Figure 2: Time series of
ice mass changes for the Greenland ice sheet estimated from GRACE monthly mass solutions for the period from April 2002 to February 2009.
Figure 2:
Ice mass changes for the Antarctic ice sheet from April 2002 to February 2009.
Not exact matches
For more than a decade these Earth - observing satellites have provided some of the first environmental measurements on a global scale, including large - scale
changes in the
mass of polar
ice.
This implies that large - scale observations —
for example, of global mean sea - level
change or of the
change mass of the Antarctic
ice sheet — will not on their own significantly narrow the range of late - century sea - level projections
for decades to come.
This spring, NASA and the German Research Centre
for Geosciences are scheduled to launch the Gravity Recovery and Climate Experiment Follow - On (GRACE - FO) mission, twin satellites that will continue the original GRACE mission's legacy of tracking fluctuations in Earth's gravity field in order to detect
changes in
mass, including the
mass of
ice sheets and aquifers.
I do think it has been clear
for a while that interactions with the ocean provide the greatest potential
for surprises and rapid
changes, and that Greenland's
ice sheet would mostly pull out of the ocean before it lost most of its
mass.
Given the level of denialism in the face of glacial
mass loss, plummeting Arctic summer
ice cover, progressive collapse of
ice shelves that have been stable
for 6000 to 10000 years, northward, upward, and seasonally earlier movements of ecosystems and other phenological
changes, increasing Greenland
ice melt, and all the other direct observations of global warming, I think denialists will go to their graves believing it can't be happening.
Figure 3: Estimated
ice mass change over time
for the entire Antarctic
ice sheet, West Antarctica, West Antarctica without the rapidly
changing Amundsen Sea Coast (ASC) region and East Antarctica.
Postscript: A grouping of 40 + scientists, including four of our Nature co-authors, participated in the NASA / ESA
Ice Sheet Mass Balance Intercomparison project (IMBIE) in an attempt to understand the reasons for previously disparate ice mass change estimat
Ice Sheet
Mass Balance Intercomparison project (IMBIE) in an attempt to understand the reasons
for previously disparate
ice mass change estimat
ice mass change estimates.
The
mass balance and d13C balance shows that vegetation as sink is not large enough to absorb all human CO2 if the oceans are a source and
ice cores show that CO2 and temperature go to a (surprisingly linear) new equilibrium
for every
change in temperature level, not a sustained increase or decrease.
Because
ice sheets contain so much
ice and have the potential to raise or lower global sea level so dramatically, measuring the
mass balance of the
ice sheets and tracking any
mass balance
changes and their causes is very important
for forecasting sea level rise.
Then in 2003 the launch of two new satellites, ICESat and GRACE, led to vast improvements in one of the methods
for mass balance determination, volume
change, and introduced the ability to conduct gravimetric measurements of
ice sheet
mass over time.
Things that could increase to higher: 1) Sun effects 2) Ocean effects 3) Feedbacks related to
changing ice mass 4) Continue whatever reason
for the warming over the last 400 years.
«Models traditionally have projected that this difference doesn't become negative (i.e. net loss of Antarctic
ice sheet
mass)
for several decades,» Mann said, adding that detailed gravimetric measurements, which looks at
changes in Earth's gravity over spots to estimate, among other things,
ice mass.
When doing this with sea level data, as with OHC, as with tropospheric sensible heat, as with glacial
ice mass loss, we are seeing a background, longer - term
change that is non-linear, and
for several decades now, accelerating.
The most - optimal values
for changes in bedrock elevation (GIA) in response to
ice sheet
mass changes have to be used
Data
for the modern rate of annual
ice sheet
mass changes indicate an accelerating rate of
mass loss consistent with a
mass loss doubling time of a decade or less (Fig. 10).
-- the atmospheric concentration of CO2 and other GHG's; — the reflective & absorptive characteristics, as a function of wavelength,
for the GHG's; — the specific heat and
mass of the earth's intermediate - term heat - storage media — the oceans (primarily) and the atmosphere; — the quantity of heat absorbed by phase -
changes =
ice - melt; and by chemical / biological processes.
Alternative explanations are available,
for example that climatic
changes are responsible
for changes in continental
ice mass that affect volcanic activity.
There is also no basis on which to postulate significant
change in
ice mass for those epochs.
In 2007, Denmark launched the Programme
for Monitoring of the Greenland
Ice Sheet (PROMICE) to assess changes in the mass balance of the ice she
Ice Sheet (PROMICE) to assess
changes in the
mass balance of the
ice she
ice sheet.
Thirteen years of GRACE data provide an excellent picture of the current
mass changes of Greenland and Antarctica, with
mass loss in the GRACE period 2002 - 15 amounting to 265 ± 25 GT / yr
for Greenland (including peripheral
ice caps), and 95 ± 50 GT / year
for Antarctica, corresponding to 0.72 mm / year and 0.26 mm / year average global sea level
change.
Estimates of the decadal variability in
ice sheet
mass loss (11) suggest the impact on acceleration estimates is ∼ 0.014 mm / y2
for a 25 - y time series, in the absence of rapid dynamical
changes in the
ice sheets.