Reconciling recent ice mass balance estimates for Antarctica

This post is a slight modification and extention of a comment made at the cliscep post The Latest Antarctic Ice Sheet Alarmist Con

As a (slightly manic) beancounter I like to reconcile data sets. The differing estimates behind the claims of accelerating ice mass loss in Antarctica do not reconcile, nor with sea level rise data.
The problem of ice loss needs to be looked at in terms of the net of ice losses (e.g. glacier retreat) and ice gains (snow accumulation). Any estimate then needs to be related to other estimates. The Guardian article referred in the  cliscep post states

Separate research published in January found that ice loss from the entire Antarctic continent had increased six-fold since the 1980s, with the biggest losses in the west. The new study indicates West Antarctica has caused 5mm of sea level rise since 1992, consistent with the January study’s findings.

The paper is Rignot et al 2018 “Four decades of Antarctic Ice Sheet mass balance from 1979–2017“. The abstract states

The total mass loss increased from 40 ±
9 Gt/y in 1979–1990 to 50 ± 14 Gt/y in 1989–2000, 166 ± 18 Gt/y
in 1999–2009, and 252 ± 26 Gt/y in 2009–2017. In 2009–2017,
the mass loss was dominated by the Amundsen/Bellingshausen
Sea sectors, in West Antarctica (159 ± 8 Gt/y), Wilkes Land, in
East Antarctica (51 ± 13 Gt/y), and West and Northeast Peninsula
(42 ± 5 Gt/y). The contribution to sea-level rise from Antarctica
averaged 3.6 ± 0.5 mm per decade with a cumulative 14.0 ±
2.0 mm since 1979, including 6.9 ± 0.6 mm from West Antarctica,
4.4 ± 0.9 mm from East Antarctica, and 2.5 ± 0.4 mm from the
Peninsula (i.e., East Antarctica is a major participant in the mass
loss).

Jaime @ 19 May 19 at 7:56 am points to a New Scientist article in January claiming that Antartica ice loss has trebled. The underlying article is from Nature – The IMBIE Team – Mass balance of the Antarctic Ice Sheet from 1992 to 2017. The abstract states

The Antarctic Ice Sheet is an important indicator of climate change and driver of sea-level rise. Here we combine satellite observations of its changing volume, flow and gravitational attraction with modelling of its surface mass balance to show that it lost 2,720 ± 1,390 billion tonnes of ice between 1992 and 2017, which corresponds to an increase in mean sea level of 7.6 ± 3.9 millimeters (errors are one standard deviation). Over this period, ocean-driven melting has caused rates of ice loss from West Antarctica to increase from 53 ± 29 billion to 159 ± 26 billion tonnes per year; ice-shelf collapse has increased the rate of ice loss from the Antarctic Peninsula from 7 ± 13 billion to 33 ± 16 billion tonnes per year. We find large variations in and among model estimates of surface mass balance and glacial isostatic adjustment for East Antarctica, with its average rate of mass gain over the period 1992–2017 (5 ± 46 billion tonnes per year) being the least certain.

The key problem is in the contribution to sea level rise. The Rignot study from 1979-2017 gives 3.6 mm a decade from 1989-2017, about 4.1 mm and from 1999-2017 about 5.6 mm. The IMBIE team estimates over the period 1992-2017 7.9 mm sea level rise, or 3 mm per decade. The Rignot study estimate is over 50% greater than the IMBIE team. Even worse, neither the satellite data for sea level rise from 1992, nor the longer record of tide gauges, show an acceleration in sea level rise.

For instance from NOAA, the satellite data shows a fairly steady 2.9mm a year. rise in sea levels from 1992.

Using the same data, the University of Colorado estimates the average sea level rise to be 3.1 mm a year.

Note that in both the much greater variability in the Jason 2 data, and the slowdown in rise after 2016 when Jason 3 started operating.

The tide gauges show a lesser rate of rise. A calculation from 155 of the best tide gauges around the world found the mean and median rate of sea level rise to be 1.48 mm/yr. 

Yet, if Rignot is correct in recent years Antarctic ice loss must now account for around 22-25% of the sea level rise (satellite record) or almost 50% (tide gauges) of the measured sea level rise. Both show no accleration. What factors have a diminishing contribution to sea level rise over the last 25 years? It cannot be less thermal expansion, as heat uptake is meant to have increased post 2000, more than offsetting the slowdown in surface temperature rise when emissions accelerated. 

Kevin Marshall

Postscript

This is not the first time I have covered rather extreme claims in one of Prof Eric Rignot’s estimates of accleration in ice melt. Six years ago I looked at Rignot et al 2011 – Acceleration of the contribution of the Greenland and Antarctic ice sheets to sea level rise

I compared the 12 monthly rise in sea surface temperatures with the corressponding chart of ice mass balance loss for Greenland and Antarctica. The peaks and troughs corressponded nicely, with about 18 months between ice loss and sea level rise. This is quite remarkable considering that from Rignot et 2011 in the 1990s ice loss would have had very little influence on sea level rise. It is almost as though the modelling has taken the sea level data, multiplied by 360, flipped it, moved it back a few months then tilted to result show acceleration. 

Yet the acceleration of 14.5 ± 2 Gt/yr2 for Antarctica results in decadal increases not too dismillar from those in the abstract of Rignot et al 2018. This would validate the earlier results except for another paper. Shepherd et al Nov 2012 – Reconciled Estimate of Ice-Sheet Mass Balance had a long list of authors including Rignot and three of the four co-authors of the Rignot et al 2011. It set the standard for the time, and was  the key article on the subject in IPCC AR5 WG1. Shepherd et al Nov 2012 has the following Table 1.

For Antartica as  experienced no significant acceleration in ice mass loss in the period 1992-2011. 

Monopoly Water Company campaigns to control its customers

At Guido Fawkes this morning I was confronted with a bright green and yellow advert.

It is an appeal for increased regulation. The reason for the regulation is political.

Water is not part of the climate change debate
It is treated like an add on when it is critical to life. We need to change this now.

Water might be critical to life, but that does not mean the supply is critical. Provision of food and healthcare are also critical to life, and successful provision of both is much more complex and challanging than the supply of the most basic and plentiful of commodities.

If we don’t act now we face a £40 billion water crisis
Sign our petition at change.org

Clicking on the link takes us to a Change.org petition headed

Water efficiency is critical to climate change. Act now to prevent a water crisis.

The petition starts with the statement

We need to mobilise support and act now. The conservation of water can no longer wait.
Water efficiency is critical to the debate on climate change – an issue pushed to the forefront by Greta Thunberg and Extinction Rebellion. If we do not act now, we will suffer a water crisis, not only our generation, but for future generations to come. This needs to change now – join our campaign #WhyNotWater.

The heading states “Water efficiency is critical to climate change” implying that changes in water efficiency will affect the actual course of the climate. But the text is “Water efficiency is critical to the debate on climate change”, where some activists claim water efficiency should be part of a debate. The heading implies backing empirical evidence, whereas the text is about beliefs.
Further, a superficial reading of the statement would give the impression that climate change is causing water shortages, and will cause a water crisis. But clicking on the Affinity Water link takes us to a press release on 10th May

Affinity Water warns of water shortages unless government acts now

The UK’s largest water only company, Affinity Water has warned that within the next 25 years and beyond, there may not be enough water due to climate change, population growth and increases in demand.

….

Unlike the advert and the petition there are mentions of other factors that might affect climate change, but no data on the relative magnitudes.

Note that Affinity Water is a limited company, with gross revenues in year to 31 March 2018 of £306.3m, operating profit of £72.3m and profit after tax of £29.6m (Page 107).

The piece finishes with

To find out more about the manifesto visit www.whynotwater.co.ukand to sign a petition to demand the legislation needed for water efficient labelling and water efficient goods and housing visit www.affinitywater.co.uk/ourpetition

The whynotwater website is a bit more forthcoming with the data.

Why should we act?

  • Climate change is likely to reduce our supply of water in our area by 39 million litres of water per day by 2080.
  • The population is growing and is expected to increase 51% by 2080. This is equivalent to approximately 1.8 million more people in our supply area, putting further strain on our resources.
  • Using water wisely is critical in the South East – a severely water-stressed area; did you know there was less rainfall than other parts of the country? Between July 2016 and April 2017 the area received 33% less rainfall than the national average.
  • Customers in the South East also use more water daily – 152 litres per person per day, which is higher than the national average of 141 litres per person per day.

From the above population in the supply area is projected to increase from 3.53 to 5.33 million. With unchanged average water usage of 152 litres, this is implies an increase in consumption of 274 million litres. Population change is projected to have seven times the influence on water demand than climate change on supply. It should be noted that these figures is domestic consumption. Currently Affinity Water supplies around 900 million litres per day, implying over 350 litres per day is from other sources. Based on total average supply, climate change ove 60 years is projected to reduce supply by just 4.3%.

But which projection is more robust, that of population increase, or of falls in water availability? With population it is possible to extrapolate from existing data. From the World Bank data, the population of the UK increased by 11% from 2001 to 2016. At this rate, in 2076 the population will be 52% higher than 2016. Within the South East using national data might be unreliable, as population shifts between regions. But it is likely that by 2080 population in Affinity’s supply areas will be significantly higher than today.

Water availability is not so precise, yet the fall due to climate change of 39 million litres per day is just 7% of existing domestic demand, or 4.3% of total water usage. There are some records at the Met Office of rainfall. In particular in the South East are records for Heathrow Airport and Manston in Kent. I have graphed annual rainfall data, with averages of the last 10 years.

In the past twenty years rainfall has increased in both Manston and Heathrow. Compared to 1979-1998, average annual rainfall in 1999-2018 was 17% higher in Manston and 9% higher in Heathrow. In 60 years from now it might be higher or lower due to random natural climate variability. Any projection of a 4-7% reduction in rainfall is guesswork. If this is still a scientific estimate of unmitigated human-induced climate change, then Affinity better pass the message onto Greta Thurnberg and Extinction Rebellion. From the XR! Website.

THE TRUTH

We are facing an unprecedented global emergency. Life on Earth is in crisis: scientists agree we have entered a period of abrupt climate breakdown, and we are in the midst of a mass extinction of our own making.

This may seem sensationalist even by the the worst tabloid standards, but is the group have toned down a bit. When launched XR! were proclaiminghuman-caused (anthropogenic) climate breakdown alone is enough to wipe out the human species by the end of this century.

As there was no real water crisis in the 1980s and 1990s, why should there be in 2080? The only way there will be a water crisis is if water supply does not increase in line with the projections of rising population. Even then it will hardly contribute to the mass deaths of people in Britain as part of a species extinction. Meeting long-term changing demands should be within the control of the British Government and the regulated water companies. Instead a monopoly water company appears to be falsely attributing the whole problem to an issue outside of its control, campaigning to introduce regulations that are aimed at controlling consumer demand. Rather than serving their client base by additional investment, Affinity Water looks to be deriving fixed demand by controlling them. That investment in new reservoirs, wells, water recycling plants, pipelines from wetter places (Scotland has on average twice the rainfall of the South-East) and even desalination plants could cost billions of pounds. In so doing Affinity Water is listening to a bunch of revolutionaries rather than serving their customers. This must be especially galling for the Affinity Water customers who commute into London and have been inconvenienced by Extinction Rebellion’s blockades over recent months.

Kevin Marshall

Postscript at 4.00pm

The screenshot of the petition petition was taken at around 9.30 this morning, with 594 signatures. It now has 622 signatures. That is less than 5 signatures per hour. In that time Guido Fawkes has likely had over 10,000 unique visitors, based on last weeks figures,

Update 16/05/19 at 23.50

Another day of advertising a Guido Fawkes (and maybe elsewhere) has seen the number of signatures rise to 678. The petition was raised two weeks ago.