Storm warning

 

New category 6 for recent mega-hurricanes

From New Atlas

Climate change looks set to trigger stronger storms more often, and the threat may not be properly communicated to people in the line of fire. Now, scientists at Lawrence Berkeley National Laboratory suggest there’s room for a Category 6 on the scale – with five storms in the past decade already reaching that strength.

Currently, the National Hurricane Center uses a measure called the Saffir-Simpson Windscale to classify the intensity of hurricanes in the Western Hemisphere and alert people in the area to take appropriate precautions. It’s based on the maximum wind speeds in the storm averaged over a minute – it starts at 74 mph (119 km/h) for a Category 1 hurricane, and goes through different thresholds all the way up to Category 5, which is everything over 157 mph (252 km/h). But because the destructive power of wind increases exponentially, and with hurricane strength growing in recent years, scientists at Berkeley Lab and the First Street Foundation weren’t sure if that scale told the full story.

“Our motivation is to reconsider how the open-endedness of the Saffir-Simpson Scale can lead to underestimation of risk, and, in particular, how this underestimation becomes increasingly problematic in a warming world,” said Michael Wehner, first author of the study.

Tropical storms form out of interactions between warm ocean water and warm, humid air, and those temperatures are increasing rapidly, thanks to human-induced climate change. This seems set to boost not just the intensity of hurricanes but the speed that they gain power.

In the new study, the team added an extra hypothetical category to the scale. Based on the ranges of lower categories, they suggested that Category 5 would cover storms with wind speeds between 157 and 192 mph (252 and 309 km/h), while the new Category 6 would include any storm that became more powerful than that upper bound.

When the researchers analyzed historical data of hurricanes from 1980 to 2021, they identified five storms that reached strengths high enough to fall into that hypothetical Category 6. That includes Hurricane Patricia, the most powerful tropical cyclone on record, which battered Central America with winds of up to 215 mph (345 km/h) in 2015.

Worryingly, but perhaps not surprisingly, all five hypothetical Category 6 hurricanes occurred within the last nine years. That lends weight to the contributions of climate change to their intensity. The team admits the research isn’t a formal proposal for a restructure of the Saffir-Simpson Scale, but is intended to bring attention to its potential shortcomings.

“Tropical cyclone risk messaging is a very active topic, and changes in messaging are necessary to better inform the public about inland flooding and storm surge, phenomena that a wind-based scale is only tangentially relevant to,” said James Kossin, co-author of the study. “While adding a 6th category to the Saffir–Simpson Hurricane Wind Scale would not solve that issue, it could raise awareness about the perils of the increased risk of major hurricanes due to global warming.”

The research was published in the journal PNAS.

Source: Lawrence Berkeley National Laboratory

 

Hurricane Patricia, the strongest hurricane on record, as captured by astronaut Scott Kelly from the International Space Station in 2015

Scott Kelly/NASA

Ida checked all the boxes

 

From CNN

Human-caused climate change is making hurricanes more dangerous. They are producing more rainfall, moving slower once they make landfall and generating larger storm surges along the coast. Hurricane Ida was a prime example of those changes, and scientists say storms like this will become more common as the planet warms.

Fueled by warmer-than-normal water in the Gulf of Mexico, Hurricane Ida destroyed homes, uprooted trees and cut off power to more than 1 million residents. It battered Mississippi and the already storm-ravaged state of Louisiana, and officials there say they expect the death toll to increase in the coming days.

Hurricane Ida was just the latest in back-to-back storms that have slammed Louisiana in recent years. But Katharine Hayhoe, chief scientist at the Nature Conservancy and professor at Texas Tech University, said an important distinction is not the frequency of the storms but their severity.

"We've always had hurricanes, we've always had heat waves, we've always had floods and droughts, but what climate change is doing is loading the weather dice against us," Hayhoe told CNN. "It's sneaking in when we're not looking, changing the numbers as we're rolling and asking what is this, how could this happen?"

"The answer to that is climate change," she said.

Hurricanes are getting stronger 

Hurricanes — also called tropical cyclones or typhoons outside North America — are being made more intense by the warming ocean, which studies have shown has absorbed approximately 90% of the planet's excess heat trapped by human-produced greenhouse gas emissions. And a recent study found that the planet is trapping roughly double the amount of heat than it did nearly 15 years ago.

As the planet heats up, storms get stronger.

The recent state-of-the-science United Nations report on climate change concluded that the global proportion of cyclones ranging from Category 3 to 5 — the most intense storms — has increased over the last four decades due to rapidly warming ocean temperatures. For every additional degree of warmth, scientists say not only will the proportion of intense cyclones continue to climb, but extreme rain events are also forecast to intensify by about 7%.

"We know that, in general, hurricanes are intensifying faster," Hayhoe said. "They are bigger and stronger than they would be otherwise; they have a lot more rainfall associated with them, and rising sea level exacerbates storm surge."

Before making landfall on Sunday, Hurricane Ida went through a remarkable period of strengthening: its maximum sustained winds increased by 65 mph in just 24 hours.

Scientists define rapid intensification — a process that historically has been rare — as an increase of 35 mph in 24 hours or less. Hurricane Ida nearly doubled that definition.

For rapid intensification to occur, warm ocean water must extend well below the surface, going hundreds of feet deep, to provide enough engine for the hurricane to strengthen. This has led scientists to believe that storms are more likely to undergo rapid intensification as a result of warmer oceans.

"If you increase the speed limit, you make more room for the storms to strengthen, so it can intensify more quickly," Jim Kossin, a senior scientist with the Climate Service, an organization that provides climate risk analysis to governments and businesses, told CNN.

Ida made landfall in Louisiana as a Category 4, and is now tied in the record books with Laura in 2020 as the strongest hurricane to make landfall there.

Hurricanes are wetter and moving slower

Storms are also generating more rainfall. For every degree of warming, the atmosphere can hold 7% more water vapor that could fall as rain. After flooding from Hurricane Harvey devastated the Houston area in 2017, scientists found that human-caused climate change supercharged the storm's rainfall by approximately 15%.

Hurricane Ida has dumped more than 15 inches of rain on parts of Louisiana, according to the National Weather Service. As the remnants of the storm arc from the South to New England, another 3 to 7 inches of rain is expected across at least 12 states, including areas already impacted by severe flooding this month such as Tennessee and New Jersey.

Paul Miller, a coastal meteorology scientists at Louisiana State University, said southeast Louisiana, including Baton Rouge and New Orleans, experienced one of its wettest seasons on record. According to Miller, it rained on 91% of the days between June 18 and July 19 at the New Orleans airport, compared to the region's average of 40-50%.

"It's been a historically wet year in southeast Louisiana even before Ida," he told CNN. "This really exacerbated concerns about flooding during Ida because the ground had already absorbed a lot of water this year."

Satellite data also shows that storms are getting slower, particularly after they make landfall, according to Hayhoe. Slower and larger storms means they can cover a greater area, idle and dump more rain during that time period.

And, while experts say the research is still developing, a 2020 study published in the journal Nature found storms are staying stronger farther inland than they did five decades ago. Since hurricanes are fueled by warm ocean water, they tend to weaken over land, but in recent years they have been raging longer after landfall. The study concludes that warmer sea surface temperatures are leading to a "slower decay" by increasing the amount of moisture that a hurricane can carry.

Storm surge is getting higher

As the water piles up along the coast, rivers and streams that drain into the ocean can also be blocked, forcing water levels to rise upstream. Storm surge and strong winds from Hurricane Ida reversed the flow of the Mississippi River near New Orleans on Sunday — something the US Geological Survey says is "extremely uncommon."

Scott Perrien, a hydrologist with the USGS, told CNN that the river's level on Sunday rose about 7 feet due to storm surge at the gauge located in Belle Chasse, about 20 miles south of New Orleans. At the same time, the river's flow "slowed from about 2 feet per second down to about half a foot per second in the other direction," Perrien said.

"I remember, off hand, that there was some flow reversal of the Mississippi River during Hurricane Katrina," Perrien said, "but it is extremely uncommon."

Tom Knutson, senior scientist with the National Oceanic and Atmospheric Administration, said combined with wind and rain, storm surge is "one of the more dangerous aspects of hurricanes."

Nearly half of all deaths from tropical cyclones come from storm surge.

Louisiana's natural buffer against storm surge — its coastal wetlands — are also disappearing due to sea level rise and persistent severe hurricanes. "Watching each additional hurricane, like Ida, hit the state, is a reminder of the importance of preserving and restoring these environments," Miller said.

As the ocean gets warmer due to fossil fuel emissions, the Gulf Coast will likely experience more hurricanes that are as severe as Ida. Hayhoe said the only choice humans have left is to either rapidly cut greenhouse gas emissions or face the most catastrophic impacts of the climate crisis.

"The bottom line is climate change is not only an environmental issue or a coastal issue, climate change is an everything issue — a human issue," Hayhoe said. "To care about climate impacts and to advocate for climate action, we only have to be one thing, and that one thing is a human living on planet Earth."

It's abundantly clear: we are in a climate crisis, and every year emissions remain high means that it will only get worse.  We need to slash emissions now.

Hurricane Ida: Climate change made a monster storm

 From Open Mind

Warm sea water is what powers hurricanes. Usually, sea surface temperature (SST) in the Gulf of Mexico needs to exceed 29°C to intensify a hurricane, and every fraction of a degree above 29°C increases the chance — dramatically — of not just intensifying, but super-charging it, creating a “monster storm.”

Which makes one wonder … if a storm passes by, what are the odds the sea surface temperature (SST) will exceed 29°C? Or more? Have the odds changed over time? Of course SST isn’t the only factor at play, only fools say so, but only bigger fools deny its impact on tropical storms.

To learn more about the history of SST in the area visited by hurricane Ida during her journey from Cuba to New Orleans, I selected the region from longitude 92°W to 85°W, latitude 23°N to 30°N, and retrieved daily data for SST in that region from 1981 through Aug. 2 of this year, from the OI (optimal interpolation) v2 dataset.

There’s an obvious annual cycle (hotter in summer, colder in winter), and if we remove it to define anomaly we get this:

The red line is a trend estimate from least-squares regression, and indicates that SST has increased since 1981, by about 0.85°C. It’s overwhelmingly “statistically significant.”

For sea surface temperature and its impact on hurricanes, that amount of warming is HUGE. It’s easy to dismiss it as “quite small” with an offhand “less than 1°C.” But if you really know hurricanes, you know that “every fraction of a degree counts” is, if anything, an understatement. An increase of a “mere” 1°C is nothing like “quite small.”

Of course that’s anomaly, not temperature itself, and it’s for the entire year, not the summer months when temperatures are highest. I split the time span into four decades, from 1981 to 1991, 1991 to 2001, 2001 to 2011, and 2011 to 2021. Then I estimated the probability density function (pdf) during the summer months (Jun/Jul/Aug/Sep) for each decade by two methods: a histogram, and with a smoothed estimate (kernel smooth). I got this for the four decades:

It’s obvious; the chance of meeting or exceeding that 29°C threshhold has increased, particularly from the 1981-1991 decade to the 2011-2021 decade.

If we look at the survival function (1 minus the cumulative distribution function), not only does it give the probability of meeting or exceeding any given value, it’s straightforward to estimate uncertainty ranges for those probabilities (shaded regions surrounding solid lines):

Between the 1981-1991 decade, and 2011-2021, the chance of meeting (or exceeding) the 29°C threshhold went from about 42%, to over 70%. The chance of meeting (or exceeding) 29.5°C, offering much more energy to the storm, went from about 18% to just over 50%. As for the 30°C limit — big trouble in hurricane town — the odds go from a mere 3% chance to a whopping 21%, a 7-fold increase.

It's perfectly obvious to everybody (except those whose salaries and bonuses depend on it not being obvious, like oil company executives and marketing people) that there is a global climate emergency.  It's equally obvious that it's only going to get worse, because too little is being done to reduce emissions.  What will it take?

Hurricane Ida's unnerving intensification

This excellent piece from Axios shows just how much climate change contributed to Hurricane Ida.

Hurricane Ida jumped from a 105-mph Category 2 hurricane on Saturday to a high-end Category 4 monster by Sunday morning, in a feat enabled by climate change, seasonal timing and a dose of bad luck.

Why it matters: Understanding how Mother Nature's most powerful storms are changing is key to learning how to better protect coastal communities around the world — everywhere from the mega-cities of Southeast Asia to the small towns of the Louisiana Bayou.

Driving the news: The explosive intensification of Hurricane Ida shortly before landfall was a nightmare situation. Social media was inundated with expressions of anxiety and dread, as it was too late for anyone in harm's way to flee from what they may have thought was going to be a weaker storm.

• That the storm rapidly intensified was not a surprise to hurricane forecasters, who had been predicting this since the storm moved off the coast of Cuba on Friday.
• But even the most bullish forecast did not call for the rate or peak of intensification that ended up occurring.

By the numbers: One key measure of storm intensity is the minimum central air pressure. In this case, the pressure dropped by a whopping 41 millibars in just 14 hours, between 5pm ET Saturday and 7am ET Sunday — and 52 millibars in 24 hours, starting from 8am ET Saturday.

• During the 24-hour period, winds shot upwards by 65 mph, exceeding the National Hurricane Center's definition of rapid intensification, which is when a storm's maximum sustained winds increase by 35 mph in 24 hours.
• In keeping with another suspicious trend, Ida also intensified all the way to the coast in the northern Gulf of Mexico, something that was virtually unheard of before 2018, yet has seemingly become routine.

The intrigue ... Hurricane Ida's explosive intensification was due to three main factors, with climate change mainly affecting the first two — and most decisive — of these three:

• An ample supply of bathtub-like warm water, with the warmth extending deep into the water column. This was heightened by the storm's timing: Gulf temperatures tend to be at their hottest at this time of year. This year, though, the waters have been even hotter than average.
• Abundant moisture in the atmosphere, since dry air can get entrained into storms and disrupt their intensification process.
• A lack of wind shear or any other atmospheric factor that could stifle the storm's towering thunderstorms from organizing and forming a concentric ring around the eye.

How it works: Hurricanes are heat engines, feasting off warm, tropical waters.

• The vast majority of extra heat going into the climate system from burning fossil fuels is being absorbed by the oceans, and the seas are warming as a result.
• So, too, are air temperatures. Physics, specifically the Clausius-Clapeyron relationship, tells us that for every 1°C (1.8°F) of temperature increase, there is about a 7% increase in the water holding capacity of the atmosphere.
• A recent scientific assessment found that the planet's oceans have warmed faster during the past 100 years than at any point in the past 11,000 years.
• These two trends are causing hurricanes and tropical storms to dump more water, on average, than they used to, and for there to be a greater proportion of high-end Category 3, 4 and 5 hurricanes in some ocean basins.

Context: Sufficient studies have been published on these trends in peer-reviewed journals that the recent UN Intergovernmental Panel on Climate Change report included some changes to the role of climate change in tropical cyclones as an area of increased scientific confidence.

• For example, a 2019 study in the journal Nature found there had been a trend in the Atlantic Ocean toward more rapidly intensifying storms between 1982 and 2009, and computer modeling showed that such a trend would not have been likely without human-induced climate change.
• A 2020 study published in the Proceedings of the National Academy of Sciences found that tropical cyclones are more likely to reach higher categories across much of the globe, including the Atlantic.
• And an especially ominous 2017 study published in the Bulletin of the American Meteorological Society found that a storm that intensifies by 70 mph in the 24 hours before landfall, which occurs about once every century today, could occur as frequently as every five to 10 years by the end of this century.

The bottom line: In the end, the fact that this storm hit Port Fourchon, Louisiana, also comes with a dose of bad luck and bitter irony.

• Bad luck, since the direct hit makes the state the first to ever see back-to-back years with hurricanes that made landfall with sustained winds of 150 mph or greater, according to meteorologist Steve Bowen, head of catastrophe insight at Aon.
• And irony, because the landfall location, Port Fourchon, is home to critical facilities for operating deepwater oil and gas drilling rigs in the Gulf of Mexico. More than 1.5 million barrels of crude oil per day are transported via pipelines and through the port. Yet it's the burning of fossil fuels that helped make this storm so strong, and so badly damaged the port.

Record hurricanes, record floods, record droughts, record heat, record bushfires―how much longer before everyone recognises the reality of the climate emergency?  And does something about it?

Oceans primed for peak hurricane season

 From NASA's Earth Observatory

Heading into the peak of hurricane season, the seas around North and Central America are primed to fuel storm development and intensification in the Atlantic and Eastern Pacific. While sea surface temperatures are just one factor influencing the development of hurricanes, they are a fair predictor of the readiness of the ocean to sustain them.

The map above shows sea surface temperatures (SSTs) as measured on August 11, 2021, by a combination of satellite and ocean instruments. Meteorologists generally agree that SSTs above 27.8° Celsius (82° Fahrenheit) intensify and sustain hurricanes, cyclones, and typhoons. Surface waters above that threshold are represented in red on the map. Note the finger of warm water—the Gulf Stream—running parallel to the U.S. East Coast.

The data for the map come from the Multiscale Ultrahigh Resolution sea surface temperature analysis, produced at NASA’s Jet Propulsion Laboratory. It is based on observations from several satellite instruments, including the NASA Advanced Microwave Scanning Radiometer-EOS (AMSRE), the Moderate Resolution Imaging Spectroradiometer (MODIS) on the NASA Aqua and Terra platforms, the U.S. Navy microwave WindSat radiometer, the Advanced Very High Resolution Radiometer (AVHRR) on several NOAA satellites, and from in situ observations from NOAA.

The 2021 hurricane season started quickly. In May, Tropical Storm Andres became the earliest named storm—winds of 39 miles per hour or greater—on record in the Eastern Pacific. To date, eleven tropical storms have developed in the basin, including four hurricanes.

In the Atlantic, five named storms formed between May 19 and July 9, with Hurricane Elsa becoming the earliest fifth named storm on record. After Elsa, the Atlantic remained quiet until Tropical Storm Fred emerged on August 11. The storm lost some strength while passing near Haiti, the Dominican Republic, and Cuba, but it is forecasted to regain tropical storm force before making landfall in Florida over the weekend. Forecasters warned citizens about the potential for heavy rainfall.

In its mid-season update on August 4, scientists from the NOAA Climate Prediction Center forecasted 15 to 21 named storms in the Atlantic in 2021, including 7 to 10 hurricanes, of which 3 to 5 could become major hurricanes. They noted: “Atlantic sea surface temperatures are not expected to be as warm as they were during the record-breaking 2020 season; however, reduced vertical wind shear and an enhanced west Africa monsoon all contribute to the current conditions that can increase seasonal hurricane activity.”

Intenser, wetter, windier storms in a warming world

 From  Inside Climate News

The federal government counts 52 tropical cyclones since 1980 that, with the cost adjusted for inflation, have caused, on average, $20 billion in damages in the United States. There were a record seven so-called “billion dollar” cyclones just last year.

With climate change helping produce a global horror film of extreme weather disasters this summer, and the peak Atlantic hurricane and Western fire seasons just arriving, a new landmark United Nations climate report by the Intergovernmental Panel On Climate Change offers the most thorough evaluation of the physical science associated with global warming so far, including the climate science of tropical cyclones.

Made public Monday, the IPCC report was written by 234 scientists from 66 countries and approved by 195 member governments of the IPCC.

To meteorologists, tropical cyclones are rotating, organized systems of clouds and thunderstorms that originate over tropical or subtropical waters. In the North Atlantic, central North Pacific and eastern North Pacific they are called hurricanes once wind speeds reach 74 miles per hour. Major hurricanes, categories 3 to 5, pack wind speeds of 111 miles per hour to more than 157 miles per hour, and cause damage that ranges from devastating to catastrophic.

The IPCC authors did not do original research for their report. Rather, they assessed the state of knowledge and the confidence in it based on previously published scientific reports.

Hugh Willoughby, a professor at Florida International University in the Department of Earth and Environment who has been studying hurricanes for decades, said the IPCC report’s assessment of hurricanes reveals an unsurprising picture of evolving science.

“It is consistent with what we have thought for 40 years,” said Willoughby, who flew more than 400 missions into hurricanes as a meteorologist with the federal government and led the National Oceanic and Atmospheric Administration’s Hurricane Research Center from 1995 to 2002. “What is new is more and more (hurricane) events that fit the pattern, and that is what you would expect.” 

To determine six, key takeaways about tropical cyclones and climate change from the IPCC report, Inside Climate News interviewed Willoughby and two academic researchers whose work was cited by the report’s authors: Colin Zarzycki, an assistant professor of meteorology and climate dynamics at Pennsylvania State University and Phil Klotzbach, a hurricane expert and research scientist at Colorado State University’s Department of Atmospheric Science.

• More Major Tropical Cyclones. It is likely, the report found, that the percentage of major tropical cyclones—those reaching categories 3 to 5—increased over the last four decades. Scientists are confident in saying that there will be more frequent storms in the highest intensity categories of 4 and 5.
• Wetter, Windier Tropical Storms. Warmer air holds more moisture, and human-driven climate change is making tropical cyclones wetter. The authors found that, generally, storms with extreme daily precipitation are projected to intensify by about 7 percent for each 1 degree Celsius of global temperature warming. The authors also expressed high confidence in projections that peak wind speeds in the most intense tropical cyclones—categories 4 and 5—will increase with increasing global warming.

• Tropical Storms are Shifting North. In the North Pacific, tropical cyclones are reaching their maximum intensity farther north than before, potentially exposing areas that have no experience with tropical cyclones to a risk of dealing with them in the future. The report said this is partly explained by changes in global-scale tropical atmospheric circulation. 
• More Explosive Tropical Cyclones. With warmer sea-surface temperatures, the frequency of storms that rapidly intensify has increased.
• Slower [Moving] Tropical Cyclones that Can Do More Damage. When slower moving cyclones make landfall, they can drop more rain, cause more wind damage and sustain a larger storm surge simply because they hang around longer. The IPCC authors cited research in 2019 that provided evidence that translation speed for Atlantic storms decreased 17 percent from 1900 to 2017. In addition, what scientists call “meanders” and “stalls” in tropical cyclone paths have become increasingly common, along with the slower speeds.

[Read more detail here]

Hurricane Harvey struck the Texas coast in August 2017. Credit: NOAA

Slightest heat magnifies hurricane risk

 From Climate News Network

Any climate change at all will mean a hurricane risk for the storm-prone Caribbean, even if global average temperatures are contained to a rise of no more than 1.5°C by 2100. But a rise of 2°C could be disastrous: the hurricane hazard could grow fivefold.

The figures – each representing a rise above the long-term average for most of human history – are significant. In 2015 195 nations, including the US, signed up to the Paris Agreement – a promise to contain the rise in global heating to “well below 2°C” by the century’s end. The undeclared but widely-understood intention was a limit of 1.5°C.

In the last century, in response to a rise in carbon dioxide emissions from fossil fuel use, planetary average temperatures have already risen by 1°C, and the Atlantic states of the US and the islands of the Caribbean have been hit by a series of ever more devastating windstorms, as ocean temperatures warm and make hurricanes more probable.

And researchers warn that as global heating continues – with forecasts of a rise of more than 3°C by 2100 – more are on the way.

But the US is wealthy and resilient. British scientists report in the journal Environmental Research Letters that they decided to take a look at the probability of windstorm and heavy rainfall assault on the Caribbean, where half of the 44 million people of the archipelago live within 1.5kms of the coast, and where devastation can be so intense it could take six years to recover.

The poorer and more vulnerable you are, the greater your hurricane risk. Even a tiny heat rise can spell disaster.

Tropical cyclones have become more destructive

Two severe tropical cyclones over northern Australia. Analysis of satellite records from 1979 to 2017 has found a clear rise in the most destructive storms, in keeping with climate predictions about global heating. Photograph: Nasa Earth Observatory/EPA

From The Guardian:

Tropical cyclones have become more intense around the globe in the past four decades, with more destructive storms forming more often, according to a study that further confirms the theory that warming oceans would drive more dangerous cyclones.

Analysis of satellite records from 1979 to 2017 found a clear rise in the most destructive cyclones – also known as hurricanes or typhoons – that deliver sustained winds in excess of about 185km/h.

Experts told Guardian Australia the finding was in line with climate model predictions and the knowledge that increasing ocean temperatures gave tropical storms more energy.  Dr Hamish Ramsay, a senior research scientist at CSIRO who studies cyclones, said: “This study confirms what the climate models have been predicting for some time – that the proportion of the most intense storms will increase as the climate warms.”

While climate scientists have long predicted that global heating would deliver stronger cyclones, a trend that was statistically significant has been challenging to identify in part due to the natural swings in the world’s climate masking changes.

Published in the leading journal the Proceedings of the National Academy of Sciences, the study was carried out by scientists at the US government’s National Oceanic and Atmospheric Administration.

The scientists did not try to find a cause for the increase in more dangerous cyclones, but said the trends were consistent with understanding of physics and modelling, and the finding “increases confidence that [tropical cyclones] have become substantially stronger, and that there is a likely human fingerprint on this increase”.

The probability of a cyclone reaching wind speeds greater than 185km/h had risen by about 15% over the 39 years studied.

“[The study] suggests that the climate change signal in the data is potentially already emerging and this is something that climate scientists have been saying for some time,” Ramsay said. “We maybe at a point now where we are starting to evidence from observational data that supports what the models have been telling us.”

Ramsay said as well as increasing the wind speeds in cyclones, warming oceans would also likely see cyclones delivering more rainfall. There was still uncertainty as to whether the numbers of all categories of cyclones would rise or fall under climate change.

Previous research has found that when cyclones form, they are tending to move more slowly, while delivering more rain.

Dr Greg Holland, a senior scientist emeritus at the National Center for Atmospheric Research in Colorado, has studied cyclones for about 40 years.  The Melbourne-based scientist said while there were legitimate arguments over the finer details of trends and intensity in relation to tropical cyclones: “The work all points in the same direction – the proportion of the most intense cyclones is going up.”

He said: “There is nobody saying the trend will go the other way. The physics has been well set out for 30 or 40 years. If you get a warmer ocean then the intensities of cyclones goes up. That’s a 5% or 10% increase in maximum winds for every 1C of warming in the ocean. The world is warming and its because we have put more greenhouse gases into the atmosphere.

[Read more here]

Lorenzo's ominous climate message

From Climate Denial Crock of the Week:

There has never been a hurricane of this strength so far east before.

Here are some remarkable facts about Lorenzo and recent Category 5 activity in the Atlantic:

• It became a Category 5 over 600 miles east-northeast of the previously farthest east Category 5s on record – Isabel and Hugo.

• It became the sixth Category 5 since 2016 (after Matthew, Irma, Maria, Michael, and Dorian). There have only been 26 Category 5 since 1960.

• 2019 becomes just the seventh year with more than one Category 5 in the Atlantic, joining 1932, 1933, 1961, 2005, 2007, and 2017.

• Its pressure of 925 millibars Saturday night was the lowest on record east of 50 degrees west longitude. The lower the pressure, the stronger the storm.

 Abnormally warm waters in the Atlantic, likely boosted by climate change, aided Lorenzo in attaining such strength. “The water under Lorenzo when it was a Category 5 hurricane is about 28°C (82.4), which is about 1°C (1.8°F) warmer than average… just enough to give it that extra jolt,” wrote Brian McNoldy, Capital Weather Gang’s tropical weather expert. As Tropical Storm Karen withers away, Hurricane Lorenzo has become “one of the largest and most powerful hurricanes of record for the tropical central Atlantic,” according to the National Hurricane Center.

Now packing 140 mph winds, Lorenzo became a Category 4 storm Thursday farther east than any other previous storm on record, save for Julia in 2010. While far from any populous land masses at the moment, Lorenzo could be having an impact on the Azores in less than a week’s time — all the while marking a potentially ominous climate signal. 

We are experiencing a climate emergency right now.  We don't have to wait till some far off future to see the effects of our dumping CO₂ and methane into the atmosphere.  It's already obvious.  And it's just going to get worse.

Flying into the nose of a hurricane

A cartoon by Gary Larson.  Hat tip to ClimateCrocks.

Hurricane Dorian #ClimateEmergency

Read the Guardian's live blog here. 

The strongest hurricane ever.  Global heating (perhaps) didn't cause this particular hurricane, but it almost certainly made it worse.

What are you going to do about it, world?  When are you going to start reducing emissions, people of the world?  How bad must it get before we act?  And will it be too late by then? 

I despair.  Mankind is soooo stupid.

Hurricane Dorian seen from the Space Station

Hurricane Dorian approaches the US coast

SE Asia's lowest solar bid ever

Source: Tony Seba

The cost of solar PV has been plunging. In very sunny deserts, solar is now below 1.8 cents/kWh ($18/MWh).  Obviously, in non-desert places, even those in the low latitudes, rainfall reduces the output of solar which raises its cost.  And there is a learning curve, too.  It takes a while for all those involved to learn how to install solar, how to regulate it, how to integrate it into the grid.  Prolly Philippines solar will never be as cheap as solar in Mexico or Saudi Arabia, but this is not the end of the cost decline.

In a tender for 50 MW of solar, local PV module manufacturer and project developer, Solar Philippines submitted a bid of P2.34 (US$0.044) per kWh.

The Philippines-based solar company submitted an offer of P2.34 ($0.044) per kwh in a tender held by the country’s power utility, Meralco for 50 MW of solar power.

In a statement to pv magazine, company CEO, Leandro Leviste said the offer is currently the lowest bid for large-scale solar in Southeast Asia. The previous lowest offer was P2.99 ($0.056), which was submitted by the same company in a previous solar tender held by Meralco in 2017.

The Philippines recently moved from FITs to auctions for supporting the build out of large-scale solar. “While solar energy prices across Southeast Asia on average remain among the highest in the world, we hope these prices will lead the way towards solar prices across the region catching up with global standards,” Leviste  said.

[Read more here]

Once again, the Philippines isn't choosing solar to save the world.  Of course they care about global warming.  Global warming is making typhoons stronger, and that country was devastated by typhoon Haiyan in 2012.   They are installing solar because it's cheaper.

FYI, Manila's days of rainfall through the year:

Source: Weather Atlas

Slowing tropical cyclones very bad news

Hurricane Harvey caused $126bn of damage. Image: By Jill Carlson (jillcarlson.org), via Wikimedia Commons

A report from Climate News Network:

Tropical cyclones are moving more slowly. As temperatures rise, the pace at which a hurricane storms across a landscape has slowed perceptibly in the last 70 years. But the slowdown means each hurricane has more time to do more damage and deliver more flooding.

“Tropical cyclones over land have slowed down 20% in the Atlantic, 30% in the northwestern Pacific and 19% in the Australian region,” said James Kossin, of the US National Oceanic and Atmospheric Administration’s national centres for environmental information.

“These trends are almost certainly increasing local rainfall totals and freshwater flooding, which is associated with a very high mortality risk.”

He reports in the journal Nature that thanks to atmospheric warming as a consequence of the profligate combustion of fossil fuels in the last century, the summer tropical circulation has slowed and, along with it, hurricane and typhoon speeds. Overall, since 1940, cyclone movements have slowed by 10%; over some land areas, they have slowed much more.

But as the temperature goes up, the capacity of the atmosphere to hold moisture increases – by at least 7% with each degree Centigrade. That means a tropical cyclone – a whirling system of terrifying winds bearing huge quantities of water – has both more water, and more time to drop it over land.

And Dr Kossin cites the example of Hurricane Harvey which in 2017 dumped more than 1.25 metres of water on Houston, Texas and the surrounding countryside in just five days. Devastating floods displaced 30,000 people, and 89 died. Economic losses were assessed at more than $126bn.

[Read more here]

$126 billion!!!!  And the denialists still maintain that it's "too expensive" to reduce carbon emissions.  The effects of global warming are being felt right now.  We don't have to wait for decades to go by to feel the impact of climate change.  All that will happen is that the effects will just get worse.  Start slashing emissions now, world, before it's too late.

Natural disasters to cost £72bn this year

Swiss Re, which is an insurer to insurers, or a "re-insurer", insuring insurance companies when they have catastrophic risks, (obviously) carefully monitors the rate of catastrophic climate and other events.

Recent catastrophes such as hurricanes in the Caribbean and an earthquake in Mexico will cost the global insurance industry around $95bn (£72bn), Swiss Re has said, although it admitted that the estimates "are subject to a higher than usual degree of uncertainty and may need to be subsequently adjusted."

The world's second largest reinsurer said it alone faces losses of $3.6bn (£2.7bn) from the "extremely powerful" series of natural disasters that took place in the third quarter of this year.

Swiss Re said the two powerful earthquakes to hit Mexico last month will lead it to incur losses of around $175m, meaning most of its claims during the period came from hurricanes Harvey, Irma and Maria.

This has been one of the worst ever years for natural disasters, with insurers facing hundreds of millions in claims and many being forced to issue profit warnings. Reinsurers such as Swiss Re, which insure the insurers, are expected to be hit particularly hard.

Faced with such huge losses, the insurance sector is under immense pressure to help limit the damage caused by climate change as the world prepares for extreme weather to become the new norm.

Maurice Tulloch, Aviva’s chairman of global general insurance, told The Telegraph earlier this year that the frequency of severe events was increasing year on year. "I’m no longer having to convince people when I speak to them that we’re going to see more of these," he said. "As an industry we’ve got a role to play, we have to act now."  

[Read more here]

The sea floods Miami

An extraordinary sight.

Source

In harm's way

It looks as if hurricane Irma will hit Miami over the weekend.  It's the most intense Atlantic hurricane ever.  Here's a good explanation of why global warming has made hurricanes more intense.  Miami is barely above sea level, and already floods regularly from heavy rainfalls or high tides.  The pictures below, from the New York Times show how much development has taken place on what are essentially sand bars, and how vulnerable Miami is to catastrophe.

Yet the Florida Governor has forbidden State bureaucrats from mentioning global warming, and Senator Marco Rubio is an out and out denialist.   In fact it is hard to find any Republicans who are not denialists.

Miami in 1925 and 2017 (Source)

We have to talk about Harvey

We can't say with any certainty that hurricane Harvey which produced extraordinary rain across Houston a few days ago was caused by climate change.  What we can say, though, is that it was made much worse by climate change.

The science of  attributing extreme weather to climate change is complicated and developing every day. Here’s a guide of what we know about the links between climate change and Harvey to help unpack the elements that contributed to this historic and unfolding storm. 

As seas warm, more water evaporates to the atmosphere. A warmer atmosphere can hold more water, fueling extreme rainfall and increasing flood risk. Record-breaking rainfall is a classic signature of climate change, and the fingerprint of climate change has been firmly identified in the observed global trend of increasing extreme precipitation.

Many areas of Southeast Texas have received rain so extreme that historical data indicates it should only happen once every 1,000 years.

 Houston is experiencing its third ‘500-year’ flood in 3 years. 

 Since the 1950s, Houston has seen a 167 percent increase in the frequency of the most intense downpours. 

 A rain gauge in Mont Belvieu, about 40 miles east of Houston, registered 51.88 inches of rain through late afternoon Tuesday. Once verified, this amount would break not only the Texas state rainfall record but also the record for the remaining Lower 48 states.

 A formal attribution study of last year’s historic flood in Louisiana found that climate change to date had most likely doubled the frequency of the extreme rainfall that drove that flood.

Kevin Trenberth, a senior scientist at the U.S. National Center for Atmospheric Research, said, “The human contribution can be up to 30 percent or so of the total rainfall coming out of the storm.”

Another major contributor to the extreme rainfall totals was that Harvey stalled for many days over southeast Texas. Waves in the jet stream can stall in place (instead of moving eastward), leading to blocking and persistent weather patterns that fuel the intensity and duration of rainfall events.

• A study from March 2017 found that climate change is altering large scale weather patterns, such as the jet stream, which have the ability to dramatically amplify extreme weather events, such as extreme rainfall, during the summer.

• According to Michael Mann, the stalled weather pattern during Hurricane Harvey “is precisely the sort of pattern we expect because of climate change.”

[Read more here]

There's more in the piece by Climate Code Red and if you get a chance you should read it.

We are making progress towards a zero carbon economy.  But not fast enough.

See also:

Warming linked to Storm Harvey devastation
South Asia floods kill 1,200 and shut 1.8 million children out of school
In an era of dire climate records the US and South Asia floods won't be the last
So Let’s Talk About the Science of How Climate Change Kicked Harvey into Higher Gear
Why are the crucial questions about Hurricane Harvey not being asked?