New Study: Climate Change Has Doubled the Number of Category 4 and 5 Storms Striking East and Southeast Asia

The atmospheric-ocean heat engine. It’s a pretty simple mechanism for pumping up the power of storms. But as simple as it is, the results can be devastating when this engine gets revved up by human-forced climate change, according to a new study released Monday in Nature Geoscience.

The Heat Engine in Action

As the ocean surface warms, it heats the local atmosphere. This generates an updraft that pushes higher and higher into the air above. Heat also causes water at the ocean surface to evaporate. This evaporated water is borne up on the winds and air currents rising above the heating water. A low-pressure system forms and the water vapor condenses into clouds which ultimately become thunderstorms. The Coriolis effect gives it all a nudge and the storms and clouds start to spin…

pacific_typhoon_tracks_1980-2005

(Pacific Ocean typhoon paths from 1980 through 2005. A new study shows that the destructive power of landfalling typhoons in East and Southeast Asia has increased by nearly 50 percent since 1977. Meanwhile, the number of category 4 and 5 storms striking land has doubled. All impacts due to ocean-surface warming related to human-caused climate change. Image source: Commons.)

The process described above happens every day at the ocean surface. Sometimes these storms form into the powerful cyclones we call hurricanes and typhoons. Under normal global temperature conditions, the kinds and intensities of these storms are what we have generally come to expect. But if you add heat to the Earth System, as we do when we burn fossil fuels and dump carbon into the atmosphere, the whole storm formation process gets amped up — and produces the powerful outlier storms that have become more common over recent years.

Add Human-Forced Warming and End up With More Powerful Storms

The fact that such added heat tends to generate more powerful storms has been a generally accepted part of our understanding of climate science for some time now. However, it was not until recently that this signal of rising storm intensity became visible in the science. Now, a new study published today in Nature Geoscience indicates that’s exactly what’s happening in parts of the Western Pacific.

It’s a pretty earth-shattering revelation with multiple climate change-related findings which are worth reading about in full here. These findings boil down to the following:

  1. The number of category 4 and 5 storms striking southeast Asia has doubled since 1977.
  2. The overall destructive power of storms striking this region has increased by nearly 50 percent over the same period.
  3. This increase in powerful storms has been caused by ocean warming related to climate change.

Standing alone, any one of these findings would be significant. Taken together, they paint a picture of significantly rising risk of storm damage and related loss of life due to climate change in one of the world’s most highly populated regions. In other words, the storms firing and running in to land in this region are not the same as they once were. They have been dramatically altered by the massive volume of greenhouse gasses hitting the world’s atmosphere due to fossil-fuel burning, accumulating over the decades.

The study notes that:

Here, we apply analysis to corrected data and show that, over the past 37 years, typhoons that strike East and Southeast Asia have intensified by 12 to 15 percent… a nearly 50 percent increase in instantaneous destructiveness… with the proportion of category 4 and 5 storms doubling or even tripling… We find that increasing intensity of landfalling typhoons is due to strengthened intensification rates which are, in turn, tied to locally enhanced surface warming on the rim of East and Southeast Asia.

Ramping Storm Intensity

This scientific study helps validate and clarify what many weather and climate observers have already noted during recent years. The destructiveness of storms striking land in East and Southeast Asia is not normal. And, land-falling category 4 and 5 storms are occurring with greater frequency over broader regions.

4-storms-take-aim-on-southeast-asia

(Four Pacific typhoons take aim on Southeast Asia during July of 2015. A new study finds that the landfall intensity of storms like these is increasing due to human-caused climate change. Image source: NOAA.)

The Western Pacific basin is now capable of producing storms like Haiyan, whose destructive intensity at landfall was mostly theoretical decades before. This increase in intensity has been observed during a period of rapid Earth warming. And with more warming in store, the storms are likely to grow even more intense. From the Nature Geoscience study:

The projected ocean surface warming pattern under increased greenhouse gas forcing suggests that typhoons striking eastern mainland China, Taiwan, Korea, and Japan will intensify further. Given disproportionate damages by intense typhoons, this represents a heightened threat to people and properties in the region.

Links:

Intensification of landfalling typhoons over the northwest Pacific since the late 1970s, Wei, M. and Xie, S.

NOAA

Asian typhoons becoming more intense, study finds

Commons

The Coriolis effect

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Rains Failing Over India: Feeble 2014 Monsoon Heightens Concerns That Climate Change is Turning A Once-Green Land into Desert

El Nino has yet to be declared. Though signs of the Pacific Ocean warming event abound, they are still in the early stages. But for all the impact on the current Indian Monsoon — the rains this vast sub-continent depends on each year for a majority of its crops — the current pre-El Nino may as well be a monster event comparable to 1998.

For the rains that have come so far have been feeble. By June 18, precipitation totals were more than 50% below the typical amount by this time of year for northern and central India and 45% below average for the country as a whole. A stunted Monsoon that many are saying is about as weak as the devastatingly feeble 2009 summer rains. And with Pacific Ocean conditions continuing to trend toward El Nino, there is concern that this year’s already diminished rains will snuff out entirely by mid-to-late summer, leaving an already drought-wracked India with even less water than before.

Through June 25th, the trend of abnormally frail monsoonal rains continued unabated:

India Monsoon June 25, 2013India Monsoon June 25, 2014

(India cloud cover on June 25, 2013 [left frame] compared to India cloud cover on June 25 of 2014 [right frame]. Note the almost complete lack of storms over India for this year compared to 2013 when almost the entire country was blanketed by rains. Image source: LANCE-MODIS.)

India’s Rain Pattern Has Changed

It’s not just that 2014 is a bad year for India. It’s that the current weakened monsoon comes at the tail end of a long period in which the rains have increasingly failed. Where in the past it took a strong El Nino to stall the rains, ever-increasing human atmospheric and ocean warming have pushed the threshold for Monsoonal failure ever lower. Now even the hint of El Nino is enough to set off a dry spell. A growing trend of moisture loss that is bound to have more and more severe consequences.

A new study by Stanford University bears out these observations in stark detail. For the yearly monsoon that delivers fully 80 percent of India’s rains has fallen in intensity by more than 10% since 1951. And though a 10% loss may seem relatively minor, year on year, the effects are cumulative. Overall, the prevalence of dry years increased from 1981 to 2011 by 27% and the number of years experiencing 3 or more dry spells doubled.

Meanwhile, though a general drying trend has taken hold, rain that does occur happens in more intense bursts, with more rain falling over shorter periods. These newly intensified storms are more damaging to lands and homes, resulting in both increasing destruction of property while also greatly degrading the land through more intense erosion.

25 Percent of India’s Land is Turning to Desert

Loss of annual monsoonal rains is coming along with a dwindling of water flows from the melting Himalayan glaciers. These two climate change induced drying effects are already having stark impacts.

For according to the Indian Government’s Fifth National Report on Desertification, Land Degradation and Drought, a quarter of India’s land mass is now experiencing desertification even as 32 percent is suffering significant degradation due to heightening dryness and erosion. This amounts to more than 80 million hectares of land facing desertification while more than 100 million hectares are steadily degrading. The report also noted that areas vulnerable to drought had expanded to cover 68% of the Indian subcontinent.

From the report:

Desertification and loss of biological potential will restrict the transformation of dry lands into productive ecosystems. Climate change will further challenge the livelihood of those living in these sensitive ecosystems and may result in higher levels of resource scarcity.

Monsoonal Delay, Weakening Continues

India daily rainfall

(India daily rainfall as of June 26, 2014. Image source: India Monsoon.)

By today, June 26, the long disrupted and weakened monsoon continues to sputter. Moisture flow remains delayed by 1-2 weeks even as the overall volume of rainfall is greatly reduced. Though storms have exploded over some provinces, resulting in flash flooding, much of the country remained abnormally dry. Overall, preliminary negative rainfall departures remained at greater than 40% below average for most of the nation with only five provinces receiving normal rainfall and the remaining 31 receiving either deficient or scant totals.

 

Links:

LANCE-MODIS

National Drought Fears Loom as India Receives Deficient Rainfall

India’s Rain Pattern Has Changed: Researchers Warming of Future of Extreme Weather

A Quarter of India’s Land is Turning Into Desert

India Monsoon

Monsoon at Dead Halt

Hat Tip to Colorado Bob

 

 

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