Climate Scientists Worry About The Costs Of Sea Level Rise

The Guardian - John Abraham

New research addresses the economic costs of damages associated with sea level riseThe remnants of the Jet Star roller coaster is pictured in the ocean, almost five months after Superstorm Sandy, in Seaside Heights, New Jersey March 21, 2013. Photograph: Lucas Jackson/REUTERS

As humans add greenhouse gases to the atmosphere, it not only warms the planet, but also raises the oceans. Ocean waters are rising for a number of reasons including thermal expansion of water (as water warms, it expands to a larger volume), as well as ice melt which then flows as liquid into the ocean. My next post will cover four recent studies that quantify how much ocean levels will rise in the future. However, here I will focus on the economic costs of rising seas.
A paper was just published by Drs. Boettle, Rybski and Kropp that dealt with this question. The authors of this study note that if you are concerned about societal and economic costs, the rate of sea rise isn't the entire story. Much of the damage is caused by extreme events that are superimposed on a rising ocean. Damage is highly nonlinear with sea rise.
To explain this, let's think about flooding. Consider a river that has a dike system capable of confining a rise of water up to six feet. Such a system would have little or no economic/societal damage for "floods" up to six feet, but just one more foot of water rise would put the waters over the dike and could cause significant losses. So what really matters is, do events overshoot some level that commences damage?
How does this relate to climate change? Well as we warm the planet we are raising the baseline level of water from which extremes happen. Second, we are making some extreme weather events more likely. To measure the changes to extreme events in the future, the authors use a statistical method to estimate economic losses from coastal flooding. Using Copenhagen and other locations as test cases, they found that economic losses double when water rises only 11 cm. They also find that the costs rise faster than sea level rise itself. So, if we expect a linear increase in sea level over the next century, we should anticipate costs that increase more rapidly.
The authors also look at what are called "tail events" of storm surges. These are unusual events that can cause a large fraction of losses. Superstorm Sandy is an example; the storm surge from that event was very extreme and cause more loss than the combination of many smaller storm surge events.
I asked the authors why this study is important. They told me,

While there is considerable progress in the understanding and projections of future sea level rise, there is little understanding about the damage costs from coastal floods which are expected to intensify with sea level rise. Most work focuses on case studies and there was no general understanding. Due to limited funds for adaptation it is very valuable to have a transferable and comparable approach for any coastal region.

I also asked how this work was novel and different from prior research.

For the first time we derive general relations on how damage from coastal floods increases with sea level rise and on how the damage decreases with the height of hypothetical protection measures such as sea walls. The results are based on mathematical proofs exploring extreme value statistics and are of universal validity. We conclude that the expected annual damage always, i.e. for an arbitrary case study, increases faster than the sea level itself.
Additionally, despite growing awareness of sea level rise, knowledge about the economic consequences in the form of damage costs is still very limited. A concise estimation, however, is essential in order to perform a reliable cost-benefit analysis regarding potential adaptation measures.
Our paper presents an entirely new view of the assessment of sea level rise impacts. Within a stochastic framework we provide for the first time universal expressions to describe the behavior of future damages, as well as their variability, for a varying mean sea level. Furthermore, an accurate characterization of the damage-reducing effect of coastal protection is included. All results are derived analytically and are confirmed by real-world examples (as shown in the study e.g. by two examples, however we applied the methodology already to more than 100 cities in Europe. This is, however, content of a subsequent paper).
We prove that sea level rise leads to an increase in coastal flood damages following one of three possible patterns. Additionally, the uncertainty of the estimations is analyzed in terms of the standard deviation quantifying the enormous variability of annual damages due to the stochasticity of flood events. The generality and simplicity of our findings facilitate an easy incorporation into integrated assessment models in the context of climate impact research.
Our work is ground-breaking since it bridges the gap between several fields of research and provides a full picture of the interplay between sea level rise, extreme events and the corresponding economic impacts. The manuscript addresses climate change, natural hazard and coastal research scientist.
The research was performed in the broader context of a European funded research framework, namely RAMSES, which is coordinated by Dr. Kroppf.

This work is important for a few reasons. First, we need tools to better understand what a future world will look like in a changed climate. We also need to make decisions to allocate resources toward adaption or mitigation. But how do we make decisions unless we have good information about costs and consequence? This study helps get us to an informed state.

Links

• Earth is warming 50x faster than when it comes out of an ice age
• Fossil fuel funded report denies the expert global warming consensus
• Republicans' favorite climate chart has some serious problems

Food Scarcity Caused By Climate Change Could Cause 500,000 Deaths By 2050, Study Suggests

Washington Post - Chelsea Harvey

Vegetables, including broccoli, white onions and carrots, are displayed for sale on a fruit and vegetable stall at a market in Guildford, U.K., on Friday, Dec. 14, 2012. Photographer: Simon Dawson/Bloomberg

The effects of climate change on food production around the world could lead to more than 500,000 deaths by the year 2050, according to a grim new study. Climate-related impacts on agriculture could lead to an overall global decline in food availability, the research suggests, forcing people to eat fewer fruits and vegetables and less meat. And the public health impacts of these changes could be severe.
Climate experts have long predicted severe consequences for global food security if serious steps are not taken to mitigate climate change. Rising temperatures, more frequent droughts and more severe weather events are expected to cause agriculture in certain areas to suffer, all while the global population — and its demand for food — continues to skyrocket.
So there’s been a great interest in recent years in using models to predict the ways climate change will affect agriculture under various scenarios and what those effects might mean for future human societies. In the new study, which was published Wednesday in the journal The Lancet, a group of scientists from the U.K. took their research a step further.
They decided to take a look at not only how climate-induced changes in agricultural production will affect human food consumption, but also how these dietary changes might influence human mortality. It’s known that diet is connected with human health in many intimate ways, and poor diet has been linked with a number of serious diseases, including diabetes and heart disease.
The researchers, led by Marco Springmann of Oxford University’s Oxford Martin Programme on the Future of Food, used an agricultural model to simulate the effects of future climate change on global food production and consumption. They assumed a severe climate change scenario, one in which global air temperature by 2050 is about two degrees higher than it was in the time period between 1986 and 2005. They then used a health model to predict the way these changes in food production and consumption would affect human health. They compared all of these effects to a reference scenario, which assumes a future with no climate change.
If no climate change were to occur, the model predicted that global food availability would actually increase by 10.3 percent by the year 2050. But under the effects of climate change, it’s a different story, and the model predicted that global food availability would be 3.2 percent lower than was predicted in the scenario with no climate change. Specifically, it found that people would eat 4 percent less fruit and vegetables and 0.7 percent less meat.
These dietary changes translate into hundreds of thousands of preventable deaths. If there were no climate change, the health model found that the projected future increases in global food availability would actually save nearly 2 million lives in 2050 compared with conditions in 2010. But the model predicted that the effects of climate change will reduce the number of lives saved by about 28 percent — this translates into about 529,000 deaths that would not have occurred if there were no climate change.
The food-related deaths would be caused by two major factors: people not getting the right type of nutrition, and people simply being underweight. The majority of all the predicted deaths were found to be caused by the nutrition factors, mostly by people being forced to eat fewer fruits and vegetables. However, the effects were somewhat variable in different regions of the world.
The fruit and vegetable-related deaths, for instance, were most prevalent in high-income countries, as well as low- or middle-income countries in the Western Pacific, Europe and Eastern Mediterranean. Deaths related to weight — in other words, insufficient calorie intake — were a bigger risk factor in Africa and Southeast Asia. Overall, the most climate-related deaths were seen in the Western Pacific and Southeast Asia — particularly in China and India.
It’s worth noting that a few countries were predicted to have climate-related decreases in deaths, related to a lower caloric intake. The changes in food availability and consumption were predicted to reduce obesity in some places — a condition also linked with disease and an increased risk of mortality. Regions where lives were actually saved included Central and South America and parts of Africa and the Eastern Mediterranean. But these saved lives were far outnumbered by the amount of extra deaths caused by climate change.
“The results of this study indicate that even quite modest reductions in per-person food availability could lead to changes in the energy content and composition of diets that are associated with substantial negative health implications,” the authors write in the paper. It’s a sobering look at just a single facet of the climate change dilemma. Of course, the impacts of climate change are expected to cause human deaths in a variety of other ways as well. The increased risk of infectious disease, natural disasters, forced migration and civil unrest are just a few examples.
But as far as food security goes, the paper does raise the need for more targeted public health programs in various parts of the world that can start preparing for the potential dietary impacts of a warming climate. “Strengthening of public health programmes aimed at preventing and treating diet and weight-related risk factors could be a suitable climate change adaptation strategy with a goal of reducing climate-related health effects,” the authors write, noting that such interventions should be tailored by region to account for the specific challenges that different parts of the world are expected to face.
In the meantime, climate mitigation efforts could prevent thousands of deaths. The researchers found that by applying a moderate climate change scenario, instead of a severe one, the number of climate related deaths fell by about 30 percent. And in a scenario that assumed highly stringent mitigation efforts, the number of deaths fell by more than 70 percent.
So the public health impact of serious mitigation efforts is clear. And in a comment published in The Lancet alongside the new study, Alistair Woodward of the University of Auckland argues that future research should look at even more long-term effects to really drive the point home.
“Restriction of our view of the consequences of climate change to what might happen in the next 30–40 years is understandable in terms of conventional concerns with data quality and model stability,” he noted, “but might underestimate the size of future risks, and therefore undervalue present actions needed to mitigate and adapt.”
He also pointed out that issues with data caused some small nations, such as the highly climate-vulnerable Pacific Island states, to be left out of the study. This means we still don’t have a complete picture of how individual nations throughout the world might suffer the effects of climate change.
And, of course, there are many questions that the study simply did not have the scope to address. Those include issues related to the ways climate change will directly affect fisheries and livestock or the nutritional quality of produce, as well as the ways that some climate mitigation practices — culling livestock to cut down on methane emissions, for instance — could also affect global food security.
Combining research of different types can help address the many interrelated questions related to climate change, its environmental impacts and their implications for human health. For now, at the very least, the new study serves as a stark reminder that taking climate change seriously is no longer a luxury, but a matter of life and death for thousands of people around the world.

Regional Climate Change and National Responsibilities

Huffington Post - Dr. James Hansen

Nick Shepherd via Getty Images

Global warming of about 1°F (0.6°C) over the past several decades now "loads the climate dice." Fig. 1 updates the "bell curve" analysis of our 2012 paper¹ for Northern Hemisphere land, which showed that extreme hot summers now occur noticeably more often than they did 50 years ago. Our new paper² shows that there are strong regional variations in this bell curve shift, and that the largest effects occur in nations least responsible for causing climate change.
In the United States the bell curve shift is just over one standard deviation in summer and less than half a standard deviation in winter (Fig. 2). Measured in units of °F (or °C) the warming is similar in summer and winter in the U.S., but the practical implication of Fig. 2 is that the public in the U.S. should notice that summers are becoming hotter but is less likely to notice the change in winter. Summers cooler than the average 1951-1980 summer still occur, but only ~19% of the time. Extreme summer heat, defined as 3 standard deviations or more warmer than 1951-1980 average, which almost never occurred 50 years ago, now occur with frequency about 7%.
Warming in Europe (see paper) is modestly larger than in the U.S. In China (Fig. 2) warming is now almost 1½ standard deviations in summer and one standard deviation in winter, a climate change that should be noticeable to people old enough to remember the climate of 50 years ago. Bell curve shifts in India (see paper) are slightly larger than in China.
In the Mediterranean and Middle East the bell curve shift in summer is almost 2½ standard deviations (Fig. 2). Every summer is now warmer than average 1951-1980 climate, and the period with "summer" climate is now considerably longer. Given that summers were already very hot in this region, the change affects livability and productivity as noted below. Bell curve shifts in the tropics, including central Africa (see paper) and Southeast Asia (Fig. 2), which also was already quite hot, are about two standard deviations and occur all year round.

Fig. 1. Frequency of occurrence of local temperature anomalies (relative to 1951-80 mean) divided by local standard deviation (horizontal axis) for Northern Hemisphere land. Upper row is for summer (Jun-Jul-Aug) and lower row is winter (Dec-Jan-Feb). Further discussion in our 2012 and 2016 papers.

Fig. 2. Frequency of occurrence of local temperature anomalies (relative to 1951-80 mean) divided by local standard deviation (horizontal axis) for land areas shown on map. Area under each curve is unity. Numbers above map are percent of globe covered by the selected region. "Shift" refers to the dashed curve fit to 2005-2015 data and are relative to the base period.

The tropics and the Middle East in summer are in danger of becoming practically uninhabitable by the end of the century if business-as-usual fossil fuel emissions continue, because wet bulb temperature could approach the level at which the human body is unable to cool itself under even well-ventilated outdoor conditions.³ Lesser warming still makes life more difficult and reduces productivity in these regions, because temperatures are approaching the limit of human tolerance and both agricultural and construction work are mainly outdoor activities. Middle latitude countries have a near optimum average temperature for work productivity, while warmer countries such as Indonesia, India and Nigeria are on a steep slope with rapidly declining productivity as temperature rises (see Fig. 2 of Burke et al.⁴, 2015).
Warming and climate effects are not uniform within the regions that we illustrate. In the U.S., e.g., warming is largest in the Southwest, consistent with expected amplified warming in dry subtropical regions.⁵ Similarly summer warming is amplified in the Mediterranean and Middle East region, where at minimum it intensifies drought conditions such as those of Syria in recent years, if not being a principal cause of the drought.⁶
Increasing temperature seems to have a significant effect on interpersonal violence and human conflict, as indicated by a body of empirical evidence in a rapidly expanding area of scientific study. In an assembly of 60 quantitative studies⁷ covering all major world regions, it is found that interpersonal violence increases by 4% and intergroup conflict by 14% for each standard deviation increase of temperature. Such findings do not constitute natural laws, but they provide a useful empirical estimate of impacts of temperature change.

Fig. 3. Cumulative fossil fuel CO2 emissions by national source (a) and per capita (b). Results for additional individual nations are available at www.columbia.edu/~mhs119/CO2Emissions/.

Human health is affected by higher temperature via impacts on heat waves, drought, fires, floods and storms, and indirectly by ecological disruptions brought on by climate change including shifting patterns of disease (see Chapter 11 of IPCC, 2014, and references therein). Vector-borne diseases, usually involving infections transmitted by blood-sucking mosquitoes or ticks, can spread to higher latitudes and greater altitudes as global warming increases.
National responsibilities for global warming can be assigned because fossil fuel CO2 is the main cause of long-term warming. Deforestation and agricultural activities contribute to airborne CO2, but restoration of soil and biosphere carbon is possible via improved agricultural and forestry practices and, indeed that is required if climate is to be stabilized. In contrast, fossil fuel carbon will not be removed from the climate system for millennia.⁸ Other trace gases contribute to climate change, but CO2 causes 80% of the increase of greenhouse gas climate forcing in the past two decades⁹ and much of the other 20% is related to fossil fuel mining or fossil fuel use.
Climate change is accurately proportional to cumulative CO2 emissions (Fig. 3a). The U.S. and Europe are each responsible for more than a quarter of cumulative emissions, China for about 10% and India 3%. The disparity between developed and developing country emissions is even greater with consumption-based accounting of emissions.¹⁰ Even without consumption-based accounting, the per capita emissions of the U.S. and Europe are at least an order of magnitude greater than most developing countries.
There is thus a striking incongruity between locations of largest climate change and responsibility for fossil fuel emissions. Largest bell curve shifts are in tropical rainforest, Southeast Asia, the Sahara and Sahel, where fossil fuel emissions are very small. Climate change is also large in the Middle East, where emissions are large and rapidly growing, with several nations having higher per capita emissions than the United States (see paper).

Discussion
We conclude that continued business-as-usual fossil fuel emissions will begin to make low latitudes inhospitable. If accompanied by multi-meter sea level rise,¹¹ resulting forced migration and economic disruption could be devastating.
Even global warming as small as 2°C, sometimes called a safe guardrail, may have large effects. Bell curve shifts shown for 2005-2015 result from global warming of ~0.6°C relative to 1951-80. Thus 2°C warming relative to pre-industrial (1.7°C relative to 1951-1980) will result in bell curve shifts and climate impacts about three times greater than those that have occurred already. Global warming of 2°C is expected to cause sea level rise of several meters,¹² leading to inference that the potential sea level rise this century is dangerous.¹³
The overall message that climate science delivers to society, policymakers, and the public alike is this: we have a global emergency. Fossil fuel CO2 emissions should be reduced as rapidly as practical. We argue that country-by-country goals, the approach of the 21st Conference of the Parties cannot lead to rapid phasedown of fossil fuel emissions, as long as fossil fuels are allowed to be the cheapest energy. It will be necessary to include a carbon fee that allows the external costs of fossil fuels to be incorporated in their price. Border duties on products from countries without a carbon fee, would lead to most nations adopting a carbon fee.
In view of the disparity between developed country and developing country emissions, there is a recognized obligation of assistance from developed countries. Developing countries have strong leverage to achieve that assistance, because their cooperation in improved agricultural and forestry practices is needed to store more carbon in the soil and biosphere and to limit trace gas emissions. In addition, international cooperation in generating more affordable carbon-free energies is needed, because otherwise economic development in many nations will continue to be based on fossil fuels, despite pollution and climate impacts.

Notes:
1. Hansen, J., Sato, M. and Ruedy, R.: Perception of climate change, Proc. Natl. Acad. Sci. 109, 14726-14734, 2012.
2. Hansen J. and Sato M.: Regional climate change and national responsibilities, Environ. Res. Lett. (in press).
3. Sherwood, S.C. and Huber, M.: An adaptability limit to climate change due to heat stress, Proc. Natl. Acad. Sci. 107, 9552-9555, 2010.
4. Burke, M, Hsiang, S.M. and Miguel, E.: Global non-linear effect of temperature on economic production, Nature 527, 235-239, 2015.
5. Cook, K.H. and Vizy, E.K.: Detection and analysis of an amplified warming of the Sahara, J. Clim. 28, 6560-6580, 2015.
6. Kelley, C.P., Mohtadi, S., Cane, M.A., Seager, R. and Kushnir, Y.: Climate change in the Fertile Crescent and implications of the recent Syrian drought, Proc. Natl. Acad. Sci. USA 112, 3241-3246, 2015.
7. Hsiang, S.M., Burke, M. and Miguel, E.: Quantifying the influence of climate on human conflict, Science 341, doi:10.1126/science.1235367
8. Archer, D.: Fate of fossil fuel CO2 in geologic time, J. Geophys. Res. 110, C09S05, 2005.
9. Hansen, J., Kharecha, P. and Sato, M.: Climate forcing growth rates: doubling down on our Faustian bargain, Environ. Res. Lett. 8, 011006, 2013.
10. Peters, G.P.: From production-based to consumption-based national emissions inventories, Ecolog. Econ. 65, 13-23, 2008.
11. Hansen, J., et al.: Ice melt, sea level rise and superstorms: Evidence form paleoclimate data, climate modeling and modern observations that 2°C global warming is dangerous, arXiv:1602.01393
12. Dutton, A., Carlson, A.E., Long, A.J., Milne, G.A., Clark, P.U., DeConto, R., Horton, B.P., Rahmstorf, S., and Raymo, M.E.: Sea-level rise due to polar ice-sheet mass loss during past warm periods, Science, 349, doi:10.1126/science.aaa4019, 2015
13. Davenport, C.: Nations Approve Landmark Climate Accord in Paris, New York Times, 12 December, 2015.