Once trusted faces on the news, meteorologists now brave threats, insults and slander online from conspiracy theorists and climate change deniers who accuse them of faking or even fixing the weather.

Users on Twitter and other social media falsely accused Spain's weather agency of engineering a drought, Australia's of doctoring its thermometers and France's of exaggerating global warming through misplaced weather stations.

"The coronavirus is no longer a trend. Conspiracy theorists and deniers who used to talk about that are now spreading disinformation about climate change," Alexandre Lopez-Borrull, lecturer in Information and Communication Sciences at the Open University of Catalonia, told AFP.

"These scientific bodies are seen as part of the establishment, so anything they say may get disputed on social networks.

"They are providing evidence against what the climate deniers claim, so the latter try to discredit them."

- Meteorologists threatened -

In a harsh drought and with local elections looming, Spain's State Meteorological Agency (AEMET) spoke out after its members were threatened in Twitter messages, phone calls and emails.

"Murderers", "Criminals", "You'll pay for this", "We're watching you", the messages shouted.

They came from people who believe the widely debunked theory that aeroplane condensation trails are really "chemtrails" sprayed by the authorities to poison people or create weather disasters.

Some referred to the "2030 agenda", a debunked theory that global elites are plotting to subjugate people through Covid and climate policies.

"Do you want us to publish your contact details and those of your family?" read one Tweet aimed at an AEMET employee.

"Crooks! You are destroying nature on the orders of the damned 2030 agenda," said another.

"We have seen an increase in insulting messages as a result of a thread we published about condensation trails" on April 10, AEMET spokesperson Estrella Gutierrez-Marco told AFP.

"What makes no sense is that they are insulting an institution that is constantly watching out for their interests, whose aim is... to contribute to people's safety."

Lopez-Borrull noted a "significant increase" in climate change denial –- particularly among far-right supporters who see it as a leftist cause and oppose reforms aimed at curbing its impacts.

"People distrust politicians, judges and the media, and the cost of living is rising," he said.

"In this context people feel alienated and end up listening to people they never listened to before, with messages appealing directly to the emotions."

- Australian thermometers -

In another case investigated by AFP Fact Check, conservative media and Facebook users shared unfounded claims that Australia's Bureau of Meteorology (BOM) doctored its temperature readings.

In an analysis of data obtained via a freedom of information request, prominent climate sceptic Jennifer Marohasy said BOM's electronic probes returned readings up to 0.7 degrees Celsius warmer than those of its older mercury thermometers.

Experts who analysed the data said the claims were inaccurate.

Monash University emeritus environment professor Neville Nicholls said the difference between most readings on the electronic probes and the mercury thermometers was negligible -- between zero and 0.1C (0.18 degrees Fahrenheit).

"This difference is very small compared to the strong warming trend in average temperature over Australia" -- about 1.4C over the past century -- Nicholls told AFP.

The World Meteorological Organization told AFP that the BOM's measurements were in line with its standards, contrary to Marohasy's allegation.

- Temperatures in France -

After a series of heat records in March in southwestern France, a critic on social media published a thread alleging that the country's national weather service overstated warming by relying on readings from stations in urban districts, where temperatures are typically higher.

The thread received more than 139,000 views and spread to Facebook.

"Yet another way of making us feel scared and guilty," one woman commented on the thread, referring to the weather service, Meteo-France.

"Luckily fewer and fewer people believe them after the Covid business. I'm glad not to watch their forecasts on France TV."

Climatologists consulted by AFP debunked the claims, pointing out that the limited network of 30 weather stations referred to in the thread is not what scientists use to measure climate change, and the climate is also observed to be changing in rural districts.

"Meteo-France researchers use all possible measures and create computer models with various hypotheses and a longer timeframe for analysis," said Christine Berne, a climatologist in the service.

"You can be sure we don't just have our 30 little weather stations."

One Twitter user accused Dutch broadcaster RTL Nieuws of exaggerating a late-April heatwave in Spain, posting as evidence a screenshot showing moderate temperatures in the Costa Blanca.

However, his screenshot was taken three days after the heatwave, in the cool of the morning.