Sentences with phrase «other anthropogenic forcings on»

The authors find that the results from each of these analyses are consistent, showing that the effects of changes in greenhouse gases, aerosols and other anthropogenic forcings on the climate of the Arctic region can be detected.

Not exact matches

But our main point does not depend on that and is robust: with any model and any reasonable data - derived forcing, the observed 20th Century warming trend can only be explained by anthropogenic greenhouse gases, while other factors can explain the shorter - term variations around this trend.

The only way to explain the upturn in temperatures during the 20th century, as shown by Crowley (2000) and many others, is indeed through the additional impact of anthropogenic forcing, on top of any natural forcing.

Some of them are optimal fingerprint detection studies (estimating the magnitude of fingerprints for different external forcing factors in observations, and determining how likely such patterns could have occurred in observations by chance, and how likely they could be confused with climate response to other influences, using a statistically optimal metric), some of them use simpler methods, such as comparisons between data and climate model simulations with and without greenhouse gas increases / anthropogenic forcing, and some are even based only on observations.

But our main point does not depend on that and is robust: with any model and any reasonable data - derived forcing, the observed 20th Century warming trend can only be explained by anthropogenic greenhouse gases, while other factors can explain the shorter - term variations around this trend.

However, the dominance of well - mixed greenhouse gases on the anthropogenic forcing over the last few decades is robust to almost any estimate of the uncertainty in the other forcings.

In 2013, the Intergovernmental Panel on Climate Change Fifth Assessment Report stated a clear expert consensus that: «It is extremely likely [defined as 95 - 100 % certainty] that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic [human - caused] increase in greenhouse gas concentrations and other anthropogenic forcings together.»

In this approach based on detection and attribution methods, which is compared with other approaches for producing probabilistic projections in Section 10.5.4.5, different scaling factors are applied to the greenhouse gases and to the response to other anthropogenic forcings (notably aerosols); these separate scaling factors are used to account for possible errors in the models and aerosol forcing.

Results on the importance and contribution from anthropogenic forcings other than greenhouse gases vary more between different approaches.

Regarding one other point you touched on, it's worth noting that climate models do poorly with ENSO and other chaotic variations, but well with long term temperature trends as a function of anthropogenic forcing.

Judith Curry:» With the IPCC focus on anthropogenic forcing, these other issues have received insufficient scrutiny.

We see that this gets us to somewhere between 0.35 and 0.65 deg C for a CO2 increase from 290 to 390 ppmv, depending on whose estimate we accept for the % forcing from CO2 (IPCC at 93 %, several independent solar studies at 50 %, both based on the IPCC assumption that all other anthropogenic forcing factors cancelled one another out).

«We evaluate to what extent the temperature rise in the past 100 years was a trend or a natural fluctuation and analyze 2249 worldwide monthly temperature records from GISS (NASA) with the 100 - year period covering 1906 - 2005 and the two 50 - year periods from 1906 to 1955 and 1956 to 2005... The data document a strong urban heat island eff ect (UHI) and a warming with increasing station elevation... About a quarter of all the records for the 100 - year period show a fall in temperatures... that the observed temperature records are a combination of long - term correlated records with an additional trend, which is caused for instance by anthropogenic CO2, the UHI or other forcings... As a result, the probabilities that the observed temperature series are natural have values roughly between 40 % and 90 %, depending on the stations characteristics and the periods considered.»

But interpretation isn't easy, since internal variability and forcings (natural and anthropogenic) other than CO2 can move individual points up and down on the temperature axis without any movement left or right along the cumulative CO2 emissions axis.

They also find that anthropogenic forcings other than greenhouse gases have offset about 60 % of the warming that would have occurred if greenhouse gases had acted on their own.

With the IPCC focus on anthropogenic forcing, these other issues have received insufficient scrutiny.

(Parenthetically, if it were due to the sun, the same would apply, but elsewhere, Dr. Curry, I, and others have cited references indicating that solar forcing, even with some amplification beyond total solar irradiance, would have only minor moderating effects on significant anthropogenic warming even in the case of a severe solar lull.

The average of the two scaling factors implies that the CMIP5 models analysed on average exaggerate the response to aerosols, ozone and other non-greenhouse gas anthropogenic forcings by almost 70 %.

In order to separate out the effects of greenhouse gases (GHG), these analyses typically regress time series of many observational variables — including latitudinally and / or otherwise spatially distinguished surface temperatures — on model - simulated changes arising not only from separate greenhouse gas and natural forcings but also from other separate non-GHG anthropogenic forcings.

On the other hand, the anthropogenic component and the aerosol forcing, which were neglected in our study, may induce additional predictable trends.

Over at RealClimate, on this topic they claim» It is extremely likely that more than half of the observed increase in global average surface temperature from 1951 to 2010 was caused by the anthropogenic increase in greenhouse gas concentrations and other anthropogenic forcings together.

We propose here a new paradigm of anthropogenic impacts on seawater pH. This new paradigm provides a canonical approach towards integrating the multiple components of anthropogenic forcing that lead to changes in coastal pH. We believe that this paradigm, whilst accommodating that of OA by anthropogenic CO2, avoids the limitations the current OA paradigm faces to account for the dynamics of coastal ecosystems, where some ecosystems are not showing any acidification or basification trend whilst others show a much steeper acidification than expected for reasons entirely different from anthropogenic CO2 emissions.

And before we know that, we will have to know whether or not our climate has changed primarily due to anthropogenic forcing (as assumed by the IPCC models) or by natural factors (as some others have concluded), whether or not the net impact of potential future human forcing of our climate (i.e. the 2xCO2 climate sensitivity) will be positive or negative and inconsequential or substantial and whether or not the specific mitigation actions we propose will have any perceptible impact on our climate.

Not that it would prove that anthropogenic emissions don't cause warming, just that there must be something else going on to force things in the other direction?

Forster et al. (2007) described four mechanisms by which volcanic forcing influences climate: RF due to aerosol — radiation interaction; differential (vertical or horizontal) heating, producing gradients and changes in circulation; interactions with other modes of circulation, such as El Niño - Southern Oscillation (ENSO); and ozone depletion with its effects on stratospheric heating, which depends on anthropogenic chlorine (stratospheric ozone would increase with a volcanic eruption under low - chlorine conditions).

The «pause» discussion continues (see RC for a summary of recent coverage), which seems a bit silly to me, because it isn't really a «pause» at all, just a continued anthropogenically - forced warming with some other (anthropogenic and natural) forcings and internal variability added on, such that the trend is a little lower than most expected.

Here luck was on Broecker's side: the warming by other greenhouse gases and the cooling by aerosols largely cancel today, so considering only CO2 leads to almost the same radiative forcing as considering all anthropogenic effects on climate (see IPCC AR4, Fig.

PS I believe the physical observations on CO2 and temperature since 1850 would preclude any CS in excess of 4.5 C (it calculates out to around 1.4 C, or less than one - third of this amount, using the IPCC estimates on natural forcing plus other anthropogenic forcing beside CO2).

All other anthropogenic forcings (aerosols, other GHGs, etc.) are estimated by IPCC (AR4) to have cancelled one another out over the past (AR5 actually has them slightly positive on balance).