Wednesday, October 04, 2006

Suppressed NOAA hurricane consensus statement

I copiied this from another blog. They did more research, and you might want to read their whole introduction, which also has some history of the supression effort. Follow the link below the title.

NOAA Fact Sheet: Atlantic Hurricanes and Climate

What has been Atlantic hurricane activity during the 20th Century?

-- Atlantic hurricane seasons since 1995 have been significantly more active, e.g. more hurricanes and more intense hurricanes, that the previous two decades (figure 1)
-- Earlier periods, such as from 1945 to 1970 (and perhaps earlier), were apparently as active as the most recent decade.
-- The past decade has seen increased U.S. landfalls, however periods of even higher landfalls occurred early in the century (figure 2)
-- Strong natural decadal variations, as well as changes in data quality, density, sources, and methodologies for estimating hurricane strengths, lie at the heart of arguments whether or not a global warming contribution to a trend in tropical cyclone intensities can be detected.

How have ocean temperatures varied?

-- Over the 20th Century, global ocean temperatures and sea surface temperatures in the main development region (MDR) for hurricanes in the tropical Atlantic, (and Gulf of Mexico) have warmed at similar rates, indicating a role for global warming in these regions. (Figure 3)
-- Anomalous MDR, tropical Atlantic temperatures were significantly warmer than the global average from about 1930 to 1970 and after 2000. This warming is attributed to the Atlantic Multi-decadal Oscillation (AMO)

What factors influence seasonal to multi-decadal hurricane activity

-- Hurricanes respond to a variety of environmental factors besides local ocean temperatures.
-- The tropical multi-decadal phenomenon and the El Nino/La Nina cycle are important factors in determining the conditions for seasonal to multi-decadal extremes in hurricane activity.
-- Research indicates that global warming can also increase hurricane intensities; there is less evidence for impacts on frequency.

How long will the current active period last?

-- Scientists disagree as to whether currently a sound basis exists for making projections on how long the current active period will last. The viewpoints are:

o Limited understanding of natural decadal variability, combined with its irregular temporal behavior, preclude definitive statements about how long the active period will last. (NOAA)
o One might expect ongoing high levels of hurricane activity and U.S. landfalls for the next decade and beyond since the previous active period (1945-1970) lasted at least 25 years. (NOAA)
o Because of global warming the active period could persist

Programs of improvements to data sets, diagnostic studies for improved understanding, and systematic numerical experimentation studies will help to reveal the underlying causes for the recent active period and to predict how long the period of increased activity will last. NOAA is actively engaged in each of these activities.

Key Problems NOAA is working on

-- Understanding the dynamics of the AMO, its links to the larger-scale tropical climate variability, and developing an ocean monitoring and decadal prediction capability
-- Improving the quality and scope of hurricane relevant data sets
-- Numerically simulating and ultimately understanding seasonal to decadal hurricane variability
-- Understanding whether or not and to what degree anthropogenic forcing is having an influence on hurricanes
-- Developing a predictive understanding of global climate variability and trends and the impacts of these on extreme events
-- Making improvements to short range hurricane track and intensity forecasts through improved models and development of additional capabilities for hurricanes.

NOAA Resources for Additional Information

-- NWS/NCEP/CPC intraseasonal to multi-season climate forecasts; seasonal hurricane forecasts; diagnostic studies of major climate anomalies; real time monitoring of climate.
-- NWS/NCEP/TPC/NHC issue daily and seasonal (in conjunction with CPC and HRD) operational hurricane forecasts; maintain and update the official Atlantic and Northeast Pacific hurricane databases from which observational climate studies are conducted
-- NESDIS/NCDC official archive for climate data sets; development of global tropical cyclone databases, analysis of historical frequency and strength of Atlantic Basin hurricanes to support engineering design and levee rebuilding in New Orleans, analyses of climate trends, monitoring and historical perspective on current seasons.
-- OAR/AOML/HRD & PHoD physical understanding of hurricane dynamics through use of research aircraft and field studies; improvements to hurricane track and intensity forecasts; monitoring of Atlantic ocean circulations; studies of Atlantic climate
-- OAR/GFDL studies of climate variability and change; development and use of the required climate models; development of models used for operational hurricane forecasts by NOAA and the NAVY; numerical studies of climate impacts on hurricanes and their decadal variability
-- OAR/ESRL diagnostic studies of climate variability and changes; impacts of climate on extreme events.
-- NOAA Climate Office intramural and extramural support for development of a predictive understanding of the climate system, the required observational capabilities, delivery of climate services.

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