Sentences with phrase «global albedo of»

Moreover, epoch superposition analysis of Forbush decreases reveals no detectable albedo response to cosmic ray decreases, thereby placing an upper limit on the possible influence of cosmic ray variations on global albedo of 0.0029 per 5 % decrease.

If we allow that all those clouds are cumulus with an albedo of 0.8 and that they block water with an albedo of 0.1, that translates to a change in global albedo of 0.014.

Not exact matches

Whereas carbon levels can affect warming on a global scale, the effects of increased albedo and poor evotranspiration would affect temperatures only on a regional level.

Such model included meteorological factors like levels of aerosols, anthropogenic and biogenic volatile organic compounds (VOCs), ozone, carbon dioxide, methane, and other items that influence global temperature — the surface albedo among them.

«Scientists have talked about Arctic melting and albedo decrease for nearly 50 years,» said Ramanathan, a distinguished professor of climate and atmospheric sciences at Scripps who has previously conducted similar research on the global dimming effects of aerosols.

Another positive feedback of global warming is the albedo effect: less white summer ice means more dark open water, which absorbs more heat from the sun.

Critics argue that albedo modification and other «geoengineering» schemes are risky and would discourage nations from trying to reduce their emissions of carbon dioxide, the heat - trapping gas that comes from the burning of fossil fuels and that is causing global warming by absorbing increasing amounts of energy from sunlight.

Keith adds, however, that the few existing studies suggest albedo modification could help ameliorate some effects of global warming.

They tend to believe that as the planet warms, low - level cloud cover will increase, thus increasing planetary albedo (overall reflectiveness of the Earth), offsetting the increased greenhouse effect and preventing a dangerous level of global warming from occurring.

In her global maps of Europa, Callisto and Ganymede, the color gradient represents the surface temperature — blue means colder and therefore, presumably a more reflectively surface (higher albedo).

Takemura, T., et al., 2002: Single scattering albedo and radiative forcing of various aerosol species with a global three - dimensional model.

Ice sheet albedo forcing is estimated to have caused a global mean forcing of about — 3.2 W m — 2 (based on a range of several LGM simulations) and radiative forcing from increased atmospheric aerosols (primarily dust and vegetation) is estimated to have been about — 1 W m — 2 each.

In addition, since the global surface temperature records are a measure that responds to albedo changes (volcanic aerosols, cloud cover, land use, snow and ice cover) solar output, and differences in partition of various forcings into the oceans / atmosphere / land / cryosphere, teasing out just the effect of CO2 + water vapor over the short term is difficult to impossible.

I was interested not so much in the forcing effect of clouds themselves so much as the change in albedo which might result from a change in the overall extent of global cloud cover.

[1] CO2 absorbs IR, is the main GHG, human emissions are increasing its concentration in the atmosphere, raising temperatures globally; the second GHG, water vapor, exists in equilibrium with water / ice, would precipitate out if not for the CO2, so acts as a feedback; since the oceans cover so much of the planet, water is a large positive feedback; melting snow and ice as the atmosphere warms decreases albedo, another positive feedback, biased toward the poles, which gives larger polar warming than the global average; decreasing the temperature gradient from the equator to the poles is reducing the driving forces for the jetstream; the jetstream's meanders are increasing in amplitude and slowing, just like the lower Missippi River where its driving gradient decreases; the larger slower meanders increase the amplitude and duration of blocking highs, increasing drought and extreme temperatures — and 30,000 + Europeans and 5,000 plus Russians die, and the US corn crop, Russian wheat crop, and Aussie wildland fire protection fails — or extreme rainfall floods the US, France, Pakistan, Thailand (driving up prices for disk drives — hows that for unexpected adverse impacts from AGW?)

While the local, seasonal climate forcing by the Milankovitch cycles is large (of the order 30 W / m2), the net forcing provided by Milankovitch is close to zero in the global mean, requiring other radiative terms (like albedo or greenhouse gas anomalies) to force global - mean temperature change.

Calculations as to the magnitude of this effect (that is, how dust is needed to significantly decrease glacier albedo) certainly have been done, though probably not on a global basis.

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.

I think that only illustrates the bizarre use of the global average and models that in effect suggest cutting down trees would increase albedo and cool the planet.

Gavin disputes that the main driver of the sea ice retreat is the albedo flip, but we are seeing not only polar amplification of global warming but positive feedback, which would not be explained simply by radiative forces and ocean currents.

Please note shortwave albedo of Earth has large spatio - temporal variations, but its annual global average is restricted to a narrow range, even if it is not determined by simple material constraints, but by an intricate interplay between many internal degrees of freedom.

Your illogic is to think that this somehow would be some sort of legitimate argument that the (inverse) cause and effect relationship between albedo and global temperature established by the laws of physics is false.

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.

With respect to Mr. Best's post, which I may be unfairly implying is a good example, one of the fallacious but clever debate manipulations utilized by CC deniers and (way too many) lukewarmers is to focus relentlessly (often inaccurately) on climatological research frontiers such as climate sensitivity, or relations between evaporation, cloudiness, and global albedo.

In Hansen Nazarenko 2004, Hansen wrote that «Our estimate for the mean soot effect on spectrally integrated albedos in the Arctic... is about one quarter of observed global warming.»

So for example deglaciation warmed global mean temps by about 5 C over 10k years with a radiative forcing of about 6.5 W / m2 (total of both GHG increases and albedo decreases).

(Orbital forcing doesn't have much of a global annual average forcing, and it's even concievable that the sensitivity to orbital forcing as measured in terms of global averages and the long - term response (temporal scale of ice sheet response) might be approaching infinity or even be negative (if more sunlight is directed onto an ice sheet, the global average albedo might increase, but the ice sheet would be more likely to decay, with a global average albedo feedback that causes warming).

Is there a point in global warming where albedo would suddenly increase instead of decreasing?

http://www.springerlink.com/content/lm0024kv72t3841w/ «The simulated magnitude of hydrological changes over land are much larger when compared to changes over oceans in the recent marine cloud albedo enhancement study since the radiative forcing over land needed (− 8.2 W m − 2) to counter global mean radiative forcing from a doubling of CO2 (3.3 W m − 2) is approximately twice the forcing needed over the oceans (− 4.2 W m − 2).

http://www.springerlink.com/content/9569172415150486/ Climate Dynamics Volume 37, Numbers 5 - 6 (2011), 915 - 931, DOI: 10.1007 / s00382 -010-0868-1 Albedo enhancement of marine clouds to counteract global warming: impacts on the hydrological cycle G. Bala, Ken Caldeira, Rama Nemani, Long Cao, George Ban - Weiss and Ho - Jeong Shin

Global climate models have successfully predicted the rise in temperature as greenhouse gases increased, the cooling of the stratosphere as the troposphere warmed, polar amplification due the ice - albedo effect and other effects, greater increase in nighttime than in daytime temperatures, and the magnitude and duration of the cooling from the eruption of Mount Pinatubo.

«Our results suggest that, in contrast to other proposals to increase planetary albedo, offsetting mean global warming by reducing marine cloud droplet size does not necessarily lead to a drying, on average, of the continents.

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).

The melt of the Greenland glaciers is accelerating at an incredible rate and it can't be long before the Arctic sea ice disappears altering global albedo irrevocably.

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.

Subject of some specific concern about global warming because of large temperature rises predicted for the arctic, and because of some arctic - specific feedback effects (e.g. the albedo feedback following loss of arctic sea ice).

Global average temperature is lower during glacial periods for two primary reasons: 1) there was only about 190 ppm CO2 in the atmosphere, and other major greenhouse gases (CH4 and N2O) were also lower 2) the earth surface was more reflective, due to the presence of lots of ice and snow on land, and lots more sea ice than today (that is, the albedo was higher).

One could write a book that surveys the scientific assessments of the causes of global warming, including feedbacks (albedo flip, etc.), that totally ignores public policy.

J Latham (1990), «Control of global warming», Nature, vol 347, pp330 - 340; J Latham (2002), «Amelioration of global warming by controlled enhancement of the albedo and longevity of low - level maritime clouds», Atmospheric Science Letters, vol 3, pp52 - 58.

If part of the result of increased GHG's is increased cloudiness, leading to a higher SW albedo, then the overall global temperature need not increase, because the amount of energy actually entering the system has been reduced.

The mechanism by which the effect of oceanic variability over time is transferred to the atmosphere involves evaporation, conduction, convection, clouds and rainfall the significance of which has to date been almost entirely ignored due to the absence of the necessary data especially as regards the effect of cloudiness changes on global albedo and thus the amount of solar energy able to enter the oceans.

as we can we may be able to influence albedo on an ocean scale — and hopefully create a little bit of global cooling.

Our observational studies (Gray and Schwartz, 2010 and 2011) of the variations of outward radiation (IR + albedo) energy flux to space (ISCCP data) vs. tropical and global precipitation increase (from NCEP reanalysis data) indicates that there is not a reduction of global net radiation (IR + Albedo) to space which is associated with increased global or tropical - regional raialbedo) energy flux to space (ISCCP data) vs. tropical and global precipitation increase (from NCEP reanalysis data) indicates that there is not a reduction of global net radiation (IR + Albedo) to space which is associated with increased global or tropical - regional raiAlbedo) to space which is associated with increased global or tropical - regional rainfall.

In the real world the most obvious and most common reason for an increase in the speed of energy flow through the system occurs naturally when the oceans are in warm surface mode and solar input to the oceans due to reduced global albedo is high as apparently occurred during the period 1975 to 1998.

In this new study, the researchers showed that increasing the albedo of a 1m2 surface by 0.01 would have the same effect on global temperature, over the next 80 years, as decreasing emissions by around 7 kg of CO2.

Total global snow / ice / albedo effects of course encompass far more than the Arctic sea.

The result is cooling oceans able to gradually absorb and lower atmospheric CO2, enabling restoration of albedo at higher latitude / altitude, producing further slow global cooling.

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 insignificant.

http://arxiv.org/pdf/physics/0512170 Google scholar threw up this interesting paper on surface albedo, and how much of a global impact there'd be from whitening of urban structures (about the equivalent of 10 ppm of CO2 it seems).

For instance the earth's global ocean already has an albedo close to zero so greenhouse gases are limited there and because GHGs modus operandi is restricting radiative cooling and the ocean is still free to cool evaporatively there is no first order significant effect of greenhouse gases over a liquid ocean.