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Another challenge to confront with geoengineering: Ocean plankton toxins

Wednesday, November 10th, 2010

There have been several critiques of geoengineering as a climate mitigation tool.  Two of the most incisive, in my opinion, come from science and ethics.

The first is a 2007 paper in PNAS by Matthews and Caldeira showing that if we establish aerosol clouds or space reflectors while doing nothing to reduce carbon emissions, we run the risk of catastrophic rates of warming (2-4 degrees C per decade) if these systems were to fail.

The second is a recent piece in Slate by my colleague, Dale Jamieson, who argued that there is no moral and legal authority to know how and when to deploy geoengineering or by how much.

One proposed geoengineering tool is fertilizing the world’s oceans with iron.  The premise behind this idea was developed by John Martin in 1990, who is often quoted as saying something like, “Give me a tanker of iron, and I’ll give you an ice age.” Micronutrients like iron and zinc are extremely limiting to phytoplankton growth in the open ocean—orders of magnitude moreso than nutrients we typically think of in common fertilizers, like nitrogen and phosphorus.  Dumping iron into the oceans has been shown to stimulate algal blooms, and the creation of this biomass consumes CO2 from the surface waters and atmosphere, thereby helping to mitigate rising CO2 from fossil fuels.  In theory, some of this biomass should sink to the deep ocean where it is sequestered for centuries, but this has yet to be shown definitively on a wide scale.

In a forthcoming paper in the Proceedings of the National Academy of Sciences, Mary Silver and colleagues show that there is another potential risk of geoengineering resulting from ocean iron fertilization…


Posted in climate adaptation, climate change science, geoengineering, solutions, technology, toxics | 1 Comment »

New insights on global threats to water security

Wednesday, September 29th, 2010

Water security is making a bit of a splash this week.  CNBC ran this story on the water crises in western U.S. states, where the region is possibly closing in on a day of reckoning, as described by Felicity Barringer in the NY Times, and creating a climate of pessimism among some western water managers.

The scientific community is also weighing in.  C.J. Vörösmarty and colleagues published a review paper in this week’s issue of Nature in which they evaluate the worldwide risk of water security and threats to aquatic biodiversity (edited slightly to remove citations and statistics):

We find that nearly 80% (4.8 billion) of the world’s population (for 2000) lives in areas where either incident human water security or biodiversity threat exceeds the 75th percentile. Regions of intensive agriculture and dense settlement show high incident threat, as exemplified by much of the United States, virtually all of Europe (excluding Scandinavia and northern Russia), and large portions of central Asia, the Middle East, the Indian subcontinent and eastern China. Smaller contiguous areas of high incident threat appear in central Mexico, Cuba, North Africa, Nigeria, South Africa, Korea and Japan. The impact of water scarcity accentuates threat to drylands, as is apparent in the desert belt transition zones across all continents (for example, Argentina, Sahel, Central Asia, Australian Murray–Darling basin).

What is the disparity of risk between rich vs. poor nations?

Most of Africa, large areas in central Asia and countries including China, India, Peru, or Bolivia struggle with establishing basic water services like clean drinking water and sanitation, and emerge here as regions of greatest adjusted human water security threat. Lack of water infrastructure yields direct economic impacts. Drought- and famine-prone Ethiopia, for example, has 150 times less reservoir storage per capita than North America and its climate and hydrological variability takes a 38% toll on gross domestic product (GDP). The number of people under chronically high water scarcity, many of whom are poor, is 1.7 billion or more globally, with 1.0 billion of these living in areas with high adjusted human water security threat.

They also argue that as wealth increases in a nation, the apparent ability to deal with water security issues improves, leading to the perception that threat level is declining:

Contrasts between incident and adjusted human water security threat are striking when considered relative to national wealth. Incident human water security threat is a rising but saturating function of per capita GDP, whereas adjusted human water security threat declines sharply in affluent countries in response to technological investments. The latter constitutes a unique expression of the environmental Kuznets curve, which describes rising ambient stressor loads during early-to-middle stages of economic growth followed by reduced loading through environmental controls instituted as development proceeds. The concept applies well to air pollutants that directly expose humans to health risks, and which can be regulated at their source. The global investment strategy for human water security shows a distinctly different pattern. Rich countries tolerate relatively high levels of ambient stressors, then reduce their negative impacts by treating symptoms instead of underlying causes of incident threat.

Biodiversity threats from river use appear to be significant globally:

The worldwide pattern of river threats documented here offers the most comprehensive explanation so far of why freshwater biodiversity is considered to be in a state of crisis. Estimates suggest that at least 10,000–20,000 freshwater species are extinct or at risk, with loss rates rivalling those of previous transitions between geological epochs like the Pleistocene-to-Holocene.

And what about future prospects?

We remain off-pace for meeting the Millennium Development Goals for basic sanitation services, a testament to the lack of societal resolve, when one considers that a century of engineering know-how is available and returns on investment in facilities are high. For Organisation for Economic Co-operation and Development (OECD) and BRIC (Brazil, Russia, India and China) countries alone, 800 billion US dollars per year will be required in 2015 to cover investments in water infrastructure, a target likely to go unmet. The situation is even more daunting for biodiversity. International goals for its protection lag well behind expectation and global investments are poorly enumerated but likely to be orders of magnitude lower than those for human water security, leaving at risk animal and plant populations, critical habitat and ecosystem services that directly underpin the livelihoods of many of the world’s poor.

…with a not-so-comforting conclusion:

Left unaddressed, these linked human water security–biodiversity water challenges are forecast to generate social instability of growing concern to civil and military planners.

Vörösmarty, C., McIntyre, P., Gessner, M., Dudgeon, D., Prusevich, A., Green, P., Glidden, S., Bunn, S., Sullivan, C., Liermann, C., & Davies, P. (2010). Global threats to human water security and river biodiversity Nature, 467 (7315), 555-561 DOI: 10.1038/nature09440


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Posted in biodiversity science, climate adaptation, climate change science, risk analysis, water | No Comments »

City dwellers of the future: Urban heat island warming may be as large as doubling CO2

Monday, April 19th, 2010

I remember driving on a freeway in Phoenix after midnight in 1990.  The temperature was a cool 102 degrees F after breaking the all-time heat record of 126 F that day.  Deserts are good at cooling off at night.  But with all of the built environment in Phoenix storing heat from the day, the sidewalks, roads, and even swimming pools felt like they were being heated.

We all have probably experienced urban heat islands—the mass of dark asphalt and concrete absorbing solar radiation and radiating it back to space as heat.  The lack of water exacerbates the situation because there is little-to-no evaporative cooling.  Waste heat from cars, machines, air conditioners, and even human bodies also heat up the air.  And the warmer it gets, the stronger the tendency to crank up the air conditioners, generating even more waste heat.

The problem is potentially large in areas like the Middle East, India, parts of Africa, and the American Southwest, where rapid urbanization in warm, dry environments has the potential to make some urban areas much warmer at night than surrounding rural areas.

In a forthcoming article in Geophysical Research Letters1, Mark McCarthy and colleagues at the Met Office, Hadley Centre, UK used a climate model that examines what climate might look like in a doubled CO2 world and calculates the added warming caused by urbanization and wasted heat.

Their results were eye-opening:

  • Urban regions in places like the Arabian Peninsula, Iran, and India may experience night time warming by as much as 3-5 degrees C above and beyond that caused by doubled CO2 alone.
  • The number of hot nights per year (defined as temperatures in the 99th percentile of nonurban areas) increase in the following cities:
    • London: 1-2 hot nights now vs. up to 10 hot nights in 2050
    • Sydney: 1-2 hot nights now vs. up to 15 hot nights in 2050
    • Delhi: 5-10 hot nights now vs. up to 30 hot nights in 2050
    • Beijing: 3-6 hot nights now vs. up to 50 hot nights in 2050
    • Los Angeles: 8-12 hot nights now vs. up to 40 hot nights in 2050
    • Tehran: 20 hot nights now vs. up to 60 hot nights in 2050
    • Sao Paulo: <5 hot nights now vs. up to 80 hot nights in 2050
    • Lagos (Nigeria): <5 hot nights now vs. up to 150 hot nights in 2050

As mentioned in an earlier post, we only need to remember Chicago in 1995 to recall the deadly impact that heat waves can have on urban people.  And as we saw in that unfortunate example, the victims were disproportionately the elderly and African American.

Although we may not be able to mitigate this warming, basic adaptation steps should be set into motion, including re-thinking urban design, making cities more resilient to hot environments, developing better energy and technology solutions (including cooling), installing green roofs, and putting into place emergency disaster plans and social safety nets for vulnerable populations.

1Mark McCarthy, Martin Best, and Richard Betts (2010). Climate change in cities due to global warming and urban effects Geophysical Research Letters : 10.1029/2010GL042845

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Posted in climate adaptation, climate change science, energy, environmental justice, health, land use, population, race and class, sustainability, technology, urban | 3 Comments »

Natural climate factors unlikely to put the brakes on greenhouse-gas-driven sea level rise this century

Wednesday, March 10th, 2010

The IPCC 2007 report projected a conservative sea level rise of about 18-59 cm by the year 2100.

Why conservative?  Because it mainly accounted for things we know are happening and can measure well—like thermal expansion of the ocean and melting of land glaciers (see here for a discussion of the Kilimanjaro example).  What it doesn’t do so well is account for all of the potential ways that the big ice sheets (Greenland and Antarctica) can contribute to sea level rise.  Things like ice flow and mass loss are generally assumed to be constant, even though recent research papers discussed in previous posts (here and here) suggest they are accelerating.

Since the publication of the IPCC report in 2007, there have been several studies suggesting that sea level rise will be 1-2 meters or more by 2100 (one example here).  One study looked at geological evidence for sea level rise during the previous interglacial period 125,000 years ago, which was 1-2 degrees C warmer than today.  Their work indicated that there was a 95% chance that sea level rose by 6 meters (22 feet).

In a forthcoming issue of Geophysical Research Letters,  Svetlana Jevrejeva and colleagues used statistical models to project sea level rise by 2100.1 But they also did something else interesting.  They looked back several thousands of years to the most extreme events that could cause climate cooling—things like severe volcanic eruptions, which create stratospheric dust clouds that block sunlight.

If events like this were to happen again, they asked, would they cause enough cooling to be able to slow sea level rise caused by greenhouse gases?

The answer is no.  There appears to be no natural factors like vulcanism that will significantly slow greenhouse-gas-driven sea level rise that we are already committed to or future sea level rise that we may experience if we continue to emit fossil fuels.

Excerpts (emphasis mine):

  • With the assumption that sea level will continue to respond over the next 100 years to the same forcings that have influenced it during the past 1000 years, we estimate 0.6 -1.6 m of global sea level rise in the 21st century using a statistical model driven by projected natural and anthropogenic forcings.
  • In contrast to the 20th century sea level rise that was associated with a significant contribution of 25% from natural (solar and volcanic) forcing, 21st century sea level rise will be clearly dominated by the changes in CO2 and other greenhouse gases.
  • Alternative scenarios for solar forcing with a potential decrease in solar irradiance of 1W/m2 (using the lowest level recorded throughout the last 9300 years) only produce a 10-20 cm reduction in our estimate of 21st century sea level rise.
  • If we utilize the 13th century past volcanic forcing to estimate a possible (but unlikely) contribution from volcanic activity, then an almost negligible 8 cm decrease is projected in the estimated sea level rise.
  • The suggested reduction of radiative forcing by injections of SO2 into atmosphere (equivalent to a Pinatubo eruption every 4 years) would be equivalent to delaying sea level rise by 12 -20 years.
  • A “no changes in radiative forcing” scenario produced 16-22 cm (with lower limit of 10 cm and upper limit of 31 cm) sea level rise in the 21 century due to the inertia of the climate system, providing evidence that conditions established during the past centuries have already committed us to a considerable global sea level rise during the next 100 years.

1Jevrejeva, S., J. C. Moore, and A. Grinsted (2010). How will sea level respond to changes in natural and anthropogenic forcings by 2100? Geophysical Research Letters : 10.1029/2010GL042947

UPDATE:  RealClimate provides more explanation of the IPCC being too cautious about sea level rise.


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Posted in climate adaptation, climate change science, polar ice, sea level rise | No Comments »

Can we alter climate by installing white roofs?

Monday, January 11th, 2010


When reviewing the most popular words of 2009, I was surprised to see that “albedo” didn’t crack the top 5—Tweet, Obama, H1N1, Stimulus, and Vampire.  I bet you were equally shocked.

Albedo is a simple concept—the reflectivity of a landscape—but it’s hugely important in understanding how the surface of the Earth impacts climate.  As we saw in a recent post, things like thawing sea ice, northward advancing treeline, and asphalt paving all darken landscapes, causing more solar radiation to be absorbed and temperatures to climb—one of the reasons for the so-called urban heat island effect.

So what would happen if we were to install white roofs?  In a forthcoming article1 in Geophysical Research Letters (subscription required), Keith Oleson and colleagues use biophysical models to address this.

Their answer:  White roofs reflect more sunlight and cool buildings.  Averaged over all urban areas in the world, the urban heat island effect declines by 33%, causing maximum and minimum daily temperatures to decrease by 0.6 and 0.3 degrees C, respectively.

At face value, this sounds great.  But, there’s a potential hidden cost of cool buildings—heating.  Interestingly, they found that white roofs caused space heating to increase more than air conditioner use declined, suggesting that energy use might actually increase with white roofs!

1Oleson, K. et al. (in press) The effects of white roofs on urban temperature in a global climate model. Geophysical Research Letters.

Related post:   New ideas about how changing vegetation at high latitudes can cause climate warming to accelerate


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Posted in behavior, climate adaptation, climate change science, energy, solutions, sustainability, technology | No Comments »

Extreme climate and the vulnerability of least-developed countries

Wednesday, January 6th, 2010


Happy New Year, everyone.  Sorry for the lag in posts, but there wasn’t a lot happening in the news or journals over the past week.

A few years ago, I saw a talk by Thomas Schelling (Nobel laureate in economics) who argued that we need to accelerate the economic development of poor countries so that they are able to cope with climate change.  This analysis is interesting, if not fraught with additional challenges, such as development in a carbon-based energy world hastening the very problem to which these nations are attempting to adapt.

In an article1 in the Early Edition of the Proceedings of the National Academy of Sciences (open access), Anthony Patt and colleagues argued that the need for assistance by Least Developed Countries (LDCs) is dependent on vulnerability, which, in turn, depends on both exposure to climate change and how socioeconomic factors affect the sensitivity of LDCs to climate change.

To assess this hypothesis, they first examined how deaths caused by disasters (floods, droughts, and storms) varied across the level of development in several LDCs.  They used the UN Human Development Index—HDI, a composite metric of income, education, and life expectancy—as a proxy for development.

Here’s what they found…


Posted in climate adaptation, climate economics, policy, race and class, risk analysis, social science, sustainable development | No Comments »

Where might farmers turn for help with climate change?

Saturday, December 12th, 2009


In the Online First edition of Climatic Change, Tyler Tarnoczi and Fikret Berkes assess1,2 the sources and availability of information about climate adaptation to farmers in the Canadian provinces of Manitoba, Saskatchewan, and Alberta.

Farmers rely on several information sources for agricultural practices, which will likely be vital in helping food producers learn how to adapt to climate warming:

  • social networks/experiential learning
  • government
  • industry (e.g., seed, machinery)
  • producer and conservation organizations
  • media

Here’s what they found…


Posted in climate adaptation, communication and framing, food and agriculture, nature and culture, policy | No Comments »

Ecosystem stewardship: sustainability strategies for a rapidly changing planet

Saturday, December 12th, 2009

That’s the title of a new article1,2 by Terry Chapin and colleagues in a forthcoming issue of Trends in Ecology and Evolution.

Human actions are having large and accelerating effects on the climate, environment and ecosystems of the Earth, thereby degrading many ecosystem services. This unsustainable trajectory demands a dramatic change in human relationships with the environment and life-support system of the planet. Here, we address recent developments in thinking about the sustainable use of ecosystems and resources by society in the context of rapid and frequently abrupt change.

To deal with these challenges, they advocate “ecosystem stewardship,” which has three core principles.  Here are excerpts of these principles (slightly condensed/adapted by me); please check out the paper for details:


Posted in climate adaptation, nature and culture, policy, risk analysis, solutions, sustainable development | No Comments »

When the levees break, we’ll have a more sustainable landscape again

Thursday, December 10th, 2009


We don’t ordinarily think about climate change and land use change as being a synergistic threat to society.  However, the combination of impervious surfaces that increase runoff, declining wetlands, levees, and more severe storms pack a quadruple whammy that could lead to some major flooding in the future.  From the cool adaptation work done in Keene, NH, we know that much of our infrastructure (roads, bridges, culverts) can’t handle the added stress of streams and rivers with higher discharge.  We’re looking at a potential nightmare of increased costs associated with infrastructure damage.

In this week’s issue of Science, Jeffrey Opperman and colleagues argue1 that our historical paradigm of flood control with levees needs to fundamentally change to  achieve a more sustainable socioecological system.

Their solution?  Tear down some of the levees to allow some floodplains to flood.  This can accomplish several goals:

(1) Flood risk reduction

  • Move to flood-tolerant activities in floodplains so that we don’t have to spend so much on disaster relief.
  • Storing water in floodplains takes the strain off downstream regions because floodwaters can naturally spill to where they are supposed to rather than swelling channelized rivers.  Small amounts of land can accomplish this—they cite a study of the Illinois River showing that a floodplain of 8,000 hectares would drop the likelihood of flooding 26,000 hectares of cropland by 50%.

(2) Increased floodplain goods and services

  • Several economic activities are conducive to periodic flooding:  pasture, timber, and flood-tolerant biofuel crops, such as willow.
  • Periodically flooded soils can also assist with reducing erosion and storing nutrients that would otherwise reach and pollute coastal oceans.

(3) Building resiliency to climate change

  • They argue that reconnecting rivers to floodplains can help us adapt to climate change in ways that are socioeconomically beneficial.  For instance, we presently have to keep some reservoirs partially empty to accommodate periodic flood waters.  But partially filled reservoirs can’t generate as much hydropower or provide as much drinking water.  If we used floodplains as a natural pressure relief valve, we can operate reservoirs closer to capacity and benefit economically.

Opperman and colleagues acknowledge that there are political hurdles, such as convincing some private landowners that flooding their land can be useful.

But there are creative solutions that have already been deployed.  They cite Sacramento as an example:  Some farmers allow their crops to flood, serving as a pressure-relief valve when rivers swell, thereby preventing more expensive damage.  In return, the farmers are compensated for their crop loss.  It’s a win-win situation that presumably costs less than dealing with infrastructure damage or having to build new infrastructure that handles greater flooding.

Another idea is to allow some of these areas to become wetlands and compensate people as part of a wetlands banking system to mitigate the loss of wetlands elsewhere.   This would most likely have several ecological benefits, including increasing habitat for wetland-dependent species such as waterfowl and other migrating birds.  It would also likely increase vegetation productivity and carbon storage.

It’s interesting to note that they don’t call for an end to economic activity or human use in floodplains.  Sure, we probably want to stop building McMansions in flood-prone regions.  However, there are several ways we can use floodplains for ecological and economic benefit.  These will likely require compensation, but in the long run, it’s cheaper than having to re-tool major infrastructure to handle greater discharge with climate warming.

1Opperman, J.J. et al (2009) Sustainable floodplains through large-scale reconnections to rivers. Science 326:1487-1488.


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Posted in biodiversity science, climate adaptation, food and agriculture, risk analysis, solutions, sustainable development | No Comments »

Will women bear the brunt of climate change impacts?

Wednesday, November 18th, 2009


Lydia DePillis has an interesting article over at The New Republic based on a new report from the United Nations.

Is climate change gender-neutral? Not according to the U.N. Population Fund, which earlier today released a report arguing that women suffer disproportionately from the impacts of global warming. Especially in developing countries, they can’t flee changes like desertification and sea-level rise as easily as young men, who aren’t as tied to children and households. They’re often caught up in civil conflicts ignited by scarce resources. And they’re more likely to fall victim to diseases caused by wetter weather patterns.

But on the flipside, the report argues, women are also in the best position to help mitigate both the causes and effects of rising temperatures—which is why policies to empower women, like targeted microloans and reproductive healthcare, shouldn’t be treated as separate from climate policy.

…Think of it as Nick Kristof meets Tom Friedman: keeping “women’s issues” separate from “climate issues” is a huge missed opportunity.

I love this conclusion.  It’s one of the things that environmental studies (ES) programs in higher education need to focus on—better connections to groups not traditionally affiliated with ES, such as Gender and Women’s Studies, Africana Studies, Psychology, Religion, visual and performing arts, etc.  For major environmental challenges like climate warming, everyone needs to be part of this conversation.


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Posted in behavior, climate adaptation, environmental justice, gender, higher education | No Comments »

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