 33 yr (1979 — 2011)» «New observational evidence for a positive cloud feedback that amplifies the Atlantic Multidecadal Oscillation» «Impact of dataset choice on calculations of the short - term cloud feedback&rCloud feedback mechanisms and their representation in global climate models» «A net decrease in the Earth's cloud, aerosol, and surface 340 nm reflectivity during the past 33 yr (1979 — 2011)» «New observational evidence for a positive cloud feedback that amplifies the Atlantic Multidecadal Oscillation» «Impact of dataset choice on calculations of the short - term cloud feedback&rcloud, aerosol, and surface 340 nm reflectivity during the past 33 yr (1979 — 2011)» «New observational evidence for a positive cloud feedback that amplifies the Atlantic Multidecadal Oscillation» «Impact of dataset choice on calculations of the short - term cloud feedback&rcloud feedback that amplifies the Atlantic Multidecadal Oscillation» «Impact of dataset choice on calculations of the short - term cloud feedback&rcloud feedback»
If there is a strong negative feedback in the climate system, be it clouds, lapse rate, etc it would preclude large temperature variations in global temperature caused by a perturbation in climate, regardless of the cause of the perturbation