Patricia: A Note from the Future, and Echoes of a Violent Past
For the brief remaining seconds while Patricia has focused out attention…
Above, Senior Researcher Jeffrey Kiehl, senior climate scientist at the National Center for Atmospheric Research (NCAR). I asked Dr. Kiehl about the evidence for the intensity of storms in the ancient greenhouse powered world – storms strong enough to leave their traces millions of years into the future.
A trio of researchers affiliated with Universidad Nacional Autónoma in Mexico, and VU University in the Netherlands, has conducted a study on the source of an increase in property dollar amounts lost over the past several decades due to hurricanes and has concluded that it cannot be blamed on an increase in wealth or construction—instead, they suggest in their paper published in Nature Geoscience, that it is due to more storms, because of global warming. Stéphane Hallegatte with the Climate Change Policy Team at the World Bank, offers a News & Views piece in the same journal edition on the work done by the team, outlining the process that was used, and highlighting possible problems with the results.
Mega-Insurance company Munich Re finds increases in costly natural disasters due to “Hydrological” and “Climatological” events.
Monetary losses that come about due to natural disasters are on the rise, particularly from storms such as hurricanes—that much is clear. What is not clear is whether this trend can be blamed on changes in the weather or people building more expensive stuff in the path of such storms. Some recent studies have found that it is mostly the latter, but that, the researchers with this new effort argue, is because the approach used to reach such conclusions was flawed.
The traditional way of normalizing damage from hurricanes, Hallegatte explains, involves an approach where it is assumed that an increase in damage would come about evenly with an increase in wealth—i.e. doubling wealth in an area would double the damage costs that occurred in it. But that thinking is flawed, the researchers contend, because it does not take into consideration the fact that as an area grows more wealthy, some of that money is used to prevent storm damage. They conducted their own study using a method that took such changes into account and their results showed that the economic loss increases due to hurricanes over the period 1900 to 2005 could not be solely attributed to an increase in wealth—they suggest that the other increase was due to an increased number of storms and stronger intensity (due to global warming) and further suggest that between 2 and 12 percent of losses due to such storms in the year 2005 alone (the year Katrina struck New Orleans), could be attributed to global warming.
Hallegatte agrees with the approach used by the researchers but points out that the change used to normalize the data is not proven, nor is the assumption that an increase in the number of storms, or their intensity can be blamed on global warming.
Why then did this most recent hurricane fail to deliver the cataclysm feared?
Several factors appear to have played a role. Firstly, Patricia made landfall at a relatively quiet stretch of coastline between the towns of Puerto Vallarta and Manzanillo, rather than directly—and more dangerously—over either of them. It then moved quickly enough that its rainfall was not concentrated in any one place, thus reducing the chances of flooding. Its really strong winds were to be found within 50km of its “eye”, making it a comparatively tight storm. And those same winds were rapidly weakened when they passed over the Sierra Madre Occidental, mountains near Mexico’s western coast. Topping this all off, the accompanying storm surge, which was responsible for most of Typhoon Haiyan’s fatalities, caused no problems. It seems the shape of the local seabed prevented the build-up of shallow water necessary for a large surge.
Below, PBS Nova examined evidence from Dr. Kerry Emanuel of MIT on increasing total Hurricane power. Dr. Emanuel’s measure of storm power, “power dissipation index”, in blue on the graphs below, correlates well with increases in sea surface temp, (green).
North Atlantic Storms
Emanuel devised a way to measure the amount of energy hurricanes release. He draws on wind speed data and factors in the number of days each storm lasts. Emanuel calls his measure PDI, or power dissipation index. The graph above shows the energy released annually by all storms in the North Atlantic compared to the September average sea surface temperature (SST) over a region known to generate storms. The correlation between the lines suggests that sea surface temperature influences how much energy storms release. Perhaps even more striking, the total Atlantic hurricane power dissipation has more than doubled in the past 30 years.North Pacific Storms
As in the North Atlantic, there has been a remarkable upswing in the amount of energy released by hurricanes in the western North Pacific since around 1975. Over this time, power dissipation has increased by about 75 percent. The graph above shows the power dissipation index (PDI) compared to the July-November average sea surface temperature (SST) over a storm-generating region. Some of the upward and downward swings in PDI throughout the graph are associated with El Niños and other regional forces—part of what Emanuel calls “natural variability.” Global warming, however, may be contributing to the sharp upswing in the last 30 years.Combined Data
In an effort to verify that global warming trends are impacting hurricane energy, Emanuel compared the sum of the North Atlantic and western North Pacific PDI values to the average annual sea surface temperature (SST) in a wide swath around the equator. Once again, a significant rise in the amount of storm energy released in recent decades mirrors a rise in sea surface temperature. As this graph shows, the combined PDI has nearly doubled over the past 30 years.
Many experts, however, warn that at around the end of this century there may be super typhoons that make landfall on Japan while retaining their “super” status.
Kazuhisa Tsuboki, professor of meteorology at Nagoya University, compares a typhoon to a car, calling the eye the “engine,” and the water vapor it takes up the “gasoline.” When water at the ocean surface is over 26 degrees Celsius, some water evaporates and is sucked up into the typhoon. The air in the eye is heated and becomes lighter, which further reduces air pressure. This boosts the flow of surrounding winds into the eye, which strengthens the typhoon.
The waters around the Philippines when Typhoon Haiyan hit were 29 degrees Celsius. In September and October, the waters around Japan do not go above 26 degrees Celsius, so typhoons during that period weaken as they pass these waters, but if global warming progresses, the situation will change.
Tsuboki calculated a scenario in which the average air temperature of the world at the end of this century is 2.8 degrees Celsius higher than it was at the end of last century. He determined that a super typhoon with central air pressure of 857 hectopascals and wind speeds of 88 meters per second, more powerful than Typhoon Haiyan, would form. The scenario also showed a number of typhoons nearly as powerful as that super typhoon making landfall on Japan.
“We need to raise the level of what we consider a worst-case scenario, and create (evacuation plans),” says Tsuboki.
“In short, the historical Atlantic hurricane record does not provide compelling evidence for a substantial greenhouse warming induced long-term increase.”
“Therefore, we conclude that despite statistical correlations between SST and Atlantic hurricane activity in recent decades, it is premature to conclude that human activity-and particularly greenhouse warming-has already caused a detectable change in Atlantic hurricane activity.”
“However, human activity may have already caused some some changes that are not yet detectable …”
“Both the increased warming of the upper troposphere relative to the surface and the increased vertical wind shear are detrimental factors for hurricane development and intensification, while warmer SSTs favor development and intensitification. To explore which effect of these effects might “win out” …”
“A new modeling study projects a large (~100%) increase in Atlantic category 4-5 hurricanes over the 21st century, but we estimate that this increase may not be detectable until the latter half of the century.”
Landsea also draws attention to the “big” – increasing (during the 20th century), urbanization of coasts.
Cherry pick much? Did you even read the entire source you cited? It’s quite a trick to be able to read something, dismiss 95+% of what it says, and try to make the other 5% into the only truth. You are either a deliberate liar and denier or one very deluded motivated reasoner. We extend our sympathies.
North Atlantic Storms
North Pacific Storms
Combined Data
T. Knutson – “adversary” K. Emanuel, NOAA (http://www.gfdl.noaa.gov/global-warming-and-hurricanes):
“In short, the historical Atlantic hurricane record does not provide compelling evidence for a substantial greenhouse warming induced long-term increase.”
“Therefore, we conclude that despite statistical correlations between SST and Atlantic hurricane activity in recent decades, it is premature to conclude that human activity-and particularly greenhouse warming-has already caused a detectable change in Atlantic hurricane activity.”
“However, human activity may have already caused some some changes that are not yet detectable …”
“Both the increased warming of the upper troposphere relative to the surface and the increased vertical wind shear are detrimental factors for hurricane development and intensification, while warmer SSTs favor development and intensitification. To explore which effect of these effects might “win out” …”
“A new modeling study projects a large (~100%) increase in Atlantic category 4-5 hurricanes over the 21st century, but we estimate that this increase may not be detectable until the latter half of the century.”
Landsea also draws attention to the “big” – increasing (during the 20th century), urbanization of coasts.
Cherry pick much? Did you even read the entire source you cited? It’s quite a trick to be able to read something, dismiss 95+% of what it says, and try to make the other 5% into the only truth. You are either a deliberate liar and denier or one very deluded motivated reasoner. We extend our sympathies.