Sentences with phrase «about climate sensitivity from»

Given the large and growing (my opinion) uncertainty of the aerosol forcing, how can we make meaningful statements about the climate sensitivity from paleo - experiments?

Not exact matches

From this, they could estimate the climate sensitivity and the result was that where it was about 4.5 degrees C before the PETM, the temperature rose to about 5.1 degrees during the PETM.

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.

When Otto calculated the climate sensitivity from his data, he found it was about 2 °C — with a range of 0.9 to 5 °C — well below the IPCC's best estimate of 3 °C.

Specifically, Newell and a co-author from the Air Force named Thomas Dopplick challenged the prevailing view that a doubling of the earth's CO2 blanket would raise temperatures about 3 °C (5 °F)-- a measure known as climate sensitivity.

Sure, there might be a few papers that take climate sensitivity as a given and somehow try to draw conclusions about the impact on the climate from that... But, I hardly think that these are swamping the number of papers trying to determine what the climate sensitivity is, studying if the water vapor feedback is working as expected, etc., etc..

The rest of the climate sensitivity above the about 1 degree C is tied to the obvious questions: where does the CO2 come from, and where does it go, and over what time period.

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..

One recent study examining the Palaeocene — Eocene Thermal Maximum (about 55 million years ago), during which the planet warmed 5 - 9 °C, found that «At accepted values for the climate sensitivity to a doubling of the atmospheric CO2 concentration, this rise in CO2 can explain only between 1 and 3.5 °C of the warming inferred from proxy records» (Zeebe 2009).

Because this climate sensitivity is derived from empirical data on how Earth responded to past changes of boundary conditions, including atmospheric composition, our conclusions about limits on fossil fuel emissions can be regarded as largely independent of climate models.

Other ways that the standard or «consensus» calculations bias the climate sensitivity upward also exist and are also not negligible (or at least there is no scientific case that they are negligible), but for now it is sufficient to think about, and try to estimate, the magnitude of the increase in H2O and latent heat flow from surface to upper troposphere.

In a phone chat, he said that arguments about specific levels of climate sensitivity, or specific goals for carbon dioxide concentrations, have little meaning as long as the world is not slowing down from its accelerating path on emissions.

2) The committed warming: effectively the greenhouse gas increase from pre-industrial to now has committed the planet to a surface warming of 2.4 °C (using IPCCs central value for climate sensitivity), and only about 0.6 °C of this has been realized thus far.

Analysis of the Pliocene (c.f. the Nature geoscience article by Lunt et al) would tend to support total climate sensitivities at or even beyond the high end of the IPCC range (I make that about 4.5 C for a doubling, extrapolating from Lunt's Pliocene warming).

Aslo, regarding climate sensitivity a very key thing to remember, especially if sensitivity turns out to be on the high side, is that the «final» equilibrium temperature (Alexi's concerns about there being such a thing aside) calculated from climate sensitivity does not take into account carbon cycle feedbacks OR ice sheet changes.

My first question was how come I was seeing «around 3 degrees» for climate sensitivity when the physics says to expect about one degree of warming from doubling CO2.

The most likely value of climate sensitivity from the AR4 [the fourth report from the Intergovernmental Panel on Climate Change] was about 3 dclimate sensitivity from the AR4 [the fourth report from the Intergovernmental Panel on Climate Change] was about 3 dClimate Change] was about 3 degrees.

Given the last 30 years there is no reason to believe, from a policy perspective, that spending more money on climate change will lead to any more certainty about climate sensitivity.

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?

Note that «equilibrium» in this thread — up through response 162 — was in terms of climate sensitivity, answering the question about where the «extra heat» comes from.

About the comments from Urs, The climate sensitivity to solar variations can not be 1/2 (as Urs claims) or 2 times (as Rasmus claims) larger that what I estimated for the simply reason that there would be no match between the data patterns.

Given CO2 warming over the last 130 PPM was at best 0.37 to 0.75 degrees and the implied climate sensitivity from that is therefore 0.77 to 1.35 degrees per doubling, therefore the magic 2 degree figure (noting that the IPCC says up to 2 degrees of warming will be positive for the human race) is likely 500 — 1000 years away from happening, why are we even worried about it?

Scientists often talk about it in terms of the equilibrium climate sensitivity (ECS), which is the long - term temperature increase that we expect from a permanent doubling of atmospheric CO2.

IPCC's replot moved the median climate sensitivity from about 1.6 C to 2.3 C and gave a much fatter tail.

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.

A sense of how wide the guesses about aerosols are can be seen from the range of model climate sensitivities.

We know the planet will warm between about 1.5 and 4.5 °C in response to the increased greenhouse effect from a doubling of atmospheric carbon dioxide (the «climate sensitivity»).

@Jeff Id From what I now understand about the relationship between IPCC and UNFCCC (IPCC provides the basis for Paris next year) it indeed can take a while before the «insights» about climate sensitivity will be accepted and more important — highlighted — by IPCC.

I find the following section immensely telling about climate modeling: «The bottom line is that, although there has been some narrowing of the range of climate sensitivities that emerge from realistic models [Del Genio and Wolf, 2000], models still can be made to yield a wide range of sensitivities by altering model parameterizations.

Steve, you write «c) The observational record is still too short to constrain climate sensitivity (in part because of lack of knowledge about some of the forcings), so weakening evidence from this record doesn't change the result.»

Fred, I completely disagree about the relative strength of evidence as to climate sensitivity from simulations by AOCGMs (Chapter 8 of WG1 «Climate Models and Their Evaluation») and from observational evidence that is either direct or intermediated through simple Energy Balance climate sensitivity from simulations by AOCGMs (Chapter 8 of WG1 «Climate Models and Their Evaluation») and from observational evidence that is either direct or intermediated through simple Energy Balance Climate Models and Their Evaluation») and from observational evidence that is either direct or intermediated through simple Energy Balance Models.

However, for the low sensitivity obtained from the actual climate system, we see that sensitivity is narrowly constrained to about 0.5 C...

The balance of evidence that the warming may continue to rise is from a theoretical perspective only, and yes I agree entirely that the longer the pause continues the more it says about climate sensitivity.

There was immediate disagreement about the amount of climate sensitivity from double and triple atmospheric CO2.

On the contrary, I want to separate out the effects on climate sensitivity estimation of varying GMST responses to different forcing agents, which is what MEA15 is about, from the effects of time - varying climate sensitivity in GISS - E2 - R.

The answer will tell us a lot about the validity of the model - based estimate for climate sensitivity used by IPCC (based on an «argument from ignorance», as has been pointed out)..

I remain very concerned about abrupt climate change, but I am also working to demonstrate that if you accept the IPCC framing of the climate change problem, e.g. «forced», that models are over sensitive and the sensitivity is lower than inferred from climate models.

In most cases, these range from about 2 to 4.5 C per doubled CO2 within the context of our current climate — with a most likely value between 2 and 3 C. On the other hand, chapter 9 describes attempts ranging far back into paleoclimatology to relate forcings to temperature change, sometimes directly (with all the attendant uncertainties), and more often by adjusting model parameters to determine the climate sensitivity ranges that allow the models to best simulate data from the past — e.g., the Last Glacial Maximum (LGM).

BH: Some of them are talking about climate sensitivity at 1.2 C, at 1.5 C. I think this is completely implausible because the basic energetics of the climate system responding to the additional greenhouse gas emissions almost from simple physics, has to be at least 1.2 C and possibly more before you begin to take into account any of the feedbacks in the system from water vapour in clouds and so on.

Because this climate sensitivity is derived from empirical data on how Earth responded to past changes of boundary conditions, including atmospheric composition, our conclusions about limits on fossil fuel emissions can be regarded as largely independent of climate models.

Their climate sensitivity varies from values small enough to reduce concerns about a doubling of CO2 to values that are quite scary.

The equilibrium climate sensitivity will be about 50 % greater than this due to the ocean acting as a heat sink, so the ECS will be about 3C, in line with the mean estimate from the models.

And it's worse with the climate sensitivity, which the models report as being from 0.5 °C per W - m ^ 2 to 1.9 °C per W - m ^ 2, a range of about four to one.

e.g. Lindzen (2009) finds: ``... ERBE data appear to demonstrate a climate sensitivity of about 0.5 °C which is easily distinguished from sensitivities given by models.»

It is the evidence evaluated from the combined results that has led to the current estimate climate sensitivity range of about 2 - 4.5 C per CO2 doubling, typically with 90 percent confidence limits.

«The team emphasized that clouds are particularly sensitive to subtle differences in surface warming patterns, and researchers must carefully account for such pattern effects when making inferences about cloud feedback and climate sensitivity from observations over short time periods.»

L&S estimate the equilibrium climate sensitivity to doubled CO2 from their model at «about 1 - 1.5 °C or less».

«From the corresponding paper: «our study says nothing about the equilibrium climate sensitivity; it only suggests that the equilibrium greenhouse sensitivity is zero.»

This «climate sensitivity» estimate has emerged as a key climate question, with estimates ranging from a low of about 2.7 °F (1.5 °C) to highs of more than 8 °F (4.5 °C) of warming in this century.

Professor Nordhaus chooses 3.0 degrees C for doubling of CO2, 9 a value that empirical evidence suggests is greatly exaggerated.10 To illustrate the point, for a climate sensitivity of 1.0 degree, a value suggested by a number of empirical studies, Professor Nordhaus's «DICE» model calculates that the optimum policy's net benefits drop from about $ 3 trillion to a net cost of about $ 1 trillion, and the benefit - to - cost ratio plunges from 2.4 to 0.5.