PART 9/ Opdaterede Sol/Is/temp/hav data

Niels K Sørensen skrev:
Det er imod bedre viden, at hævde, at øget snefald på Grønland opvejer øget afsmeltning.

Forskere arbejder med at undersøge dette på Grønland, og resultatet er, at afsmeltningen øges til trods for, at øget luftfugtighed giver mere nedbør, som falder som regn eller sne.
Få indblik i forskernes udfordringerne i denne video.
https://www.facebook.com/332420313626948/videos/913609395508034/

Niels K Sørensen skrev:
Niclasen. Jason Box er i modsætning til dig klimaforsker

Niels K Sørensen skrev:
PS: Niclasen: hold nu op med de der børnehavekommentarer som, "jeg tvivler på du kan".

Jørgen Petersen skrev:
Med et nettomassetab på (kun) 200GT pr. år er der is nok til over 13.000 års afsmeltning.

Jørgen Petersen skrev:
Som bekendt overlevede indlandsisen på Grønland i fin stil varmeperioden under
holocæn klimatisk optima. Det siger ikke så lidt om hvor modstandsdygtig indlandsien er overfor varme.

Shelters have been opened as the plight of rough sleepers is a major concern. Some 59 people have died across the continent, AFP news agency reports.

Meanwhile, the extreme cold has forced the closure of airports in Scotland, Switzerland, France, and Ireland, and left hundreds of drivers stranded on snowy highways Thursday.

The unusually cold spell brought by a Siberian weather system was being felt as far south as the Mediterranean.

Future projections of the Greenland ice sheet SMB were carried out over 2006–2100 for the scenarios RCP 4.5 and RCP 8.5 with the regional climate model MAR forced by the global
model CanESM2. The CanESM2 model has been chosen because it is one of the global
models from the CMIP5 data base which simulates the best the current climate at 500hPa over
Greenland in respect to the European reanalysis. The differences between MAR forced by
the ERA-40 reanalysis and forced by CanESM2 over 1970–1999 are not statistically significant
except in the north-west of the ice sheet. However, at the scale of the whole Greenland ice
sheet, MAR forced by ERA-40 and CanESM2 over current climate compare very well.
As future projections, MAR simulates a significant decrease of the SMB along the ice sheet
margin due to increasing melt and a low SMB increase in the interior of the ice sheet due
to heavier snowfall. At the scale of the ice sheet, the increase of precipitation does not
compensate the increase of melt and MAR simulates a mean surface mass loss of about
∼ −300 (resp. ∼ −800) GT/yr over 2070–2099 for the RCP 4.5 (resp. RCP 8.5) scenario in
respect to current climate (1970–1999). These surface mass losses correspond to cumulated
sea level rises of about ∼ +6.5 ± 1.5 and ∼ +14 ± 2 cm in 2100 respectively. The error
ranges in these projections estimate the uncertainties coming from CanESM2 used to force
these regional projections. The uncertainties coming from MAR are difficult to evaluate in
view of lack of in situ data of SMB at the scale of the whole Greenland ice sheet. Knowing
that the future projections of CanESM2 are in the range of other global models of the CMIP5
multi-model data base and that the SMB simulated by MAR compare well with rates coming
from other regional models (Fettweis, 2007), this shows that the biggest uncertainties for sea
level rise come rather from the used scenario than from the models themselves. However,
future projections of MAR forced by another global model (e.g. HadGEM2-ES) from the
CMIP5 data base will allow to evaluate better the uncertainties coming from the forcing
model.
It is important to note that these projections of sea level rise from Greenland ice sheet mass loss
do not take into account changes in ice dynamics (influencing the mass changes from iceberg
calving) and in surface topography which could amplify the deglaciation of Greenland due to
the positive elevation feedback. At the end of this century, according to the RCP 4.5 scenario,
cumulated anomalies of surface height could reach 150m in some areas along the ice sheet
margin, emphasizing the necessity of taking into account changes in topography. That is why
it will be very interesting to couple MAR with an ice sheet model in addition to the coupling
with a snow model to evaluate the feedbacks due to elevation and ice mask changes to the
SMB. Moreover, this double coupling will allow to evaluate changes in total Greenland ice
sheet mass balance and so to evaluate the sea level rise coming from all changes of mass of
the ice sheet.

Tidligere var det sålededes, at stævnede en af de danske statsisbrydere ud, var det isvinter.

De danske statsisbrydere blev solgt i 2015, og med de danske isbrydere ude af de danske farvande har man fået en ny definition, for de danske farvande kan stadig fryse til i en hård vinter.

kulden-varmen skrev:
https://www.dmi.dk/groenland/maalinger/indlandsisens-massebalance/

Sådan som jeg læser grafen så øges Grønlands indlandsis med ca. 350 GT/år i gennemsnit hvert år

Frank Lansner skrev:
Indenfor de næste 5-10 år vil vi købe isbrydere igen. Og inden dette sker vil nogen få røde ører over at have solgt dem.

Det kunne være interessant at undersøge, hvad isbryderne blev solgt for, og hvad nye koster. Og mon ikke der er leveringstid på store, tunge isbrydere?

Kosmos skrev:
- mon ikke udbredelsen af (kommercielle) skibe med stærkere skrog og mere maskinkraft gradvis har reduceret behovet for 'dedikerede' isbrydere i danske farvande?

Men jeg ved det ikke. Har du viden på området?

John Niclasen skrev:

Kosmos skrev:
- mon ikke udbredelsen af (kommercielle) skibe med stærkere skrog og mere maskinkraft gradvis har reduceret behovet for 'dedikerede' isbrydere i danske farvande?

Har moderne skibe stærkere skrog og mere maskinkraft?

Uden at vide det, så giver det mere mening, hvis man har optimeret ved at bygge så tynde skrog, som muligt, ligesom man kan optimere ved kun at have absolut nødvendig maskinkraft.

Tykke skrog og kraftige maskiner lyder som noget, man så bag jerntæppet for 50+ år siden.

Men jeg ved det ikke. Har du viden på området?

C. Fröhlich, 2006, "Solar Irradiance Variability Since 1978:
Revision of the {PMOD} Composite During Solar Cycle 21",
Space Science Rev. 125: 53-65, 2006, available from
ftp://ftp.pmodwrc.ch/pub/Claus/ISSI_WS2005/ISSI2005a_CF.pdf