Thread: Any doubts about Climate Change?

• Berkeley Earth - September 2023 was the warmest September recorded

September also contained the annual maximum in Antarctic sea ice. It was by far the lowest maximum for sea ice extent in the modern satellite record (since 1979), and also one of the earliest dates for the peak to be observed.

Rest of 2023 - The statistical approach that we use, looking at conditions in recent months, now believes that 2023 is virtually certain to become the warmest year on record (>99% chance).

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• Climate crisis costing $16m an hour in extreme weather damage, study estimates

The damage caused by the climate crisis through extreme weather has cost $16m (£13m) an hour for the past 20 years, according to a new estimate.

Storms, floods, heatwaves and droughts have taken many lives and destroyed swathes of property in recent decades, with global heating making the events more frequent and intense. The study is the first to calculate a global figure for the increased costs directly attributable to human-caused global heating.

It found average costs of $140bn (£115bn) a year from 2000 to 2019, although the figure varies significantly from year to year. The latest data shows $280bn in costs in 2022. The researchers said lack of data, particularly in low-income countries, meant the figures were likely to be seriously underestimated. Additional climate costs, such as from crop yield declines and sea level rise, were also not included.

The researchers produced the estimates by combining data on how much global heating worsened extreme weather events with economic data on losses. The study also found that the number of people affected by extreme weather because of the climate crisis was 1.2 billion over two decades.

Two-thirds of the damage costs were due to the lives lost, while a third was due to property and other assets being destroyed. Storms, such as Hurricane Harvey and Cyclone Nargis, were responsible for two-thirds of the climate costs, with 16% from heatwaves and 10% from floods and droughts.

The researchers said their methods could be used to calculate how much funding was needed for a loss and damage fund established at the UN’s climate summit in 2022, which is intended to pay for the recovery from extreme weather disasters in poorer countries. It could also rapidly determine the specific climate cost of individual disasters, enabling faster delivery of funds.

“The headline number is $140bn a year and, first of all, that’s already a big number,” said Prof Ilan Noy, at the Victoria University of Wellington in New Zealand, who carried out the study with colleague Rebecca Newman. “Second, when you compare it to the standard quantification of the cost of climate change [using computer models], it seems those quantifications are underestimating the impact of climate change.”

Noy said there were a lot of extreme weather events for which there was no data on numbers of people killed or economic damage: “That indicates our headline number of $140bn is a significant understatement.” For example, he said, heatwave death data was only available in Europe. “We have no idea how many people died from heatwaves in all of sub-Saharan Africa.”

The study, published in the journal Nature Communications, took a different approach based on how climate change had exacerbated the extreme weather events. Hundreds of “attribution” studies have been done, calculating how much more frequent global heating made extreme weather events. This allows the fraction of the damages resulting from human-caused heating to be estimated.

The researchers applied these fractions to the damages recorded in the International Disaster Database, which compiles available data on all disasters in which 10 people died, or 100 were affected, or the country declared a state of emergency or requested international assistance.

The central estimate was an average climate cost of $140bn a year, with a range from $60bn to $230bn. These estimates are much higher than those from computer models, which are based on changes in average global temperature rather than on the extreme temperatures increasingly being seen in the world.

The years with the highest overall climate costs were 2003, when a heatwave struck Europe; 2008, when Cyclone Nargis hit Myanmar; and 2010, when drought hit Somalia and a heatwave hit Russia. Property damages were higher in 2005 and 2017 when hurricanes hit the US, where property values are high.

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• Scientists "uneasy" about Earth's sped-up warming

The globe's pronounced and unexpected temperature spike during the past few months is provoking unease among some of the most level-headed climate scientists.

The big picture: September was the most unusually warm month in recorded history. This followed record heat in June and July — which was also the planet's hottest month — as well as August.

• Climate scientists point to several factors propelling the climate into uncharted territory. These include a strengthening El Niño in the tropical Pacific Ocean to an undersea volcanic eruption last year, which injected water vapor into the upper atmosphere.
• Other developments, such as changes in fuel mixtures for large marine vessels and weather patterns in the North Atlantic, are coming under scrutiny too.

Of note: Yet the largest factor at work is long-term, human-caused climate change from burning fossil fuels like coal and gas.

Yes, but: The climate scientists Axios spoke with for this story noted there may be some aspects of the recent record-shattering global heat that are not fully understood.

• This isn't reason for panic, however; but it does showcase that climate change involves surprises.
• And as the climate continues to warm, there may be even more consequential and unforeseen shocks down the road.
• "Future researchers will be writing dissertations trying to unpack the mix of factors that led us to blow away all prior records this year," Zeke Hausfather, climate lead at the payments company Stripe, told Axios.

Between the lines: The Pacific Ocean has seen a rapid swing from a cool, three-year-long La Niña phase into an El Niño, which features unusually mild ocean temperatures in the central and eastern tropical Pacific.

• That may be pushing global average surface temperatures higher at faster-than-usual rates.
• "Climate change comes on top of natural fluctuations in the climate system, and in a hotter-than-average world there will be hotter and cooler years," Kate Marvel, a senior climate scientist at Project Drawdown, told Axios.
• "The usual suspects — climate change plus El Niño — go a long way toward explaining the excess heat of this summer," Marvel said. She cautioned that other sources of internal variability may be at play too and historically have led to unexpected outcomes.
• "There is always the possibility that something is going on that we've missed, but the Earth system is a strange beast even when it's not being disturbed," Marvel said.

Zoom out: At the start of the calendar year, few climate experts expected it would be the planet's warmest on record. Yet that is now a virtual lock in nearly every data set, from NASA to the Copernicus Climate Change Service.

• Much of the planet's high fever is traceable to record warm oceans worldwide, a characteristic of 2023's climate imperiling sensitive marine ecosystems.
• Berkeley Earth, an independent temperature tracking group, pegs the odds that 2023 will have a global average surface temperature that is more than 1.5°C (2.7°F) above pre-industrial levels at 90%, up from just 55% one month ago, and 1% before the year began.
• This is a symbolic milestone, since it is the more ambitious target in the Paris Climate Agreement. However, the Paris text refers to an average over multiple decades, not a single year.

• "The fact that this forecast has shifted so greatly serves to underscore the [extraordinary] progression of the last few months, whose warmth has far exceeded expectations," Berkeley Earth's Robert Rohde wrote in an analysis published Wednesday.

What they're saying: Andrew Dessler, a climate scientist at Texas A&M University, said the "sudden jump" in temperatures during just a few months' time has been the biggest surprise.

• Because all of the human-caused responses act on longer and slower time scales, this would suggest some combination of internal, largely natural climate variability, together with climate change.
• "It may be some compound mode or something weirder," he said, noting that while the temperature uptick is not a completely unforeseen outcome in climate model simulations, they depict it as being highly unlikely.
• "I think this makes everybody in the climate science community uneasy."
• Gavin Schmidt is the director of NASA's Goddard Institute for Space Studies, which is slated to release its September temperature data on Friday. He expects the temperature departures from average to shrink each month as we head into winter in the Northern Hemisphere.
• Yet with the strong to very strong El Niño forecast to last into 2024, global average temperatures are likely to stay unusually high. Typically, global temperatures peak a few months after El Niño does.

The bottom line: "2023 will be the warmest year (something I gave a 10% probability to at the end of 2022), but I think 2024 will be warmer still," Schmidt said.

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• Study: Climate change to drive temperatures too hot for humans

Billions of people are at risk of temperatures exceeding survivability limits if global temperatures increase by 1°C (1.8°F) or more above current levels, a new study warns. Even young, healthy people could find it unbearably hot during part of the year, the study finds.

Driving the news: Regions in the Middle East and South Asia would "experience the brunt of deadly or intolerable conditions," researchers noted. Toward the higher end of warming scenarios, "potentially lethal combinations of heat and humidity could spread" to areas including U.S. Midwestern states.

Why it matters: The study, published in the journal Proceedings of the National Academy of Sciences on Monday, finds that temperatures are increasing and heat waves are becoming "more frequent, intense, and longer-lasting due to climate change."

• Some areas are already exceeding the limits of the human body's tolerance for the combined impacts of heat, humidity, sun exposure and other factors, known as the wet bulb temperature.
• This year, the world has endured some of the hottest summer and early fall temperatures on record, with global average surface temperatures temporarily exceeding the Paris Agreement's temperature target of 1.5°C (2.7°F) compared to preindustrial levels multiple times in 2023.

Yes, but: The Paris Agreement's threshold isn't truly broken until that higher level is maintained for about 30 years.

• This study by scientists from Penn State and elsewhere warns this could occur if significant emissions cuts aren't made.

What they did: Researchers modeled temperature scenarios ranging from the Paris Agreement's target of 1.5°C of warming through 4°C and identified regions most at risk from rising heat and humidity for the study.

• Researchers adopted a wet bulb temperature threshold, beyond which humans have great difficulty surviving, and used a slightly lower wet bulb temperature than the oft-mentioned 35°C (95°F) — based on the notion that humans may be more sensitive to humid heat than previously thought.

What they found: The regions projected to be the worst affected in scenarios that reach upward to 2 °C are equatorial and Sahel regions of Africa and eastern China, per the study. Researchers note this is "a viable outcome by the end of the century, perhaps sooner, without drastic reductions in greenhouse gas emissions."

• "Continued warming above 3 °C and 4 °C, respectively, causes North and South America, as well as northern Australia, to experience extended periods of dangerous heat," per the study.

Zoom out: The study bolsters other recent research showing human survivability limits being challenged in some parts of the world at current or higher levels of warming. A separate study last year warned of the emergence of an "extreme heat belt" from Texas to Illinois.

• That hyperlocal analysis of current and future extreme heat events by the nonprofit First Street Foundation found the heat index in these areas could reach 125°F at least one day a year by 2053.

• Another study published in 2020 found that intolerable heat was already occurring in some parts of the world, including the Middle East, and has been increasing in frequency.

Of note: Preliminary data from the Copernicus Climate Change Service shows the global average surface temperature for June through August was the hottest on record, as studies show climate change boosted the deadly heat in the U.S. and Europe.

• One study found it would have been "virtually impossible" without it.

The bottom line: "In the future, moist heat extremes will lie outside the bounds of past human experience and beyond current heat mitigation strategies for billions of people," per the study.

• "While some physiological adaptation from the thresholds described here is possible, additional behavioral, cultural, and technical adaptation will be required to maintain healthy lifestyles."

What they're saying: "This will be a critical benchmark for future studies," said atmospheric scientist Jane Baldwin of University of California Irvine who was not involved in the research, to Reuters.

• "Unfortunately, it's a somewhat grimmer picture than you would have gotten with the 35C limit."

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Looking ahead……

Zeke Hausfather - Here are where we expect to see final October temperatures compared to all other Octobers in the dataset. This would likely end up somewhere around 1.5C to 1.7C above preindustrial levels: https://twitter.com/hausfath/status/1711409015929082164