Sentences with phrase «caused by internal variability»

The observed trends are extremely unlikely (< 5 %) to be caused by internal variability, even if current models were found to strongly underestimate it.

There is medium confidence that the GMST trend difference between models and observations during 1998 — 2012 is to a substantial degree caused by internal variability, with possible contributions from forcing error and some CMIP5 models overestimating the response to increasing greenhouse - gas forcing.»

Not exact matches

Starting from an old equilbrium, a change in radiative forcing results in a radiative imbalance, which results in energy accumulation or depletion, which causes a temperature response that approahes equilibrium when the remaining imbalance approaches zero — thus the equilibrium climatic response, in the global - time average (for a time period long enough to characterize the climatic state, including externally imposed cycles (day, year) and internal variability), causes an opposite change in radiative fluxes (via Planck function)(plus convective fluxes, etc, where they occur) equal in magnitude to the sum of the (externally) imposed forcing plus any «forcings» caused by non-Planck feedbacks (in particular, climate - dependent changes in optical properties, + etc.).)

Roy Spencer is the driving force behind the «internal variability» hypothesis, which posits that some unknown and undefined mechanism is causing cloud cover to change, which, by changing the overall reflectivity of the Earth, is the driving force behind the current global warming.

This difference between simulated and observed trends could be caused by some combination of (a) internal climate variability, (b) missing or incorrect radiative forcing and (c) model response error.

If the models are unable to predict the forced response of the climate (i.e. the climate change caused by changes in forcings such as CO2) then I don't see how they can be expected to accurately model the unforced response (internal climate variability).

The temperature of the troposphere is constantly being affected by variations in the rate of energy flow from the oceans driven by internal ocean variability, possibly caused by temperature fluctuations along the horizontal route of the thermohaline circulation and by variations in energy flow from the sun that affect the size (and thus density) of the atmosphere and the rate of energy loss to space.

The models currently assume a generally static global energy budget with relatively little internal system variability so that measurable changes in the various input and output components can only occur from external forcing agents such as changes in the CO2 content of the air caused by human emissions or perhaps temporary after effects from volcanic eruptions, meteorite strikes or significant changes in solar power output.

«Our results show that it is extremely likely that at least 74 % (+ / - 12 %, 1 sigma) of the observed warming since 1950 was caused by radiative forcings, and less than 26 % (+ / - 12 %) by unforced internal variability.»

As you can see, over periods of a few decades, modeled internal variability does not cause surface temperatures to change by more than 0.3 °C, and over longer periods, such as the entire 20th Century, its transient warming and cooling influences tend to average out, and internal variability does not cause long - term temperature trends.

And so they suggest early Arctic warming was a random event caused by «internal variability» that can't be modeled.

But we know that the mechanisms responsible for the variation of Ts are different in internal variability on these time scales and in forced climate change, then my questions is that: is it possible that the spread in ECS might not be so directly caused by low - cloud feedback, although the low cloud feedback is a very good indictor for the model uncertainty?

It doesn't matter whether that temperature change is caused by the Sun, fossil fuels, internal variability, or invading Martians.

If the temperature change is caused by natural internal variability, then this argument is not useful.

«Ultimately the causes of this inconsistency will only be understood after careful comparison of simulated internal climate variability and climate model forcings with observations from the past two decades, and by waiting to see how global temperature responds over the coming decades.»

As they stand at present the models assume a generally static global energy budget with relatively little internal system variability so that measurable changes in the various input and output components can only occur from external forcing agents such as changes in the CO2 content of the air caused by human emissions or perhaps temporary after effects from volcanic eruptions, meteorite strikes or significant changes in solar power output.

A recurrent multidecadal oscillation is found to extend to the preindustrial era in the 353 - y Central England Temperature and is likely an internal variability related to the Atlantic Multidecadal Oscillation (AMO), possibly caused by the thermohaline circulation variability.

«Modelling studies are also in moderately good agreement with observations during the first half of the 20th century when both anthropogenic and natural forcings are considered, although assessments of which forcings are important differ, with some studies finding that solar forcing is more important (Meehl et al., 2004) while other studies find that volcanic forcing (Broccoli et al., 2003) or internal variability (Delworth and Knutson, 2000) could be more important... The mid-century cooling that the model simulates in some regions is also observed, and is caused in the model by regional negative surface forcing from organic and black carbon associated with biomass burning.