by Matt Owens December 30, 2012
Things are coming into very clear focus now, and this is quite an exciting time. Sadly, most people are willfully blind to the impending climate changes, with the consequence that major losses will radiate to everyone – even including those who are climate-aware today. However, with the rapidly improving projections, we who are aware are now coming into a position to act and safeguard ourselves against many of the direct losses others will suffer.
Specifically, sea level rise (SLR) is the issue of focus here.
In light of updated and improved records of ice loss from Shepherd et al. (2012), NASA researcher James Hansen and Makiko Sato have revised their projections for future ice loss rates.
The pair's previous estimates were actually released earlier this year, and used data that was about 3 years old as the basis of projections. The speed at which developments are now happening is a testament to how serious and rapid climate change has become.
The main conclusions from Hansen and Sato's updated estimate:
Sea level rise will likely follow an exponential path.
Other attempts to establish upper limits on ice sheet disintegration rates are based on fundamentally flawed logic.
A reasonable projection that fits with observed rates of ice loss so far has 1 meter of SLR by 2045.
Negative feedbacks are modeled to start once SLR reaches 1 meter, and rates of SLR thereafter would be expected to, and could slow therefore - but not stop altogether. [SLR might also come much faster - i.e. 5 to 20 meters in a handful of years - if larger areas of ice sheets disintegrate in a structurally catastrophic manner.]
The negative feedbacks would result from massive volumes of ice floating away from the polar ice caps and interfering with ocean temperature and density patterns.
As a consequences of the floating ice, initial model results suggest that global warming in such a context would slow, but not stop; and, that a strong difference in regional temperature between polar and temperate regions would result in extremely intense storm activity (which does not equate to alleviation of the very serious global drought conditions already forecast for temperate farming regions by mid-century).
This chart represents the 5-year doubling time scenario; negative feedbacks kick in after 1 meter of sea level rise is reached in 2045, and by 2067 rates of sea level rise slow significantly - but still continue at a devastating rate. I have added an approximately inverse rate of slowing SLR (starting before the 5 meter point) to demonstrate one potential rate of negative feedback. [UPDATE Jan. 11, 2013: more in-depth analysis of possible negative feedback.]
Including projections from another recent study on housing unit property losses at various levels of sea level rise (Strauss et al. 2012) reveals a dramatic toll on society (see chart below).
The initial stages of the loss curve is less certain, as resolution below 1 meter of sea level rise is hazy (due to poor resolution of topographical data, see study for detailed explanation). Here, I have filled the first portion (from 0 to 1 meter) of the curve using an approximation where half the housing unit losses by 1 meter of SLR occur between 0.75 and 1.0 meters SLR, and where one quarter occur between 0.5 and 0.75 meters SLR, with the remaining quarter occurring between 0 and 0.5 meters SLR.
Regardless of uncertainties arising from resolution, the data is very clear at 1 meter intervals, and shows that by 1 meter of SLR, nearly 2 million housing units will be lost to the seas. This happens by 2045 in the Hansen and Sato 5-year doubling time projection. By 2050 the total losses rise another million, to 3 million lost. The trend continues through 2055, by when another million are lost and the total reaches 4 million.
Then, the trend accelerates and by 2060, after just five years more, 2 million more units have gone under, bringing the total to about 6 million. By 2070, in just another 10 years, the total rises over 10 million housing units lost.
With 2.6 people per household (according to US Census), these figures mean that more than 26 million people will lose their homes to the rising ocean by 2070. And these figures are for the population today, so numbers could be higher if population grows - and especially if populations don't move away from the coastlines earlier rather than later.
The housing unit loss estimates by Strauss et al. (2012) was based on data from the 2010 US Census. Using that same US Census data source, and assuming that the ratio of housing units to location above sea level remains constant in the next few decades, I have converted the absolute loss to a percent of total housing (see below).
From 2040 onward, losses mount quickly. The US as a whole has a housing unit vacancy rate just above 10 percent - about the same percent of losses by 2070. So the housing loss alone could put a major strain on housing capacity. That is, unless new building could outpace loss.
Simply based on past rates of housing unit expansion, the US should have no problem adding enough housing inventory to accommodate the newly homeless as seas rise. The loss rate would reach about 2% per decade by 2050 and reach about 3% per decade by 2070. From 2000 to 2010, the US added about 10% to its number of housing units.
However, who could pay for building new housing? Insurance does not cover sea level rise. Government is the obvious answer. A massive program could pay for new construction. In today's dollars, an average housing unit costs around $200,000, or just a little less depending on how you calculate it.
Using $200k, a loss of 3 million units per decade at the beginning (2040-50) and then reaching about 4.5 million (2060-70) would mean $600 billion in just home losses per decade at the start, and $900 billion per decade by the 2060's. Infrastructure, planning, and other costs should be factored in too, as well as replacement costs of non-residential structures and assets. According to Burchell (1998), associated costs for new development are about $50,000 per housing unit (in today's dollars).
So, somewhat surprisingly, the cost of replacing residential property, structures, and associated infrastructure may not be especially high under the 5-year doubling time scenario. Taking $250k as the total associated costs for building a replacement housing unit, and then tripling that to account for industrial and commercial and other unexpected costs that would be needed too gives a figure of $225 billion per year from 2040-50 and $337 billion per year from 2060-70. That starts at slightly less than 4% of today's federal budget and 1.5% of the US 2011 GDP, and rises to about 6% and 2% of US federal spending and US GDP respectively by 2060-70. Both are painful, but tolerable costs - at least taken out of context where there are no other impacts from climate change.
This added expense on the backs of all Americans would under normal circumstances tend to inhibit economic expansion. But on the other hand, all the government spending would actually tend to stimulate the economy. Also worth considering, the losses of property value are not losses in the standard economic sense we're used to where the market value drops and thus destroys value. This loss is absolute, permanent, and total. The property can no longer be of any use.
In fact, submerged properties will likely become serious liabilities to us all as toxic and non-toxic chemicals and substances leach out into coastal waters. Common household products, considered non-toxic on dry land, become pollutants in water. For example, copper is toxic to most aquatic organisms, from fish to invertebrates. What's more, the vast quantity and array of chemical substances found in buildings of all types could lead to a sick cocktail in the new coastal waters.
The reality could be very complicated. More on complex water pollution here:
Another issue is saltwater intrusion ruining well-water, municipal aquifers, and farmland. Plus, increased storm activity out at sea along with iceberg hazards could cause significant inefficiencies for international commerce (via shipping and air transport) and thus cause US and international GDP to decline year after year.
Drought conditions by 2040 could also become so severe that agricultural output could drop by 30% to 40%, or possibly even more. To add insult to injury, increasingly severe and damaging storms could easily cause persistent headaches for everyday commercial activity. The average number of days taken off from work due to bad weather could rise steeply.
Much like how the pernicious build-up of carbon dioxide has been slowly pushing our climate into a warming trend, the constant aggravation from severe weather, poor climate, and sea level rise could push the US and other countries into a declining economic trend.
Keep in mind this is just the lower 48 contiguous states of the US, and this is just residential housing units. Commercial, industrial, civic, and infrastructure property of all types and importance would also be effected along with residential. And the same general effect would be felt around the world from Northern Europe to the Mediterranean, to Asia, Australia, South America, and all the way to Hawaii and Alaska.
The actual cost of these losses is therefore hard to figure. Basic infrastructure like ports and highways are not often given monetary values.
It's no wonder either, if you consider the complexity of the economic web that moves through those systems. If a port is shut down for just a few months, it can mean collapse of regional industry and commerce in the areas that are dependent on that port for exports. And with SLR, the possibility exists that ports could be shut for years.
Imagine maintaining a port's infrastructure while sea levels rise by 4 meters (13.1 feet) between 2045 and 2067, a 22 year period. That's 18 centimeters of rise per year (or 7 inches per year) on average.
With variability from year to year, there could be several years where the rise is almost nothing, followed by a year where the rise is 2 or 3 times the average - or perhaps even more. If the ice losses are concentrated over summer, and in just one or two months, that could mean a bad year sees a rise in sea level by 54 centimeters (21 inches, nearly 2 feet) in just a couple of months.
Will ports be able to build their docks higher as seas rise? Even if they can raise their docks, what about getting the goods off the docks? As the seas rise, connecting roads all around will be lost. Electrical and other connections will also be lost too. Can on-site power generation suffice? Surely the answers to these questions are highly variable depending on the specific port and its specific terrain and local topography.
Intensification of storm activity and new iceberg hazards at mid-latitudes (i.e. where there are heavily-used shipping lanes) will also need to be addressed if a scenario like Hansen and Sato have outlined unfolds.
But will their projections turn out to be correct? Unfortunately there is every reason to believe so. The update by Hansen and Sato really explains it best (see the excerpts below). The greatest area of uncertainty is the remaining ice sheet response to rising sea level and the cooling effect from broken ice rafting out across the world's oceans. The curve of a slowing increase (i.e. negative feedback) in SLR that I have added to the charts above is just one degree of feedback, and just one possible net SLR response. At the other end of the spectrum is the possibility that SLR will sufficiently destabilize much vaster areas of polar ice sheets and possibly lead to massive tens of meters of sea level rise in short time frames. Such diverse outcomes complicate planning for the future, but they need to be considered. SLR of tens of meters in mere years would require much different strategies then the comparably modest rise of the 5-year doubling time scenario examined here.
Hansen, the lead co-author of this new SLR estimate update, has so far been close to spot-on right about climate change - while so many other scientists have been, like the general public - so wrong and so reluctant to accept the truth. What else could be expected however? To arrive at the startling conclusions Hansen has reached required decades of intense ground-breaking research and synthesis of diverse scientific fields. Most scientists study something amazingly specific and are highly sceptical by nature. So how does someone effectively communicate an idea that they themselves only just learned, and by doing the research themselves at that (i.e. Plato's Cave).
Hansen was a chief architect of the GISS General Circulation Model II for global climate which came into use in 1980 and was used by NASA into the 1990's. The model is still used today as a quick first-estimation of climate impacts by some researchers. Climate model results have been warning us for decades now, although their results are typically misunderstood and therefore misinterpreted by the mainstream press.
Starting back in the 1980's and increasingly in recent years, Hansen has been outspoken about the lethal, growing danger climate change poses to his, and everyone's grandchildren. In fact, he wrote a book called "Storms of My Grandchildren" to highlight just that point.
Excerpts from the Hansen and Sato release.
Hansen and Sato's December 26th update lays out the basis for their findings:
“IPCC (2007) [the previous UN international scientific consensus report] suggested a most likely sea level rise of a few tens of centimeters by 2100. Several subsequent papers suggest that sea level rise of ~1 meter is likely by 2100. However, those studies, one way or another, include linearity assumptions, so 1 meter can certainly not be taken as an upper limit on sea level rise (see discussion and references in the appendix below, excerpted from our recent paper). Sea level rise in the past century was nearly linear with global temperature, but that is expected behavior because the main contributions to sea level rise last century were thermal expansion of ocean water and melting mountain glaciers.
“In contrast, the future sea level rise of greatest concern is that from the Greenland and Antarctic ice sheets, which has the potential to reach many meters. Hansen (2005) argues that, if business-as-usual increase of greenhouse gases continue throughout this century, the climate forcing will be so large that non-linear ice sheet disintegration should be expected and multimeter sea level rise not only possible but likely. Hansen (2007) suggests that the position reflected in IPCC documents may be influenced by a "scientific reticence". In such case the consensus movement of sea level rise estimates from a few tens of centimeters to ~1 meter conceivably is analogous to the reticence that the physics community demonstrated in its tentative steps to improve upon estimates of the electron charge made by the famous Millikan.¹”
The footnote for the Millikan reference is a quote itself, from Feynman, 1997, and is as follows:
“Millikan measured the charge on an electron by an experiment with falling oil drops, and got an answer which we now know not to be quite right. It's a little bit off because he had the incorrect value for the viscosity of air. It's interesting to look at the history of measurements of the charge of an electron, after Millikan. If you plot them as a function of time, you find that one is a little bit bigger than Millikan's, and the next one's a little bit bigger than that, and the next one's a little bit bigger than that, until finally they settle down to a number which is higher. Why didn't they discover the new number was higher right away? It's a thing that scientists are ashamed of - this history - because it's apparent that people did things like this: When they got a number that was too high above Millikan's, they thought something must be wrong - and they would look for and find a reason why something might be wrong. When they got a number close to Millikan's value they didn't look so hard.”
Continuing with the Hansen and Sato update:
“Perceived authority in the case of ice sheets stems from ice sheet models used to simulate paleoclimate sea level change. However, paleoclimate ice sheet changes were initiated by weak climate forcings changing slowly over thousands of years, not by a forcing as large or rapid as human-made forcing this century. Moreover, in a paper submitted for publication (Hansen et al., 2013) we present evidence that even paleoclimate data do not support the degree of lethargy and hysteresis that exists in such ice sheet models."
And, Hansen and Sato make a rebuttal to the best counter-claim that SLR cannot be more than 1 or 2 meters at most this century.
“Pfeffer et al. (2008) argue that kinematic constraints make sea level rise of more than 2 m this century physically untenable, and they contend that such a magnitude could occur only if all variables quickly accelerate to extremely high limits.
“They conclude that more plausible but still accelerated conditions could lead to sea level rise of 80 cm by 2100. The kinematic constraint may have relevance to the Greenland ice sheet, although the assumptions of Pfeffer at al. (2008) are questionable even for Greenland. They assume that ice streams this century will disgorge ice no faster than the fastest rate observed in recent decades. That assumption is dubious, given the huge climate change that will occur under BAU scenarios, which have a positive (warming) climate forcing that is increasing at a rate dwarfing any known natural forcing. BAU scenarios lead to CO2 levels higher than any since 32 My ago, when Antarctica glaciated. By mid-century most of Greenland would be experiencing summer melting in a longer melt season. Also some Greenland ice stream outlets are in valleys with bedrock below sea level. As the terminus of an ice stream retreats inland, glacier sidewalls can collapse, creating a wider pathway for disgorging ice.
“The main flaw with the kinematic constraint concept is the geology of Antarctica, where large portions of the ice sheet are buttressed by ice shelves that are unlikely to survive BAU climate scenarios. West Antarctica's Pine Island Glacier (PIG) illustrates nonlinear processes already coming into play. The floating ice shelf at PIG's terminus has been thinning in the past two decades as the ocean around Antarctica warms (Shepherd et al., 2004; Jenkins et al., 2010). Thus the grounding line of the glacier has moved inland by 30 km into deeper water, allowing potentially unstable ice sheet retreat. PIG's rate of mass loss has accelerated almost continuously for the past decade (Wingham et al., 2009) and may account for about half of the mass loss of the West Antarctic ice sheet, which is of the order of 100 km³ per year (Sasgen et al., 2010).
“PIG and neighboring glaciers in the Amundsen Sea sector of West Antarctica, which are also accelerating, contain enough ice to contribute 1-2 m to sea level. Most of the West Antarctic ice sheet, with at least 5 m of sea level, and about a third of the East Antarctic ice sheet, with another 15-20 m of sea level, are grounded below sea level. This more vulnerable ice may have been the source of the 25 ± 10 m sea level rise of the Pliocene (Dowsett et al., 1990, 1994). If human-made global warming reaches Pliocene levels this century, as expected under BAU scenarios, these greater volumes of ice will surely begin to contribute to sea level change. Indeed, satellite gravity and radar interferometry data reveal that the Totten Glacier of East Antarctica, which fronts a large ice mass grounded below sea level, is already beginning to lose mass (Rignot et al., 2008).
“The eventual sea level rise due to expected global warming under BAU GHG scenarios is several tens of meters, as discussed at the beginning of this section. From the present discussion it seems that there is sufficient readily available ice to cause multi-meter sea level rise this century, if dynamic discharge of ice increases exponentially. Thus current observations of ice sheet mass loss are of special interest.”