National Research Council i USA – en institution under det amerikanske videnskabernes selskab, udgav igår tre rapporter, hvori det fastslås (endnu en gang), at menneskehedens massive deponering af CO2 i atmosfæren fører til en generel opvarmning af jordsystemet.

Her er links til alle enkeltdelene af gårsdagens offentliggørelse, og her er direkte pdf-links til “briefs” af de tre rapporter:
Advancing the Science of Climate Change
Limiting the Magnitude of Future Climate Change
Adapting to the Impacts of Climate Change.

Så mangler vi bare, at Jyllands-Posten bringer dokumentationen lige så stort slået op, som dagbladet har for vane at gøre med historier, der har skeptiker-vinkel.

Related posts:

1. Dokumentation: Klimamodeller har ret

Jeg har mange gange skrevet om det nærmest grotesk underdrevne havniveaustignings-scenarie, FNs klimapanel opererer med (værst tænkelige scenarie: 59 centimeters stigning i år 2100).

Midt i konsternationen over de opdagede fejl i IPCCs tal sætter de gode folk på Realclimate-bloggen tingene i perspektiv:

Imagine this. In its latest report, the IPCC has predicted up to 3 meters of sea level rise by the end of this century. But “climate sceptics” websites were quick to reveal a few problems (or “tricks”, as they called it).

First, although the temperature scenarios of IPCC project a maximum warming of 6.4 ºC (Table SPM3), the upper limit of sea level rise has been computed assuming a warming of 7.6 ºC. Second, the IPCC chose to compute sea level rise up to the year 2105 rather than 2100 – just to add that extra bit of alarmism. Worse, the IPCC report shows that over the past 40 years, sea level has in fact risen 50% less than predicted by its models – yet these same models are used uncorrected to predict the future! And finally, the future projections assume a massive ice sheet decay which is rather at odds with past ice sheet behaviour.

Some scientists within IPCC warned early that all this could lead to a credibility problem, but the IPCC decided to go ahead anyway.

Now, the blogosphere and their great media amplifiers are up in arms. Heads must roll!

Unthinkable? Indeed. I am convinced that IPCC would never have done this.

The North Sea (see Stefan’s photostream on Flickr)
But here is what actually did happen.

In its latest report, the IPCC has predicted up to 59 cm of sea level rise by the end of this century. But realclimate soon revealed a few problems.

First, although the temperature scenarios of IPCC project a maximum warming of 6.4 ºC (Table SPM3), the upper limit of sea level rise has been computed for a warming of only 5.2 ºC – which reduced the estimate by about 15 cm. Second, the IPCC chose to compute sea level rise up to the year 2095 rather than 2100 – just to cut off another 5 cm. Worse, the IPCC report shows that over the past 40 years, sea level has in fact risen 50% more than predicted by its models – yet these same models are used uncorrected to predict the future! And finally, the future projections assume that the Antarctic ice sheet gains mass, thus lowering sea level, rather at odds with past ice sheet behaviour.**

Some scientists within IPCC warned early that all this could lead to a credibility problem, but the IPCC decided to go ahead anyway.

Nobody cared about this.

I mention this because there is a lesson in it. IPCC would never have published an implausibly high 3 meter upper limit like this, but it did not hesitate with the implausibly low 59 cm. That is because within the IPCC culture, being “alarmist” is bad and being “conservative” (i.e. underestimating the potential severity of things) is good.

Læs hele indlægget “Sealevelgate” her.

Related posts:

1. Klimapanelet undervurderer havniveaustigninger
2. År 2100: Havniveau kan stige 2 meter

Nogle af klimaskeptikerne er ved at koge over. NASAs James Hansen fortæller, at NASA i den seneste uge har modtaget over 2500 forespørgsler om muligt fusk med de data, som NASA bruger til at udregne klodens middel (luft)temperatur med.

Han fortæller samtidig, at han her i december måtte have politiets beskyttelse, da han skulle tale ved et arrangement i Houston, Texas. Kort før mødet modtag han konkrete trusler på sit liv. Så ophedede er nogle klimaskeptikere i deres vrede over, hvad de opfatter som en global opvarmningssammensværgelse – og for dem er James Hansen jo hovedarkitekten bag “klima-tsunamien”.

James Hansen reflekterer over situationen i sit seneste nyhedsbrev – og giver samtidig et autoritativt overblik over udviklingen i den globale (luft)middeltemperatur – og de data der ligger bag.

Her er udpluk fra hans brev:

… Fast forward to December 2009, when I gave a talk at the Progressive Forum in Houston Texas. The organizers there felt it necessary that I have a police escort between my hotel and the forum where I spoke.

Days earlier bloggers reported that I was probably the hacker who broke into East Anglia computers and stole e-mails. Their rationale: I was not implicated in any of the pirated e-mails, so I must have eliminated incriminating messages before releasing the hacked emails.

The next day another popular blog concluded that I deserved capital punishment. Web chatter on this topic, including indignation that I was coming to Texas, led to a police escort.

How did we devolve to this state? Any useful lessons? Is there still interesting science in analyses of surface temperature change? Why spend time on it, if other groups are also doing it?

First I describe the current monthly updates of global surface temperature at the Goddard Institute for Space Studies. Then I show graphs illustrating scientific inferences and issues. Finally I respond to questions in the above paragraph.

Læs hele artiklen her: The Temperature of Science (direkte link til pdf-fil).

Al Gores bog er et kompendie af klimaløsninger og en opdateret indsigt i energiteknologi. Foto: Center For American Progress/Flickr.

Newsweek har besøgt Al Gore i privaten i Nashville for at lave dette interview i anledning af udgivelsen af Al Gores nye bog Our Choice – A Plan To Solve The Climate Crisis.

Al Gore skriver også selv i samme nummer af Newsweek – der er tale om et udpluk fra bogen.

Revolutionerende viden om drivhuseffekten i CO2
Jeg bed mærke i, at bogen indeholder et afsnit om den allernyeste forskning i drivhusgasser og deres virkning. Al Gore har tilsyneladende inden sin bogdeadline fået adgang til de data, der ligger til grund for denne helt dugfriske videnskabelige artikel fra Science: Improved Attribution of Climate Forcing to Emissions.

Heri dokumenterer forskere fra NASA, at CO2 står for en mindre andel af den globale opvarmning, end hidtil antaget. Se hvad Newsweek skriver om det:
… methane accounts for about 27 percent of the man-made warming so far, largely because of how it interacts with atmospheric aerosols. Halocarbons have caused 8 percent of the warming; black carbon (sooty emissions from burning wood, dung, and diesel), 12 percent; carbon monoxide and volatile organics, 7 percent—and carbon dioxide, 43 percent.

Depending on your bent, you can append an “only” to that last number. On the one hand, the NASA calculations provide a glimmer of hope. Reducing CO2 emissions strikes at the lifeblood of the global economy—namely fossil fuels, which provide 86.5 percent of the world’s energy. But targeting other greenhouse gases is “likely to be much more cost-effective than CO2-only strategies,” the NASA team writes in Science. For example, methane emissions could be cut by changing farm practices and by capturing the huge quantities that are flared at oil wells.

Sitet Physorg.com har en god gennemgang af betydningen af ovenstående her : Interactions with Aerosols Boost Warming Potential of Some Gases, October 29, 2009 by Adam Voiland.

Related posts:

1. Fra Al Gore til Obama: Her er en klimaplan
2. Al Gore i 60 Minutes, CBS

RealClimate-bloggen (verdens mest læste og prisbelønnede klimablog) har to meget læseværdige nye indlæg:

• Om Henrik Svensmark og de kosmiske stråler: Den norske klimaforsker Rasmus Benestad spørger, hvorfor “sol-teorien” vedblivende får så meget opmærksomhed, når den ene videnskabelige artikel efter den anden påpeger store usikkerheder i de data, Svensmark bygger sit livsværk på.
• A Warming Pause? Læs hvorfor det (stadig) er noget vrøvl at påstå, at klodens temperaturer ikke længere stiger, blot fordi varmerekorden fra 1998 endnu ikke er blevet overgået.

Bare en kort besked: DMI skriver torsdag:

Mængden af drivhusgasser i atmosfæren stiger hurtigere end forventet, viser nye undersøgelser. Det kan udløse et væld af feedbackmekanismer i naturen som langt flere skovbrande og optøning af permafrost i Arktis. Milliarder tons kulstof kan på den måde frigives til atmosfæren og føre til markant højere temperaturer på Jorden end, forskningen hidtil har forudsagt.

Læs hele historien på DMI’s website.

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1. Flyindustrien forurener endnu mere end forventet
2. Grønne Irland bliver brunt
3. Derfor MÅ det ikke blive varmere

United States Geological Survey har netop udgivet en autoritativ forskningsbaseret rapport, som i sine konklusioner vurderer, at vi kan vente havniveaustigninger på mellem 0,8 og 2,0 meter i år 2100, med mindre der gennemføres drastiske ændringer i CO2-udledningerne. Klimapanelet siger som bekendt maksimalt 0,59 centimeters havniveaustigninger under et business as usual scenarie.

Rapporten baserer sig på nyere forskning end klimapanelet. Om isafsmeltning og havniveau hedder det:

Recent rapid changes at the edges of the Greenland and West Antarctic ice sheets show acceleration of flow and thinning, with the velocity of some glaciers increasing more than twofold. Glacier accelerations causing this imbalance have been related to enhanced surface meltwater production penetrating to the bed to lubricate glacier motion, and to ice-shelf removal, ice-front retreat, and glacier ungrounding that reduce resistance to flow. The present generation of models does not capture these processes.these adjustments will very likely become more frequent in a warmer climate. The regions likely to experience future rapid changes in ice volume are those where ice is grounded well below sea level such as the West Antarctic Ice Sheet or large glaciers in Greenland like the Jakobshavn Isbrae that flow into the sea through a deep channel reaching far inland. Inclusion of these processes in models will likely lead to sea-level projections for the end of the 21st century that substantially exceed the projections presented in the IPCC AR4 report (0.28 ± 0.10 m to 0.42 ± 0.16 m rise).

Rapportens hovedtema er ikke isoleret set havniveaustigninger, men fænomenet pludselige klimaændringer, som kendes fra studier af fortidens klima. Rapporten advarer om, at en fortsat stigende CO2-udledning også kan fremprovokere noget lignende i fremtiden med alvorlige konsekvenser til følge:

Four types of abrupt change in the geologic record stand out as being so rapid and large in their impact that, if they were to recur, they would pose clear risks to society in terms of our ability to adapt:

• Rapid change in glaciers, ice sheets, and hence sea level.
• Widespread and sustained changes to the hydrologic cycle, including drought and flooding.
• Abrupt change in the Atlantic Meridional Overturning Circulation, a critical component of global climate, characterized by the northward flow of warm, salty water in the upper layers of the Atlantic Ocean.
• Rapid release to the atmosphere of methane, a powerful greenhouse gas, trapped in permafrost and in ocean sediments.

Læs selv mere: Jeg kan især anbefale Abrupt Climate Change: Summary and Findings (pdf), hele rapporten, Pressemeddelelse fra U.S. Geological Survey.

Related posts:

1. Klimapanelet, den ægte skandale
2. År 2100: Havniveau kan stige 2 meter
3. Dobbelt så hurtig gletcher-smeltning