Sentences with phrase «of the albedo forcing»

Not exact matches

Lee, Y.H., J. - F. Lamarque, M. G. Flanner, C. Jiao, D. T. Shindell, T. Berntsen, M. M. Bisiaux, J. Cao, W. J. Collins, M. Curran, R. Edwards, G. Faluvegi, S. Ghan, L. W. Horowitz, J. R. McConnell, G. Myhre, T. Nagashima, V. Naik, S. T. Rumbold, R. B. Skeie, K. Sudo, T. Takemura, F. Thevenon (2013), Evaluation of preindustrial to present - day black carbon and its albedo forcing from ACCMIP (Atmospheric Chemistry and Climate Model Intercomparison Project), Atmos.

Courtillot et al. commit the «flat Earth» error from which our article draws its name: they give a misleading impression of the comparison of forcing by solar variability relative to greenhouse gas forcing by failing to take into account the Earth's spherical geometry and albedo.

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

They got 10 pages in Science, which is a lot, but in it they cover radiation balance, 1D and 3D modelling, climate sensitivity, the main feedbacks (water vapour, lapse rate, clouds, ice - and vegetation albedo); solar and volcanic forcing; the uncertainties of aerosol forcings; and ocean heat uptake.

On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

This method tries to maximize using pure observations to find the temperature change and the forcing (you might need a model to constrain some of the forcings, but there's a lot of uncertainty about how the surface and atmospheric albedo changed during glacial times... a lot of studies only look at dust and not other aerosols, there is a lot of uncertainty about vegetation change, etc).

26 Paul W asked, «On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

As I understand Hansen he's saying: if we double CO2 this century (so upto about 550 - 600 ppm), that will mean a forcing of about 4 W / m2 and 3 degrees C warming in the short term (decades), and thru slow feedbacks (albedo + GHG) another 4 W / m2 and 3 degrees in the long term (centuries / millennia).

The measured energy imbalance accounts for all natural and human - made climate forcings, including changes of atmospheric aerosols and Earth's surface albedo.

Specification now of a CO2 target more precise than < 350 ppm is difficult and unnecessary, because of uncertain future changes of forcings including other gases, aerosols and surface albedo.

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.

The albedo and CO2 feedbacks amplified weak orbital forcings, the feedbacks necessarily changing slowly over millennia, at the pace of orbital changes.

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.

«By comparing the response of clouds and water vapor to ENSO forcing in nature with that in AMIP simulations by some leading climate models, an earlier evaluation of tropical cloud and water vapor feedbacks has revealed two common biases in the models: (1) an underestimate of the strength of the negative cloud albedo feedback and (2) an overestimate of the positive feedback from the greenhouse effect of water vapor.

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.

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.

This positive climate feedback is greater than expected from the additional forcing alone, due to amplification by reduced surface albedo through melting of continental snow and decreased sea - ice coverage, especially in the wintertime.

This would mean that overall the albedo forcing would double, and the rate of Arctic warming would suddenly double.

This implies a forcing of 3 W / m2 for albedo changes presumably due to additional ice / snow sheets.

The Arctic sea ice melting out above 75N would have almost no impact at all if that is the forcing change of glaciers down to Chicago and sea ice down to 45N (at lower latitudes where the Albedo has much more impact).

This was a relatively stable climate (for several thousand years, 20,000 years ago), and a period where we have reasonable estimates of the radiative forcing (albedo changes from ice sheets and vegetation changes, greenhouse gas concentrations (derived from ice cores) and an increase in the atmospheric dust load) and temperature changes.

I meant that the attribution of the forcing between Ice albedo, CO2, etc. might be dependent on the temperature.

«Our estimate for the mean soot effect on spectrally integrated albedos in the Arctic (1.5 %) and Northern Hemisphere land areas (3 %) yields a Northern Hemisphere forcing of 0.3 W m2 or an effective hemispheric forcing of 0.6 W m2.»

On the studies of sensitivity based on the last glacial maximum, what reduction in solar forcing is used based on the increased Albedo of the ice - sheets, snow and desert.

For instance, the effect of soot making snow and sea ice darker has a higher efficacy than an equivalent change in CO2 with the same forcing, mainly because there is a more important ice - albedo feedback in the soot case.

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).

Claquin et al's model - derived findings show a change in tropical atmospheric forcing of «-- 2.2 to — 3.2 W m — 2» between PI and LGM earth, due to the increased albedo of atmospheric dust.

(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).

Or in other words, what's the proportion of albedo loss relative to CO2 forcing?

The hypothesis in this paper is that the ice albedo response and possibly the additional greenhouse gas feedback could respond much more quickly if the energy imbalance is larger, as it is right now with our forcing of additional CO2 into the atmosphere.

The top panel shows the direct effects of the individual components, while the second panel attributes various indirect factors (associated with atmospheric chemistry, aerosol cloud interactions and albedo effects) and includes a model estimate of the «efficacy» of the forcing that depends on its spatial distribution.

It's the same series of an initial forcing (change in insolation due to Milankovitch orbital cycles) being amplified by reinforcing feedbacks (change in albedo, change in temperature and partial pressure regulating both CO2 and H2O), but in reverse from an exit from a glacial period.

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).

your confusion is about longwave flux forcing of CO2 vs shortwave solar albedo changes.

The details of the physics of different forcings (i.e. ozone effects due to solar, snow albedo and cloud effects due to aerosols etc.) do vary the feedbacks slightly differently though.

A typo in mine at # 25 is where 40,000 m3 should read 400,000 m3, and an addendum is the reference for the forcing from the Albedo Loss feedback shown in the satellite record: «Observational determination of albedo decrease caused by vanishing Arctic sea ice» See: http://eisenman.ucsd.edu/publications/Pistone-Eisenman-Ramanathan-20Albedo Loss feedback shown in the satellite record: «Observational determination of albedo decrease caused by vanishing Arctic sea ice» See: http://eisenman.ucsd.edu/publications/Pistone-Eisenman-Ramanathan-20albedo decrease caused by vanishing Arctic sea ice» See: http://eisenman.ucsd.edu/publications/Pistone-Eisenman-Ramanathan-2014.pdf

In fact, if the physics - based understanding of «equilibrium sensitivity» to any forcing is too low, then not only will CO2 have a greater effect, so too will all other forcings, such as: changes in the sun, in cloud cover, in albedo, etc..

This might be being achieved in the face of significant CO2 forcing in a model with significant anti-solar bias in its surface albedo.

They got 10 pages in Science, which is a lot, but in it they cover radiation balance, 1D and 3D modelling, climate sensitivity, the main feedbacks (water vapour, lapse rate, clouds, ice - and vegetation albedo); solar and volcanic forcing; the uncertainties of aerosol forcings; and ocean heat uptake.

Thus, the positive λSW of the CMIP5 ensemble average and the resulting energy accumulation by enhanced ASR under GHG forcing can be expected based only on the robust physics of the water vapor feedback and the surface albedo feedback in the absence of any changes in clouds... ``

The sensitivity of an erroneous model with an error in the albedo of 0.012 (which gives a 4 W / m ^ 2 SW TOA flux error) to exactly the same forcing is 1.18 deg C.

18.4wm - 2 higher assuming the same albedo means a radiative forcing of 3.23wm - 2, which is almost the forcing you get from doubling of CO2 or increasing solar output by 2 %.

The sum of the two effects (albedo and heat loss) I believe is greater than the GHG forcing influence mostly due to CO2, but is going to have a similar trend.

One of the major areas, well covered in other posts on Climate Etc., involve the very skimpy knowledge - base on the relationship between atmospheric heating («forcing») and cloud albedo.

The albedo change resulting from the snowline retreat on land is similarly large as the retreat of sea ice, so the combined impact could be well over 2 W / sq m. To put this in context, albedo changes in the Arctic alone could more than double the net radiative forcing resulting from the emissions caused by all people of the world, estimated by the IPCC to be 1.6 W / sq m in 2007 and 2.29 W / sq m in 2013.»

By so doing, we are ignoring other low frequency forcings (such as long wavelength changes in TSI and albedo) which would have to be included to make any sense of the data.

For example, the absence from AR5 of last January's Ramanathan paper indicating a large and very significant Albedo Loss feedback forcing can not be rectified until about 2019 under the current system of periodic IPCC reports advising the UNFCCC as to the climate predicament.