19/08/2020

Death Valley Temperature Rises To 54.4c – Possibly The Hottest Ever Reliably Recorded

The Guardian - 

US National Weather Service’s automated station at Furnace Creek in California hit extreme high at 3:41pm on Sunday

If the Death Valley temperature is verified, it would beat the previous hottest August day for the United States. Photograph: Steve Marcus/Reuters

A temperature of 54.4C – or 129.9F – has been recorded in Death Valley, California, in what some extreme weather watchers believe could be the hottest reading ever reliably recorded on the planet.

The United States National Weather Service’s automated weather station at Furnace Creek near the border with Nevada hit the extreme high at 3:41pm on Sunday afternoon, a statement said.

“This observed high temperature is considered preliminary and not yet official,” a statement from NWS Las Vegas said.

“If verified, this will be the hottest temperature officially verified since July of 1913, also at Death Valley.”

If the temperature reading is verified, it would beat the previous hottest August day for the United States.

Death Valley’s all-time record high, according to the World Meteorological Organization, is 134F (56.7°C) taken on 10 July 1913 at Greenland Ranch. That reading still stands as the hottest ever recorded on the planet’s surface, according to the WMO.

The Death Valley 1913 reading was installed as the planet’s hottest after a 2013 WMO investigation dismissed a 58C temperature supposedly recorded in Libya in September 1922.

A committee concluded the Libya reading was likely wrong, with human error, the type of thermometer used and inconsistencies with other temperatures in the region all contributing to that temperature being struck off.

But Christopher Burt, from a private US meteorological service, who prompted the investigation into the Libya record, has also challenged the legitimacy of the 1913 Death Valley readings, saying they were “essentially not possible from a meteorological perspective”.

Speaking to the Washington Post, Prof Randy Cerveny, of Arizona State University, who leads a WMO group that maintains an archive of climate extremes, said of the new Death Valley temperature reading: “Everything I’ve seen so far indicates that is a legitimate observation.”

He was recommending the WMO “preliminarily accept the observation” but that the reading would be examined in detail in the coming weeks.

The only other WMO-verified temperature record higher than those taken at Death Valley are from July 1931 at Kebili in Tunisia, where a reading of 131F (55C) was taken.

But like many older temperature readings, this too has been challenged.

Some extreme weather watchers believe the most recent Death valley reading could – in time – be verified as the hottest ever reliably recorded on the planet.

Bob Henson, a meteorologist, told a blog of the American Geophysical Union: “It’s quite possible the Death Valley high set a new global heat record. The extreme nature of the surrounding weather pattern makes such a reading plausible, so the case deserves a solid review.

“There are nagging questions about the validity of even hotter reports from Death Valley in 1913 and Tunisia in 1931. What we can say with high confidence is that, if confirmed, this is the highest temperature observed on Earth in almost a century.”

Prof James Renwick, a climate scientist at Victoria University of Wellington, has taken part in WMO efforts to check temperature readings.

He said the Death Valley reading would need to be checked and verified before any record could be confidently declared. Checks would be made of the instruments to make sure there had been no changes at the Death Valley site, which is close to a visitors’ centre at Furnace Creek.

He said: “There will be a lot of cross-checking to make sure that that value is correct.”

Elsewhere in California, record high temperatures led to wildfires, at least one of which was reported to have turned into a “firenado”. This rarely recorded phenomenon occurs when hot air from a fire on the ground rises in a tall column and starts to rotate in the winds higher off the ground, giving the appearance of a tornado mixed with fire.

The heatwave in the west of the US has also given rise to lightning storms which may start further wildfires, leading agencies in the region to put out warnings.

Persistently high temperatures have been recorded in many areas of the northern hemisphere this summer, giving added weight to the prediction made earlier this year that it could be the hottest on record, as the Earth’s climate changes under human influence. Most concerning for climate scientists has been a “heatwave” recorded in the Arctic.

A record temperature of 38C was observed in Siberia in June, with the Arctic sea ice shrinking to its lowest extent for 40 years in July. Siberian temperatures were more than 5C above average from January to June. New research has suggested that on current trends the Arctic could be ice-free in summer as soon as 2035.

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Impressive data set shows July likely warmest of any month since 1850 worldwide

MLive - Mark Torregrossa

July is going to likely go down as the warmest month ever recorded in a global temperature dataset with observations back to 1850.

Berkeleyearth.org has produced their report on global temperatures for July 2020. One place I like to start on these reports is to just stare at the global temperature deviation map.

Temperature deviation from the July average of 1951 to 1980. (Source: berkeleyearth.org)

The map above shows how cold or warm July 2020 was from the long-term average July temperature. Notice we see a lot of red and not much blue.

More locations around the globe were in the warmest rankings for their locations versus locations in the coldest rankings. In fact, in just a few locations we had some of the coolest rankings.

Temperature rank in deviation from the 1951 to 1980 average (Source: berkeleyearth.org)

Analysis
  • July 2020 is tied with July 2019 as the warmest July since records began in 1850.
  • As July is usually the warmest month globally, tying the July record also means that July 2020 is tied for the warmest month overall.
  • A transition towards La Niña conditions continue in the Pacific.
  • Accounting for the likely impact of La Niña, updated projections for the rest of 2020 give a 36% chance that 2020 will be a new record warm year.
I talked with Zeke Hausfather, research scientist at berkeleyearth.org about the dataset.

It’s an impressive dataset they used for this report. They have merged several datasets together using 40,000 weather stations worldwide and 14,000 current weather stations.

Some of the weather stations have been reporting data back to 1850.

Hausfather addressed the often questioned reliability of changing technology over almost 200 years.

He says the U.S. temperature dataset had two big changes in technology to liquid and glass thermometers in the 1950s and digital thermometers in the 1980s.

If data just didn’t look consistent with surrounding stations, an individual station was taken out.

I relayed the often asked question of how jumps in technology could keep a consistent dataset.

Many feel like that jump to new technology could be the reason temperatures show up warmer. Zeke says the new technology was actually colder than older ways of reading temperatures.

Temperature deviation (in °C) from the 1951 to 1980 average global temperature. (Source: berkeleyearth.org)

Hausfather says what really strikes him is the very strong El Niño year of 1998, once the warmest year ever, is now colder than the last seven years.

Earth's average temperature by month back to 1850. (Source: berkeleyearth.org)

The funding for this report and other research at berkeleyearth.org comes from various organizations that are known to have opposite viewpoints on global warming.

Earth has warmed about two degrees Fahrenheit in the last 100 years, with much of that warming happening since 1980.

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More Than Half Of World's Oceans Already Being Affected By Climate Change

Phys.org - University of Reading

Credit: CC0 Public Domain



More than 50% of the world's oceans could already be affected by climate change, with this figure rising as high as 80% over the coming decades, a new study has shown.

Scientists used and observations in deeper areas of worldwide to calculate for the first time the point at which changes to temperatures and salt levels—good indicators of the impact of human-induced climate change—would overpower natural variations.

The study, published in Nature Climate Change, estimates that 20-55% of the Atlantic, Pacific and Indian oceans now have noticeably different temperatures and salt levels, while this will rise to 40-60% by the middle of the century, and to 55-80% by 2080.

It also found the Southern Hemisphere oceans are being affected more rapidly by climate change than the Northern Hemisphere, with changes having been detectable there since as early as the 1980s.

Professor Eric Guilyardi, co-author at the University of Reading and LOCEAN-IPSL, Laboratory of Oceanography and Climate in Paris, said: "We have been detecting ocean temperatures change at the surface due to climate change for several decades now, but changes in vast areas of the ocean, particularly deeper parts, are much more challenging to detect."

Yona Silvy, a doctoral student at LOCEAN-IPSL/Sorbonne University, and lead author of the study, said: "We were interested in whether the levels of temperatures and salt were great enough to overcome natural variability in these deeper areas, that is if they had risen or fallen higher than they ever would during the normal peaks and troughs. This affects global ocean circulation, sea level rise and poses a threat to and ecosystems."

Previous studies have gauged the impact of climate change on the ocean by looking at surface temperatures, rainfall and , but few have looked at the regional effects deeper down in the ocean to get a more complete picture.

The effects of change are harder to detect in deeper, more insulated parts of the ocean, where heat and salt spread at a slower rate due to weaker mixing processes. It is also difficult in areas that are poorly observed or where natural variability is high.

Yona Silvy and her co-authors used model simulations with and without the impact of human activity and an analysis that combines both and ocean salt to detect significant changes and their date of likely detection, also known as "time of emergence". Yet these are regions that will keep the memory of these changes for decades to centuries.

Changes detectable above natural variability were calculated to be seen in the Northern Hemisphere oceans between 2010-2030, meaning increases or decreases in temperature and levels are likely to have already taken place.

The more rapid and earlier changes seen in the Southern Hemisphere emphasises the importance of the Southern Ocean for global heat and carbon storage as surface waters make their way to the deeper ocean more easily there. However, this part of the world is also particularly poorly observed and sampled, meaning changes are likely to remain undetected for longer.

The scientists argue that improved ocean observation and greater investment in ocean modelling is necessary to monitor the extent of the impact of on the world's oceans, and predict more accurately the wider effect this could have on the planet.

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