Sentences with phrase «century warming attribution»

Not exact matches

«But it has no direct impact on attribution of 20th century warming.»

This would not give us a more informative an answer about what the relative attribution of the 20th century warming is, but would perhaps give us a range on what it could be, given our current lack of knowledge and understanding.

It's interesting that you now say that attribution of 20th century warming is unimportant, just at a time when that begins to seem rather certain.

Investigating the cause of 20th Century warming is properly done in detection and attribution studies, which analyze the various forcings (e.g., solar variations, greenhouse gases or volcanic activity) and the observed time and space patterns of climate change in detail.

In any case, the question of attribution (i.e., what caused the 20th century warming) is I think very minor, albeit interesting.

Investigating the cause of 20th Century warming is properly done in detection and attribution studies, which analyze the various forcings (e.g., solar variations, greenhouse gases or volcanic activity) and the observed time and space patterns of climate change in detail.

If true climate sensitivity is only 50 - 65 % of the magnitude that is being simulated by climate models, then it is not unreasonable to infer that attribution of late 20th century warming is not 100 % caused by anthropogenic factors, and attribution to anthropogenic forcing is in the middle tercile (50 - 50).

Curry uses the lack of data to attribute all the early 20th century warming to internal variability which she then projects willy - nilly onto the late 20th century to provide 50 % of the warming since 1950 and perhaps even amplifies it to allow for the continuing warming and / or attribution of more - than - 50 % of post-1950 warming to internal variability.

Attribution of early 20th century warming requires a more quantitative consideration of all the contributions (e.g. atmospheric aerosols, black carbon etc. as well as anthropogenic greenhouse contributions, recovery from volcanic aerosols and solar etc.).

Attribution arguments of late 20th century warming have failed to pass the detection threshold which requires accounting for the phasing of the AMO and PDO.

Investigating the cause of 20th Century warming is done in so - called detection and attribution studies, which analyze the various forcings (e.g., solar variations, greenhouse gases or volcanic activity) and the observed time and space patterns of climate change in detail.

Multi-signal detection and attribution analyses, which quantify the contributions of different natural and anthropogenic forcings to observed changes, show that greenhouse gas forcing alone during the past half century would likely have resulted in greater than the observed warming if there had not been an offsetting cooling effect from aerosol and other forcings.

As for 50 % anthropogenic early 20th century warming, I don't know where I got that idea and it doesn't look like my attribution link supports that, so consider it withdrawn.

Do either of these criticisms invalidate the attribution of the warming over the last half century?

How are these «revelations» relevant for the «very likely» assessment of attribution 20th century warming?

«Well thank you IPCC authors for letting us know what is really behind that «very likely» assessment of attribution 20th century warming.»

So, how will more realistic assessment of data set uncertainty influence the IPCC AR5 conclusions and confidence levels regarding the attribution of warming since the mid 20th century?

And I didn't hear anyone discussing the implications of all this for uncertainty in the 20th century attribution of the warming.

«how will more realistic assessment of data set uncertainty influence the IPCC AR5 conclusions and confidence levels regarding the attribution of warming since the mid 20th century?»

The growing evidence that climate models are too sensitive to CO2 has implications for the attribution of late 20th century warming and projections of 21st century climate change.

I have been arguing that the IPCC's attribution arguments are unconvincing unless they can also explain the early 20th century warming, and the longer period of overall warming prior to the 20th century.

If we assume that the LIA was caused mostly by naturally forced variability, then we have several periods in the 20th century of cooling and warming associated with modest unforced variability: The AMO's effect on GMST (0.25 degC peak to trough) isn't big enough to invalidate the IPCC's attribution statement.

As an example, lets apply the Italian flag to the issue of attribution of the 20th century warming, specifically the statement by the IPCC:

As it appears that warming has been rather constant over the last 200 + years, at about 0.5 deg C per century, then one can not make any attribution to a contribution to warming by man's emissions.

In the 20th century, the climate swings of the AMO have alternately camouflaged and exaggerated the effects of global warming, and made attribution of global warming more difficult to ascertain.

However, I believe that I have made strong arguments in terms of the importance of natural variability in the attribution of late 20th century warming and in projections of 21st century warming, and in documenting that the IPCC models and arguments are inadequate in this regard.

Much of climate science is incorrect — specifically on attribution of warming in the 20th century.

IPCC has stated (AR4 WG1 Ch.9) that the «global mean warming observed since 1970 can only be reproduced when models are forced with combinations of external forcings that include anthropogenic forcings... Therefore modeling studies suggest that late 20th - century warming is much more likely to be anthropogenic than natural in origin...» whereas for the statistically indistinguishable early 20thC warming period «detection and attribution as well as modeling studies indicate more uncertainty regarding the causes of early 20th - century warming.»

Well yes, that's what would be required of the IPCC to support their anthropogenic attribution to 20th century 0 - 700m warming (that's now at standstill last 4 years of the 21st century) but nothing forthcoming.

«Formal attribution studies now suggest that it is likely that anthropogenic forcing has contributed to the observed warming of the upper several hundred metres of the global ocean during the latter half of the 20th century -LCB- 5.2, 9.5 -RCB-»

I regard it as a fundamental flaw in logic to infer high confidence in attribution since 1950, without understanding the warming in the early part of the 20th century and the mid century hiatus.

The climate is a messy system and traditional attribution looking for the reasons for a warming of several tenths of a degree over a century can only reach the conclusion that it is «very likely», what chance, consequently, does anyone have to confidently attribute changes of a hundredth of a degree over a decade?

You say you need convincing that a «dogma» does not exist yet all you have thrived on to convince yourself it does exist is vague and broad attacks with a (with all due respect to your CV) a rather poor understanding of basic aspects of the science (such as the relevance of early 20th century attribution to modern day warming).

The question is less about whether this was anthropogenic — let's assume it is for the moment — than about the attribution of late century warming.

«The assessment is supported additionally by a complementary analysis in which the parameters of an Earth System Model of Intermediate Complexity (EMIC) were constrained using observations of near - surface temperature and ocean heat content, as well as prior information on the magnitudes of forcings, and which concluded that GHGs have caused 0.6 °C to 1.1 °C (5 to 95 % uncertainty) warming since the mid-20th century (Huber and Knutti, 2011); an analysis by Wigley and Santer (2013), who used an energy balance model and RF and climate sensitivity estimates from AR4, and they concluded that there was about a 93 % chance that GHGs caused a warming greater than observed over the 1950 — 2005 period; and earlier detection and attribution studies assessed in the AR4 (Hegerl et al., 2007b).»

Returning to the issue of the IPCC's statement in the AR4 regarding attribution of 20th century warming:

After reviewing evidence in both the latest global data (HadCRUT4) and the longest instrumental record, Central England Temperature, a revised picture is emerging that gives a consistent attribution for each multidecadal episode of warming and cooling in recent history, and suggests that the anthropogenic global warming trends might have been overestimated by a factor of two in the second half of the 20th century.

Had he been «correct» about the attribution of the warming trend observed during the first half of the twentieth century it could scarcely have made him more influential — though it surely would have made him better - remembered.

Therefore, modelling studies suggest that late 20th - century warming is much more likely to be anthropogenic than natural in origin, a finding which is confirmed by studies relying on formal detection and attribution methods (Section 9.4.1.4).»

In summary, the models all agree on the attribution of warming in the latter half of the 20th century, but do not agree on the causal factors for the early century warming and the mid-century cooling.

Eduardo echoes a lot of my concerns: What consequences, if any, do these analyses have for the attribution of the 20th century warming?