A recent Ph.D thesis by Phil Watson of the University of New South Wales (LINK) developed improved techniques to
estimate mean sea level velocity and acceleration from long ocean water level time series.
Not exact matches
The absence of crustal deformation from Tharsis
means the
seas would have been shallower, holding about half the water of earlier
estimates.
«The tide gauge measurements are essential for determining the uncertainty in the GMSL (global
mean sea level) acceleration
estimate,» said co-author Gary Mitchum, USF College of Marine Science.
The
estimated DJFM Antarctic
sea ice extent climatology for the period 1897 — 1917, with and without the inclusion of the Worby and Comiso offset (an offset between where satellites and human observers view the
sea ice edge), is plotted alongside time series of DJFM
mean sea ice extent calculated from HadISST2.2, NASA Team and NASA Bootstrap
sea ice datasets.
It bears noting that even if the
SEA mean estimate were correct, it still lies well above the ever - more implausible
estimates of those that wish the climate sensitivity were negligible.
The theoretical
mean sea level (or theoretical
mean water, MW) is an
estimate for the long - term
mean value (more precisely, expectation value) of
sea level, made for practical purposes.
Curiously, the
mean SEA estimate (2.4 ºC) is identical to the
mean KEA number, but there is a big difference in what they concluded the
mean temperature at the LGM was,....
But what exactly the new findings
mean for
sea level rise
estimates is still unknown.
B. Takes an adjustment to
sea temperatures in a defined period and implies that it impacts the global
mean temperatures trend
estimates over the entire twentieth century.
In the paper these factors are
estimated and it is concluded that the North Carolina curve should be within about 10 cm of global
mean sea level.
Which
means all
estimates on
sea level rise have a large unknown fudge factor missing.
The same holds for the specific global
mean EIV temperature reconstruction used in the present study as shown in the graph below (interestingly, eliminating the proxies in question actually makes the reconstruction overall slightly cooler prior to AD 1000, which — as noted in the article — would actually bring the semi-empirical
sea level
estimate into closer agreement with the
sea level reconstruction prior to AD 1000).
We stress that no - one (and we
mean no - one) has published an informed
estimate of more than 2 meters of
sea level rise by 2100.
However, the CRU global
mean combined land air /
sea surface temperature
estimates for Jan - Aug 2005 lag behind the 1998 annual
mean estimate by 0.08 C (0.50 C vs. 58C for 1998) while GISS indicates a lag of 0.02 C.
> A new comment on the post # 74 «Michael Crichton's State of Confusion» is > waiting for your approval > > Author: Hans Erren -LRB--RRB- > E-mail: erren21 @... > URL: > Whois:... > Comment: >
Sea - level rise > > Although satellite data (TOPEX / POSEIDON (sic) and JASON) shows a much > steeper trend over recent years (2.8 mm / yr) than the long term
mean >
estimates from tide gauges (1.7 to 2.4 mm / yr), each method compared to > itself does not indicate an accelleration.
Kauker et al. (AWI / OASys), 5.58 (+ / - 0.41), Modeling (same as June) We
estimate a monthly
mean September
sea - ice extent of 5.67 ± 0.40 million km2 (without assimilation of
sea - ice / ocean observations).
The results of the analysis demonstrate that relative to the reference case, projected atmospheric CO2 concentrations are
estimated by 2100 to be reduced by 3.29 to 3.68 part per million by volume (ppmv), global
mean temperature is
estimated to be reduced by 0.0076 to 0.0184 °C, and
sea - level rise is projected to be reduced by approximately 0.074 — 0.166 cm, based on a range of climate sensitivities.
«The global
mean sea level for the period January 1900 to December 2006 is
estimated to rise at a rate of 1.56 ± 0.25 mm / yr which is reasonably consistent with earlier
estimates, but we do not find significant acceleration»
Several other satellite altimeters have also been launched, and the data from these have been used to
estimate global
mean sea level trends since 1993.
Its
estimated ice volume and contribution to
mean global
sea level reside well within their ranges of natural variability, and from the current looks of things, they are not likely to depart from those ranges any time soon.
The theoretical
mean sea level (or theoretical
mean water, MW) is an
estimate for the long - term
mean value (more precisely, expectation value) of
sea level, made for practical purposes.
Since 1950, global
mean sea surface temperatures have risen roughly 1 ° F (0.6 ° C).6 Scientists estimate that regional sea surface temperatures in the North Sea increased by 1.6 ° F (0.9 ° C) from 1958 to 200
sea surface temperatures have risen roughly 1 ° F (0.6 ° C).6 Scientists
estimate that regional
sea surface temperatures in the North Sea increased by 1.6 ° F (0.9 ° C) from 1958 to 200
sea surface temperatures in the North
Sea increased by 1.6 ° F (0.9 ° C) from 1958 to 200
Sea increased by 1.6 ° F (0.9 ° C) from 1958 to 2002.7
«Trends and acceleration in global and regional
sea levels since 1807» «Evaluation of the global
mean sea level budget between 1993 and 2014» «Considerations for
estimating the 20th century trend in global
mean sea level» «New
estimate of the current rate of
sea level rise from a
sea level budget approach» «Reassessment of 20th century global
mean sea level rise» «The increasing rate of global
mean sea - level rise during 1993 — 2014» «Unabated global
mean sea - level rise over the satellite altimeter era» «An increase in the rate of global
mean sea level rise since 2010»
J. T. Fasullo, R. S. Nerem & B. Hamlington Scientific Reports 6, Article number: 31245 (2016) doi: 10.1038 / srep31245 Download Citation Climate and Earth system modellingProjection and prediction Received: 13 April 2016 Accepted: 15 July 2016 Published online: 10 August 2016 Erratum: 10 November 2016 Updated online 10 November 2016 Abstract Global
mean sea level rise
estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time.
Figure 3: «Considerations for
estimating the 20th century trend in global
mean sea level» Figure 1B: «Reassessment of 20th century global
mean sea level rise» «Recent global
sea level acceleration started over 200 years ago?»
Abstract: «Global
mean sea level rise
estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time.
The
mean estimates for the 2010 September
Sea Ice Outlook based on May, June, and July data were close to the observed value with a rather small quartile distribution (as a measure of deviation from the
mean).
«It is likely that the rate of global
mean sea level rise has continued to increase since the early 20th century, with
estimates that range from 0.000 -LSB--- 0.002 to 0.002] mm yr — 2 to 0.013 [0.007 to 0.019] mm yr — 2.
Kauker et al (Alfred Wegener Institute [AWI], Ocean Atmosphere Systems [OASys]-RRB-, 3.95 (± 0.39), Modeling We
estimate a monthly
mean September
sea - ice extent of 3.95 ± 0.39 million km2.
An independent
estimate of global -
mean evaporation provides additional support, but critical assumptions on relative humidity and the air -
sea temperature difference changes are made that do not have adequate observational basis and are inconsistent with climate models.»
Assuming a full - glacial temperature lapse rate of -6 °C / 1000m, depression of
mean annual temperature in glaciated alpine areas was ca 5.4 ± 0.8 °C; it is similar to values of temperature depression (5 - 6.4 °C) for the last glaciation obtained from various terrestrial sites, but contrasts with tropical
sea - surface temperature
estimates that are only 1 - 3 °C cooler than present.
All of these characteristics (except for the ocean temperature) have been used in SAR and TAR IPCC (Houghton et al. 1996; 2001) reports for model - data inter-comparison: we considered as tolerable the following intervals for the annual
means of the following climate characteristics which encompass corresponding empirical
estimates: global SAT 13.1 — 14.1 °C (Jones et al. 1999); area of
sea ice in the Northern Hemisphere 6 — 14 mil km2 and in the Southern Hemisphere 6 — 18 mil km2 (Cavalieri et al. 2003); total precipitation rate 2.45 — 3.05 mm / day (Legates 1995); maximum Atlantic northward heat transport 0.5 — 1.5 PW (Ganachaud and Wunsch 2003); maximum of North Atlantic meridional overturning stream function 15 — 25 Sv (Talley et al. 2003), volume averaged ocean temperature 3 — 5 °C (Levitus 1982).
A policymaker will take this as
meaning that
sea level rise is probably going to be less than a meter even if CO2 increases to 936 ppm, in other words, policymakers will take this «objective stuff» as serious, reliable
estimates of what to expect.
The uncertainty in the global
mean sea level trend is
estimated to be of ± 0.5 mm / yr in a confidence interval of 90 % (1.65 sigma), whereas the uncertainty of the regional
mean sea level trends is of the order of 2 - 3 mm / yr with values as low as 0.5 mm / yr or as high as 5.0 mm / yr depending on the region considered (Legeais et al., 2018, under review).
The
mean sea level evolution
estimated in the global ocean is derived from box - averaged gridded
sea level maps weighted by the cosine of the latitude.
AWI Consortium (Kauker et al.), 4.32 (± 0.30), Modeling (ice - ocean) We
estimate a monthly
mean September
sea - ice extent of 4.32 + - 0.30 million km2.
Wang, 6.31 (5.84 - 6.78), Modeling The projected Arctic
sea ice extent from CPC based on NCEP ensemble
mean CFSv2 forecast is 6.31 × 106 km2 with an
estimated error of ± 0.47 × 106 km2.
Among other things, this
means that the IPCC team, which did not have the ice melt data through the 1990s, will need to revise upward its projected rise in
sea level for this century — currently
estimated to range from 0.09 meters to 0.88 meters (from 4 to 35 inches).
However, Figure 2 of Cowtan et al 2015 shows, based on essentially the same set of CMIP5 RCP8.5 simulations as REA16 and excluding
sea - ice related effects, a
mean differential of ~ 5 % (range 1 % — 7 %), over double the 2 % I
estimate.
In addition, land stations are allowed to provide temperature
estimates for ocean cells where no
sea surface temperature is available - in practice, this
means that coastal stations around the Arctic provide temperature readings for the pole.
We compare simulation cooling from the combined forcing to a GMT reconstruction, based on a global
mean sea surface temperature reconstruction (43) that we scaled by the factor 1.84 so as to match
estimated LGM cooling (ref.
This task involved extensive time series analysis that identified Singular Spectrum Analysis (SSA) as an optimal analytic for resolving
estimates of
mean sea level from long tide gauge records with improved accuracy and temporal resolution, since it provides a superior capability to separate key time varying harmonic components of the time series.
We received 21 responses with a range of
estimates from 4.0 to 5.0 million square kilometers for the September 2012 arctic
mean sea ice extent (Figure 1).
One could choose to look at the global
mean sea level instead, which does have a physical
meaning because it represents an
estimate for the volume of the water in the oceans, but the choice is not crucial as long as the indicator used really responds to the conditions under investigation.
However, ocean temperatures have warmed almost everywhere on the planet, with 0.5 ºC being the global
mean rise of
sea surface temperature, hence Trenberth's reasonable
estimate that this much is the contribution from global forcings like CO2.
Using a 25 - y time series of precision satellite altimeter data from TOPEX / Poseidon, Jason - 1, Jason - 2, and Jason - 3, we
estimate the climate - change — driven acceleration of global
mean sea level over the last 25 y to be 0.084 ± 0.025 mm / y2.
I don't know what «benchmark island»
means, but the current best
estimate of the rate of
sea - level rise, averaged over the world during 2003 to 2008, is +2.5 millimetres / yr, give or take 0.4 mm.
... Averaged over the global ocean surface, the
mean rate of
sea level change due to GIA is independently
estimated from models at -0.3 mm / yr (Peltier, 2001, 2002, 2009; Peltier & Luthcke, 2009).
To obtain an
estimate, a
sea ice area from the Arctic Basin (excluding the pole and the multiyear
sea ice north of Greenland) is regressed with the previous years and their September
mean extents.
We received 21 responses for the Pan-Arctic report (Figure 1), with
estimates in the range of just below 4.0 million square kilometers to as high as 5.4 million square kilometers for the September arctic
mean sea ice extent.