Sentences with phrase «ipcc uncertainty range»

Assuming the conventional 1.5 - 4.5 K IPCC uncertainty range (and its translation by Wigley & Raper, 2001, into a lognormal pdf assuming the range to be a 90 % confidence interval), this risk of overshooting 2 °C is about 75 % (13 %) in equilibrium for 550ppm (400ppm) CO2 equivalence stabilization.

Terry: As far as I know you can recreate the IPCC uncertainty range for a response to CO2 doubling by using a simple energy balance model.

Both sets of observations fall well above the IPCC uncertainty range.

Not exact matches

-- gavin][Addendum: Arrhenius paper from 1896 states 4 - 6 ºC warming for CO2 - doubling; the uncertainty range in the last IPCC report is 1.5 - 4.5 ºC.

I agree (as does IPCC) that there is uncertainty, as stated, in the climate sensitivity, but you are completely unjustified in your claim that the cosmic - ray correlation (for which there is still no sound physical basis or quantified mechanism) supports the lower end of the sensitivity range.

Quoting the IPCC 1.4 to 5.8 Â °C estimate (for doubling CO2) outside current agreements among models that the uncertainty is most likely in the 2.5 to 4Â °C range or failing to point out that discrepancies (used by skeptics) between surface and troposphere warming have been resolved, is misleading in my view.

It is not all that earthshaking that the numbers in Schmittner et al come in a little low: the 2.3 ºC is well within previously accepted uncertainty, and three of the IPCC AR4 models used for future projections have a climate sensitivity of 2.3 ºC or lower, so that the range of IPCC projections already encompasses this possibility.

The two future scenarios mentioned in the text (RCP8.5 and RCP2.6) are shown in red and blue, with their «likely» uncertainty range according to the IPCC (meaning a 66 % probability to remain inside this range).

-- gavin][Addendum: Arrhenius paper from 1896 states 4 - 6 ºC warming for CO2 - doubling; the uncertainty range in the last IPCC report is 1.5 - 4.5 ºC.

[Response: I'm not a fan of false precision — since the uncertainty range on this number (as given by IPCC) is 1.13 — 3.33, I see little point in calling it 2.29 with three significant digits.

The IPCC range, on the other hand, encompasses the overall uncertainty across a very large number of studies, using different methods all with their own potential biases and problems (e.g., resulting from biases in proxy data used as constraints on past temperature changes, etc.) There is a number of single studies on climate sensitivity that have statistical uncertainties as small as Cox et al., yet different best estimates — some higher than the classic 3 °C, some lower.

That is why the IPCC in its SPM quoted above says that the 1998 - 2012 trend is +0.05 with an uncertainty range of — 0.05 to +0.15 °C per decade.

The current batch of models have a mean climate sensitivity of about 3 C to doubled CO2 (and range between 2.5 and 4.0 degrees)(Paris meeting of IPCC, July 2004), i.e an uncertainty of about 30 %.

However, even given a particular emission scenario, IPCC has always allowed for a wide uncertainty range.

So if I understand things correctly, the IPCC «scenarios» show a range of global temperature values due to the uncertainties of future forcings.

Pielke compares single scenarios of IPCC, without mentioning the uncertainty range.

The IPCC has always published ranges of future scenarios, rather than a single one, to cover uncertainties both in future climate forcing and in climate response.

Of course, IPCC can simply state that the lower end of the previous range for 2xCO2 ECS of 1.5 to 4.5 C is still OK, but that the upper end has come down as uncertainties on clouds (always «the largest source of uncertainty») have been cleared up, and there won't be too much «loss of face» there.

The IPCC forbids him to quote from it, but he is privy to all the observational best estimates and uncertainty ranges the draft report gives.

The IPCC gives a wide range of uncertainty, without any guaranty that the true value lies within this range.

Under the IPCC Business As Usual emissions scenario, an average rate of global mean sea level rise of about 6 cm per decade over the next century (with an uncertainty range of 3 — 10 cm per decade).

But the first issue here is: where is the logic in assigning such a specific value and uncertainty range to something that the IPCC declares to be associated to a * low * level of scientific understanding?

Ferd appears to give a key insight into why IPCC's uncertainty range has not dropped much: 1) Using the 1C to 18.5 C prior rather than paleo temperature range of -3.5 C to 7.5 C prior.

It is my understanding that the IPCC scenarios (plural) represented a range of carbon outputs, not just climate sensetivity uncertainties.

But more salient is IPCC's reluctance to fully couple the inevitable process of subjective judgment in a coherent way into its assessments of uncertainty and, absent this coupling, IPCC's tendency, particularly in SPMs, to resort to emphasizing ensemble means rather than fully describing the range of views.

«[I] t turns out Lewis and Crok's [uncertainty] range (not in the GWPF report, but kindly provided by Nic Lewis) is 0.9 to 2.5 degrees Celsius, which is almost identical to the range of the [IPCC's] models (1.1 - 2.6 degrees Celsius).»

So considering the uncertainty range that accompanies Lewis and Crok's estimate — something that climate skeptics are normally keen to highlight — the GWPF's estimate is very close to the IPCC's.

Regarding variability, the ISPM fails to mention that the IPCC found that the larger «natural climatic variability» is almost all in the direction of cooler temperatures, relative to «previous estimations», for the past millenium: «The additional variability shown in some new studies [since the Third Assesment Report] implies mainly cooler temperatures (predominantly in the 12th to 14th, 17th and 19th centuries), and only one new reconstruction suggests slightly warmer conditions (in the 11th century, but well within the uncertainty range indicated in the TAR).»

So... what is the official IPCC apologist explanation for the doubling of the AR4 uncertainty range, which is obviously unexplained in the actual text and chart?

If IPCC intended this range of projections to represent their uncertainty range, then that is what they should have shown in AR4 Figure 10.26 (which is more consistent with the Technical Summary than the range in the spaghetti graph.)

Figure 3: Global average radiative forcing in 2005 (best estimates and 5 to 95 % uncertainty ranges) with respect to 1750 (IPCC AR4).

In the IPCC summary there's a figure indicating land use (albedo) is responsible for a net forcing of -0.25 W / m2, with an uncertainty range of 0 to -0.5 W / m2 (the figure also indicates that scientific understanding of albedo is very low).

However, since the IPCC provides us with the 95 % confidence range of the total net anthropogenic forcing in Figure 1, we can account for the uncertainties which concern Lindzen, and evaluate how much warming we «should have seen» by now.

The first type shown in the IPCC graphs concerns the uncertainties in the background range.

You also might be interested to know that the IPCC range of uncertainty is not stratified by sensitivity across this short period.

• Poles to tropics temperature gradient, average temp of tropics over past 540 Ma; and arguably warming may be net - beneficial overall • Quotes from IPCC AR4 WG1 showing that warming would be beneficial for life, not damaging • Quotes from IPCC AR5 WG3 stating (in effect) that the damage functions used for estimating damages are not supported by evidence • Richard Tol's breakdown of economic impacts of GW by sector • Economic damages of climate change — about the IAMs • McKitrick — Social Cost of Carbon much lower than commonly stated • Bias on impacts of GHG emissions — Figure 1 is a chart showing 15 recent estimates of SCC — Lewis and Curry, 2015, has the lowest uncertainty range.

And the range of the IPCC climate sensitivities reflects to some degree those uncertainties.

When accounting for actual GHG emissions, the IPCC average «Best» model projection of 0.2 °C per decade is within the uncertainty range of the observed rate of warming (0.15 ± 0.08 °C) per decade since 1990.

This is also the best estimate of IPCC, but the range of uncertainty is wide.

Large uncertainties remain, but that's exactly the reason for the wide uncertainty range of climate sensitivity acknowledged by IPCC.

Energy budget estimates of equilibrium climate sensitivity (ECS) and transient climate response (TCR) are derived based on the best estimates and uncertainty ranges for forcing provided in the IPCC Fifth Assessment Scientific Report (AR5).

Lewis's estimate for this budget, he says, lies «well within the uncertainty range» of the IPCC, meaning it's not outside their estimates.

The disparity between the IPCC's models doesn't come close to exploring range / uncertainty of viable projections that could be made with climate models.

5) Even if we allow the (known to be false) assumption that the uncertainty of Anthro was constrained by Greenhouse and OA alone, and still follow the IPCC in dropping «very likely» to «likely» ranges, that would still only result in an «likely» range of + / - 0.16 C, and a less than 1 % chance of the Anthro contribution being less than 50 %.

It's not difficult to see that such an uncertainty range would be huge, much large than the IPCC admits, and including massive heating and cooling scenarios.

Knutti and Hegerl in the November, 2008 Natural Geoscience paper, The equilibrium sensitivity of the Earth's temperature to radiation changes, says various observations favor a climate sensitivity value of about 3 degrees C, with a likely range of about 2 — 4.5 degrees C per the following graphic whereas the current IPCC uncertainty is range is between 1.5 - 4.5 degrees C.

Based on a TCS upper bound of 1.6 o C that we determined from actual data, we compute a 2.9 o C upper bound for GHG ECS that is below the mid-point of the latest IPCC GHG ECS uncertainty range of 1.5 < ECS < 4.5 o C and 71 percent lower than maximum 10o C ECS values obtained from the IWG statistical distribution for ECS.

I think there is likewise no consensus on the studies that have recently argued for a lower climate sensitivity, yet the IPCC has widened the uncertainty range to encompass them.

Quoting the IPCC 1.4 to 5.8 Â °C estimate (for doubling CO2) outside current agreements among models that the uncertainty is most likely in the 2.5 to 4Â °C range or failing to point out that discrepancies (used by skeptics) between surface and troposphere warming have been resolved, is misleading in my view.

Should the semi-empirical models have been included in the uncertainty range of the IPCC projections?