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CLIMATE CHANGE AND LOW-LYING A plain person's
guide to global warming, sea-level rise, and the threat to |
by
(MEng, FIEAust, CPEng, MIAEM)
ABSTRACT
It is now widely acknowledged within the
scientific community that the global rate of sea-level rise is quickening – and
is likely to continue to do so – as a result of anthropogenic climate
change. It is expected, therefore, that
any resulting
increase in the frequency or intensity of extreme sea-level events will cause
serious problems for the inhabitants of low-lying coastal communities and
islands during the 21st century.
Many
This paper attempts
to provide simple and credible explanations in response to the three underlying questions which sceptics and everyday people are
preoccupied: (1) Is global warming
contributing to the rate of sea-level rise?, (2) Why do the rates of sea-level rise vary from
place to place? and (3) What is the threat to low-lying islands?
A simple analogy – the "Waterbed Effect" – is used to develop
and describe the complex interactions that link climate change and sea-level
rise, and to help understand and interpret current sea-level data to determine
whether the effects of global warming are contributing to the rate of sea-level
rise.
This paper also
suggests that scientists and those charged with the responsibility for
developing and implementing practical strategies to deal with climate change
need to look closer at the current short and medium term trends and the
extremes. While the underlying sea-level trend can look
slow and low-lying
coastal communities and island countries are concerned about gradual sea
encroachment, it is the vulnerability now and tomorrow of these communities and
countries to increasingly frequent and severe sea inundation that is a far more
real and urgent problem.
INTRODUCTION
It will perhaps be useful to explain why I have used the sub-title “A plain person’s guide….”, and why I have decided to write this paper at all.
Since publication of my paper What the South Pacific Sea Level and Climate Monitoring Project is Telling Us [1] in November 2006 I have received a number of enquiries from a wide range of people around the world seeking my views on sea-level rise analysis and climate change forecasts. (See Appendix 1 for some details.) Diverse as their professions, interests and origins are, each is seeking to gain a better understanding of the link between global warming and sea-level rise, and the likely impact on low-lying coastal communities and small islands.
Each person has
made a serious attempt at researching and understanding the mountains of
scientific literature and media commentary now readily available. But rather than finding satisfactory answers
to their questions, they have become more confused and, therefore, irritated
and uncertain as to what to believe and who to trust.
A primary reason for public frustration and disenchantment is the inability of the scientific community to translate their knowledge and expertise into a language that sceptics and everyday people can readily understand. Another reason is that, while historical and projected sea levels for islands in the tropical Pacific and Indian oceans is a subject of considerable public interest, it is also a subject of some controversy. Unfortunately, at a time when some island countries are already experiencing increasing instances of severe sea inundation, the real contribution of global warming to climate change and the rate of sea-level rise continues to be debated within the scientific community. This debate is being seized upon by sceptics (some with vested interests) and by some of the media, to question the accuracy and integrity of the science.
The three main
underlying questions that resonate through these enquiries are: (1) Is global warming contributing to the rate of
sea-level rise?, (2) Why do the rates of sea-level rise vary from place to place?, and (3) what is
the threat to low-lying islands? In this
paper I will endeavour to provide in response to all three questions an explanation
that is considerably easier to understand than those offered in current
scientific commentary.
Before I do, it is
important that I point out that I have no formal qualifications in the areas of
meteorology, climatology, oceanography or the geosciences. My expertise is in applied science. I have a postgraduate degree in engineering
and considerable practical experience in the design, installation and
maintenance of complex meteorological facilities and monitoring systems, and
their operation in gathering and reporting scientific data. This experience includes recent
responsibility for the management and operation of one of the most highly
regarded sea level and climate monitoring networks in the world.
IS global warming
contributing to the rate of sea-level rise?
The primary basis for uncertainty among the
general population about the real contribution of global warming to climate
change and the rate of sea-level rise is the ongoing debate on the subject
within certain sections of the scientific community, and the seizing by
sceptics and the media on that debate to question the accuracy and integrity of
the science. While I personally believe
that there is an undeniable link between global warming, climate change and
sea-level rise, it is a debate that I am neither qualified or willing to enter
into at a professional level. Rather, I
believe it is much more productive to engage in meaningful discussion on
practical strategies for addressing our vulnerability to climate change and
what adaptation measures can – and should – be taken to mitigate that
vulnerability.
It is timely and appropriate, therefore, that I revisit my November 2006
paper and update my comments based on the most recent data now available to me,
that being the June 2006 Pacific Country Report for Tuvalu[2]
and the November 2007 Monthly Data Report[3]
produced by the National Tidal Centre, Australian Bureau of Meteorology, under
the auspices of the South Pacific Sea Level and Climate Monitoring Project
(SPSLCMP). In doing so, keep in mind
that the SPSLCMP is first and foremost a data gathering network that enables us
to monitor what the climate in the region
is doing today, and to enable meteorologists and climatologists to predict with a moderate-to-high degree of
confidence what it will be like over the next three to six months. Remember also that data gathered by the
SPSLCMP contributes to the research
quality datasets[4] used by
international scientific organisations and agencies in their long range
modeling of climate change and the potential impacts, both regionally and
internationally.
As I mentioned in my November 2006 paper, the SPSLCMP SEAFRAME network
also plays a critical role in contributing to a regional and international
early warning capability for climate change.
I suggested that the SEAFRAME network will enable us to detect and
monitor the subtle changes in trends for air and water temperature, and
barometric pressure that are more directly driven by the increasing effects of
green house gas emissions on the earth’s atmosphere rather than the ocean. As an example I referred to the delay – or
lag – from the point where the melting of the Greenland and polar ice expanses
actually starts to have a significant impact on global sea levels, to the point
where the SEAFRAME network will enable us to detect the early stages and
monitor the ongoing trends of those impacts on sea-level change in the South
Pacific region. I indicated then that we
may be detecting those early stages already, but those stages may not yet be
discernible from the prevailing short-term trends. The capability to make these detections is
particularly relevant in the context of the waterbed analogy presented later in
this paper, which is a simple descriptive example of what I was trying to
convey.
In closing I made the comments that historical trends, and even to an
extent the then current SEAFRAME trends, suggest that we could expect sea-level
rises of an order that were considerably at variance to current scientific
commentary, and that it was possible that the effects of recent accelerations
in climate change had not yet started to have a significant contribution to or
impact on current sea levels. As my
comments are reflected in the questions of those seeking a better understanding
of the subject, let us inspect the current data available from the SPSLCMP and
see if we can make a sensible interpretation of it; an interpretation that
sceptics and the everyday person may be able to understand.
In Table 1 below I have collated the recent sea-level trends
from the SPSLCMP based on SEAFRAME data through to November 2007 (extracted
from the Monthly Data Report for November 2007) with the historical sea-level trends for Pacific Forum Stations on the Joint
Archive for Sea Level (JASL) Data Holdings as at March 2006 (extracted from the
June 2006 Pacific Island Country Report for Tuvalu). I have matched SEAFRAME stations with
Historic stations, removing the trend data for the Pohnpei (FSM) SEAFRAME
station and the two Tarawa (Kiribati) historical stations on the basis that
their record length is less than the “youngest” SEAFRAME station, PNG Manus
(13.17 years) – excluding Pohnpei in the Federated States of Micronesia (FSM).[5].
Table 1:
Comparison of Current (November 2007)
and Historic Sea-Level Rise Trends.
The first important
piece of
After taking into account the National Tidal Centres’
warning to exercise caution in interpreting the
short-term trends derived from the SPSLCMP data – and that the historical data
are not filtered to account for any fluctuations in land movement – the
difference between historical and current trends is an increase in the order of
5 to 11 times. Even at the conservative
end of the scale, an increase of 5 times is significant enough to indicate that
the rate of sea-level rise in the Pacific has accelerated in recent years.
That the rate of
sea-level rise is accelerating is not a new revelation, and there is growing
acknowledgement within the scientific community that compared to historical
trends, climate change is already having a significant impact on the current
rate of sea-level rise in the South Pacific.
Take for example the 2006 paper by eminent
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For 1950 to 2001, the average
sea-level rise (relative to land) from the six longest tide-gauge records is
1.4 mm/yr. After correcting for
glacial isostatic adjustment and atmospheric pressure effects, this rate is 2.0
mm/yr, close to estimates of the global average and regional average rate of
rise. The long tide-gauge records in
the equatorial Pacific indicate that the variance of monthly averaged
sea-level after 1970 is about twice that before 1970. The analysis clearly indicates that
sea-level in this region is rising. We
expect that the continued and
increasing rate [my emphasis] of sea-level rise
and any resulting increase in the frequency or intensity of extreme sea-level
events will cause serious problems for the inhabitants of some of these
islands during the 21st century. Our
best estimate of relative sea-level rise at |
Interestingly, any increase
in the rate of sea-level rise is not yet apparent in the Sea-Level Trend being
reported by the SPSLCMP. As can be seen
from Table 2 below, which is derived from data published in the SPSLCMP Monthly
Data Reports for November 2006 and November 2007, the trend in the 12 months to
November 2007 is relatively unchanged.
This is reflected in the Sea-Level Trend charts presented in Figure 13
of the November 2007 report (provided below for ease of reference), which show
that the trend lines across the region are relatively flat with no obvious
signs of divergence, suggesting that the recent accelerations in climate change
are yet to have an impact on the long term sea-level trend.
When then should we
expect to see an increase in the trend reflected in the charts in Figure
13? I believe it will be quite some
time, for I am concerned that the approach used to calculate and report the
Sea-Level Trend is not appropriate for the extreme climate change situation we
are facing.
Table 2:
Comparison of Mean Sea-Level
Trends for November 2006 and November
2006, using data reported by the SPSLCMP.
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CALCULATING THE
sea-level TREND
On the understanding that the Sea-Level Trend is calculated as a running average over the life
of the data record, and acknowledging that we are dealing with comparatively
small numbers, my concern is that any significant increase in the rate of
sea-level rise (i.e. an acceleration in the trend) over a relatively short
period will be smoothed out by the length of the historical record. In other words, a long stable history will
act to smooth out a relatively short turbulent present. To illustrate this, let us examine the
available sea-level trend data for
Data collected and analysed by the SPSLCMP since 1993
indicates a trend of 5.9mm/yr, whereas the historical trend from 1950 to 2001
(Church et al) – which has an eight year overlap with the SPSLCMP – is about
2mm/yr. The Monthly Mean Sea Level chart
for Tuvalu in Figure 11 does not show any evidence of a cataclysmic event that
would explain a sudden rise in sea-level trends from 2mm/yr to 5.9mm/yr since
the SPSLCMP records for Tuvalu commenced in 1993, so why is there such a
significant difference between the current and historical trends and no sign of
acceleration in either?
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Period |
Trend (mm/yr) |
Length of Record
(yrs) |
Source |
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1993 – 2007 |
+5.9 |
14.7 |
SPSLCMP Current |
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1977 – 1999 |
+0.92 |
23 |
SPSLCMP Historical |
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1950 – 2001 |
+2 ± 1 |
51 |
Church et al |
Table 3:
Comparison of Mean Sea-Level Trend
data for Tuvalu.
I believe the answer is in how the mean sea-level trend
is calculated, and hence the basis of my comment above that it will be quite
some time before we see an increase in trend reflected in the
charts in Figure 13. For example, let us
assume that we continue the historical record for
What is more
worrying is that, assuming the current trend stays constant at 5.9mm/yr until
the year 2100, the trend based on the combined record for the 150 years to 2100
will be in the order of only 4.8mm/yr, as I have illustrated in Figure 1 below. This of course will not be a true reflection
of what would be happening at the time.
Hence my concern that the approach currently being used to calculate and
report the Sea-Level Trend is not appropriate in the current situation for
determining what we need to know today about the real trend in sea-level rise
and how it will impact us tomorrow. While I touch on this point again in a later section of this paper, it
is very much a discussion for another day.
Figure 1:
A hypothetical projection of Mean
Sea-Level Trend for Tuvalu
based on combined
historic and current trends.
Why do the rates of
sea level rise differ from place to place?
The “waterbed effect”
In offering a response to this question it is important to understand that the global climate is inter-connected and that the sea level at any given location on the planet is determined by the complex interaction of many factors. Many people think of the global ocean expanse as being like water in a bath tub. Indeed, to some extent it is, except that the common perception is that the sea is at the same level around the world, somewhat like still water in a bath tub. However, as we all know, the ocean is not still. It is a hugely dynamic system, and as such is always in motion (and often an excited state of motion at that). Similarly, we can all relate to water in a bath tub sloshing around and up and down the sides of the bath at different places when it is disturbed. So yes, the bath tub analogy works – to a point – but it doesn’t really explain why the rate of sea-level rise varies between islands and around the world.
Rather than water in a bath tub, let us consider that the ocean expanses of the world as being like a large bladder filled with water and contained in a rigid enclosure – such as a waterbed[8]– and your hands are the atmospheric pressure systems. Imagine kneeling beside the long side of a waterbed and placing your hands – spread about 90cm or three feet apart from each other – gently on the surface of the waterbed. Now press down on your left hand, simulating a High Pressure System. As you press down the water displaces from under your left hand and spreads throughout the rest of the waterbed, causing the remaining surface of the waterbed to rise slightly; in other words, the water has moved to locations of relative Low Pressure. (A more graphic illustration is how water rises in the bath as you lower your body into the water; your body mass represents the high pressure system that displaces the water!)
In the context of global climate, if one region gets high pressure then another has to get low pressure and vice-versa; like a waterbed, if the sea surface is forced down in one place it will rise up somewhere else. And there are literally hundreds of High-Low Pressure System interactions randomly happening in the atmosphere and impacting on the surface of the earth all the time. To better understand this, imagine now that there are several people kneeling around the waterbed, each doing exactly the same thing as you are, but totally independent of each other; the result is not exactly what one would consider a stable system!
This relationship forms the basis of the typical short and medium term sea level changes caused by the atmospheric pressure influences of seasonal weather patterns and events, such as tropical storms, El Nino cycles, etc. Remember also that “wind’ is air moving from a region of High Pressure to a region of Low Pressure, and this is why the coincidence of a Low Pressure System with a high tide or king tide often produces an extreme sea-level event that causes severe inundation and has such a devastating impact on low-lying coastal areas, islands and coral atolls like Tuvalu. Tropical storms, cyclones, hurricanes and typhoons are intense Low Pressure Systems, and the air masses that rush toward them (like water swirls and rushes down the bath drain when the plug is removed) form their destructive winds, which in turn generate the stormy seas and storm surge conditions typically associated with them.
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In summary, variations in atmospheric pressure and sea level are inextricably
linked; a global trend of increasing atmospheric
pressure (i.e. pushing down harder on the waterbed) supports a global trend
of rising sea levels. As High Pressure
Systems become more intense more often, so must Low Pressure Systems,
bringing about an increase in the frequency and intensity of severe weather
events with their disastrous consequences, including greater sea inundation
on low-lying coastal areas and islands. |
Now consider that the waterbed has many irregular, interconnecting compartments and that these compartments represent localised “regions”. Imagine that water can flow from one compartment to another through openings of various sizes; noting that the movement of water between compartments represents the ocean currents travelling through the global regions. Consider also that the compartments can be heated or cooled by the air passing over their surface, so that the temperature of the water in one region can be different to the temperature of the water in another (i.e. such as in the Pacific Ocean, which can be several degrees warmer at Majuro in the Marshall Islands at 07°06'27"N than it is at Rarotonga in the Cook Islands at 21°11'58"S). Because water expands as it warms and contracts as it cools, sea-level change is also directly related to changes in sea surface temperature. In the global climate context, the heating and cooling of the sea is localised and occurs through a combination of air and ocean currents, such as the prevailing winds and jet streams in a particular region.
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In summary, variations in air and sea surface temperatures and sea level are also
inextricably linked; a global trend of increasing sea
surface temperature (i.e. a permanent warming of the water in the waterbed
due to a permanent rise in air temperature) supports a global trend of rising
sea level through overall ocean expansion due to the warming of the
atmosphere. |
If only it was that simple. Now consider also that the base of the waterbed – unlike a real waterbed – is extremely uneven and irregular (representing the sea bed) and that the surface of the waterbed is moulded around a variety of forms of different shapes and heights rising up from the “ocean floor”. Consider that some of these forms protrude well above the surface of the waterbed (representing the continents and volcanic islands), and others protrude only just above the surface (representing small islands and atolls). Let us also assume for this analogy, that the bladder of the waterbed is made of an extremely light weight and flexible material that is barely strong enough to contain the water within the waterbed without restricting its movement in relation to the “land forms”. By randomly pushing down on the surface of the waterbed at different places and at varying pressures, and at the same time varying the temperature of the water in its compartments up and down by small amounts, we can simulate the different variations in sea-level change around the islands and continents.
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In summary, local changes
in atmospheric pressure and temperature both directly and indirectly drive
local changes in sea level, and when the changes in atmospheric pressure and
temperature become more severe and prolonged due to climate change, the
resulting changes in sea levels will also become more severe and
prolonged. In a global context, these
changes in local sea level are averaged over the earth’s surface and are
reflected in the “global mean sea-level trend”. |
Finally, let us
now consider the impact of simultaneously adding more water to the waterbed via
a number of different points and at different rates. Imagine that several large blocks of ice are
suspended in individual bladders at various points at each end of the waterbed
(like ice block “pillows”), and that these ice blocks represent
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In summary, global air
temperatures are directly related to the rate of melt of polar ice caps and
glaciers, which in turn is directly related to the amount of water they
release. When changes in atmospheric
temperature become severe and prolonged due to climate change, the rate of
melt of ice caps and glaciers also becomes more severe and prolonged, and
more water is released at a faster rate.
In a global context, warming of the polar ice caps and glaciers
releases additional water that eventually finds its way into the oceans and
directly contributes to long term sea-level rise. |
I appreciate
that the analogy based on a waterbed, as I have attempted to use here, may not
be scientifically correct in every respect, but I believe it is sufficiently
realistic to provide everyday people with a tangible illustration that enables
them to better understand how and why sea levels vary between different islands
and around the world. I also hope that
this analogy – as simple as I have tried to make it – helps both sceptics and
everyday people better understand how climate change (whether due to global
warming or not) contributes to the global trend in rising sea levels;
restricted in my analogy only by the elasticity and strength of the material of
the waterbed bladder and the limited amount of ice in the pillows.
What is the threat to
low-lying PACIFIC islands?
While I have great respect for the scientific
community and agree that their achievements to date are much to be admired and
appreciated, to understand what is actually happening now at places like Tuvalu
and other low-lying islands in the Pacific we need to be paying more attention
– not on the long term trend based on the historical record – but on the recent
and current short term trends, particularly those of Peak Sea Levels and
Monthly Mean Sea Levels. This is because
the long term Sea-Level Trend, by definition, averages the increases in
amplitude of sea level peaks and troughs out over time to remove the short to
medium term variations in sea level.
However, it is the short to medium term variations and their trends that
tell us what is happening now and what is likely to happen in the immediate
future.
To explain this, let us return to the analogy
of the waterbed. Remember that, in
general, a High Pressure System has a corresponding Low Pressure System, and an
increase in the atmospheric pressure in a High (pushing down harder on the
surface of the waterbed, causing a greater localised drop in sea level) will
have a corresponding increase in the intensity of a Low (surface of the
waterbed rises up somewhere else, causing a localised increase in sea
level). While the short term variations
in sea level may be quite dramatic, the resultant sea-level change due to these
interactions over time may be relatively small because they act to negate each
other, or “average each other out“, over time (i.e. the mean of –8mm/month and
+20mm/month is +6mm/month, as is the mean of –2mm/month and +14mm/month). In other words, the most important
Tuvalu is an excellent example, and to
illustrate my point I have included at Figure 2 below the JASL plot of Monthly
Mean Sea Levels and Sea-Level Trend for Tuvalu, which is available online via
the University of Hawaii Sea Level Center (UHSLC)
website[9];
the two circles and the straight line connecting them are my personal
annotations.
The plot shows that in about February 1994 Tuvalu
experienced a Monthly Mean Sea Level of around 11cm (110mm) above the long term
station datum. This peak (circled), was
generally exceeded by consistent incremental rises over subsequent years,
except for the 1997-98 period when the influence on a strong El Nino prevailed
over the region. In about February 2006
– 12 years later – the Monthly Mean Sea Level at Tuvalu peaked at around 22cm
(220mm) (also circled). Over this 12
year period, Tuvalu experienced a real increase in Mean Sea Level of about
110mm, which translates to an effective sea-level trend of approximately
9.2mm/yr over the period, as illustrated by the gradient of the straight line
joining the peaks. Referring back to
Table 2, we can see that this rate is well above the current sea-level trend
for Tuvalu of 5.9 mm/yr (depicted by the squiggly red line in Figure 2) and the
long term sea-level trend of 5.5mm/yr for the region. It is also significantly greater than the
current scientific estimates of
the global average and regional average rate of sea-level rise, which are
closer to 2mm/yr as
quoted earlier from Church, White and Hunter.
Figure 2:
JASL Monthly Mean Sea Levels and Sea Level Trend data for Tuvalu.
The increase in the frequency of “bad” peaks is
clearly visible in the Monthly Mean Sea Level chart for Tuvalu in Figure 11,
which is generated from the same base data set used to produce Figure 2. Note also in Figure 11 that the charts for a
number of other Pacific Islands in the SPSLCMP network, such as the Cook
Islands, Tonga and the Solomon Islands indicate similar recent trends of
increasing bad peaks. This is an
important factor in understanding the fragile predicament of low-lying coastal
areas and small island countries, as these peaks indicate the time and
conditions when they are most vulnerable to severe sea inundation; and that
In the broader context, the peaks in Monthly
Mean Sea Level and their trend in both frequency and magnitude provide a direct
indication – and potentially a measure – of the rate and extent of sea
inundation to which low-lying coastal areas and small islands are
vulnerable. While gradual sea
encroachment (where the sea slowly overtakes the land and does not recede) due
to the long term trend in sea-level rise is of major concern to Pacific Island
countries and other Small Island Developing States (SIDS), it is their
vulnerability today to increasingly frequent and severe sea inundation
(where the sea over takes the land and then recedes) – such as those occurences
now impacting Tuvalu on an increasingly regular basis – that is a far more real
and urgent problem. It is sea inundation
– not sea encroachment – that is already having a disastrous impact on their
quality of life and the viability of sustainable habitation on their native
lands.
CONCLUSION
Over the past two years I have
travelled to many Pacific Island countries and have seen how increasing sea
inundation is already causing irreversible salinization of the land and fresh water
supplies. Unfortunately,
as long as the current trends in climate change and sea level continue to be
adverse, the situation at
For the people of these islands, the
range of practical adaptation strategies available to them to deal with the
impacts of climate change and increasing inundation is extremely limited. There is no higher ground for them to
relocate to, and it is only a matter of several rather than tens of years
before they may have no choice but to abandon their native homeland and
relocate to other shores. Unfortunately,
this is something that even good and well-intentioned people in most developed
countries are unable to relate to, and sceptics simply don’t care about. That is, until they themselves start to feel
the impact of climate change on their own shores and in their daily lives; but
by then it may be far too late for many SIDS.
For sceptics, the "bottom line" is even worse than one
supposed. The trend in the occurrence
and severity of “bad” peaks and inundation is worsening and, as a result,
becoming more crippling to those impacted.
That this trend is caused by climate change is now beyond doubt. For everyday people, slowly rising sea-level
averages must be of less concern than the fact that faster rising peak sea
levels are forcing low-lying islands and coastal areas to become quickly and
dramatically uninhabitable. What is
happening now to these lands is the result of climate change; climate change
being accelerated by existing world emissions that have very little likelihood
of being reduced in the foreseeable future.
It seems that every day, every month
and now every year new records of extremes for weather and climate phenomea are
being set; the hottest day, the hottest year, the longest dry spell, the
heaviest snow fall, the worst flood, the strongest hurricane, the highest
rainfall, the lowest rainfall, unseasonal events, etc. We need to heed these signs that clearly show
that climate change is real and upon us, and increasing in its impact.
While it is of course possible that
many people may become
de-motivated by the growing evidence of climate change and the growing reality
that there is very little we can do to avert it, we can – and need to – take significant
steps now to help each other mitigate our vulnerability to its impacts, and to
adapt to whatever environment may result from it.
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There is real data available from when the
climate last changed and global temperatures jumped 5C in three years. If we wait until we have data to prove it
is happening again, even if we spot it during the first year, it will be too
late to prevent it. Alastair McDonald (2007) |
APPENDIX 1:
Some enquiries I have received in response to my November 2006 paper.
International Expert on Coastal Zone Management
The reason for asking is that I’ve been contracted by the [organisation] to run training
on coastal V&A [Vulnerability and Adaptation] in the Pacific. I’ll be
referring to your project as a base data set.
The question though, is how should the PICs [Pacific Island
Countries] interpret the data (and how
should they go about this)!
I know this is rather a
‘how long is a piece of string’ question.
But I was hoping for some advice on the process that a PIC would go
through to use the data and then make
Renown UK-based writer, broadcaster
and commentator
Dear
http://news.bbc.co.uk/1/hi/sci/tech/7203313.stm
http://news.bbc.co.uk/1/hi/sci/tech/7195752.stm
My inclination is to say something like: [suggested text]
It is often assumed, not least by the IPCC, that man-made climate
change and its warming of the planet have caused these sea-level rises. But
there is actually a good deal of uncertainty about whether it has yet affected
sea levels at all. There is much more
agreement that at some point, and probably quite soon, it will.
Thanks a million for any
help you are able to give.
Dear Mr. Hall, I am one of the largest brokers of private islands in
the world, and the issue of sea level rise and threat from global warming to
islands has been raised in the media with me.
I have done a great deal of research already. In 2001, the IPCC’s Third Assessment Report
IPCC predicted that by 2100, global warming will lead to a sea level rise of 9
to 88 cm (0.3-2.9 ft) with regional variation. However, in my research I have discovered
that there is a great variety in short sea level rise with Tonga (+8.2 mm/year) and FSM having very high rates, and
other countries having lower rates.
Your report concludes “Historical sea level
trends, and even to an extent the current SEAFRAME sea level trends, would
suggest that we could expect sea level rises of less than 0.5m over the next
50 years, which is considerably at variance to current scientific commentary. It is possible, therefore, that the effects
of recent accelerations in climate change have not yet started to have a
significant contribution to or impact on current sea levels; but based on
international scientific opinion, it is more a case of when, rather than if “
The majority of the data seems to be based upon data from very
recently, what about the other tidal records going back over longer period
which show less effect? As the largest
body of water on earth I would guess that the Pacific would be the best
indicator of an overall sea-level rise, but the data does not back up the
projected general belief and estimates of the IPCC.
This issue is already
starting to raise worries from potential purchasers and investors for private
islands. I am not interested in
politics, or debunking climate change which is obvious and apparent, but I
would just like to get an accurate and scientifically based projection that
investors can see as a real indication of future dangers.
European-based Journalist/Editor
Dear
At the moment I am working on a story about sea level rise and
countermeasures in Central Europe, for example in the
What I have seen on your remarkable review of sea level rise within
your monitoring project SPSLCMP ("What the SPSLCMP is telling us..."):
There are big differences between Islands like Fiji + 2.7 mm/year for example,
and Tonga 8.1 mm/year. (For FSM, I understood, the time span is too
small.) The estimated rise would also in
the South Pacific differ from 27 cm to maybe 81 cm per 100 years.
Why is this gap in between so big?
Does it depend on the instrumentarium or the construction of measuring
apparatus? Are there probably images
from the instruments, you use, and the installation environment? Do you think people living in this area are
able to response on the rising level? Is
the main problem maybe, before others, than salt water from the sea intrudes in
fresh water resources?
I believe, it is more worthy to talk
to someone like you, who has been responsible for a project so far. I tried to have a look on the projects that
you are working on, and found a lot of paperwork from SIDS [Small Island Developing States] and UNFCCC [United
Nations Framework Convention on Climate Change], that is
difficult for me to sort out. So, if I
may put one question – Why are there so
wide-spread results between the different Islands – that might be
an argument for scepticists, to say: Oh, no, we see no real resaon to act by
now, it is all to uncertain etc.
AUTHOR PROFILE
In addition to business and project management consulting he is an international adviser on practical strategies for emergency management and climate change adaptation, drawing on his years of experience gained with the Australian Bureau of Meteorology – where he held several senior management positions in Observations & Engineering and Services Policy – and his long association with the South Pacific region. He was recently engaged by the Australian Government to develop the project implementation strategy and plan for the Australian Tsunami Warning System, and to serve as interim Project Director for Phase IV of the South Pacific Sea Level and Climate Monitoring Project. More recently he has participated on expert panels convened by the UNFCCC and the IPCC to consider the climate-society-environment interactions that are important to understanding climate change and its potential implications in the South Pacific region.