Creating the Solar Village

Posted by Brad Johnson Thu, 18 Oct 2007 18:00:00 GMT

Student leaders in architecture and engineering from three universities at the US Solar Decathlon on the Mall discuss special features of their leading-edge, solar-powered houses and how their experience has helped shape their future as innovators. Participants are from the University of Colorado, Boulder – a two-time solar Decathlon winner, Carnegie Mellon University (Pittsburgh, PA) and the University of Maryland, College Park. Panel moderator is Bobbie Faul-Zeitler, editor of Green News Update and mentor to the University of Maryland team. Co-sponsored by the Smithsonian office of Energy Management.

At the Smithsonian Museum of Natural History at 10th Street & Constitution Ave. NW.

Effects of Climate Change on Energy Production and Use in the United States (Senate briefing)

Posted by Brad Johnson Thu, 18 Oct 2007 17:00:00 GMT

On Thursday, October 18, 2007, the Climate Change Science Program (CCSP) will hold a Senate briefing on the release of the third in a series of 21 reports to advance climate science research. Coordinated by the U.S Department of Energy (DOE), this Synthesis and Assessment Product report, numbered 4.5 and titled “Effects of Climate Change on Energy Production and Use in the United States,” summarizes what is known about potential effects of climate change on energy production and use in the United States.

  • Dr. William J. Brennan, Acting Director of the Climate Change Science Program
  • Dr. Jeffrey S. Amthor, DOE Office of Science, Coordinator of CCSP Report 4.5
  • Dr. Thomas J. Wilbanks, CCSP 4.5 Report Lead Author, Oak Ridge National Laboratory

Black Carbon and Global Warming

Posted by Brad Johnson Thu, 18 Oct 2007 14:00:00 GMT

On October 18, the Committee will hold a hearing to examine the role of black carbon as a factor in climate change and receive testimony from experts regarding its global and regional impacts, its sources, and the risks it raises for public health.

  • Dr. Mark Z. Jacobson, Prof. of Civil and Environmental Engineering, Atmosphere/Energy Program, Stanford University
  • Dr. Tami C. Bond, Asst. Prof. of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign
  • Dr. V. Ramanathan, Prof. of Climate and Atmospheric Sciences, Scripps Institute of Oceanography, University of San Diego
  • Dr. Charles Zender, Assoc. Prof. of Earth System Science, University of California at Irvine.
  • Dr. Joel Schwartz, Professor of Environmental Epidemiology, Harvard University

Disappearing Polar Bears and Permafrost: Is a Global Warming Tipping Point Embedded in the Ice?

Posted by Brad Johnson Wed, 17 Oct 2007 14:00:00 GMT

On Wednesday, October 17, 2007, the Investigations and Oversight Subcommittee will hold a hearing on the impacts of global warming on the Arctic. This hearing will provide the Committee with an opportunity to hear from witnesses on three interrelated matters: (1) the current situation in the Arctic, including the situation facing the polar bear, (2) ways in which warming in the Arctic may accelerate global warming, especially through the emission of more greenhouse gases, and (3) interim steps that could be taken to reduce greenhouse gas emissions while the Congress weighs more elaborate carbon trade or tax proposals.

One of the themes that should emerge from this hearing is that, from a layman’s perspective, the models used to project climate change and its ramifications appear to be conservative in their projections. This is because any phenomena that are not understood well enough to be represented in models with confidence are excluded. These other phenomena may accentuate or depress warming trends. In the case of the Arctic, most of the phenomena that have been excluded from the models are believed to accentuate warming and its effects. Few will depress it. The modeling on polar bear survival, for example, uses projections from the IPCC models to estimate future changes in sea ice extent. Since the bears’ condition is very dependent upon both the extent of the sea ice and the duration of ice-free periods, projections of the bear survival are very dependent upon projections of sea ice. This summer the sea ice extent is far less than projected by the models.

The Center for Biological Diversity will appear to provide some advice on steps that can be taken to reduce warming, with particular emphasis on their efficacy in the Arctic. Among the steps they advocate are programs to reduce methane emissions and “black carbon.” Black carbon is soot that, in the Arctic, has a particularly pernicious effect. When it is deposited on snow and ice it decreases its reflectivity and increases its heat absorption leading to greater melting. As the Arctic comes under more and more industrialization with other warming, one could anticipate further production of black carbon. Methane is a powerful greenhouse gas, with an estimated global warming potential 23 times greater than carbon dioxide over a 100-year time frame. Methane is a precursor to tropospheric ozone. In that form, it traps shortwave radiation as it enters the earth’s atmosphere from the sun and then when it is reflected back again by snow and ice. As a consequence, its impact is strongest over the poles. Reducing global methane emissions would provide a particular benefit to the Arctic.

  • Dr. Richard Alley, Evan Pugh Professor of Geosciences, Pennsylvania State University, Department of Geosciences
  • Dr. Glenn Juday, Professor, University of Alaska at Fairbanks, School of Natural Resources and Agricultural Sciences
  • Dr. Sue Haseltine, Associate Director for Biology, U.S. Geological Survey, U.S. Department of Interior
  • Kassie R. Siegel, Director, Center for Biological Diversity, Climate, Air and Energy Program

10:40: Juday They are self-reliant people, and their environment is changing. Pack ice should be present right about now, and they’re not able to be safely on the ice. The permafrost definitely is warming. The boreal forest is dying. Sea ice is retreating and thinning.

10:45: Haseltine Data shows a decline of about 10% per decade in sea ice extent. This year had about 40% less ice than 1979. There’s a growing scientific concern that sea ice has been pushed past a threshhold of catastrophic change.

10:51: Siegel The polar bear will likely be listed as endangered in the next year, but the listing won’t be enough to save the polar bear or the sea ice they depend on. The polar bear depends on sea ice. The situation for polar bears in a rapidly warming Arctic is grim. We know that business as usual cannot continue and we need to limit CO2 concentrations to below 450 PPM. Anything else we do may be futile if we don’t address this most important of greenhouse gases. By attacking methane and black carbon emissions we can have an immediate effect on the Arctic and give ourselves a chance to save the polar bear in the long term. According to conservative estimates of the EPA we can eliminate 70 million metric tons of CO2 equivalent methane with no-cost or cost-benefit actions.

11:04 AM: Rohrabacher Ms. Siegel, what’s your educational background?

Siegel I got a degree in anthropology and and economics from Williams & Mary and I am an attorney.

Rohrabacher I believe Jim Hansen has received a significant amount of money from George Soros. Has anyone on the panel received money from Mr. Soros? There’s no question the earth is undergoing a warming trend. The major question is whether this is caused by human activity, and then wheter we can arrogantly think we can reverse what nature… and we’re looking at the effects of this on polar bears. I remembed the predictions of dire and doom for caribou. The caribou population has dramatically expanded since we built the pipeline. Quite often we hear people with these dire predictions to accomplish other political ends. We know the ice cores and these things give us an understanding of range in the planet. Timothy Ball stated that ice cores show that temperature leads increases in CO2. Dr. Juday was mentioning how methane gas was bubbling up as the temperature increases. Seems to me you’re backing up Dr. Ball’s observation.

Alley If I were to overpay and go into debt, I would also have to pay interest payments. We know that the historical variations in temperature are due to the earth’s orbit. The interest payments of CO2 must be included in our explanation of today’s observed warming.

Rohrabacher I must admit I don’t understand a thing you said.

Juday The only way to explain the trends. Something is dampening heat loss, not adding heat in the summer. Those are the characteristics of greenhouse gases.

11:14 AM Miller Dr. Hansen denies receiving money from Mr. Soros. He’s not here to defend himself, but we have a statement from him and we are entering it into the record.

Miller Do you know any scientists named Steve that don’t believe in global warming? How about scientists named Steve that do? [Two Steves that believe in global warming are mentioned.]

Juday We need to poke holes in the tundra and see if there’s charcoal in them. We’re seeing fires now; previous fires aren’t known to have existed, but we should check.

11:19 AM Rohrabacher I don’t have any scientists named Steve, but Patrick Michaels suggests that all the reports of melting ice on Greenland are exaggerated. Since Bill Clinton became President of the United States to get grants you had to say that global warming is caused by human beings.

This senior senior scientist says that polar bear populations are increasing.

Haseltine The 13 populations, in the reassessment we did, 5 are declining, 2 are depressed due to hunting, and none are increasing. I’m quoting from a study by Ian Serling, a senior polar bear scientist for Canada.

Rohrabacher It was a lot warmer in Greenland and I don’t know how many polar bears there were then. I’m not sure if that’s the natural number of polar bears in the world we should have now than what we have today. We have only one degree warmer, and we have five times less volcanic activity, which would tend to make it warmer, not to mention sunspots, which would imply natural causes, not an SUV, not to mention the warming going on Mars and Jupiter.

Juday I was the lead author in the Arctic climate assessment. I’d refer you to that if you’re interested in what happened when. You’ve brought up several different ideas and I’d offer to help you disentangle what happened and why.

Alley Scientists bubble with ideas and you help pay for activities to assess what makes sense and not. The National Academy of Sciences have looked at volcanoes, sunspots, etc., and have come to a high degree of scientific certainty that humans are responsible for the current warming. You quoted a scientist who claimed scientists modify their positions to get funding and personally, I’m under oath. And I would never ever ever do that. I am not lying to you.

11:30: Siegel If we take action on methane and black carbon we could start to see results by 2009.

Rohrabacher I’m surprised my staff hasn’t submitted that list yet. But here’s another respected scientist, William Grey suggests that so many people are invested in this, they’re scaring people to get more investment. How many polar bears were there 1000 years ago?

Haseltine We don’t know how many, but we know they existed then.

Rohrabacher We could assume there were fewer polar bears. What’s the natural number of polar bears?

Haseltine I don’t know if there’s a “natural” number, there’s the number the habitat can support.

Rohrabacher I think it’s wonderful seeing pictures of skinny polar bears, which then gives people the acceptance to regulate their lives the reality is 1000 years ago the polar bear population was totally different. What was the level of ice in Greenland 1000 years ago?

Alley I am one of the authors of a report that will be coming out. We’re in the temperature range we were 1000 years ago.

Rohrabacher It was dramatically warmer 1000 years ago and 8000 years go.

Juday No. We are probably warmer than we were 1000 years ago.

Miller I have one more question for Dr. Alley. You said the release of permafrost methane was a big hole in the IPCC modeling. Do you have a sense how big it could be?

Alley If we humans build all our fossil fuel, the methane feedbacks are on the order of 10-30%.

Juday If you burned up all of the readily accessible methane in the tundra it would double atmospheric CO2.

11:43 Miller Our hearing is now adjourned.

Solar Decathlon Opening Ceremony 1

Posted by Brad Johnson Fri, 12 Oct 2007 14:00:00 GMT

The Solar Decathlon is a competition in which 20 teams of college and university students compete to design, build, and operate the most attractive, effective, and energy-efficient solar-powered house. The Solar Decathlon is also an event to which the public is invited to observe the powerful combination of solar energy, energy efficiency, and the best in home design.

The event takes place on the National Mall in Washington, D.C., October 12 – 20. The team houses are open for touring everyday, except Wednesday, October 17, when they will close for competition purposes. An overall winner is announced on Friday, October 19 at 2 p.m.

Teams of college students design a solar house, knowing from the outset that it must be powered entirely by the sun. In a quest to stretch every last watt of electricity that’s generated by the solar panels on their roofs, the students absorb the lesson that energy is a precious commodity. They strive to innovate, using high-tech materials and design elements in ingenious ways. Along the way, the students learn how to raise funds and communicate about team activities. They collect supplies and talk to contractors. They build their solar houses, learning as they go.

The 20 teams transport their solar houses to the competition site on the National Mall and virtually rebuild them in the solar village. Teams assemble their houses, and then the active phase of the Solar Decathlon begins with an opening ceremony for students, media, and invited guests. The teams compete in contests, and even though this part of the Solar Decathlon gets the most attention, the students really win the competition through the many months of fund raising, planning, designing, analyzing, redesigning, and finally building and improving their homes. The public is invited to tour the solar homes and event exhibits during much of the competition.

Awards Ceremony – Winner Announced: 2:00 p.m., Friday, October 19

Houses Open for Public Tours The public is invited to tour the houses during the open hours, listed below. Expect to stand in line to tour the houses. If you wish to see all of the houses, plan to spend two days.

  • 10:00 a.m. – 5:00 p.m., weekends
  • 11:00 a.m. – 3:00 p.m., weekdays

Houses Closed Houses will be closed for 1 – 2 hours while jury evaluations are taking place October 13 – 16 and October 18 – 19. Times vary for each house. All day Wednesday, October 17, the houses are closed for controlled temperature and relative humidity measurements.

Consumer Workshops The U.S. Department of Energy (DOE) and other event sponsors are offering solar energy and energy efficiency workshops for consumers. Workshops will not be offered on Thursday, October 18, during Building Industry Day. See the daily schedule below for workshop offerings.

Ask the Experts Panel Weekends only: 11:00 am – 1:00 pm and 3:30 pm – 5:30 pm.

A group of green-building experts, coordinated by sponsor Blue Egg, will be on hand to answer questions. (Each presentation will be 30 min, with 10 min for Q&A)

Educational Exhibits Two educational exhibits are open during the following times:

  • 10:00 a.m. – 5:00 p.m., weekends
  • 11:00 a.m. – 3:00 p.m., weekdays

Energy Storage: On the Hill, On the Blogs

Posted by Brad Johnson Wed, 03 Oct 2007 18:03:00 GMT

This morning saw the House Science and Technology Committee host a hearing on Energy Storage Technologies: State of Development for Stationary and Vehicular Applications, with testimony from a wide array of government, industry, and research experts.

In addition, A Siegel at Daily Kos disscusses advances in “hydro pumped storage”, which uses excess energy from a hydroelectric plant to pump water to a reservoir which can be used to generate power when demand exceeds output.

Energy Storage Technologies: State of Development for Stationary and Vehicular Applications

Posted by Brad Johnson Wed, 03 Oct 2007 14:00:00 GMT

_Witnesses_ Panel 1
  • Patricia Hoffman, Deputy Director Research and Development, U.S. Department of Energy Office of Electricity Delivery and Energy Reliability
  • Brad Roberts, Chairman, Electricity Storage Association
  • Larry Dickerman, Director Distribution Engineering Services for American Electric Power
  • Tom Key, Technical Leader, Renewable and Distributed Generations, Electric Power Research Institute
Panel 2
  • Lynda Ziegler, Sr. Vice President for Customer Services at Southern California Edison
  • Mary Ann Wright, Vice President and General Manager Hybrid Systems for Johnson Controls
  • Denise Gray, Director Hybrid Energy Storage Systems, General Motors

Committee press release: Today, the House Committee on Science and Technology’s Subcommittee on Energy and Environment considered the status of developing competitive energy storage systems for stationary and vehicular applications – both of which could provide significant economic and environmental benefits for improving the nation’s energy storage capability.

“Better energy storage technologies will also enable us to operate electric utilities in a more flexible and efficient manner. Energy storage can also help us respond to power outages more efficiently, providing greater electricity reliability. This could be vital for maintaining operations at critical facilities such as hospitals during a natural disaster,” said Subcommittee Chairman Nick Lampson (D-TX).

In the context of the hearing, the Subcommittee also discussed draft legislation entitled Energy Storage Technology Advancement Act of 2007, a bill soon to be introduced by Committee Chairman Bart Gordon (D-TN).

“Energy storage is also critical for the next generation of vehicles, which will help reduce our dependence on foreign oil and lower greenhouse gas emissions,” added Chairman Gordon. “I also think public-private partnerships can improve the production process for advanced vehicle components so that the U.S. becomes a leader in manufacturing these breakthrough technologies. With so many benefits of energy storage technologies, I think additional federal investment to research, test and advance these systems should be a priority.”

Broad deployment of energy storage technologies can help to improve the operational efficiency and reliability of our electricity delivery system, and allow for more diversified electricity sources and vehicle models that reduce our dependence on foreign energy supplies and address concerns about global climate change. However, there is concern that the U.S. is falling behind in the race to develop and manufacture a wide range of energy storage technologies, and a significant effort is underway to build up a domestic energy storage industry for both stationary and vehicular applications.

At this hearing Committee Members sought a better understanding of the state of energy storage technologies and how the U.S. Department of Energy’s (DOE) energy storage program could further advance these technologies.

Today, electricity is generated as it is used, with very little electricity being stored for later use. While this system has worked for decades, it is not very efficient. Demand for power varies greatly throughout the day and throughout the year as demands for lighting, heating and cooling fluctuate through the seasons. Because the capacity for generation of power matches the consumption of power, the electricity supply system must be sized to generate enough electricity to meet the maximum anticipated demand, or peak demand.

This inefficiency becomes more evident when considering that it is possible that the peak electricity demand for any given year could be for a very short period – a few days or even hours. Rather than maintain massive generation systems that are designed around a short-lived peak demand, energy storage technologies would provide a means to stockpile energy for later use and essentially reduce the need to generate more power during times of peak electricity demand.

Advances in energy storage technologies are often regarded as key to increasing the reliability and widespread use of many renewable energy technologies. Together, potential benefits from broad deployment of energy storage technologies would help to improve our energy security. Because our economy relies heavily on an affordable and reliable electricity delivery system, the energy security benefits achieved from greater use of energy storage systems could be significant.

“With both stationary and mobile energy storage, we cannot let an opportunity to establish a domestic manufacturing base for these technologies pass us by. And unfortunately, we may already be losing this race. New R&D activities with the Department of Energy are critical to advancing energy storage technologies, and we should pursue this aggressively to ensure U.S. participation in this field,” added Chairman Lampson.

Witnesses reported that there are a number of promising energy storage technologies being developed for different applications, but there is still a role for the federal government to help accelerate energy storage technologies into the marketplace.

Ms. Lynda Ziegler, Sr. Vice President for Customer Services at Southern California Edison testified, “We believe that with continued engineering advances and appropriate public policy support, the widespread use of advanced batteries in plug-in vehicles and in stationary storage applications will become one of the nation’s most effective strategies in the broader effort to address energy security, reduce greenhouse gas emissions and reduce air pollutants.”

Ms. Mary Ann Wright, Vice President and General Manager Hybrid Systems for Johnson Controls added, “I passionately believe that electrification of the vehicle powertrain in part or in whole can make a dominant contribution to America’s energy security and transportation sustainability. Electric powertrains by nature are incredibly more efficient than their internal combustions counterparts.”

S.1543, to establish a national geothermal initiative to encourage increased production of energy from geothermal resources

Posted by Brad Johnson Wed, 26 Sep 2007 14:00:00 GMT

Panel I
  • Olafur Ragnar Grimsson, president of Iceland
Panel II
  • Alexander Karsner, assistant secretary of Energy for energy efficiency and renewable energy
  • Mark Myers, director, U.S. Geological Survey
Panel III
  • Susan Petty – AltaRock Energy
  • Lisa Shevenell – Mackay School of Earth Sciences and Engineering, University of Nevada
  • David R. Wunsch – New Hampshire Geological Survey
  • Kenneth H. Williamson – geothermal consultant

National Hurricane Research Initiative

Posted by Brad Johnson Tue, 25 Sep 2007 16:17:00 GMT

At last week’s American Meteorological Society Hurricanes and Climate Change panel, Greg Holland highlighted the importance of the National Hurricane Research Initiative Act of 2007 (HR 2407, S 931).

The bill, introduced by the Florida delegation in the spring, would establish a multi-agency board to set strategy and make grants for hurricane research. From CRS:
Requires the Under Secretary for Oceans and Atmosphere of the Department of Commerce and the Director of the National Science Foundation (NSF) to establish a National Hurricane Research Initiative and to cooperate with other specified federal agencies to carry it out. Requires such Initiative to set research objectives (based on a National Science Board report on the need for such Initiative) to: (1) make recommendations to the Board; (2) assemble the expertise of U.S. science and engineering capabilities through a multi-agency effort focused on infrastructure, the natural environment, and improving understanding of hurricane prediction, intensity, and mitigation on coastal populations; and (3) make grants for hurricane research, including regarding hurricane dynamics, modification, and observation, air-sea interaction, relationships between hurricanes and climate, predicting flooding and storm surge, coastal infrastructure, building construction, emergency communication networks, information utilization by public officials, and sharing computational capability. Directs the White House Office of Science and Technology Policy, through the National Science and Technology Council, to coordinate U.S. activities related to the Initiative as a formal program with a well-defined organizational structure and execution plan. Directs the Under Secretary and the Director to: (1) establish a National Infrastructure Database to catalog infrastructure, provide information to improve information public policy related to hurricanes, and provide data to improve researchers’ abilities to measure hurricane impacts in order to improve building codes and urban planning; and (2) develop a National Hurricane Research Model to conduct integrative research and facilitate the transfer of research knowledge to operational applications

Hurricanes and Climate Change: What's Resolved and What Remains To Be Resolved? 2

Posted by Brad Johnson Fri, 21 Sep 2007 16:00:00 GMT

Is there a scientific basis for anticipating that human-induced climate warming does and/or will affect hurricanes in some way, over and above natural climate variability? Do observations and model simulations support that expectation, or are there issues with data and observations that make the task of sorting out linkages more difficult? If the latter, what are the observational and data issues that continue to make this a challenging scientific problem? What do we know now that we did not know two years ago? What role do model simulations play in helping to sort out linkages, if any, between global warming and hurricanes, in the absence of data/observation or the presence of unreliable data/observations? How can we best develop a coordinated national effort to provide urgently required information for planning, community response and infrastructure development.

  • Dr. Anthony Socci, Senior Science Fellow, American Meteorological Society
  • Dr. Kerry Emanuel, Professor of Atmospheric Science, Massachusetts Institute of Technology, Cambridge, MA
  • Dr. William K. M. Lau, Chief, Laboratory for Atmospheres, NASA/Goddard Space Flight Center, Greenbelt, MD
  • Dr. Greg Holland, Director, Mesoscale and Microscale Meteorology Division, Earth and Sun Systems Laboratory, National Center for Atmospheric Research, Boulder, CO
  • Dr. Gabriel Vecchi, Research Oceanographer, Climate diagnostics Group, Geophysical Fluid Dynamics Lab/NOAA, Princeton, NJ.
  • Thomas R. Knutson, Research Meteorologist, Climate Dynamics and Prediction Group, Geophysical Fluid Dynamics Lab/NOAA, Princeton, NJ.

Overview of Hurricanes and Climate Change (a.k.a. global warming)

The understanding of climate change, including its effects on hurricanes, rests on three essential scientific techniques: theory, observation, and computational modeling. Each of these three approaches has unique strengths and limitations. In this talk, I will discuss the application of each of these to understanding the effect of climate change on hurricane activity and demonstrate that while each approach is compromised by uncertainties, taken together they present a persuasive picture of increasing hurricane risk as the climate warms.


The science of hurricanes and climate rests on all three of observations, theory, and computer models.

There’s no significant trend in the number of storms recorded per year, nor do we know what determines that number.

Tropical cyclone power dissipation. There’s a strong correlation between cyclonic power dissipation and sea-surface temperature before 1987, then the record is highly variable.

We no longer fly planes into storms in the western Pacific. We can’t do everything with satellites.

Good correlation in the Atlantic. Since the 1980s Atlantic hurricane strength has doubled.

Paleotempestology: Jeff Donnelley, Jon Woodruff, Phil Lane, WHOI. May be able to show longer record of changing hurricane activity.

We have the theory of potential intensity. Observed potential intensity has gone up dramatically since 1990.

What is causing SST changes in the northern hemisphere? The tropical Atlantic’s SST changes are consistent with the entire northern hemisphere SST.

You can explain a lot of the difference between Atlantic SST and global mwan temperatures by aerosol forcing.

There are beginnings of downscaling techniques to seed GCMs with fledgling cyclonic storms. Their preliminary results show decreases overall, some increases. Decrease in frequency but increase in intensity and rainfall. But they predict less change than we have already observed over the past 50 years.

Rainfall Extremes, Saharan Dust, Tropical Cyclones and Climate Change

Trends in tropical rainfall are more readily detectable in the form of changes in rainfall characteristics, rather than in rainfall total. From satellite data, we find that in the tropics there is a strong positive trend in extreme heavy and very light rains, coupled to a negative trend in moderate rain. Climatologically over tropical oceans, a large portion (over 60%) of most extreme heavy rainfall (top 5%) can be identified with those coming from tropical cyclones. Over the Atlantic, the contribution of tropical cyclones to heavy rain events has almost doubled in the last quarter century. Over the Pacific basin, the increase is lesser at about 10%. The differences in the basin may be related to the percentage change in the warm pool (SST> 28 ºC) areas in both oceans. Overall, tropical cyclones appear to be feeding more extreme rainfall events in the tropics in recent decades.

Saharan dust can affect tropical cyclones development, and may be a factor contributing to long-term hurricane statistics and possibly in seasonal hurricane forecasts. The Saharan Air Layer (SAL) can suppress tropical cyclogenesis through entrainment of hot, dry air into a developing cyclone, increasing stability and denying the developing system of its moisture supply. Saharan dust may also pre-condition the Atlantic, cooling the ocean surface through attenuation of solar radiation, during the early hurricane season. Additionally, differential radiative heating of the atmosphere by Saharan dust may induce changes in the large-scale circulation over the West Africa and Atlantic region. All these effects may provide a feedback on the coupled ocean-atmosphere system over the Atlantic, modulating the seasonal statistics of hurricanes. Analyses of satellite data and historical records show a more (less) active hurricane season is generally associated with less (more) Saharan dust over the Atlantic.

Global Warming and Hurricane Activity

The past century has seen North Atlantic hurricanes occurring in three periods of relatively stable frequency separated by sharp upward transitions. Each period has experienced 50% more hurricanes than the previous one and each was associated with a distinct change in eastern Atlantic sea surface temperatures (SSTs). After taking account of missing cyclones in earlier periods due to poor observing systems, we have experienced an 80-100% increase in hurricane frequency over since the early 1900s. Natural variability has contributed to some of the observed changes, but the compelling conclusion is that the overall increase has been substantially influenced by greenhouse warming. Superimposed on this increasing hurricane frequency is a completely independent oscillation in the proportions of major and minor hurricanes (compared to all storms). This oscillation has no distinguishable net trend and may arise largely from internal oscillations of the climate system. The period of enhanced major hurricane activity during 1945-1964 arose entirely from this oscillation. Unfortunately, the period since 1995 has experienced a double-whammy of a sharp increase in both numbers of hurricanes and the proportion of major hurricanes.

This heightened hurricane activity is unlikely to decrease in the future and we may see further increases. If so, current planning, building and coastal levee systems may prove to be inadequate, leading to more New Orleans-type disasters. The National Hurricane Research Initiative is designed to provide us with the tools to assess this future threat, to develop improved forecast and community response approaches, and to establish coastal planning approach to minimize the potential for future disasters. It is an initiative of critical national importance, which deserves strong and urgent support.

Long-term changes in Tropical Cyclone Activity: Looking Forward and Looking Back

To understand how human-induced climate change influences global and Atlantic tropical cyclone activity it is essential to have accurate records of past tropical cyclone variations and to model future climate conditions. The ways that tropical cyclones are measured have evolved over time, thereby influencing the homogeneity of the record. Statistical techniques can help, however, to estimate these deficiencies in the century-scale record. To project future conditions, global climate models (GCMs) – though not perfect – are our best tools. Although current computing power prevents GCMs from explicitly representing tropical cyclones, GCMs do indicate robust changes in many of the large-scale environmental conditions that are known to influence tropical cyclone activity, such as the thermodynamic structure of the atmosphere and vertical wind shear. Analyses of climate models and reconstructions of past tropical cyclone records indicate:

  • Observational evidence for century-scale changes in tropical cyclone activity is mixed, depending on the metric chosen, on the statistical correction applied to the data and on the time interval being examined.
  • Climate model projections of the Atlantic and East Pacific response to global warming exhibit mixed changes in cyclone-relevant parameters, with both an increase in thermodynamic potential intensity of tropical cyclones and an increase in vertical wind shear. More refined methods are needed to understand the detailed response of tropical cyclones to these environmental changes.
  • Outside of the Atlantic and East Pacific, projected changes to both the thermodynamic potential and the wind shear indicate conditions more favorable to tropical cyclone activity under global warming.
  • Although questions remain about the detailed response of tropical cyclone activity to human-induced climate change, we have relatively much greater confidence in the projected response of other large-scale climate conditions to increasing greenhouse gases (e.g., global warming, surface temperatures over land warm faster than over ocean, Arctic sea ice reduction, increase in ocean heat content, etc.).

Estimating how many tropical storms we missed before satellite observations, based on ship tracks. We have real observation gaps during WWI and WWII.

Model results show temperatures and wind shear increasing in most areas, not pointing in a clear direction for potential intensity. In the West Pacific and Indian Ocean, however, the trends all point toward increased cyclonic frequency.

Modeling the Response of Atlantic Hurricanes to Climate Variability and Change

A pressing question concerning ongoing global warming is whether human-caused warming of the planet has had any discernible impact on Atlantic hurricane activity. Confidence in any such a link is currently hampered by both data quality issues for the hurricane observational record and by limited work specifically targeting this question from a modeling perspective. Based on existing studies to date:

  • Observed data, including consideration of data problems, give conflicting indications on whether there have been significant increases in Atlantic tropical storm and hurricane numbers. U.S. land-falling numbers have not increased. Models have not yet reproduced some reported long-term (~100 yr) increasing trends in basin-wide numbers.
  • High resolution models consistently project increasing hurricane intensities and rainfall rates for the late 21st century, but whether there will be more or fewer hurricanes remains uncertain.
  • A new modeling approach reproduces many important aspects of Atlantic hurricane activity observed since 1980, and thus shows promise as a tool for both understanding past variations and for making more reliable projections of future hurricane activity.

Biographies Dr. Kerry Emanuel is a professor of atmospheric science at the Massachusetts Institute of Technology, where he has been on the faculty since 1981, after spending three years as a faculty member at UCLA. Professor Emanuel’s research interests focus on tropical meteorology and climate, with a specialty in hurricane physics. His interests also include cumulus convection, and advanced methods of sampling the atmosphere in aid of numerical weather prediction. He is the author or co-author of over 100 peer-reviewed scientific papers, and three books, including Divine Wind: The History and Science of Hurricanes, recently released by Oxford University Press and aimed at a general audience, and What We Know about Climate Change, published by the MIT Press.

Dr. William Lau is currently the Chief of the Laboratory for Atmospheres at NASA, Goddard Space Flight Center, and Adjunct Professor at Department of Meteorology U. of Maryland. His research work spans three decades and covers a wide range of topics including climate dynamics, tropical and monsoon meteorology, ocean-atmosphere interaction, and climate variability and change.

Dr. Lau has received numerous awards for his research and his scientific leadership, including among others, the AMS Meisinger Award in 1997; the John Lindsay Award,1998; the NASA Exceptional Science Achievement Award, 1991; the William Nordberg Award (GSFC highest award in Earth Sciences), 2002. He is a Goddard Senior Fellow, a fellow of the American Meteorological Society since 1988, and a fellow of the American Geophysical Union, 2007. Dr. Lau has published over 190 refereed papers, book Chapters in refereed journals. He is the principal author of a book “Intraseasonal Variability in the Tropical Ocean-Atmosphere System”, published in 2006. Dr. Lau received his B. Sc. in Physics and Mathematics from the University of Hong Kong, and his Ph.D. in Atmospheric Sciences from the University of Washington, Seattle.

Dr. Greg Holland is currently Director of the Mesoscale and Microscale Meteorology Division at the National Center for Atmospheric Research in Boulder, where he is involved scientifically with hurricane landfall, genesis and climate related work. He is a fellow of the American Meteorological Society as well as the Australian Meteorological and Oceanographic Society. Dr. Holland has several areas of research interests which have carried through to applications and include improved forecasting of tropical cyclone motion, scale interactions associated with cyclogenesis, establishment of field facilities, establishment of programs on coastal impacts of tropical cyclones and the development of Unmanned Aerial Vehicles (UAVs).

Dr. Holland has authored or co-authored more than 120 peer-reviewed scientific journal articles and book chapters, as well as dozens of planning documents, scientific prospectuses and workshop papers. He has given several hundred invited talks worldwide, as well as many contributed presentations at national and international conferences on hurricanes and related. He has also convened several national and international workshops, and served on several national and international committees and science-planning initiatives.

Dr. Gabriel Vecchi is a Research Oceanographer at the Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey, where he has been working since 2003. GFDL, which is part of the National Oceanic and Atmospheric Administration (NOAA), is one of the world’s leading climate modeling centers. Dr. Vecchi received a B.A. in Mathematics from Rutgers University, and an M.S. in Oceanography, an M.S. in Applied Mathematics and a Ph.D. in Oceanography from the University of Washington. His scientific research focuses on the interactions between the atmosphere and oceans on timescales from weeks to centuries. His recent research has focused on understanding long-term changes to tropical circulation and variability, including characterizing changes relevant to the possible impact of climate change on hurricanes.

Dr. Vecchi currently serves on the Climate Variability and Predictability (CLIVAR) Indian Ocean Panel, and is an Associate Editor of the Journal of the Atmospheric Sciences. His awards include the Presidential Early Career Award for Scientists and Engineers (PECASE), the American Geophysical Union’s Editor’s Citation for Excellence in Refereeing for Geophysical Research Letters, and the Cook College, Rutgers University Marine Sciences Student of the Year. He has over 30 publications in peer-reviewed science journals or book chapters.

Thomas R. Knutson has been a Research Meteorologist at the Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey since 1990. GFDL, which is part of the National Oceanic and Atmospheric Administration, is one of the world’s leading climate modeling centers. Mr. Knutson has authored several modeling studies in major scientific journals on the potential impact of climate change on hurricanes. He now leads a project at GFDL aimed at simulating past and future Atlantic hurricane activity using regional high-resolution models.

He currently serves on the World Meteorological Organization (WMO) Expert Team on Climate Impacts on Tropical Cyclones, and was a major contributor to the December 2006 WMO “Statement on Tropical Cyclones and Climate Change”. He is a member of a U.S. Climate Change Science Program (CCSP) committee developing an assessment report on “Weather and Climate Extremes in a Changing Climate,” the AMS Climate Variability and Change Committee, and is an Associate Editor of the Journal of Climate. Mr. Knutson has over 30 publications in peer-reviewed science journals or book chapters.

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