Sentences with phrase «global albedo changes»

In my articles to date I have been unwilling to claim anything as grand as the creation of a new model of climate because until now I was unable to propose any solar mechanism that could result directly in global albedo changes without some other forcing agent or that could account for a direct solar cause of discontinuities in the temperature profile along the horizontal line of the oceanic thermohaline circulation.

I have now realised that the global albedo changes necessary and the changes in solar energy input to the oceans can be explained by the latitudinal shifts (beyond normal seasonal variation) of all the air circulation systems and in particular the net latitudinal positions of the three main cloud bands namely the two generated by the mid latitude jet streams plus the Inter Tropical Convergence Zone (ITCZ).

I submit that we are seeing similar water based amplification processes both as regards CO2 in the air and as regards global albedo changes.

v) They even acknowledge that energy input to the oceans is affected but fail to link it explicitly to cloudiness and global albedo changes.

Figure 1: Global albedo change 1984 — 2004.

Not exact matches

If this change in global albedo is what is causing global warming, how did the process get started?

He then uses what information is available to quantify (in Watts per square meter) what radiative terms drive that temperature change (for the LGM this is primarily increased surface albedo from more ice / snow cover, and also changes in greenhouse gases... the former is treated as a forcing, not a feedback; also, the orbital variations which technically drive the process are rather small in the global mean).

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.

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.

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.

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.

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.

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).

Nighttime increases in cloud cover will contribute to global warming — only daytime changes and the concurrent increase in albedo would give negative forcing.

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 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.

E.g., human - caused albedo variations from desertification, and to some extent tropical deforestation, were connected with past global climate changes by Sagan et al. (1979); a pioneering model confirming «the long - held idea that the surface vegetation... is an important factor in the Earth's climate» was Shukla and Mintz (1982); Amazon Basin: Salati and Vose (1984); more recently, see Kutzbach et al. (1996).

That allows latitudinal sliding of the jets and climate zones below the tropopause leading to changes in global cloudiness and albedo with alters the amount of energy getting into the oceans.»

The sun is clearly driving changes in global air circulation and thus global albedo as per my model:

Finally, while economics may be critical to your definition of «catastrophic» anthropogenic global warming, economics says nothing about the science underlying the projections of sea level rise, the physics of Arctic amplification, changes to albedo that lead to greater warming that may lead to significant releases of methane clathrate deposits, regional projections of reduce (or enhanced) precipitation, and so on.

: besides arresting inflation by reflating Zimbabwe's gold reserves with the hefty Nobel prize medal, it can halt global warming by parlaying the award money into world - wide albedo change.

To some extent, I actually agree with Dr. Hansen on this point, additional global warming would cause an albedo change - I just disagree that CO2 would have any affect.

The albedo value changes with the size of the daytime global cloud cover, which is the umbrella of the globe.

The Arctic provides an early indicator of global climate change through feedback systems associated with factors such as the high albedo of snow and ice [Holland and Bitz, 2003].

To date, while various effects and feedbacks constrain the certainty placed on recent and projected climate change (EG, albedo change, the response of water vapour, various future emissions scenarios etc), it is virtually certain that CO2 increases from human industry have reversed and will continue to reverse the downward trend in global temperatures that should be expected in the current phase of the Milankovitch cycle.

Global Cooling: Increasing World - wide Urban Albedos to Offset CO2, Climatic Change, 94, 275 - 286; Weber, G.W., et al. (2017).

Svensmark demonstrated the amplification possible from cosmic rays and cloud formation changing the Albedo by more than enough to account for any observed temperature change over the past 150 years and other cycles come into play for the longer period global temperature variations.

I was surprised there was no mention of changes in global albedo or cloud cover in the paper, but I assume that AR5 includes them under «natural variability» rather than forcings.

Ice albedo feedback change is mainly limited to high latitude NH * land * during deglaciation, and its effects — though strong — are limited compared to those of a radiative forcing over the global ocean.

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!)

Marvel, et al., assume land use changes slightly increase global albedo (negative forcing).

The change of the heat content of the globe (mainly in the oceans) is dH / dt = S (1 - a)-- E, where S is the solar radiation, a the albedo, E the global infrared emission; such a relation is likely and there are historical series for H (figure 13 - A), E (figure 14 - A) for S and a; whether global averaging makes sense is debatable.

But again such global averages are of little value: regional observations should be related to the regional cloud coverage and albedo and possibly to changes of the strength of surface currents.

1) His findings on orbital movements are sound, but have no implications about climate without an albedo model to change the minor seasonal variations into a significant global variation;

Project Earthshine (Earthshine is the ghostly glow of the dark side of the Moon) has been measuring changes of the terrestrial albedo in relation to cloud coverage data; according to cloud coverage data available since 1983, the albedo of the Earth has decreased from 1984 to 1998, then increased up to 2004 in sync with the Mean Global Temperature.

There is consistence [70] between the estimates of the ISCCP, the global albedo, the insolation measured at the surface and the length of the daily insolation observed in many places: all of them are likely to explain the temperature changes.

Hall and Qu (2006) showed that differences among models in seasonal northern hemisphere surface albedo changes are well correlated with global - warming albedo changes in CMIP3 models.

Global temps vary for many reasons beyond CO2 levels including but not limited to: planetary motion, changes in albedo, stratospheric aerosols, and solar variability to name a few, but the only area of genuine study by the IPCC has been rising CO2 levels.

The only thing that I would contend could be added would be long slow cumulative changes in solar output other than raw TSI namely changes in the mix of particles and wavelengths over longer periods of time such as MWP to LIA to date and which seem to have some effect on surface pressure distribution and global albedo so as to alter solar shortwave into the oceans and thus affecting the energy available to the ENSO process.

This leads me to believe that CO2 forcing is a minor component of the temperature rise (even Hansen in his paper «Global Warming in the 21st century, an Alternative Scenario» has assigned much warming to e.g. black carbon, methane etc, and an inquisitive mind might easily think of others such as albedo change).

Seasonal changes in SWR from clear skies have little to do with the surface albedo feedback that will follow global warming (aka ice - albedo feedback).

Major changes in global albedo move at a glacial pace.

Vegetation cover changes caused by land use can alter regional and global climate through both biogeochemical (emissions of greenhouse gases and aerosols) and biogeophysical (albedo, evapotranspiration, and surface roughness) feedbacks with the atmosphere, with reverse effects following land abandonment, reforestation, and other vegetation recoveries (107).

Using measured amounts of GHGs during the past 800000 years of glacial — interglacial climate oscillations and surface albedo inferred from sea - level data, we show that a single empirical «fast - feedback» climate sensitivity can account well for the global temperature change over that range of climate states.

Interestingly the whole scenario is a mirror image of the way the oceans and the water cycle also amplify changes to global albedo in response to small changes in the level of solar activity.

Motivated by findings that major components of so - called cloud «feedbacks» are best understood as rapid responses to CO2 forcing (Gregory and Webb in J Clim 21:58 — 71, 2008), the top of atmosphere (TOA) radiative effects from forcing, and the subsequent responses to global surface temperature changes from all «atmospheric feedbacks» (water vapour, lapse rate, surface albedo, «surface temperature» and cloud) are examined in detail in a General Circulation Model.

Other potential causes of climate change include the depletion of stratospheric ozone in recent decades, again through human activities, and global changes in the surface reflectivity — or albedo — of the planet, as we modify the patterns of vegetation that cover the land.

Polar albedo changes, hurricanes, ocean dynamics, forest feedbacks, soil chemistry, boundary layer physics, global solar energy fluxes, cloud feedbacks, etc..

Internal conditions change, orbital forcing roughly constant during (relatively brief) duration of YD, global average temperature barely changes despite major albedo increase, YD ends, deglaciation continues apace...