Klimamodellenes svikt og feilkilder

Å tro at man kan "modellere" klodens klima på en vitenskapelig tilfredsstillende måte grenser til stormannsgalskap, og har følgelig også endt med en strøm av pseudovitenskapelige "projeksjoner" som feiler i tur og orden mot observasjoner.

Først, dere som foretrekker korte slagordpregede innlegg vil trolig ikke like dette lange innlegget, men det er nødvendig for å både bære fram et samlet argument samt dokumentere disse påstandene med kilder. Jeg håper kommentarene også vil respektere denne debattformen.

Generelt om svakhetene i IPCCs klimaprojeksjoner

Det foreligger en mengde publisert materiale som viser at det ikke er mulig å foreta tilstrekkelig presise projiseringer av globalt klima til å forsvare påstandene om fremtidig temperatur- og havstigninger utover helt normale sykluser. En av dem som tydelig har advart om dette er Freeman Dyson, Professor Emeritus ved School of Natural Sciences, Institute for Advanced Study; Fellow of the Royal Society, som i 2011 skrev bl.a. dette i en email-utveksling med en journalist:

"The computer models are very good at solving the equations of fluid dynamics but very bad at describing the real world. The real world is full of things like clouds and vegetation and soil and dust which the models describe very poorly”.

“The carbon dioxide in the atmosphere is strongly coupled with other carbon reservoirs in the biosphere, vegetation and top-soil, which are as large or larger. It is misleading to consider only the atmosphere and ocean, as the climate models do, and ignore the other reservoirs.”

“The climate of the earth is an immensely complicated system and nobody is close to understanding it.”

Klimasensitivitet for CO2:
IPCC har med SPM-framleggelsen høsten 2013 og det som foreløpig er sluppet om den vitenskapelige delen av AR5 – etter som klimamodellenes temperaturprojeksjoner de siste 17 årene har vist et stadig større avvik ifht. faktiske observasjoner i den virkelige verden - måttet halvere sine opprinnelige estimater for «klimafølsomhet» for CO2, dvs. deres estimat for hvor mye en dobling av atmosfærens CO2-innhold vil øke global temperatur.

Men denne retretten har vært på trappene lenge: Philip Stott, professor emeritus i biogeography ved University of London sa allerede i 2007: "It is claimed, on the basis of computer models, that this should lead to 1.1 – 6.4 C warming. What is rarely noted is that we are already three-quarters of the way into this in terms of radiative forcing, but we have only witnessed a 0.6 (+/-0.2) C rise, and there is no reason to suppose that all of this is due to humans."

En av verdens mest kjente klimaforskere, Richard Lindzen, Professor of Atmospheric Science ved MIT og medlem av National Academy of Sciences har uttalt seg om det samme i en rekke sammenhenger, sier f.eks.:

“We are not in a position to confidently attribute past climate change to CO2 or to forecast what the climate will be in the future."

Sallie Baliunas, astronom, Harvard-Smithsonian Center for Astrophysics sa i en forelesning i 2002 for The Heritage Foundation:

"Most of the increase in the air's concentration of greenhouse gases from human activities—over 80 percent—occurred after the 1940s. That means that the strong early 20th century warming must be largely, if not entirely, natural.”

Og hvis noen fremdeles tør å hevde at det ikke finnes fagfellevurdert litteratur som understøtter tvilen til IPCCs sensitivitetspåstander og AGW/CO2-hypotesen:

Studier som er kritiske til IPCCs påstander på disse fagområdene:

Modeling Volcanic Aeorsol Impacts on Atmospheric Water Vapor (29 January 2014)
Simulating California (USA) Extreme Heat Conditions (15 January 2014)
Reconstructing the Increasing "Breath" of Earth's Biosphere (25 December 2013)
Atmospheric Blocking in the Northern Hemisphere (17 December 2013)
Solar and Planetary Influences on Global Climate Change (10 December 2013)
Simulating the MJO and Convectively Coupled Equatorial Waves (4 December 2013)
The Amundsen-Bellingshausen Seas Low in CMIP5 Climate Models (26 November 2013)
Simulating North Atlantic Extratropical Cyclones (20 November 2013)
The North American Regional Climate-Change Assessment Program (19 November 2013)
CMIP3 and CMIP5 Wind Stress Climatology (29 October 2013)
The Coupled Model Intercomparison Project (CMIP): Phase 3 vs. Phase 5 (22 October 2013)
CMIP5 Backward Projections of Temperature and Precipitation (15 October 2013)
Modeling Temperature, Sea Level Pressure and Precipitation: CMIP5 vs. CMIP3 (24 September 2013)
Deficiencies of Modeled Temperature Extremes (20 August 2013)
Last Millennium Climate Simulations Still Falling Short of Reality (14 August 2013)
Global Climate Model Simulations of Southern South America (13 August 2013)
Meet the New Models: Are They Any Better Than the Old Models? (7 August 2013)
Permafrost Thermal Dynamics in CMIP5 Earth System Models (30 July 2013)
Climate Models: Still Struggling to "Get It Right" (3 July 2013)
IPCC AR4 Projections of Indian Summer Monsoon-ENSO Links (12 June 2013)
Wind Speeds over China: AR5 Climate Models vs. Real-World Data (28 May 2013)
How Well Do Climate Models Mimic Atmospheric Teleconnections? (15 May 2013)
Modeling Northern Hemispheric Winters (30 April 2013)
Biases in the Output of Global and Regional Circulation Models (9 April 2013)
Modeling the Link Between ENSO and North Australian SSTs (13 February 2013)
Model Simulations of Climatic Effects of Volcanic Eruptions (5 February 2013)
Drifting Along with the CMIP3 Models (2 January 2013)
Going Back in Time: The (un)Predictability of Climate (5 December 2012)
An Astronomically-Based Decadal-Scale Climate Model vs. All of the IPCC (2007) General Circulation Models of the Atmosphere (27 November 2012)
Testing Version 4 of the Community Climate System Model (6 November 2012)
Examining Flow Variability in a Simple Model: Friction in Jet Stream Behavior (30 October 2012)
With a Hint and a Nudge, Climate Model Downscaling Can be Improved (17 October 2012)
The Weather Research and Forecasting Model: Turning a Weather Model into a Climate Model (16 October 2012)
Simulating the Present-Day Arctic Atmosphere (5 September 2012)
The South Pacific Convergence Zone: A Real "Swinger" Under the Influence of CO2? (21 August 2012)
Tropical Influences on North Pacific Sea Surface Temperatures (14 August 2012)
A Model Passes the Test for Tropical Cyclones (18 July 2012)
New Model Test Experiments, Same old Results (27 June 2012)
The Siberian High in a Supposedly Warming World (17 April 2012)
Climatic Impacts of Intermittent Tropical Cyclone-Induced Alterations in Sea Surface Temperature (11 April 2012)
Historical Simulations of an Astronomically-Based Climate Model vs. Those of the Global Circulation Models Promoted by the IPCC (21 March 2012)
The Relative Merit of Multiple Climate Models (21 February 2012)
Global Climate Models and Simulating the Arctic: How do They Perform in the Cold? (1 February 2012)
Exciting El Niño News: More Evidence of a Solar Trigger (4 January 2012)
ENSO Variability Over the Past Millennium (3 January 2012)
Trying to Understand Interactions Among Isoprene, Ozone and Methane within the Context of Rising Air Temperatures and CO2 Concentrations (21 December 2011)
The Madden Julian Oscillation (MJO): A Climate Model Increases its "Mojo" (20 December 2011)
The Next Forty Years of Hypothetical Global Warming (29 November 2011)
Predicting Future Climate: How Good Are Today's Models? (22 November 2011)
Regional Climate Modeling: Are Prospects for Improvement Dim or Brightening? (15 November 2011)
Abrupt Climate Change Simulations (26 October 2011)
Predicting the Course of Climate Change Over the Next Decade (25 October 2011)
Tropical Cyclones: The Models Project More of Them in Our Future, or is it Fewer (12 October 2011)
Interannual Variability of 20th-Century Climate in CMIP3 Models (11 October 2011)
One More Alarmist Claim Not Supported by the Latest Science -- Fears of a Permanent El Niño (4 October 2011)
Getting Back to Basics: Atmospheric Blocking (4 October 2011)
Assessing Model Performance: Are All Models Created Equal? (21 September 2011)
Atmospheric Models: Keeping It Simple (6 September 2011)
Will It Be Species Extinction or Species Persistence? (10 August 2011)
Microrefugia: An Important Hedge Against Extinction (26 Jul 2011)
Why Climate Change Effect Studies are Pessimistic (20 Jul 2011)
Atmospheric Models: Keeping it Simple (19 Jul 2011)
Detecting the Footprint of Man in Tropical Cyclone Damage Data (7 June 2011)
Climate Models Need to Render the Past Before Projecting the Future (25 May 2011)
Using Statistical Models to Understand Earth's Climate: The Intertropical Convergence Zone (26 April 2011)
Model Assessments of Warming-Induced Changes in the Frequency of Northern Hemisphere Summer Cyclones (6 April 2011)
Getting to the "Core" of Output Differences as Produced by Climate Models (30 March 2011)
A Shifting of Paradigms in the Study of Ice-Sheet Grounding Lines (16 March 2011)
The Late-1980 Extratropical Warming of the Northern Hemisphere (9 March 2011)
The Relative Merit of Multiple Climate Models (8 March 2011)
Three Decades of Modeling Climate Sensitivity to CO2 (2 March 2011)
Have Natural Variations in the Arctic and North Atlantic Region influenced Recent Global Temperatures? (26 January 2011)
Improving GCMs through the Representation of Aerosol Composition (25 January 2011)
Natural Variability, Not CO2, Accounts for Late 20th Century Warming (6 January 2011)
Atmospheric Blocking and Extreme Weather Events (5 January 2011)
Irreversible CO2-Induced Global Warming? (22 December 2010)
ENSO Prediction by Coupled Ocean-Atmosphere Models (17 November 2010)
Climatic Change Effects on Earth's Biosphere (22 September 2010)
Highly Uncertain Forecasts of Future European Climate (26 August 2010)
How Good Are Current Climate Models? (22 July 2010)
Assessing the Skill of Coupled Atmosphere-Land-Ocean Climate Models (16 July 2010)
Climate Models Are Sensitive to Errors in Initial Conditions (14 June 2010)

Historiske sykluser/temperaturtrender

En strøm av forskere har protestert mot visse kretser i IPCC-miljøet, som systematisk siden slutten av 1980-tallet har forsøkt å nedskrive tidligere varmeperioder og tilsvarende oppskrive varmeperioden siden 1976. Motiv:

a) Et tydelig bilde av tidligere varmeperioder (les: før dagens økte CO2-utslipp) kan undergrave hele CO2-argumentet

b) Et inntrykk av relativt høyere temperatur de siste tiårene kan styrke CO2-argumentet

Studier som er kritiske til IPCCs påstander på disse fagområdene:

Two Decades of Overestimated Global Warming (29 January 2014)
Creating Global Climate Models for Agricultural Impact Research (10 December 2013)
24 CMIP5 Global Climate Models Applied to the Tibetan Plateau (25 September 2013)
Modeling Temperature, Sea Level Pressure and Precipitation: CMIP5 vs. CMIP3 (24 September 2013)
ENSO Behavior in Evolving Climate Models: CMIP5 vs. CMIP3 (29 May 2013)
CMIP3 Models Simulating Temperature and Precipitation in China (26 March 2013)
How Sensitive are Atmosphere-Ocean GCMs: Their Response to a Radiative "Push" (28 November 2012)
Arctic vs. Global Air Temperature Change (2 May 2012)
Regional Climate Change: How Well to the IPCC Models Really Perform? (20 April 2011)
The Late-1980 Extratropical Warming of the Northern Hemisphere (9 March 2011)
Surface Air Temperatures Over the Arctic Ocean (1 March 2011)
Arctic vs. Global Air Temperature Change (23 February 2011)
Temperature and Precipitation Extremes: Models vs. Reality (15 February 2011)
Have Natural Variations in the Arctic and North Atlantic Region influenced Recent Global Temperatures? (26 January 2011)
Climate Models Fail to Match Observed Historical Data (25 January 2011)
Natural Variability, Not CO2, Accounts for Late 20th Century Warming (6 January 2011)
Natural and Anthropogenic Influences on Earth's Climate (7 December 2010)

Havstigning

Nils-Axel Mörner, pensjonert sjef for Paleogeofysikk og Geodynamikk ved Stockholm University og tidligere styreleder for INQUA Commission on Sea Level Changes and Coastal Evolution (1999-2003) sa i et vitneprov gitt i 2005 til en såkalt “select committee”:

"In conclusion, observational data do not support the sea level rise scenario. On the contrary, they seriously contradict it. Therefore we should free the world from the condemnation of becoming extensively flooded in the near future”.

Studier som er kritiske til IPCCs havpåstander:

Relating to the Reliability of Seasonal to Decadal SST Forecasts (19 February 2014)
A Climate Model that Apparently Produces No Realistic Predictions (18 February 2014)
Modelling Decadal to Centennial Climate in the Equatorial Pacific (4 February 2014)
Westerly Biases Over the Equatorial Atlantic (15 January 2014)
Antarctic Sea Ice Trends: Modelled vs. Measured (14 January 2014)
Modeling Oceanic Carbon Uptake and Storage (24 December 2013)
Arctic Clouds and Sea Ice in CMIP5 Climate Models (10 December 2013)
The Indian Ocean Dipole in CMIP5 Models (3 December 2013)
Predicting Tropical Pacific Sea Surface Temperatures (12 November 2013)
Southern Ocean Water Mass Circulation and Characteristics (11 September 2013)
Modeling the East Asian-Western North Pacific Monsoon & ENSO (10 September 2013)
Modeling Southern Ocean Bottom Water Characteristics (4 September 2013)
Modeling the Indian Ocean Dipole: A Progress Report (of Sorts) (3 September 2013)
Proper Modeling of the Seychelles Dome: Is Progress Being Made? (21 August 2013)
Southern Ocean Bottom Water Formation in CMIP5 Models (23 July 2013)
The Equatorial Cold Tongue Bias in CGCMs: Its Impact on ENSO (9 July 2013)
Recent Antarctic Sea Ice Extent in CMIP5 Models (25 June 2013)
Simulating the Southwestern Indian Ocean's Seychelles Dome (5 June 2013)
Problems Modeling Air-Sea Fluxes and Sea Surface Temperatures (7 May 2013)
More Problems with State-of-the-Art Climate Models (23 April 2013)
More Problems with Decadal Climate-Model Prediction Skills (3 April 2013)
Simulating the North Atlantic European Regional Climate (19 March 2013)
Tropical Sea Surface Temperature Biases in CMIP 3 & 5 Models (5 March 2013)
Simulating the Indian Ocean Subtropical Dipole (5 March 2013)
Initial Testing of IPCC Fifth Assessment Report Climate Models (16 October 2012)
Simulating the Equatorial Pacific Cold Tongue (9 October 2012)
Simulating Earth's Southern Ocean and Its Climate (12 September 2012)
Modeling Changes in Arctic Ocean Sea Ice Characteristics (17 January 2012)
Climate Model Failures in the Southeast Pacific Ocean (14 December 2011)
Testing the Entire Suite of IPCC AR4 Models (24 August 2011)
Bias in Model Simulations of Climate (26 Jul 2011)

Nedbør

De fleste forskere, også de som er trygt plassert innenfor IPCC-miljøet, innrømmer at dette er et fagområde der klimamodellene kommer veldig til kort.

Studier som er kritiske til IPCCs påstander på disse fagområdene:

Modeling Southern Hemisphere Mid-latitude Precipitation Trends (29 January 2014)
The "Best Available Tools" for Predicting Climate Change (22 January 2014)
Northeast Monsoon Rainfall Over South Peninsular India (8 January 2014)
Predicting Precipitation Extremes via CMIP5 Climate Models (7 January 2014)
Projecting Global Changes in Precipitation Extremes (11 December 2013)
Creating Global Climate Models for Agricultural Impact Research (10 December 2013)
How Close is Modeled Precipitation to Measured Precipitation? (19 November 2013)
ENSO Teleconnections in CMIP Models Simulating Precipitation (13 November 2013)
CMIP5 Backward Projections of Temperature and Precipitation (15 October 2013)
24 CMIP5 Global Climate Models Applied to the Tibetan Plateau (25 September 2013)
Modeling Temperature, Sea Level Pressure and Precipitation: CMIP5 vs. CMIP3 (24 September 2013)
CMIP5 Modeling of Extreme Precipitation in Europe (17 September 2013)
Global Climate Model Simulations of Southern South America (13 August 2013)
Modeling Multi-Scale Precipitation Variability in the Southwest US (6 August 2013)
Northern Hemisphere Land Snow Cover: Simulations vs. Reality (30 July 2013)
Tropical Precipitation Extremes: How Well Are They Modeled? (23 July 2013)
Modeling Extreme Precipitation in the Tropics (10 July 2013)
Climate Models: Still Struggling to "Get It Right" (3 July 2013)
PMIP2 Characterizations of the Mid-Holocene African Monsoon (3 July 2013)
Storm-Track Activity: Modeled vs. Measured (11 June 2013)
Modeling Precipitation Over the Mediterranean Region (29 May 2013)
Predicting Decadal to Multi-Decadal Variability in Precipitation (2 April 2013)
CMIP3 Models Simulating Temperature and Precipitation in China (26 March 2013)
Simulated Climate Change Impacts on Streamflow in Vietnam's Be River Catchment (26 March 2013)
Mediterranean Precipitation Simulated by CMIP5 Climate Models (12 March 2013)
With a Hint and a Nudge, Climate Model Downscaling Can be Improved (17 October 2012)
The Weather Research and Forecasting Model: Turning a Weather Model into a Climate Model (16 October 2012)
Simulations of Seasonal Snow in the Upper Colorado River Basin (19 September 2012)
Do Regional Climate Models Realistically Represent Precipitation? (28 August 2012)
Will Storminess Increase in a Warmer World: Models Can't Clear the Skies (7 August 2012)
Regional Climate Models: How Well Do They Work? (7 August 2012)
More Intense Precipitation Extremes: Are They Linked to Human Activity? (24 April 2012)
Extreme Rainfall Events Throughout the Himalayas (24 April 2012)
Water-Year Runoff of the Conterminous United States: 1900-2008 (10 April 2012)
Snowfall Regimes within the Italian Alps (24 January 2012)
State-of-the-Art Climate Models and Extreme Meteorological Events and Consequences (2 August 2011)
Precipitation Extremes Along North America's West Coast (22 June 2011)
The Climatic Impacts of Precipitating Ice and Snow (27 April 2011)
Regional Climate Change: How Well to the IPCC Models Really Perform? (20 April 2011)
The Importance of the Oceans and Topography in Climate Simulations (19 April 2011)
Simulating 21st-Century Precipitation (23 February 2011)
Climate Model Problems: Clouds and Precipitation (16 February 2011)
Temperature and Precipitation Extremes: Models vs. Reality (15 February 2011)
Climate Models Fail to Match Observed Historical Data (25 January 2011)
Precipitation: Models vs. Reality (25 January 2011)
Regional Climate Models Differ in Extreme Precipitation Event Forecasts (26 August 2010)

Vanndamp/skyer

Vanndamp og skyer er en åpenbart stor, uforstått, dynamisk og kompleks feilkilde i dagens klimamodeller, og kan alene stå for så store feilkilder at alt snakk om statistisk sikkerhet for «klimaprojeksjoner» blir en vitenskapelig absurditet.

Studier som er kritiske til IPCCs påstander på disse fagområdene:

Arctic Clouds and Sea Ice in CMIP5 Climate Models (10 December 2013)
Cloud Tuning in a Malleable Climate Model (26 November 2013)
Modeling Top-of-the-Atmosphere Cloud Radiative Effects (1 October 2013)
Stratocumulus Clouds of the Subtropical North and South Atlantic (1 October 2013)
The Outlook for Modeling Clouds (Adequately) ... is Still Cloudy (24 September 2013)
Modeling Climate Feedbacks Based on Short-Term Climate Variations (25 June 2013)
More Problems with State-of-the-Art Climate Models (23 April 2013)
Problems of CMIP5 Climate Models with Tropical Low Clouds (19 March 2013)
CMIP5 Model Representations of Cloud Vertical Structure (26 February 2013)
Low-Level Liquid-Containing Arctic Clouds (26 February 2013)
Cloud Ice Water Content & Cloud Ice Water Path in CMIP5 GCMs (5 February 2013)
The Result is Clear: A Weather Forecast Model has Trouble with Clouds (12 December 2012)
The Trouble with Clouds (4 December 2012)
The Impact of Atmospheric Aerosols on North Atlantic Climate (24 October 2012)
Convective Clouds Continue to Confound a GCM (14 August 2012)
Aerosol Radiative Forcing of Climate (13 March 2012)
Errors in General Circulation Models: It Could Be "Double" Trouble (7 February 2012)
The Sensitivity of GCM Output to Aerosol Parameterization (16 August 2011)
Simulating Arctic Cloud Cover and Sea Ice (2 March 2011)
Aerosol Properties of the Global Atmosphere As Input Data to Climate Models (1 March 2011)
Climate Model Problems: Clouds and Precipitation (16 February 2011)
Improving GCMs through the Representation of Aerosol Composition (25 January 2011)
Climate Models Do Not Simulate Real-World Cloud Structures Well (26 August 2010)

Strålingsenergi

Dette er et stort forskningsområde utenfor IPCC-miljøet, men et stebarn innenfor. Her er noen typiske studier som viser at IPCCs klimamodeller ikke dekker disse fagområdene tilstrekkelig:

Studier som er kritiske til IPCCs påstander på disse fagområdene:
The Top-of-the-Atmosphere Radiation Budget: Model Simulations vs. Direct Measurements over the Tropics (7 March 2012)
The Sensitivity of GCM Output to Aerosol Parameterization (16 August 2011)
Modeling the Pattern of Tropical Ocean Warming (18 May 2011)
The Top-of-the-Atmosphere Radiation Budget: Model Simulations vs. Direct Measurements over the Tropics (9 March 2011)

Atmosfæriske forhold (stratosfære, troposfære)

Her finner vi bl.a. en av de store AGW-verkebyllene: fraværet av det deklamerte «hot spot» som et sentralt «bevis» for AGW/CO2-hypotesen. Som kjent glimrer både hot spot’et og andre projeksjonerte påstander med sine fravær fremdeles:

Studier som er kritiske til IPCCs påstander på disse fagområdene:

Troposfæren:
Modelling Thermal Characteristics of the Cold Point-Tropopause (21 January 2014)
The Top Ten Problems of the New-and-Improved ECHAM6 Model (21 January 2014)
Another Test of CMIP5 Models: What Problems Were Detected? (18 June 2013)
Tropical Upper Tropospheric Warming: Models vs. Measurements (21 May 2013)
Tropospheric Humidity and CO2-Induced Global Warming (9 May 2012)
Upper Tropical Tropospheric Temperature: Simulations vs. Reality (15 November 2011)
Warming of the Tropical Upper Troposphere (5 October 2011)
Models Warm the Lower Troposphere Too Much: A Fingerprint Test with Updated Data (22 September 2010)

Stratosfæren:
Including the Stratosphere in Models of Global Climate Change (5 February 2014)
Another Test of CMIP5 Models: What Problems Were Detected? (18 June 2013)
Global Warming: A Stratospheric Surprise (20 May 2010)

Karbonsyklusen

Naturlig karbonsyklus og graden av naturlige lagringsprosesser: Forskere som lener seg ensidig på drivhuseffekten (AGW/CO2-hypotesen) er lite komfortable med å forholde seg til overveldende faglig dokumentasjon på at karbonkretsløpet har langt flere naturlige håndteringsmåter enn deres ensidige enveis-argumentasjon om at karbon har svært lang levetid i atmosfæren og ikke minst å underspille i hvor stor grad karbon utfelles og på ulike måter lagres i fast form i naturen. Kort sagt: En rekke tunge naturvitenskapsfolk har vist at «karbonregnskapet» i klimamodellene omgås ellers aksepterte naturfaglige fakta på en klart utilstrekkelig/tendensiøs måte for å styrke det alarmistiske AGW-busdskapet.

Studier som er kritiske til IPCCs påstander på disse fagområdene:

Reconstructing the Increasing "Breath" of Earth's Biosphere (25 December 2013)
Modeling Oceanic Carbon Uptake and Storage (24 December 2013)
Another Negative Feedback to Curtail Global Warming (23 November 2010)
The Effect of Nitrogen Deposition on Forest Soil Respiration (6 October 2010)

Oppsummert:

Ikke på noe fagområde finnes der bred vitenskapelig støtte for klimamodellenes sentrale parametre nevnt ovenfor. Hvordan kan man da hevde nærmere 100% «sikkerhet» (det heter forøvrig «usikkerhet» i reell statistisk vitenskap, der håndsopprekking kommer langt ned på verdiskalaen…) for projeksjoner som savner det meste av vitenskapeligunderlag og troverdighet?