Supercomputer simulation shows that 'tropical cyclones are becoming larger due to global warming'

It is said that hurricanes attacking the United States are increasing year by year, and the total damage of hurricane · harve that landed in August 2018 blew out 125 billion dollars (about 14 trillion yen), and in October of the same year hurricane · It has happened that Waraka erased the whole island of Hawaii all over the night. Meanwhile, a researcher at the Lawrence Berkeley National Laboratory in the United States said, "Hurricane rainfall tends to increase due to global warming, in the future rainfall in tropical cyclones will increase by up to 30% There is a possibility of bringing it. "

Anthropogenic influences on major tropical cyclone events | Nature
https://www.nature.com/articles/s41586-018-0673-2

Mr. Michael Wehner of Lawrence Berkeley National Laboratory and Mr. Christina Patricola of Climate Scientist, in order to model how global warming affects the tropical climate, Hurricane Andrew , Hurricane · Katrina , Hurricane · Matthew , Haiyan Typhoon, etc., simulated the formation, landing and wind speed of real tropical cyclones on the supercomputer.

The following movie shows that Hurricane Katrina's landing was actually simulated. The trajectory of Katrina is indicated by a red dot.

Simulation of Hurricane Katrina at 3 km resolution - YouTube


After confirming the accuracy of the simulation on the supercomputer, Mr. Werner and Patricola re-run 15 tropical cyclone simulations with a cooler climate than now, assuming that there was no impact of global warming Did. In addition, it seems that it takes a whole week to run the simulation for several weeks for one test, and it is a very time-consuming process.

As a result of the simulation, we found that the average rainfall of hurricane · Katrina, hurricane · Irma , Hurricane · Maria increased by 4 ~ 9% due to the effect of global warming. Also, we found that wind speed and sea level pressure are hardly affected by climate change.

Especially, in the case of Hurricane Irma and Hurricane Maria, rain is concentrated in the central area of ​​the hurricane, and large flood damage in areas immediately under the hurricane is caused by combining rainfall increased by global warming and hurricane windstorm It was also found out that it was.

In addition, Mr. Wegner and Patricola performed a simulation that sets the situation which is expected to be 3 to 4 degrees higher than the average average temperature as the impact of global warming in the future. Then, the wind speed that had not been affected at the present time also changed, and the two reported that they reached a maximum of 29 miles per hour (47 kilometers).

Studies on tropical cyclones have been going on rapidly in recent years and it has been pointed out that the hurricanes and typhoons are becoming larger over the last few years is greatly affected by human activities. For example, in another study published by researchers at the University of Iowa and Princeton University, "Houston, Texas's biggest city, suffered a major blow to Hurricane Herbie because high-rise buildings along Houston became resistant and rain It was argued that it promoted an increase in quantity ". Also, in large cities such as Houston, the temperature rises due to heat-prone concrete, rising air current occurs, rainfall increases, most of the ground is paved with concrete, so it will not soak in rain It also points out that flood damage is exacerbated by. Furthermore, there are also survey results that the risk of flooding has increased by 21 times by combining these multiple factors.

Mr. Werner and Patricola argued that future climate change could alter the strength and precipitation of tropical cyclones and exacerbate social impacts on high waves / wind storms, floods, forests and ecosystems , Commenting that it is necessary to simulate with more models before extensive conclusion is made.