Sentences with phrase «estimates of climate sensitivity by»

That a robust behaviour in models of apparent (effective) climate sensitivity being lower in the early years after a forcing is imposed than subsequently, rather than remaining constant, requires multiplying estimates of climate sensitivity by a further factor of ~ 1.25 in order to convert what they actually estimate (effective climate sensitivity) to ECS.

The low estimates of climate sensitivity by Chylek and Lohmann (2008) and Schmittner et al. (2011), ~ 2 °C for doubled CO2, are due in part to their inclusion of natural aerosol change as a climate forcing rather than as a fast feedback (as well as the small LGM - Holocene temperature change employed by Schmittner et al., 2011).»

Modelers have chosen to compensate their widely varying estimates of climate sensitivity by adopting cloud feedback values countering the effect of climate sensitivity, thus keeping the final estimate of temperature rise due to doubling within limits preset in their minds.

He attacked mainstream estimates of climate sensitivity by a misapplication of the Stefan - Bolzmann equation.

Not exact matches

This new research takes away the lower end of climate sensitivity estimates, meaning that global average temperatures will increase by 3 °C to 5 °C with a doubling of carbon dioxide.»

By studying the relationship between CO2 levels and climate change during a warmer period in Earth's history, the scientists have been able to estimate how the climate will respond to increasing levels of carbon dioxide, a parameter known as «climate sensitivity».

About our estimates of the climate transfer sensitivity to solar variations at 11 years and 22 years, Dr. Benestad makes again a great confusion by misquoting and misunderstanding our paper.

Where (equilibrium / effective) climate sensitivity (S) is the only parameter being estimated, and the estimation method works directly from the observed variables (e.g., by regression, as in Forster and Gregory, 2006, or mean estimation, as in Gregory et al, 2002) over the instrumental period, then the JP for S will be almost of the form 1 / S ^ 2.

The calculations of prospective warming in the OXONIA lecture and the accompanying discussion papers are based on the new climate sensitivity estimates by Murphy et al which were published in Nature, 12 August 2004, vol.

If one accepts Ruddiman's hypothesis, one implicitly agrees that: i) CO2 and CH4 can be affected by human activity, ii) greenhouse gases have a significant forcing role, and iii) climate sensitivity is in the ballpark of mainstream estimates.

In fact, scientists have long recognized the importance of solar variability as one of the factors governing climate (see the very scholarly review of the subject by Bard and Frank, available here at EPSL or here as pdf) An understanding of solar variability needs to be (and is) taken into account in attribution of climate change of the past century, and in attempts to estimate climate sensitivity from recent climate variations.

It is important to regard the LGM studies as just one set of points in the cloud yielded by other climate sensitivity estimates, but the LGM has been a frequent target because it was a period for which there is a lot of data from varied sources, climate was significantly different from today, and we have considerable information about the important drivers — like CO2, CH4, ice sheet extent, vegetation changes etc..

Using Mg / Ca paleothermometry from the planktonic foraminifera Globigerinoides ruber from the past 500 k.y. at Ocean Drilling Program (ODP) Site 871 in the western Pacific warm pool, we estimate the tropical Pacific climate sensitivity parameter (λ) to be 0.94 — 1.06 °C (W m − 2) − 1, higher than that predicted by model simulations of the Last Glacial Maximum or by models of doubled greenhouse gas concentration forcing.

Another way to estimate climate sensitivity from both models AND observations is to calculate the ratio of observed warming to forecast warming... then multiply that by the ECS value used in the model.

Climate model studies and empirical analyses of paleoclimate data can provide estimates of the amplification of climate sensitivity caused by slow feedbacks, excluding the singular mechanisms that caused the hyperthermal Climate model studies and empirical analyses of paleoclimate data can provide estimates of the amplification of climate sensitivity caused by slow feedbacks, excluding the singular mechanisms that caused the hyperthermal climate sensitivity caused by slow feedbacks, excluding the singular mechanisms that caused the hyperthermal events.

The calculations of prospective warming in the OXONIA lecture and the accompanying discussion papers are based on the new climate sensitivity estimates by Murphy et al which were published in Nature, 12 August 2004, vol.

Dan has yet to acknowledged is that the fossil record clearly shows that the best value of the known feedbacks, whatever their «exact» values may be, are included in the IPCC's approximate estimate of the climate sensitivity, and that this is strongly supported by the GCMs.

This is also a good recent presentation of the various estimates of climate sensitivity and of the amount of uncertainty associated with them — found by doing a Google image search on the terms:

captdallas2 @ 130 — To become more impressed by the estimate of about 3 K for Charney equilibrium climate sensitivity, read papers by Annan & Hargreaves.

Do you think that in the same way that the Solanki et al paper on solar sunspot reconstructions had a specific statement that their results did not contradict ideas of strong greenhouse warming in recent decades, this (the fact that climate sensitivity projections are not best estimates of possible future actual temperature increases) should be clearly noted in media releases put out by scientists when reporting climate sensitivity studies?

Using Mg / Ca paleothermometry from the planktonic foraminifera Globigerinoides ruber from the past 500 k.y. at Ocean Drilling Program (ODP) Site 871 in the western Pacific warm pool, we estimate the tropical Pacific climate sensitivity parameter (λ) to be 0.94 — 1.06 °C (W m − 2) − 1, higher than that predicted by model simulations of the Last Glacial Maximum or by models of doubled greenhouse gas concentration forcing.

As stated last year, the Scenario B in that paper is running a little high compared with the actual forcings growth (by about 10 %)(and high compared to A1B), and the old GISS model had a climate sensitivity that was a little higher (4.2 ºC for a doubling of CO2) than the best estimate (~ 3ºC).

However, it is important to keep in mind that we might easily more than double it if we really don't make much effort to cut back (I think the current estimated reserves of fossil fuels would increase CO2 by a factor of like 5 or 10, which would mean a warming of roughly 2 - 3 times the climate sensitivity for doubling CO2 [because of the logarithmic dependence of the resulting warming to CO2 levels]-RRB-... and CO2 levels may be able to fall short of doubling if we really make a very strong effort to reduce emissions.

In particular, Annan and Hargreaves (2006) used a Bayesian statistical approach that combines information from both 20th century observations and from last glacial maximum data to produce an estimate of climate sensitivity that is much better constrained than by either set of observations alone (see our post on this, here).

A detailed reanalysis is presented of a «Bayesian» climate parameter study (Forest et al., 2006) that estimates climate sensitivity (ECS) jointly with effective ocean diffusivity and aerosol forcing, using optimal fingerprints to compare multi-decadal observations with simulations by the MIT 2D climate model at varying settings of the three climate parameters.

Trenberth et al. suggest that even the choice of a different data set of ocean heat content would have increased the climate sensitivity estimate of Otto et al. by 0.5 degrees.

So how cool is it then that the recent paper by Fasullo and Trenberth estimates the net climate sensitivity without getting into the details of the cloud feedback then?

In essence Tung & Zhou are dining at the denialist's last - chance saloon by invoking a 60 - year natural cycle (their cycle of choice being AMO) resulting in a reduced anthropogenic influence on climate, although they make sure to not directly challenge climate sensitivity by asserting that their findings will impact on assessment of net anthropogenic forcing and leave climate sensitivity estimates unchallenged.

Using the IPCC model - based estimate for climate sensitivity and the same logarithmic calculation as for the UK alone, we will have averted 1.2 °C of warming by 2100 by shutting down the world carbon - based economy.

The results of the analysis demonstrate that relative to the reference case, projected atmospheric CO2 concentrations are estimated by 2100 to be reduced by 3.29 to 3.68 part per million by volume (ppmv), global mean temperature is estimated to be reduced by 0.0076 to 0.0184 °C, and sea - level rise is projected to be reduced by approximately 0.074 — 0.166 cm, based on a range of climate sensitivities.

It's NOT a matter of me being «stubborn», it is a matter of you failing to cite studies providing empirical evidence to support the Myhre et al. estimates of 2xCO2 climate sensitivity (upon which the whole IPCC CAGW house of cards rests), as requested by Jim Cripwell and myself.

Its median climate sensitivity estimate of 1.6 C wsn't materially changed by the replot, but the upper tail was fattened, with the upper 97.5 % confidence limit being increased from 4.1 C to 8.6 C.

This Nature Climate Change paper concluded, based purely on simulations by the GISS - E2 - R climate model, that estimates of the transient climate response (TCR) and equilibrium climate sensitivity (ECS) based on observations over the historical period (~ 1850 to recent times) were biasClimate Change paper concluded, based purely on simulations by the GISS - E2 - R climate model, that estimates of the transient climate response (TCR) and equilibrium climate sensitivity (ECS) based on observations over the historical period (~ 1850 to recent times) were biasclimate model, that estimates of the transient climate response (TCR) and equilibrium climate sensitivity (ECS) based on observations over the historical period (~ 1850 to recent times) were biasclimate response (TCR) and equilibrium climate sensitivity (ECS) based on observations over the historical period (~ 1850 to recent times) were biasclimate sensitivity (ECS) based on observations over the historical period (~ 1850 to recent times) were biased low.

This is an example of energy transport affecting the energy balance and a valid argument by itself that the paleo records aren't a reliable way to estimate current climate sensitivity, isn't it?

Until we have an actual way of measuring climate sensitivity, these guesses merely recognize that the previous estimates, which were claimed to be accurate by the IPCC, are merely only guesses.

Notice, for instance, that one account of the consensus (more accurate than Grimes's) holds that «most of the warming in the second half of the twentieth century has been caused by man», and does not exclude the majority of climate sceptics, who typically argue that the IPCC over estimates climate sensitivity.

I estimate dT increased from 1980 to 2010 by about 0.4 K. Given equilibrium climate sensitivity of 0.75 K / Wm2, the amount of forcing neutralised by said dT is; 0.4 * 0.75 = 0.3 W / m2.

An updated estimate of the equilibrium climate sensitivity distribution (ECS)-- a measure of CO2's temperature impact — reduces the 2020 estimate of SCC by more than 40 percent; and

Because we can now accurately estimate the 20th century CO2 warming by multiplying the known CO2 forcing over the 20th century by the claimed climate sensitivity of 1.6 - 1.7 C.

The most popular observationally - constrained method of estimating climate sensitivity involves comparing data whose relation to S is too complex to permit direct estimation, such as temperatures over a spatio - temporal grid, with simulations thereof by a simplified climate model that has adjustable parameters for setting S and other key climate properties.

I find Nic Lewis's estimate of 1.6 C for climate sensitivity as a strong indication that previous estimates by the IPCC were exaggerated.

Alec Rawls, on the other hand, points out that if his criticism of Chapter 7 of the AR5 is valid, and it has been accepted by the authors of Chapter 7, then the value of climate sensitivity estimated by Nic Lewis is a MAXIMUM value, which could be less depending on the effect of clouds.

(The «I think» was because I was hoping to extricate myself from CE for a while to finish off a paper explaining why climate sensitivity as currently defined can neither be measured nor estimated with an error bar less than 1 C per doubling, and proposing a different definition that shrinks the error bar by an order of magnitude.

Evans follows up his misunderstanding of climate sensitivity estimates by demonstrating an extreme degree of confusion about the tropical troposphere «hot spot»:

Using the IPCC climate sensitivity of 3.2 C, the CO2 level by 2100 would need to double by 2100, from today's 392 to 784 ppmv, to reach this warming (the high side IPCC «scenario and storyline» A2 is at this level, with estimated warming of 3.4 C above the 1980 - 1999 average, or ~ 3.2 C above today's temperature).

(By this I mean could one show a perceptible impact on our planet's future climate at a reasonable cost per degree C global warming averted a) at an estimated 2xCO2 climate sensitivity of 3C or b) at a CS of 1C?)

Assuming the same climate sensitivity, Lindzen's estimate of a 2.5 °C drop for a -30 W / m2 forcing would imply that currently doubling CO2 would warm the planet by only a third of a degree at equilibrium, which is well outside the bounds of IPCC estimates and even very low by most skeptical standards.

If however you're referring to the two - year - long process by which I arrived at the poster, in order to see the pre-1970 oscillations more clearly I detrended HadCRUT3 with an estimate of CO2 - induced global warming, without however committing to any particular climate sensitivity.

A general agreement that IF this trend continues for another «X» years despite continued increase of GHG concentrations, there will be enough evidence in the red column to seriously question the ability of the GCMs cited by IPCC: a) to correctly assess human attribution of past climate change b) to estimate climate sensitivity c) to make meaningful projections of future climate changes due to AGW

The standard modern estimate of climate sensitivity — 3 °C, plus or minus 1.5 °C — originates with a committee on anthropogenic global warming convened in 1979 by the National Academy of Sciences and chaired by Jule Charney.