NOAA Atlantic Hurricane Season Outlook evasive on climate change

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NOAA’s 2010 Atlantic Hurricane Season Outlook, which predicts a likelihood of 8-14 hurricanes and 3-7 major hurricanes, was drafted by the same NOAA meteorologists who presented the notorious Bush-era hurricane season wrap-up in 2005 after Katrina that explicitly denied any link between anthropogenic global warming and increased hurricane intensity and failed to mention research by NOAA scientists on projected future increases that suggested otherwise. This is an active area of research with much uncertainty. But if presenting a high-profile hurricane outlook that completely evades any reference to hurricanes and climate change is NOAA’s idea of how to provide “climate services” to the nation, then there is cause for concern.

Post by Rick Piltz

Also see the June 1 post by Nick Sundt on the World Wildlife Fund climate blog: “NOAA Sees Potential for “Hyperactive” Hurricane Season; Record High Sea Surface Temperatures Among Contributing Factors”

The National Oceanic and Atmospheric Administration press release on NOAA’s 2010 Atlantic Hurricane Season Outlook, issued May 27, includes the following:

2010 Atlantic Hurricane Season Outlook: Summary

NOAA’s 2010 Atlantic Hurricane Season Outlook calls for an 85% chance of an above normal season. The outlook indicates only a 10% chance of a near-normal season and a 5% chance of a below-normal season. See NOAA definitions of above-, near-, and below-normal seasons. The Atlantic hurricane region includes the North Atlantic Ocean, the Caribbean Sea, and the Gulf of Mexico.

This outlook reflects an expected set of conditions that is very conducive to increased Atlantic hurricane activity. This expectation is based on the prediction of three climate factors, all of which are conducive historically to increased tropical cyclone activity. These climate factors are:

1) the tropical multi-decadal signal, which has contributed to the high-activity era in the Atlantic basin that began in 1995,

2) exceptionally warm sea surface temperatures in the tropical Atlantic Ocean and Caribbean Sea (called the Main Development Region), and

3) either ENSO-neutral or La Niña conditions in the tropical Pacific, with La Niña becoming increasingly likely. In addition, dynamical models forecasts of the number and strength of tropical cyclones also predict a very active season.

The conditions expected this year have historically produced some very active Atlantic hurricane seasons. The 2010 hurricane season could see activity comparable to a number of extremely active seasons since 1995. If the 2010 activity reaches the upper end of our predicted ranges, it will be one of the most active seasons on record.

We estimate a 70% probability for each of the following ranges of activity this season:

14-23 Named Storms,
8-14 Hurricanes
3-7 Major Hurricanes
An ACE [Accumulated Cyclone Energy] range of 155%-270% of the median.

The seasonal activity is expected to fall within these ranges in 7 out of 10 seasons with similar climate conditions and uncertainties to those expected this year. They do not represent the total possible ranges of activity seen in past similar years. …

While NOAA does not make an official seasonal hurricane landfall outlook, the historical probability for multiple U.S. hurricane strikes, and for multiple hurricane strikes in the region around the Caribbean Sea, increases sharply for exceptionally active (i.e. hyperactive) seasons (ACE > 175% of median).

Among the three key factors NOAA cites as suggesting a particularly active season is record warm sea surface temperatures (SSTs) in the region of the Atlantic Ocean where storms often develop. NOAA explains:

A set of factors likely combined to produce the record warmth now in the Atlantic. Based on the observations, the likely cause of the extreme Atlantic warming is a pronounced weakening of the northeasterly trade winds that led to a sharp increase in Atlantic SSTs during February and March. This increase occurred in combination with the typical warming associated with El Niño. It is also superimposed upon the background warming associated with the warm Atlantic phase of the multi-decadal signal that has been in place since 1995, and with longer term trends.

Though the hurricane outlook does not specify what the “longer term trends” are and how they contribute to the potentially “hyperactive” hurricane season, NOAA and others have elsewhere made it clear that SSTs are rising in the Main Development Region, that rising greenhouse gases very likely have contributed to the rising SSTs, and that the higher SSTs are correlated with more energetic hurricane seasons.

However, despite the salience and significance to the science community, policymakers, and the public of the question of what the relationship between climate change and hurricane activity might be, the authors of NOAA’s hurricane outlook said not one word about the possible observed or projected connection between greenhouse gases, rising sea surface temperatures, and hurricane intensity.

According to Weather and Climate Extremes in a Changing Climate (2008), a report from the U.S. Global Change Research Program (USGCRP) for which NOAA was the lead agency:

It is very likely that the human-induced increase in greenhouse gases has contributed to the increase in sea surface temperatures in the hurricane formation regions. Over the past 50 years there has been a strong statistical connection between tropical Atlantic sea surface temperatures and Atlantic hurricane activity as measured by the Power Dissipation Index (which combines storm intensity, duration, and frequency). This evidence suggests a human contribution to recent hurricane activity. However, a confident assessment of human influence on hurricanes will require further studies using models and observations, with emphasis on distinguishing natural from human-induced changes in hurricane activity through their influence on factors such as historical sea surface temperatures, wind shear, and atmospheric vertical stability.

In June 2009 NOAA Administratrator Jane Lubchenco and White House Office of Science and Technology Policy Director John Holdren submitted to Congress the report, Global Climate Change Impacts in the United States. Tom Karl, the director of the NOAA National Climatic Data Center, newly appointed chair of the USGCRP, and lead NOAA official for Climate Services, was a lead author of the report.

Here is what Global Climate Change Impacts in the United States says about the connection between rising SSTs and more active hurricane seasons:

Tropical storms and hurricanes develop and gain strength over warm ocean waters. As oceans warm, they provide a source of energy for hurricane growth. During the past 30 years, annual sea surface temperatures in the main Atlantic hurricane development region increased nearly 2°F. This warming coincided with an increase in the destructive energy (as defined by the Power Dissipation Index, a combination of intensity, duration, and frequency) of Atlantic tropical storms and hurricanes. The strongest hurricanes (Category 4 and 5) have, in particular, increased in intensity.”

[There is a] strong correlation between hurricane power and sea surface temperature in the Atlantic and the overall increase in both during the past 30 years….

Evidence of increasing hurricane strength in the Atlantic and other oceans with linkages to rising sea surface temperatures is also supported by satellite records dating back to 1981. An increase in the maximum wind speeds of the strongest hurricanes has been documented and linked to increasing sea surface temperatures.

An expert team established by the World Meteorological Organization (WMO) published a detailed review article, “Tropical cyclones and climate change,” in the February 21, 2010, issue of Nature Geosciences. This review – co-authored by Thomas R. Knutson, John L. McBride, Johnny Chan, Kerry Emanuel, Greg Holland, Chris Landsea, Isaac Held, James P. Gosslin, A.K. Srivastava, and Masato Sugi – concluded, in part:

Whether the characteristics of tropical cyclones have changed or will change in a warming climate – and if so, how – has been the subject of considerable investigation, often with conflicting results….[I]t remains uncertain whether past changes in tropical cyclone activity have exceeded the variability expected from natural causes. However, future projections based on theory and high-resolution dynamical models consistently indicate that greenhouse warming will cause the globally averaged intensity of tropical cyclones to shift toward stronger storms….[H]igher resolution modelling studies typically project substantial increases in the frequency of the most intense cyclones, and increases of the order of 20% in the precipitation rate within 100 km of the storm centre.

Given the range of authors and viewpoints represented in this review article, this may be the closest we have to a current “consensus” in the research community. (The full text of the paper can be accessed via the WMO by clicking on this link and running the 4.5 MB executable file.)

We suggest that Jane Lubchenco and Tom Karl intervene to see to it that the NOAA “climate service” of presenting an annual hurricane outlook be upgraded to include some summary discussion, and certainly some links, on the climate change-hurricane issue, to add something about the “longer term trends” that the recently released outlook summary mentions, then abandons.

Addressing this issue of providing the public with a broader perspective should involve additional NOAA participation beyond current hurricane outlook co-authors like Gerry Bell and Chris Landsea.

For the record, lest history be swept under the rug:

•  Gerry Bell has a history of dismissing any connection with climate change, including an infamous incident in late 2005 described in the Government Accountability report, Redacting the Science of Climate Change: An Investigative Report (2007), by Tarek Maasarani. 

•  Chris Landsea is a former protégé of notorious global warming contrarian/denier Bill Gray and has argued against the possibility of a significant connection between rising GHG concentrations and hurricane activity. Most recently, on NOAA’s climate services website (”Does a Warmer World Make Hurricanes Stronger?”) he says “there is a very tiny sensitivity” of hurricanes to increases in atmospheric greenhouse gas concentrations.

In contrast, Thomas R. Knutson of NOAA’s Geophysical Fluid Dynamics Laboratory lab (in “Global Warming and Hurricanes: An Overview of Current Research Results”) acknowledges the possibility that “human activity may have already caused substantial changes that are either below the ‘detection threshhold’ or are not properly modeled yet (e.g., aerosol effects).”

Here from the report Redacting the Science of Climate Change is an account of what Gerry Bell said at a NOAA press conference at the end of the 2005 hurricane season. A few months after Hurricane Katrina, at a moment when considerable public attention was focused on the possible connection between global warming and hurricanes, and thus a balanced perspective urgently needed, NOAA Administrator Conrad Lautenbacher, a self-described loyal servant of the Bush-Cheney White House, engineered an entirely one-sided presentation designed to steer public attention away from any connection between greenhouse gas emissions and a possible increase in hurricane intensity, with Gerry Bell as a mouthpiece:

Max Mayfield and Gerry Bell were present to answer reporters’ questions on NOAA’s behalf. As director of the Tropical Prediction Center/National Hurricane Center (NHC) and founding meteorologist of NOAA’s seasonal Atlantic hurricane outlooks respectively, this line-up was not, in itself, inappropriate. On the other hand, the NHC and the Climate Prediction Center, where Bell is stationed, fall under the National Weather Service and deal primarily with short-term climate variability and forecasting. Thus, neither scientist was a specialist in long-term climate dynamics; nonetheless they fielded all inquiries concerning global warming and hurricanes. Indeed, one NOAA official noted in an email that “Max won’t believe the research until it is unanimous.356

As reported in the New Republic, when asked about recent reports at the press conference that “global warming may have been responsible for the intensity of the storms,” Bell states categorically “we see absolutely no indication whatsoever that greenhouse warming is causing any of it.” Instead the storms’ intensity was “part of the multi-decadal signal that we see. It’s not related to greenhouse warming.357

That was a categorical statement of one side of a complex and ongoing scientific exploration. The one-sidedness in the NOAA media presentation was matched later in Congressional testimony by Max Mayfield. Coupled with evidence that NOAA and the White House were colluding to control which NOAA scientists were and were not allowed to talk with the media about hurricanes and climate change – skeptic Chris Landsea was elevated because his views suited the climate politics of the Bush White House, for example, while Tom Knutson, whose research pointed to a likely future increase in intense hurricanes under anthropogenic global warming, was restricted – NOAA’s public positioning on this issue was seen as lacking in integrity, including among NOAA scientists.

NOAA’s 2010 hurricane outlook lists only five references: two co-authored by Bell, one co-authored by Landsea, and two by Bill Gray. None of the references are more recent than 2006.

As we head into what may turn into a dramatic hurricane season in which the connections to climate change are likely to be actively discussed, surely the current NOAA leadership can offer the public more food for thought than this.  When NOAA representatives step to the microphone during this hurricane season, we’ll be watching to see who is in the cast of characters, and whether their discussion of hurricanes ever includes the larger context of global climatic disruption.

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