Sentences with phrase «volcanic forcing data»

Not exact matches

By combining this data with Ridgwell's global climate model, the team deduced the amount of carbon added to the ocean and atmosphere and concluded that volcanic activity during the opening of the North Atlantic was the dominant force behind the PETM.

Since the data show southern Greenland temperatures over the last 150 years, it would be most useful to look at model simulations for exactly that period, run with the best guesses for CO2, solar and volcanic forcing etc..

Earlier periods, say 1850 going back to the 1500s or so, have reasonable coverage from paleo - proxy data, and only have solar and volcanic forcing.

This should be done properly (and could be) but assuming the slight difference in period for the RAOBCORE v1.4 data or the selection of model runs because of volcanic forcings aren't important, then using the standard deviations in their Table IIa you'd end up with something like this:

Given the total irrelevance of volcanic aerosols during the period in question, the only very modest effect of fossil fuel emissions and the many inconsistencies governing the data pertaining to solar irradiance, it seems clear that climate science has no meaningful explanation for the considerable warming trend we see in the earlier part of the 20th century — and if that's the case, then there is no reason to assume that the warming we see in the latter part of that century could not also be due to either some as yet unknown natural force, or perhaps simply random drift.

For ENSO I used the MEI index, for volcanic forcing I used data from Ammann et al. 2003, GRL 30, 1657.

Both rely mostly on adjusting the data with ENSO and volcanic forcings.

The short - term cooling imparted by volcanic aerosols is clearly non-anthropogenic, but these forcings are reasonably well known from relevant observational data.

Previous large natural oscillations are important to examine: however, 1) our data isn't as good with regards to external forcings or to historical temperatures, making attribution more difficult, 2) to the extent that we have solar and volcanic data, and paleoclimate temperature records, they are indeed fairly consistent with each other within their respective uncertainties, and 3) most mechanisms of internal variability would have different fingerprints: eg, shifting of warmth from the oceans to the atmosphere (but we see warming in both), or simultaneous warming of the troposphere and stratosphere, or shifts in global temperature associated with major ocean current shifts which for the most part haven't been seen.

«The solar and volcanic forcings we use are derived from reconstructions based on proxy data and are therefore also subject to considerable uncertainties, although recent explosive volcanic eruptions are likely to have cooled climate, and independent records of solar activity levels inferred from the cosmogenic isotope 10Be (43) and geomagnetic records (44) provide support to reconstructions (22, 45) that show generally increasing solar activity during the 20th century (12).»

Moreover, to cover the full range of uncertainty in the historical volcanic eruption data, we even try the case with 3 times the best estimate of volcanic forcing.

But even if so, they make clear that they are using a different process designed more for the purpose than the data you have picked up compiled for the volcano paper, and they allude to this directly: «So while these reconstructions have proved valuable for studying climate variability and the role of various forcing factors acting on relatively short timescales, such as volcanic eruptions [Briffa et al 1998a], they are of limited use for judging the warmth of 20th century warmth in a multicentury context.

``... a physically based state - of - the - art data assimilation system, to infer TL2m given only CO2, solar, and volcanic radiative forcing agents...»

They also tried using Southern Oscillation Index (SOI) data for ENSO, sunspot number data for solar activity, and a volcanic radiative forcing reconstruction from Ammann et al. (2003), but found these changes made little difference to their results:

The net impact on temperature attributed to each different forcing, solar, ghg (co2, methane), volcanic, aerosol, albedo whatever are based on historical temp data and checked for accuracy against models yes?

-- paleoclimate data reflecting past climate states very different from today — climate response to volcanic eruptions, solar changes and other non-greenhouse gas forcings — timescales different from those relevant for climate stabilization, such as the climate response to volcanic eruptions

But the data shows that volcanic eruptions do NOT cause the large effects that they would perforce have if the sensitivity to forcing were as large as they claim.

It is difficult to digitise the Figure 8.18 values for years affected by volcanic eruptions, so I have also adjusted the widely - used RCP4.5 forcings dataset to reflect the Section 7.5.3 observational estimate of current aerosol forcing, using Figure 8.18 and Table 8.7 data to update the projected RCP4.5 forcings for 2007 — 2011 where appropriate.

On this basis, the question you should perhaps be posing to yourself is not whether there is a kludge to reduce the impact of volcanic forcing (it is not necessary to postulate one to explain the data), but why the reduction factor is not even larger.

To accurately evaluate the efficacy of volcanic forcing you would need to have better ocean heat content data for the period following a major eruption.