Pacific Warming, Atlantic Hurricanes & Global Climate Non-Disruption

Source:  Resilient Earth

by Doug L. Hoffman

In an example of what Presidential Science Advisor John Holdren would label ?global climate disruption,? a 2009 report claimed that warming surface water in the Pacific Ocean was having an impact on the frequency of tropical storms. Moreover, landfalls along the Gulf of Mexico coast and Central America were supposedly increased. Now a new study appearing in Geophysical Research Letters has found these claims to be untrue. It seems that there is little correlation between the Atlantic hurricane activity and Pacific Ocean warming. In fact, the increased tropical storm frequency in 1969 and 2004 can be readily explained by increased warmth in the Atlantic where the storms form. Once again, those looking for a smoking gun in the form of human caused climate change are forced to look elsewhere.

In July 2009, Kim et al. suggested that the influence of sea surface warming events in the Central Pacific Ocean contributed to more frequent landfall of North Atlantic tropical cyclones in the Gulf of Mexico and Central America. Their Science report, ?Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones,? concluded that the location of the Pacific warming affects the location of cyclone (hurricane) formation and the tracks of tropical cyclones.

?Two distinctly different forms of tropical Pacific Ocean warming are shown to have substantially different impacts on the frequency and tracks of North Atlantic tropical cyclones,? the report stated. ?The eastern Pacific warming (EPW) is identical to that of the conventional El Niño, whereas the central Pacific warming (CPW) has maximum temperature anomalies located near the dateline.? If that were true, the predictability of Atlantic hurricane behavior could be improved by taking into account the state of the Pacific.

Composites of SST anomalies during August to October.Shown in the figure above are composites of sea surface temperature (SST) anomalies during the August to October period for (A) EPW, (B) CPW, and (C) EPC. (D) The average number of North Atlantic tropical cyclones per month from June to November for climatology (gray bar), EPW (red), CPW (green), and EPC (blue). The time series has been detrended to eliminate the effects of decadal variability or climate trends. The claim is that this correlation represents a causal relationship and, because the IPCC reports had predicted such a link to climate change, some hailed this as proof that global warming was increasing hurricane activity.

To be fair, Kim et al. do not make the direct assertion that anthropogenic climate change is responsible for the warming events. Their report cites uncertainty caused by inadequate models and a lack of data:

At present, it is difficult to assess why there has been an increased frequency of CPW events during the past few decades while EPW events have declined. Determining whether the CPW is a new mode associated with a general warming of the tropical oceans, or is connected to decadal modes of Pacific variability that have strong SST expressions in the central tropical Pacific such as the North Pacific Gyre Oscillation, is hampered by both data and model inadequacies. Many of the models used in the Intergovernmental Panel on Climate Change (IPCC) AR-4 constructions do not reproduce major elements of interdecadal variability. Furthermore, SST data in the equatorial central and eastern Pacific before the 1920s were sparse, and it is difficult to determine what form of Pacific warming took place during earlier phases of the Pacific Decadal Oscillation.

But Kim et al.’s apologetics may be moot. A new analysis in Geophysical Research Letters, entitled ?On the impact of central Pacific warming events on Atlantic tropical storm activity,? researchers from NOAA’s Atlantic Oceanographic and Meteorological Laboratory in Miami, Florida, assert that temperature fluctuation in Atlantic waters is sufficient to explain the variation in hurricane frequency and landfall patterns. Sang-Ki Lee, Chunzai Wang and David B. Enfield directly refute Kim et al.’s conclusions:

A recent study by Kim et al. (2009) claim that central Pacific warming (CPW) events in 1969, 1991, 1994, 2002 and 2004 are associated with a greater-than-average frequency of tropical storms and increasing landfall potential along the Gulf of Mexico coast and Central America. Based on an independent data analysis of tropical cyclone activity in the five CPW years, it is shown here that only 1969, 2002 and 2004 were characterized with significantly greater-than-average cyclone activity in the Gulf of Mexico and Caribbean Sea, whereas 1991 and 1994 were characterized with significantly lower-than-average activity. Coincidently, the Atlantic warm pool (AWP) was significantly larger than average during 1969 and 2004, and significantly smaller than average during 1991 and 1994. By performing multiple sets of ensemble model experiments using the NCAR atmospheric general circulation model, it is shown here that the increased tropical storm frequency in 1969 and 2004 can be readily explained by a large AWP and the associated vertical wind shear reduction and enhanced moist convective instability in the main development region for Atlantic hurricanes, without invoking a remote influence from the tropical Pacific. Therefore, we conclude that it is premature to associate CPW events to an increasing frequency of cyclone activity in the Gulf of Mexico and Caribbean Sea.

Scientific disagreements are seldom stated more clearly than that. Lee et al. note that an earlier paper by Yeh et al. argued that, as the CPW has been occurring more frequently since the 1990s, the modification of El Niño pattern due to anthropogenic global warming is already in progress (see ?El Niño in a changing climate? in Nature, Sept. 24, 2009). ?However, it is shown in this study that neither our independent data analysis of Atlantic tropical cyclones nor further numerical modeling experiments supports the suggested impact of CPW events on increasing Atlantic tropical storm activity,? counter Lee et al.

In yet another recent study, scientists measured historical changes in El Niño. Lead author Tong Lee of NASA’s Jet Propulsion Laboratory and Michael McPhaden of NOAA’s Pacific Marine Environmental Laboratory measured changes in El Niño intensity since 1982. They analyzed NOAA satellite observations of sea surface temperature, checked against and blended with directly-measured ocean temperature data. The strength of each El Niño was gauged by how much its sea surface temperatures deviated from the average.

El Niños Are Growing Stronger.The NASA investigators say the stronger El Niños help explain a steady rise in central Pacific sea surface temperatures observed over the past few decades in previous studies?a trend attributed by some to the effects of global warming. Lee and McPhaden found the intensity of El Niños in the central Pacific has nearly doubled, with the most intense event occurring in 2009-10.

While Lee and McPhaden observed a rise in sea surface temperatures during El Niño years, no significant temperature increases were seen in years when ocean conditions were neutral, or when El Niño’s cool water counterpart, La Niña, was present. ?Our study concludes the long-term warming trend seen in the central Pacific is primarily due to more-intense El Niños rather than a general rise of background temperatures,? said Lee.

Lee added that further research is needed to evaluate the impacts of these increasingly intense El Niños and determine why these changes are occurring. ?It is important to know if the increasing intensity and frequency of these central Pacific El Niños are due to natural variations in climate or to climate change caused by human-produced greenhouse gas emissions,? he said. Tong Lee’s party line closing comment cannot change the fact that, once again, no smoking gun for anthropogenic global warming has been found.

On August 5, NOAA released its mid-season 2010 forecast. It was revised slightly downwards, to 14?20 named storms, 8?12 hurricanes, and 4?6 major hurricanes. The agency noted that the new estimate was revised downwards from the initial estimate since the latter included the possibility of even more early season activity. However, NOAA indicated that a La Niña event had in fact developed, and that the conditions for an active season remained in place.

The 2010 Atlantic hurricane season as of Sept. 16.Combine over-hyped claims of increased hurricane danger with the news media’s strident coverage of even minor storm threats since the Katrina disaster and the public is left believing that this all may be true. The fact is, without an occasional tropical storm the US Southern and Gulf states rapidly descend into drought?hurricanes are a normal and necessary part of the area’s climate cycle. This fact is not new, nor is the observation that, as more people crowed the US coastal regions, the deadlier and more damaging hurricanes become. In 2006, MIT climate scientist Kerry Emanuel and colleagues issued a statement on the perceived US hurricane problem:

As the Atlantic hurricane season gets underway, the possible influence of climate change on hurricane activity is receiving renewed attention. While the debate on this issue is of considerable scientific and societal interest and concern, it should in no event detract from the main hurricane problem facing the United States: the ever-growing concentration of population and wealth in vulnerable coastal regions. These demographic trends are setting us up for rapidly increasing human and economic losses from hurricane disasters, especially in this era of heightened activity. Scores of scientists and engineers had warned of the threat to New Orleans long before climate change was seriously considered, and a Katrina-like storm or worse was (and is) inevitable even in a stable climate.

Though they obviously should have known better, this spate of new research must still disappoint global warming boosters like Obama’s science czar John Holdren, who has recently tried to re-brand global warming as ?global climate disruption.? Sorry John, this is an example of global climate non-disruption. It should be obvious even to the clueless that employing such evasive verbal tactics is just another sign of the troubled state of climate science.

While the frequency of strong El Niños is increasing, at least as measured over the past quarter century, science doesn’t have a clue why. Ocean surface temperatures in the central Pacific are up, but only part of the time. Regardless, CPW does not seem to be affecting hurricane frequency or storm paths. Even so, despite their own evidence to the contrary, scientists cannot help but reflexively blame hurricane activity on global warming. Bottom line?Central Pacific Warming is not caused by global warming and CPW does not influence Atlantic hurricane frequency.

Never have so many scientists looked so long and so hard for corroborating evidence to prop up a theory. After looking for a smoking gun for 50 years, it is about time for the eco-alarmists and warm-mongering climate change supporters to admit that their pet theory is not supported by the facts. The reason they have not found the proof they seek is simple?the anthropogenic global warming theory is wrong and changing its name to global climate disruption will not make it right.

Be safe, enjoy the interglacial and stay skeptical.