Sentences with phrase «fast feedback climate sensitivity»

«we conclude that this relatively clean empirical assessment yields a fast feedback climate sensitivity in the upper part of the range suggested by the LGM Holocene climate change, i.e., a sensitivity 3 — 4 °C for 2 × CO2» (p. 23)

It's also another piece of evidence that is consistent with fast feedback climate sensitivity of around 0.75 °C / W / m ².

Not exact matches

The conclusion that limiting CO2 below 450 ppm will prevent warming beyond two degrees C is based on a conservative definition of climate sensitivity that considers only the so - called fast feedbacks in the climate system, such as changes in clouds, water vapor and melting sea ice.

The climate sensitivity classically defined is the response of global mean temperature to a forcing once all the «fast feedbacks» have occurred (atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.), but before any of the «slow» feedbacks have kicked in (ice sheets, vegetation, carbon cycle etc.).

One issue that I have wondered about for some time is to what extent the paleoclimate record supports the distinction between slow - feedback and fast - feedback climate sensitivity.

I'm not even an amateur climate scientist, but my logic tells me that if clouds have a stronger negative feedback in the Arctic, and I know (from news) the Arctic is warming faster than other areas, then it seems «forcing GHGs» (CO2, etc) may have a strong sensitivity than suggested, but this is suppressed by the cloud effect.

A 2008 study led by James Hansen found that climate sensitivity to «fast feedback processes» is 3 °C, but when accounting for longer - term feedbacks (such as ice sheet disintegration, vegetation migration, and greenhouse gas release from soils, tundra or ocean), if atmospheric CO2 remains at the doubled level, the sensitivity increases to 6 °C based on paleoclimatic (historical climate) data.

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.

For instance, the sensitivity only including the fast feedbacks (e.g. ignoring land ice and vegetation), or the sensitivity of a particular class of climate model (e.g. the «Charney sensitivity»), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 aftersensitivity only including the fast feedbacks (e.g. ignoring land ice and vegetation), or the sensitivity of a particular class of climate model (e.g. the «Charney sensitivity»), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 aftersensitivity of a particular class of climate model (e.g. the «Charney sensitivity»), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 after 70 climate model (e.g. the «Charney sensitivity»), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 aftersensitivity»), or the sensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 aftersensitivity of the whole system except the carbon cycle (the Earth System Sensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 afterSensitivity), or the transient sensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 aftersensitivity tied to a specific date or period of time (i.e. the Transient Climate Response (TCR) to 1 % increasing CO2 after 70 Climate Response (TCR) to 1 % increasing CO2 after 70 years).

At its present temperature Earth is on a flat portion of its fast - feedback climate sensitivity curve.

This empirical fast - feedback climate sensitivity allows water vapor, clouds, aerosols, sea ice, and all other fast feedbacks that exist in the real world to respond naturally to global climate change.

Plotting GHG forcing (7) from ice core data (27) against temperature shows that global climate sensitivity including the slow surface albedo feedback is 1.5 °C per W / m2 or 6 °C for doubled CO2 (Fig. 2), twice as large as the Charney fast - feedback sensitivity.»

The long lifetime of the fossil fuel carbon in the climate system and the persistence of ocean warming for millennia [201] provide sufficient time for the climate system to achieve full response to the fast feedback processes included in the 3 °C climate sensitivity.

However, this climate sensitivity includes only the effects of fast feedbacks of the climate system, such as water vapor, clouds, aerosols, and sea ice.

The climate sensitivity classically defined is the response of global mean temperature to a forcing once all the «fast feedbacks» have occurred (atmospheric temperatures, clouds, water vapour, winds, snow, sea ice etc.), but before any of the «slow» feedbacks have kicked in (ice sheets, vegetation, carbon cycle etc.).

http://arxiv.org/pdf/0804.1126 «Paleoclimate data show that climate sensitivity is 3 °C for doubled CO2, including only fast feedback processes.

This empirical climate sensitivity corresponds to the Charney (1979) definition of climate sensitivity, in which «fast feedback» processes are allowed to operate, but long - lived atmospheric gases, ice sheet area, land area and vegetation cover are fixed forcings.

I am thinking that the permafrost feedback article we were discussing was refering to a non-runaway feedback, but rather a delayed feedback, which is otherwise just like the fast feedbacks except that it's slow response would make clear that it does feedback on itself according to the climate sensitivity from all other feedbacks (it drives itself, via climate change, to go farther, but it approaches a limit asymptotically).

Global temperature change is about half that in Antarctica, so this equilibrium global climate sensitivity is 1.5 C (Wm ^ -2) ^ -1, double the fast - feedback (Charney) sensitivity.

Charney sensitivity refers to the climate sensitivity when fast - reacting feedbacks (Planck response is a given — also, water vapor, clouds,... I think sea ice, seasonal snow) occur but with other things (land - based ice sheets,... vegetation -LRB-?)-RRB-

And presumably it shows that the «slow» feedbacks which are not included in the Charney climate sensitivity roughly doubles the effect of the «fast» feedbacks which are.

Essentially Charney climate sensitivity is calculated only with the fast feedbacks: water vapor, sea ice, etc..

The carbon cycle feedback is potentially important to 21st century climate projections, but is not conventionally included in the climate sensitivity as it is not a fast feedback.

It is standard practice to include only the fast feedback processes, including changes in water vapour, in the calculation of climate sensitivity, but to exclude possible induced changes in the concentrations of other greenhouse gases (as well as other slow feedback processes).

It specifically states that climate sensitivity does not conventionally include carbon cycle feedback as it is «not a fast feedback.»

As such, even in the case of the carbon cycle, it would appear that WG1 AR4 deviated very little if at all from fast feedback Charney climate sensitivity.

Based on evidence from Earth's history, we suggest here that the relevant form of climate sensitivity in the Anthropocene (e.g. from which to base future greenhouse gas (GHG) stabilization targets) is the Earth system sensitivity including fast feedbacks from changes in water vapour, natural aerosols, clouds and sea ice, slower surface albedo feedbacks from changes in continental ice sheets and vegetation, and climate — GHG feedbacks from changes in natural (land and ocean) carbon sinks.

Hansen et al. 2013 (a) CO2 amount required to yield a global temperature, if fast - feedback climate sensitivity is 0.75 °C per W m − 2 and non-CO2 GHGs contribute 25 % of the GHG forcing.

Traditionally, only fast feedbacks have been considered (with the other feedbacks either ignored or treated as forcing), which has led to estimates of the climate sensitivity for doubled CO2 concentrations of about 3 ◦ C.

The empirical fast - feedback climate sensitivity that we infer from the LGM - Holocene comparison is thus 5 °C / 6.5 W / m2 ~ 3/4 ± 1/4 °C per W / m2 or 3 ± 1 °C for doubled CO2.

The conclusion that limiting CO2 below 450 ppm will prevent warming beyond two degrees C is based on a conservative definition of climate sensitivity that considers only the so - called fast feedbacks in the climate system, such as changes in clouds, water vapor and melting sea ice.

The long lifetime of the fossil fuel carbon in the climate system and the persistence of ocean warming for millennia [201] provide sufficient time for the climate system to achieve full response to the fast feedback processes included in the 3 °C climate sensitivity.

The Equilibrium Climate Sensitivity (ECS) The Economist refers to is how much Earth temperatures are expected to rise when one includes fast feedbacks such as atmospheric water vapor increase and the initial greenhouse gas forcing provided by CO2.

Third, our calculations are for a single fast - feedback equilibrium climate sensitivity, 3 °C for doubled CO2, which we infer from paleoclimate data.

However, this climate sensitivity includes only the effects of fast feedbacks of the climate system, such as water vapor, clouds, aerosols, and sea ice.

Moreover the recent decline of the yearly increments d (CO2) / dt acknowledged by Francey et al (2013)(figure 17 - F) and even by James Hansen who say that the Chinese coal emissions have been immensely beneficial to the plants that are now bigger grow faster and eat more CO2 due to the fertilisation of the air (references in note 19) cast some doubts on those compartment models with many adjustable parameters, models proved to be blatantly wrong by observations as said very politely by Wang et al.: (Xuhui Wang et al: A two-fold increase of carbon cycle sensitivity to tropical temperature variations, Nature, 2014) «Thus, the problems present models have in reproducing the observed response of the carbon cycle to climate variability on interannual timescales may call into question their ability to predict the future evolution of the carbon cycle and its feedbacks to climate»

Second, the abstract admits that, «Pleistocene climate oscillations yield a fast - feedback climate sensitivity of 3 ± 1 °C for a 4 W m − 2 CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective» and also «Ice sheet response time is poorly defined».

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).»

Note also that the Earth System Sensitivity is deduced from various past climate change events like the Paleocene — Eocene Thermal Maximum (PETM), but the qualitative estimates of longer - term climate sensitivity are less precise than the HS12 fast feedback sensitivitySensitivity is deduced from various past climate change events like the Paleocene — Eocene Thermal Maximum (PETM), but the qualitative estimates of longer - term climate sensitivity are less precise than the HS12 fast feedback sensitivitysensitivity are less precise than the HS12 fast feedback sensitivitysensitivity estimates.

The fast - feedback climate sensitivity is a reasonably smooth curve, because the principal fast - feedback mechanisms (water vapor, clouds, aerosols, sea ice) do not have sharp threshold changes.

Figure 1: Schematic diagram of the equilibrium fast - feedback climate sensitivity and Earth system sensitivity that includes surface albedo slow feedbacks.

Hansen and Sato also differentiate between fast feedback and longer - term climate sensitivity, as illustrated in Figure 1 above.

Yesterday we saw that combining ocean thermal inertia, ocean carbon cycle inertia and climate sensitivity fast feedback inertia, there may still be a warming time lag of up to 10 years (the first years of which show rapid warming, beyond which we see progression to asymptote).

The average fast - feedback climate sensitivity over the LGM — Holocene range of climate states can be assessed by comparing estimated global temperature change and climate forcing change between those two climate states [3,86].

Pleistocene climate oscillations yield a fast - feedback climate sensitivity of 3 ± 1 °C for a 4 W m − 2 CO2 forcing if Holocene warming relative to the Last Glacial Maximum (LGM) is used as calibration, but the error (uncertainty) is substantial and partly subjective because of poorly defined LGM global temperature and possible human influences in the Holocene.

Improved empirical data can define climate sensitivity much more precisely, provided that climate - induced aerosol changes are included in the category of fast feedbacks (human - made aerosol changes are a climate forcing).

Using measured amounts of GHGs during the past 800000 years of glacial — interglacial climate oscillations and surface albedo inferred from sea - level data, we show that a single empirical «fast - feedback» climate sensitivity can account well for the global temperature change over that range of climate states.

Empirical assessment of fast - feedback climate sensitivity is obtained by comparing two quasi-equilibrium climate states for which boundary condition climate forcings (which may be slow feedbacks) are known.

Accurate data defining LGM — Holocene warming would aid empirical evaluation of fast - feedback climate sensitivity.

(a) CO2 amount required to yield a global temperature of figure 4a if fast - feedback climate sensitivity is 0.75 °C per W m − 2 and non-CO2 GHGs contribute 25 % of the GHG forcing.