Sentences with phrase «change in forcing net»

Since the time of AR4, neither global mean temperature nor OHU have increased, while the IPCC's own estimate of the post-1750 change in forcing net of OHU has increased by over 60 %.

In the meantime, back in cotton wool land: «Since the time of AR4, neither global mean temperature nor OHU have increased, while the IPCC's own estimate of the post-1750 change in forcing net of OHU has increased by over 60 %.»

Not exact matches

In Personal Insurance, net written premiums grew 8 %, benefiting from renewal premium change of 10 % in agency auto and continued momentum in our leading homeowners business where we grew policies in force by 5 In Personal Insurance, net written premiums grew 8 %, benefiting from renewal premium change of 10 % in agency auto and continued momentum in our leading homeowners business where we grew policies in force by 5 in agency auto and continued momentum in our leading homeowners business where we grew policies in force by 5 in our leading homeowners business where we grew policies in force by 5 in force by 5 %.

The 2012 changes, referred to as the «Net Worth Sweep,» demanded terms that forced the GSEs to «sweep» any future profits directly into Treasury's coffers in perpetuity.

Rohling: Yeah, so what we see is that for a current level of forcing, so 1.6 watts per meter square net forcing, if we look in the relationship that we now recognize between sea - level change and climate forcing, we're are, more or less, looking at in the equilibrium state, natural equilibriumstate, where the planet would like to be that is similar to where we were 3.5 million years ago and that's where we're looking at sea level, you know, at least 15 meters, maybe 25 meters above the present.

The total forcing from the trace greenhouse gases mentioned in Step 3, is currently about 2.5 W / m2, and the net forcing (including cooling impacts of aerosols and natural changes) is 1.6 ± 1.0 W / m2 since the pre-industrial.

While a relatively minor part of the overall aerosol mass, changes in the anthropogenic portion of aerosols since 1750 have resulted in a globally averaged net radiative forcing of roughly -1.2 W / m2, in comparison to the overall average CO2 forcing of +1.66 W / m2.

The change in temperature you'd need to balance a forcing of 4 W / m2 with no feedbacks is around 1.2 ºC and the difference between that and the real sensitivity (around 3 ºC) is a measure of how strong the net feedbacks are.

The easiest is the «instantaneous forcing» — the change is made and the difference in the net radiation at the tropopause is estimated.

In addition, researchers calculated the changes in the shortwave and longwave and net radiation between the pre-industrial simulation and the present - day simulations to estimate the radiative forcing resulting from the aerosol effects on cirrus cloudIn addition, researchers calculated the changes in the shortwave and longwave and net radiation between the pre-industrial simulation and the present - day simulations to estimate the radiative forcing resulting from the aerosol effects on cirrus cloudin the shortwave and longwave and net radiation between the pre-industrial simulation and the present - day simulations to estimate the radiative forcing resulting from the aerosol effects on cirrus clouds.

A limit of approximately 500 GtC on cumulative fossil fuel emissions, accompanied by a net storage of 100 GtC in the biosphere and soil, could keep global temperature close to the Holocene range, assuming that the net future forcing change from other factors is small.

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.

Gerald Marsh offered this opinion in «A Global Warming Primer» (page 4 - excerpt) «Radiative forcing is defined as the change in net downward radiative flux at the tropopause resulting from any process that acts as an external agent to the climate system; it is generally measured in W / m2.

The total forcing from the trace greenhouse gases mentioned in Step 3, is currently about 2.5 W / m2, and the net forcing (including cooling impacts of aerosols and natural changes) is 1.6 ± 1.0 W / m2 since the pre-industrial.

There is no modelling of any orbital variations in incoming energy, either daily, yearly or long term Milankovitch variations, based on the assumption that a global yearly average value has a net zero change over the year which is imposed on the energy forcing at the TOA and the QFlux boundary etc..

In fact, all climate models do predict that the change in globally - averaged steady state temperature, at least, is almost exactly proportional to the change in net radiative forcing, indicating a near - linear response of the climate, at least on the broadest scaleIn fact, all climate models do predict that the change in globally - averaged steady state temperature, at least, is almost exactly proportional to the change in net radiative forcing, indicating a near - linear response of the climate, at least on the broadest scalein globally - averaged steady state temperature, at least, is almost exactly proportional to the change in net radiative forcing, indicating a near - linear response of the climate, at least on the broadest scalein net radiative forcing, indicating a near - linear response of the climate, at least on the broadest scales.

But more generally, something I've wondered is: while in the global annual average, aerosols could be said to partly cancel (net effect) the warming from anthropogenic greenhouse forcing, the circulatory, latitudinal, regional, seasonal, diurnal, and internal variability changes would be some combination of reduced changes from reduced AGW + some other changes related to aerosol forcing.

The easiest is the «instantaneous forcing» — the change is made and the difference in the net radiation at the tropopause is estimated.

[Response: All forcings are calculated by changing the boundary conditions (in this case the distribution of glacial ice, and looking to see what the change in net radiation is while keeping everything else constant.

The only way for the TOA imbalance to be equal to the net forcing change would be for the Earth to somehow not warm over the last 250 years in the presence of that imbalance.

Before allowing the temperature to respond, we can consider the forcing at the tropopause (TRPP) and at TOA, both reductions in net upward fluxes (though at TOA, the net upward LW flux is simply the OLR); my point is that even without direct solar heating above the tropopause, the forcing at TOA can be less than the forcing at TRPP (as explained in detail for CO2 in my 348, but in general, it is possible to bring the net upward flux at TRPP toward zero but even with saturation at TOA, the nonzero skin temperature requires some nonzero net upward flux to remain — now it just depends on what the net fluxes were before we made the changes, and whether the proportionality of forcings at TRPP and TOA is similar if the effect has not approached saturation at TRPP); the forcing at TRPP is the forcing on the surface + troposphere, which they must warm up to balance, while the forcing difference between TOA and TRPP is the forcing on the stratosphere; if the forcing at TRPP is larger than at TOA, the stratosphere must cool, reducing outward fluxes from the stratosphere by the same total amount as the difference in forcings between TRPP and TOA.

If we isolate the ocean for diagnosis, there is a rather short list of suspect forcings and feedbacks (ie changes in shortwave reaching ocean surface possibly from strong negative aerosol feedbacks, net positive rate change in loss of longwave from the ocean (which would have implications for the positive WVF), net positive heat loss through evaporation without balancing compensation (with other implications for positive WVF).

Radiative forcing RF at a level is equal to a decrease in net upward flux (either SW, LW, or both; the greenhouse effect refers to LW forcing) at that given level, due to a change in (optical) properties, while holding temperatures constant.

The system can have a net negative feedback and still change very much provided a radiative forcing from sunlight or CO2 is sufficiently large, although for typical changes in these variables that Earth encounters, one would indeed expect only relatively small climate changes to occur if negative feedbacks did in fact dominate.

* & & * — if the stratosphere were optically thick and warmed at the bottom even if the whole experiences net cooling, then the stratospheric feedback adds to the initial TRPP forcing, and the end result could require warming below TRPP to change the flux at TRPP to an amount greater than the TRPP after stratospheric adjustment, because of the additional warming that would occur in the (lower) stratosphere.

What could hypothetically happen if a very large change in GHG amount / type is made, is that the forcing could increase beyond a point where it becomes saturated at the tropopause level at all wavelengths — what can happen then is that the equilibrium climate sensitivity to the nearly zero forcing from additional GHGs may approach infinity, because in equilibrium the tropopause has to shift upward enough to reach a level where there can be some net LW flux up through it.

Currently, although only 20 % of the accumulated anthropogenic rise in carbon dioxide originates from land use and land cover change (LULCC), 40 % of the net positive radiative forcing from human activities is attributable to LULCC sources (Ward et al 2014).

-------- * & & * — if the stratosphere were optically thick and warmed at the bottom even if the whole experiences net cooling, then the stratospheric feedback adds to the initial TRPP forcing, and the end result could require warming below TRPP to change the flux at TRPP to an amount greater than the TRPP after stratospheric adjustment, because of the additional warming that would occur in the (lower) stratosphere.

The details varied for each scenario, but the net effect of all the changes was that Scenario A assumed exponential growth in forcings, Scenario B was roughly a linear increase in forcings, and Scenario C was similar to B, but had close to constant forcings from 2000 onwards.

Warming must occur below the tropopause to increase the net LW flux out of the tropopause to balance the tropopause - level forcing; there is some feedback at that point as the stratosphere is «forced» by the fraction of that increase which it absorbs, and a fraction of that is transfered back to the tropopause level — for an optically thick stratosphere that could be significant, but I think it may be minor for the Earth as it is (while CO2 optical thickness of the stratosphere alone is large near the center of the band, most of the wavelengths in which the stratosphere is not transparent have a more moderate optical thickness on the order of 1 (mainly from stratospheric water vapor; stratospheric ozone makes a contribution over a narrow wavelength band, reaching somewhat larger optical thickness than stratospheric water vapor)(in the limit of an optically thin stratosphere at most wavelengths where the stratosphere is not transparent, changes in the net flux out of the stratosphere caused by stratospheric warming or cooling will tend to be evenly split between upward at TOA and downward at the tropopause; with greater optically thickness over a larger fraction of optically - significant wavelengths, the distribution of warming or cooling within the stratosphere will affect how such a change is distributed, and it would even be possible for stratospheric adjustment to have opposite effects on the downward flux at the tropopause and the upward flux at TOA).

The effect of band widenning is a reduction in net upward LW flux (this is called the radiative forcing), which is proportional to a change in area under the curve (a graph of flux over the spectrum); the contribution from band widenning is equal to the amount by which the band widens (in units ν) multiplied by - Fνup (CO2).

«The overall slight rise (relative heating) of global total net flux at TOA between the 1980's and 1990's is confirmed in the tropics by the ERBS measurements and exceeds the estimated climate forcing changes (greenhouse gases and aerosols) for this period.

«Radiative forcing Radiative forcing is the change in the net, downward minus upward, radiative flux (expressed in W m — 2) at the tropopause or top of atmosphere due to a change in an external driver of climate change, such as, for example, a change in the concentration of carbon dioxide or the output of the Sun.»

Furthermore, if we are trying to explain why the rate of warming went up in say 1975 we don't want to look at just the rate of change in forcing due to well - mixed greenhouse gases and reflective aerosols by the rate of change in net forcing.

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.»

The point is the computational mandate that temperature change is in response to the time - integral of the net forcing; not proportionately to the instantaneous value of the net forcing itself.

radiative forcing a change in average net radiation at the top of the troposphere resulting from a change in either solar or infrared radiation due to a change in atmospheric greenhouse gases concentrations; perturbance in the balance between incoming solar radiation and outgoing infrared radiation

@DP: The point is the computational mandate that temperature change is in response to the time - integral of the net forcing; not proportionately to the instantaneous value of the net forcing itself.

The comparable net change in radiative forcings illustrated in AR4 WG1 Figure 2.23, as used by another GCM, seems to be even higher, at around 1 Wm - 2 between 1861 — 1900 and 1957 — 1994.

The Milankovitch cycles are weak from the point of view of net solar forcing, but they affect the albedo through systematic changes in northern ice cover during the months when there is more daylight.

In isothermal equilibrium, the system is in perfect force balance, there is no net dynamical transport of mass up or down, no net change whatsoever of gravitational potential energy — but heat conduction still functions to maintain equal temperature and restore equilibrium after a perturbatioIn isothermal equilibrium, the system is in perfect force balance, there is no net dynamical transport of mass up or down, no net change whatsoever of gravitational potential energy — but heat conduction still functions to maintain equal temperature and restore equilibrium after a perturbatioin perfect force balance, there is no net dynamical transport of mass up or down, no net change whatsoever of gravitational potential energy — but heat conduction still functions to maintain equal temperature and restore equilibrium after a perturbation.

Irrespective of what one thinks about aerosol forcing, it would be hard to argue that the rate of net forcing increase and / or over-all radiative imbalance has actually dropped markedly in recent years, so any change in net heat uptake can only be reasonably attributed to a bit of natural variability or observational uncertainty.

A postulated 3.7 W / m ^ 2 increase in CO2 - related «forcings» pales in comparison to documented changes in cloud, humidity, etc. net forcings.

Radiative forcing - Radiative forcing is the change in the net, downward minus upward, irradiance (expressed in W m - 2) at the tropopause due to a change in an external driver of climate change, such as, for example, a change in the concentration of carbon dioxide or the output of the Sun.

As I made clear in my «essay», my reason for comparing the natural changing insolation values (in W / m2) against the IPCC net AGW figures (the AGW «forcing») is simply this: is the insolation change significant, or is it a value only one part in a million of the IPC AGW value?

Rather, Y is the slope coefficient for an (approximately) linear dependence of net radiative balance N, minus the change in forcings Q, on changes deltaT in mean surface temperature.

IPCC AR4 WG1 tells us that the all anthropogenic forcing components except CO2 (aerosols, other GHGs, land use changes, other changes in surface albedo, etc.) have essentially cancelled one another out, so we can use the estimated radiative forcing for CO2 (1.66 W / m ^ 2) to equate with total net anthropogenic forcing (1.6 W / m ^ 2).

Between 2000 and 2010 there is no clear net change in forcing (perhaps slightly negative), mainly because the decade begins with a solar maximum and ends with a solar minimum.

Attempts to relate net temperature changes to forcing over an extended time interval would represent a different study, and one that is beset with problems in correctly quantifying the forcings unless the interval is very long (and even then there are problems).

As such, it can not capture the slow - down in net anthropogenic forcings that allows the effects of declining solar radiation and changes from El Nino or La Nina to dominate the 1999 — 2008 period.