Archives par mot-clé : Model(s)

Alarm about alarmism

by Judith Curry, July 15, 2017 in ClimateEtc.


In understanding climate change risk, and deciding on the ‘if’ and ‘what’ of ‘action’,  we need to acknowledge that we don’t know how the climate of the 21st century will play out (Deep Uncertainty, folks).  Four possibilities:

  1. It is possible that human-caused climate change will be swamped by much larger natural climate variability.

  2. It is possible/plausible  that the sensitivity of the climate is on the low end of the IPCC envelope (1.0-1.5C), with a slow creep of warming superimposed on much larger natural variability.

  3. It is possible/plausible that the IPCC projections are actually correct (right for the wrong reasons; too much wrong with the climate models for much credibility, IMO).

  4. It is possible that AGW and natural variability could conspire to cause catastrophic outcomes

Focusing on worst case climate futures doesn’t work. It shouldn’t work

by Larry Kummer, July 15, 2017 in WUWT


After 30 years of failure to gain support of the US public for massive public policy measures to fight climate change, climate activists now double down on the tactics that have failed them for so long. This post explains why it will not work. Nor should it. Instead they should trust the IPCC and science, showing both the good and bad news.

Temperature and Forcing

by Willis Eschenbach, July 13, 2017 in WUWT


Over at Dr. Curry’s excellent website, she’s discussing the Red and Blue Team approach. If I ran the zoo and could re-examine the climate question, I’d want to look at what I see as the central misunderstanding in the current theory of climate.

This is the mistaken idea that changes in global temperature are a linear function of changes in the top-of-atmosphere (TOA) radiation balance (usually called “forcing”).

Does a new paper really reconcile instrumental and model-based climate sensitivity estimates

by Nic Lewis, July 8, 2017 in Climate Audit


A new paper in Science Advances by Cristian Proistosescu and Peter Huybers “Slow climate mode reconciles historical and model-based estimates of climate sensitivity” (hereafter PH17) claims that accounting for the decline in feedback strength over time that occurs in most CMIP5 coupled global climate models (GCMs), brings observationally-based climate sensitivity estimates from historical records into line with model-derived estimates. It is not the first paper to attempt to do so, but it makes a rather bold claim and, partly because Science Advances seeks press coverage for its articles, has been attracting considerable attention.

Pronounced differences between observed and CMIP5-simulated multidecadal climate variability in the twentieth century

by Sergey Kravtsov, June 15, 2017


The observed internal variability so estimated exhibits a pronounced multidecadal mode with a distinctive spatiotemporal signature, which is altogether absent in model simulations. This single mode explains a major fraction of model-data differences over the entire climate index network considered; it may reflect either biases in the models’ forced response or models’ lack of requisite internal dynamics, or a combination of both.

Climate Change: The Facts 2017

by Jennifer Marohasy, June3, 2017


Important new book coming out  …

Contributors to Climate Change: The Facts 2017 do not conform to a unitary view.   As I explain in the book’s introduction:

“An advantage of my approach in the compiling of the chapters for this book – an approach where there has been no real attempt to put everything into neat boxes – is that there are many surprises. I am referring to the snippets of apparently anomalous information scattered through the chapters. These can, hopefully, one day, be reconciled. As this occurs, we may begin to see the emergence of a coherent theory of climate – where output from computer-simulation models bears some resemblance to real-world measurements that have not first been ‘homogenised’.

 

 

80 Graphs From 58 New (2017) Papers Invalidate Claims Of Unprecedented Global-Scale Modern Warming

by Kenneth Richard, May 29, 2017


Last year there were at least 60 peer-reviewed papers published in scientific journals demonstrating that  Today’s Warming Isn’t Global, Unprecedented, Or Remarkable.
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Just within the last 5 months,  58 more papers and 80 new graphs have been published that continue to undermine the popularized conception of a slowly cooling Earth temperature history followed by a dramatic hockey-stick-shaped uptick, or an especially unusual global-scale warming during modern times.

 

Onset and ending of the late Palaeozoic ice age triggered by tectonically paced rock weathering

by Yves Goddéris et al., April 10, 2017, Nature Geoscience


The onset of the late Palaeozoic ice age about 340 million years ago has been attributed to a decrease in atmospheric CO2 concentrations associated with expansion of land plants, as plants both enhance silicate rock weathering—which consumes CO2—and increase the storage of organic carbon on land. However, plant expansion and carbon uptake substantially predate glaciation

The Art and Science of Climate Model Tuning

by Hourdin et al., March 2017,

Bulletin of the American Meteorological Society

We also discuss the challenges and opportunities in applying so-called objective methods in climate model tuning. We discuss how tuning methodologies may affect fundamental results of climate models, such as climate sensitivity. The article concludes with a series of recommendations to make the process of climate model tuning more transparent.

Climate models for the layman

by Judith Curry, Feb 2017


Professor Judith A. Curry is the author of over 180 scienti c papers on weather and climate and is a recipient of the Henry G. Houghton Research Award from the Amer- ican Meteorological Society in 1992. She recently retired from the Georgia Institute of Technology, where she held the positions of Professor and Chair of the School of Earth and Atmospheric Sciences. She is currently President of Climate Forecast Appli- cations Network.