Page N4.2 . 31 October 2007                     
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    Climate Findings Update

    continued

    Sea-Level Rise

    Sea level is predicted to rise with global warming, although exactly how much is uncertain. The IPCC's February report puts the estimated rise at between 19 and 58 centimeters (7.5 and 22.8 inches) by 2100. But a report published in the journal Science around the same time warned that sea levels may be rising even faster, possibly up to 1.4 meters (4.6 feet) by 2100.2

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    That increase would inundate many coastlines — and coastal cities — around the world, with particular impact at river deltas, in low-lying areas, and in cities that rely on artificial coastal defense structures. Higher sea levels are expected to increase the risk of storm-related flooding. Another study published in Geophysical Research Letters in January 2007 suggested significant variability in the rate of sea-level rise.3

    Rainfall and Moisture

    A study published in the journal Nature in July 2007 detected human effects on precipitation trends in the 20th century.4 Anthropogenic influences were estimated to have "contributed significantly to observed increases in precipitation in the Northern Hemisphere mid-latitudes, drying in the Northern Hemisphere subtropics and tropics, and moistening in the Southern Hemisphere subtropics and deep tropics." Those now-wetter northern "mid-latitudes" include most of Europe and much of North America. Among the areas that became drier during the 1900s was the Sahel region, just south of the Sahara in Africa. Notably, the models' hindsight predictions underestimated the actual changes reflected in the rainfall data.

    Those underestimates were consistent with earlier findings, published in a May 2007 report in Science, that climate models in general may be underestimating precipitation increases due to global warming.5 The analysis of weather satellite data from 1987 to 2006 concluded that worldwide precipitation had increased at the rate of seven percent per degree of warming, rather than the one to three percent predicted by current climate models.

    The southwestern United States and other subtropical regions are projected to become drier in the future, according to results published in Science in April 2007.6 Over the next 20 to 30 years, moisture may drop on the order of 15 percent in those areas and subtropical arid regions are expected to expand. The trend applies to the U.S. Southwest, northern Mexico, and arid and semiarid regions in the Middle East and the Mediterranean.

    Extreme rainfall events during summer monsoons in India have increased in frequency since the early 1950s, according to results published in Science in December 2006.7 These intense rainfall events — in which a large amount of rain falls during a short time — are more likely to cause flooding and, thus, destruction, than more average monsoon rains.

    Whether this particular trend in India has been caused by global warming is unclear, although most climate models suggest similar general patterns. The increase in the number of weather-related disasters in India is "all consistent with what climate models predict," says Peter Höppe of Munich Re, a reinsurance company that has compiled data on the topic, as quoted in a Nature news story in November 2006.8

    Arctic Ice Melt

    Some of the newest climate news illustrates the point that the IPCC consensus can't help but lag behind in some areas. On September 16, 2007, the extent of sea-ice in the Arctic Ocean had already reached 4.13 million square kilometers (1.59 million square miles), its lowest point since record-keeping began in the 1970s, according to data from the U.S. National Snow and Ice Data Center.9 And the 2007 summer melt season may not be over yet.

    Model predictions accepted by the IPCC had previously put the first summer day free of sea ice some time between 2050 and 2100, but newer data suggest that it could be earlier, with some estimates for a fully ice-free summer as early as 2030.10 Among its many implications, this loss of summer sea ice could cause polar bear populations to plummet, according to the U.S. Geological Survey.11

    Disastrous Future?

    Natural disasters bring the question of future scenarios into sharp relief. Were the recent flooding in the United Kingdom and India, and the recent fires in the Mediterranean, caused by global warming? Are they a preview of what is to come? Will there be ever more Hurricane Katrinas?

    "It is impossible to say with certainty that climate change is the cause of any single hurricane, heat wave, flood or drought," says Saleemul Huq, head of the Climate Change Group at the International Institute for Environment and Development in the United Kingdom and a lead author on the IPCC's April publication on the impacts of climate change,12 as quoted in a Nature news story in April 2007.13 "But taken together, the increase in frequency and intensity of such events during the last decade of the twentieth century provides strong evidence that climate change is already occurring and is no longer a problem of the future."

    Prevention and Adaptation

    Planning for and adapting to a changed future climate is certainly a new concept in the world of design and building. Until now, the focus of "green" building has been largely preventative. The energy efficiencies and resource conservation suggested by U.S. Green Building Council's LEED guidelines, and other standards, add up to reduced environmental impact — that is, they guide designers to help prevent climate change.

    Those preventative measures have lost none of their importance. But adaptation should now be considered in addition, as part of sustainable design.

    To complicate matters, the short-term and long-term effects of global warming may differ. A report published in Science in August 2007 predicted that variability internal to the climate system will balance anthropogenic warming for the next few years, with net warming starting only after 2008.14

    And while climate models and their predictive ability are being improved, significant uncertainties still exist. Feedback effects between different components of the carbon cycle could increase or decrease the effects of climate change. Clouds aren't adequately accounted for in current models, contributing to uncertainty in predictions about regional weather effects. Data sets contain gaps, and often are lack uniformity.

    Due to the complexity and uncertainty inherent in much climate data, at least at this stage in the game, it may too early for architects to make very many specific changes in their designs to prepare for climate change. Some may plan now with some certainty; for example, Spain is likely to have hotter summers in the future.1 Mid-northern latitudes can expect to get wetter, while many dry areas should expect to be getting significantly drier. And of course the earth as a whole will be getting gradually warmer.

    Until today, to the extent that building design has taken climate into account, that climate has been correctly understood to be changing so slowly relative to the lives of most buildings that it is essentially a constant if complex factor overall, natural variations in weather and season notwithstanding.

    Now, it is scientifically clear that over the next half century, for instance — the design lifetime for many buildings on the boards today — our biosphere will experience progressively different climatic conditions at unprecedented rates of change. While the distinction between a climate that is effectively constant and a climate that will be undergoing significant change within the service period of today's new buildings may appear subtle at present, it is fundamental. And as such, it has potentially profound implications.

    Our highest priority must be to fundamentally change consumption patterns so as to reduce the worst effects of climate change as much as possible. At the same time, continued attention to emerging research findings may now be required for professionals who would plan, design, and build accurately for the increasingly different climates in our foreseeable future.

    Discuss this article in the Architecture Forum...


    1. IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller, Eds. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
    2. Rahmstorf S., et al. A semi-empirical approach to projecting future sea-level rise. Science, 315: 368-370 (19 January 2007), 10.1126/science.1135456. Originally published in Science Express on 14 December 2006.
    3. Holgate S. J., et al. On the decadal rates of sea level change during the twentieth century. Geophys. Res. Lett., 34, L01602, (4 January 2007), doi:10.1029/2006GL028492.
    4. Zhang, X. et al. Detection of human influence on twentieth-century precipitation trends. Nature 448: 461-465 (26 July 2007), doi:10.1038/nature06025.
    5. Wentz, F.J., et al. How much more rain will global warming bring?. Science, 317: 233-235 (13 July 2007), doi:10.1126/science.1140746. Originally published in Science Express on 31 May 2007.
    6. Seager, R., et al. Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America. Science, 316: 1181-1184 (25 May 2007), doi:10.1126/science.1139601. Originally published in Science Express on 5 April 2007.
    7. Goswami, B.N., et al. Increasing trend of extreme rain events over India in a warming environment. Science, 314: 1442-1445 (1 December 2006), doi:10.1126/science.1132027.
    8. Schiermeier, Q. Extreme monsoons on the rise in India. Nature.com, 30 November 2006, doi:10.1038/news061127-12.
    9. Overview of current sea ice conditions (data), 20 September 2007. National Snow and Ice Data Center, Boulder, Colorado.
    10. Adam, D. Ice-free Arctic could be here in 23 years. The Guardian. 5 September 2007.
    11. USGS Science Strategy to Support U.S. Fish and Wildlife Service Polar Bear Listing Decision. Forecasting the Range-wide Status of Polar Bears at Selected Times in the 21st Century. Steven C. Amstrup, Bruce G. Marcot, and David C. Douglas. Administrative Report. Department of the Interior, U.S. Geological Survey, Reston, Virginia, 2007.
    12. IPCC, 2007: Summary for Policymakers. In: Climate Change 2007: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. M.L. Parry, O.F. Canziani, J.P. Palutikof, P.J. van der Linden and C.E. Hanson, Eds. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.
    13. Hopkin, M. Effects of climate change tallied up. Nature.com: 6 April 2007, corrected online 10 April 2007, doi:10.1038/news070402-10.
    14. Smith, D. M., et al.Improved surface temperature prediction for the coming decade from a global climate model. Science, 317: 796-799 (10 August 2007), doi:10.1126/science.1139540.

     

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    Flooding throughout India in August and September 2007 displaced more than three million people.
    Photo: Ruchir Agarwal

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    Hardships due to extreme weather are becoming increasingly familiar in some countries.
    Photo: Matthew Logelin

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    Since ice reflects sunlight and open water absorbs it, the melting of glaciers begets more even more melting — just one of the "positive feedback" effects that climate models must take into account.
    Photo: Aman Sagar Extra Large Image

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    Many coastlines around the world are vulnerable to flooding as sea levels rise — one consequence of global climate change.
    Image: Courtesy Architecture 2030 Extra Large Image

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    Between 1970 and 2004, the net global trend was warming, and that trend will continue, according to the IPCC.
    Image: Courtesy Intergovernmental Panel on Climate Change Extra Large Image

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    As global temperatures increase, changes in land, water, and ecosystems are predicted, with significant effects on human safety and comfort.
    Image: Courtesy Intergovernmental Panel on Climate Change Extra Large Image

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    In Yorkshire, England, heavy rainfall led to flooding in June 2007.
    Photo: Darryl Hunt

     

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