Sentences with phrase «assumes climate sensitivity»

You state that «based on this logarithmic relationship (still valid today) Broecker assumes a climate sensitivity of 0.3 ºC warming for each 10 % increase in CO2 concentration, which amounts to 2.2 ºC warming for CO2 doubling.»

Based on this logarithmic relationship (still valid today) Broecker assumes a climate sensitivity of 0.3 ºC warming for each 10 % increase in CO2 concentration, which amounts to 2.2 ºC warming for CO2 doubling.

That uncertainty is represented in the latest crop of global climate models, which assume a climate sensitivity of anywhere from about 3 to 8 degrees F.

All risk numbers given above assume the climate sensitivity pdfs to be truncated at 10K, if necessary.

Assuming a climate sensitivity of 0.7 K / W / m ^ 2, this would contribute less than 0.06 C of the estimated 0.6 C mean global warming between the Maunder Minimum and the middle of last century, before significant anthropogenic contributions could be involved.»

As noted earlier, our main conclusions are insensitive to the precise details of the forcing estimates used, the volcanic scaling assumptions made, and the precise assumed climate sensitivity.

Furthermore, if the U.S. reduced its CO ₂ emissions by 100 % it would only avert 0.137 °C of temperature rise by 2100, according to this (assuming a climate sensitivity of 3 °C).

Occam's razor would have told Hansen from the start that since the observations only showed half as much warming as his models had predicted, his models were obviously wrong (assumed climate sensitivity = too high).

Figure 3 shows the same records, with the addition of the results from the average models from the Forster study, the results that the models were calculated to have on average, and the results if we assume a climate sensitivity of 3.0 W / m2 per doubling of CO2.

«Lets start by assuming climate sensitivity is low burning coal and petroleum is bad!

Let me rephrase, paleoclimate implies that a person would be stupid to assume a climate sensitivity of zero.

This has become one the biggest mysteries and most controversial issues in climate science today, throwing doubt over the assumed climate sensitivity to CO2.

All risk numbers given above assume the climate sensitivity pdfs to be truncated at 10K, if necessary.

So if the assumed climate sensitivity is high by a factor of two or even three (as it now appears likely), the projected warming by 2100 will only be an imperceptible 0.3 to 1.3 C, and really nothing to worry about at all.

Not exact matches

Michael Mann, a meteorology professor at Penn State who was not involved with the study, said it's «speculative» but «plausible» that global climate models have been underestimating climate sensitivity by assuming too much cloud glaciation.

So in order to constrain the climate sensitivity from the paleo - data, we need to find a period under which our restricted subsystem is stable — i.e. all the boundary conditions are relatively constant, and the climate itself is stable over a long enough period that we can assume that the radiation is pretty much balanced.

Hi, I don't mean to turn this into yet another sceptic thread, but I've read in another site that there apparently are doubts about current models assuming that climate sensitivity is constant.

Our conclusions related to the «over-estimated» response could be dealt with using a 2x decrease in the assumed forcing, or a 2x decrease in the climate sensitivity, or a 2x increase in the low frequency change in the proxies (although not all at once!).

Hansen's model assumed a rather high climate sensitivity of 4.2 °C for a doubling of CO2.

But as far as I can tell, most sceptics don't flat out deny greenhouse gas warming, but they incorporate their «extra» forcing by assuming a lower climate sensitivity.

The real «equilibrium climate sensitivity,» which is the amount of global warming to be expected for a doubling of atmospheric CO2, is likely to be about 1 °C, some three times smaller than most models assumed.

All this discussion of the Schmittner et al paper should not distract from the point that Hansen and others (including RichardC in # 40 and William P in # 24) try to make: that there seems to be a significant risk that climate sensitivity could be on the higher end of the various ranges, especially if we include the slower feedbacks and take into account that these could kick in faster than generally assumed.

Note that the observational approach needs to assume a constant climate sensitivity between different states, whereas perturbed physics ensembles don't (though you still need to understand what feedback processes are important between different climate states to have confidence in the results).

He did explain clearly to me why climate sensitivity is, as he calculates it, one degree (here's how: twin each CO2 molecule, two for one, with nothing else changing; assuming all else is held constant, he's right; not in the real world, but in theory, correct).

Note that (somewhat confusingly) she * assumes * the attribution is 100 % in her papers on estimating climate sensitivity.

Most discussions of the climate sensitivity in the literature implicitly assume that these are fixed.

This kind of forecast doesn't depend too much on the models at all — it is mainly related to the climate sensitivity which can be constrained independently of the models (i.e. via paleo - climate data), moderated by the thermal inertia of the oceans and assuming the (very likely) continuation of CO2 emissions at present or accelerated rates.

Of course, these evaluations rely on the models being able to mimic the sensitivity of the real climate system and assume that paleoclimatic reconstructions of the temperature do adequately describe the past climate variations.

They perform a probability calculation assuming that any of the climate sensitivities in the IPCC range are equally likely.

Just to follow - up on John Finn's question (# 10), if one puts in a rough value for the emissivity of the earth (whatever that might be), so one is no longer assuming it is a perfect blackbody, then does the resulting estimate for climate sensitivity correspond to what one would expect in the absence of any feedback effects?

Additionally, they take the ratio of temperature change to CO2 change in the ice core record and assume that is the climate sensitivity of climate to CO2 as opposed to the other way around.

But Annan and Hargreaves have argued that this gives too much weight to very high values of climate sensitivity — after all, it makes no sense to assume as a prior that climate sensitivity of 3 deg.

Transient climate sensitivity: The global mean surface - air temperature achieved when atmospheric CO2 concentrations achieve a doubling over pre-industrial CO2 levels increasing at the assumed rate of one percent per year, compounded.

I assume you are using a climate sensitivity of 3 degrees, but the amplification values seem a little high.

We should not assume that the climate sensitivity is constant either, unless there are studies suggesting it is.

Assuming a 50 - 50 chance that climate sensitivity is at or below this value, we thus have a 50 - 50 chance of holding warming below 2C if cumulative emissions are held to a trillion tonnes.

If climate senstivity to CO2 is eventually shown (rather than just assumed) to be close to the sensitivity to solar, I think a case can then be made that the GHG attribution should be equal or higher than the solar attribution, despite the large uncertainty in our knowledge of the increase in solar forcing.

Cox et al.'s calculations of the equilibrium climate sensitivity used a key metric which was derived from the Hasselmann model and assumed a constant C:.

The study of «climate sensitivity» traditionally assumes no change in ice sheets and no GHG feedbacks.

If a doubling of CO2 resulted in a temperature increase of approximately 1 K before any non-Planck feedbacks (before water vapor, etc.), then assuming the same climate sensitivity to the total GHE, removing the whole GHE would result in about a (setting the TOA / tropopause distinction aside, as it is relatively small relative to the 155 W / m2 value) 155/3.7 * 1 K ~ = 42 K. Which is a bit more than 32 or 33 K, though I'm not surprised by the difference.

Your estimates of climate sensitivity come from the IPCC, which assumes that aerosols will continue to provide a very strong cooling effect that offsets about half of the warming from CO2, but you are talking about time frames in which we have stopped burning fossil fuels, so is it appropriate to continue to assume the presence of cooling aerosols at these future times?

I assume the programmer of a model can adjust parameters and / or code which then will at some point will produce an output which can be interpreted as adjusted climate sensitivity.

Indeed, this was found to be true for any of several different published volcanic forcing series for the past millennium, regardless of the precise geometric scaling used to estimate radiative forcing from volcanic optical depth, and regardless of the precise climate sensitivity assumed.

[Response: Climate models (GCMs) calculate their climate sensitivities, they don't assumClimate models (GCMs) calculate their climate sensitivities, they don't assumclimate sensitivities, they don't assume them.

A good start might be a piece which justifies the high climate sensitivity which is assumed by the authors of the report and also apparently by climate models.

Since 1990, observed sea level has followed the uppermost uncertainty limit of the Intergovernmental Panel on Climate Change (IPCC) Third Assessment Report (TAR), which was constructed by assuming the highest emission scenario combined with the highest climate sensitivity and adding an ad hoc amount of sea - level rise for «ice sheet uncertainty&raquClimate Change (IPCC) Third Assessment Report (TAR), which was constructed by assuming the highest emission scenario combined with the highest climate sensitivity and adding an ad hoc amount of sea - level rise for «ice sheet uncertainty&raquclimate sensitivity and adding an ad hoc amount of sea - level rise for «ice sheet uncertainty» (1).

They result in different predicted atmospheric CO2 levels by year 2100, which are then used together with the assumed 2xCO2 climate sensitivity, to arrive at a net GH warming expected by year 2100.

Assuming a constant external forcing, different models would show different surface temperature change and so the climate sensitivity of different models would also be different.

That would be the General Fluid Dynamics Laboratory which produced the lower «climate sensitivity» range, (Manabe) which was «averaged» with the much higher GISS estimate to produce a high end estimate that was assumed to be real science, when it was actually an average of WAGs.

However, this method assumes that the observed change in temperature since pre-industrial times is primarily a response to anthropogenic forcings, that all the other anthropogenic forcings are well quantified, and that the climate sensitivity parameter (Section 6.1) predicted by the GCM is correct (Rodhe et al., 2000).