Climate Change ☀️
With drop in LA's vehicular aerosol pollution, vegetation emerges as major source
Organic aerosol pollutants have decreased in the Los Angeles area due to strict vehicle emissions controls, but aerosol levels still rise in hot weather to unhealthful levels. While some attribute these aerosols to household cleaning products, researchers have identified a more probable cause: chemicals emitted by vegetation. Given the number of trees in LA, like the isoprene-emiting Mexican fan palm, it's likely that 25% of organic aerosols are from plants.

California's restrictions on vehicle emissions have been so effective that in at least one urban area, Los Angeles, the most concerning source of dangerous aerosol pollution may well be trees and other green plants, according to a new study by University of California, Berkeley, chemists.

Aerosols -- particles of hydrocarbons referred to as PM2.5 because they are smaller than 2.5 microns in diameter and easily lodge in the lungs -- are proven to cause cardiovascular and respiratory problems.

As a result of strict vehicle emissions laws, organic aerosol levels have been significantly reduced throughout the United States, but the drop has been particularly dramatic in Los Angeles, which started out at a higher level.
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Extreme temperatures, heat stress and forced migration
Heat extremes will lead to climate-induced waves of migration toward the cooler north.

To avoid such extreme heat events in the region, the scientists recommend immediate and effective climate change mitigation measures. "Such measures include drastic decreases of the emissions of greenhouse gases such as carbon dioxide and methane into the atmosphere, but also adaptation solutions for the cities in the area," says Lelieveld. It is expected that in the next 50 years, almost 90 percent of the exposed population in the MENA will live in urban centers, which will need to cope with these societally disruptive weather conditions. "There is an urgent need to make the cities more resilient to climate change," emphasizes Zittis.
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Once-in-a-century UK wildfire threats could happen most years by end of century
Researchers looked at current frequency of weather conditions in the UK that present 'very high' or 'exceptional' fire danger, and found these conditions could occur hundreds of times more often in some regions by the 2050s and 2080s as temperatures rise and summer rainfall decreases.

Extremely hot and dry conditions that currently put parts of the UK in the most severe danger of wildfires once a century could happen every other year in a few decades' time due to climate change, new research has revealed.

... Wildfires need a source of ignition which is difficult to predict, so wildfire risk is typically measured by the likelihood that a fire would develop after a spark of ignition. This fire danger is affected by weather conditions. As temperatures rise and summer rainfall decreases, conditions highly conducive to wildfire could be nearly five times more common in some regions of the UK by the latter part of the century.

In the driest regions, this could put habitats at risk for up to four months per year on average, the scientists found.
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E.P.A. to Review Attacks on Science Under Trump
The Biden administration is taking the unusual step of making a public accounting of the Trump administration’s political interference in science, drawing up a list of dozens of regulatory decisions that may have been warped by political interference in objective research.

The effort could buttress efforts to unwind pro-business regulations of the past four years, while uplifting science staff battered by four years of disregard. It is particularly explicit at the Environmental Protection Agency, where President Biden’s political appointees said they felt that an honest accounting of past problems was necessary to assure career scientists that their findings would no longer be buried or manipulated.

In a blunt memo this month, one senior Biden appointee said political tampering under the Trump administration had “compromised the integrity” of some agency science. She cited specific examples, such as political leaders discounting studies that showed the harm of dicamba, a popular weedkiller that has been linked to cancer and subsequently ruling that its effectiveness outweighed its risks.

The broader list of decisions where staff say scientific integrity was violated is expected to reach about 90 items, according to one person involved in the process. It currently includes well-known controversies like the ricochet of decisions around Pebble Mine, a proposed copper and gold mine in Alaska’s Bristol Bay region, as well as rulings around relatively obscure toxic chemicals.

“Manipulating, suppressing, or otherwise impeding science has real-world consequences for human health and the environment,” the E.P.A. administrator, Michael Regan, said in an agencywide email message on Tuesday. “When politics drives science rather than science informing policy, we are more likely to make policy choices that sacrifice the health of the most vulnerable among us.”

... President Donald J. Trump’s well-documented attacks on science include doctoring a map with a black Sharpie to avoid acknowledging that he was wrong about the path of a hurricane and then pressuring scientists to back his false claim; meddling in federal coronavirus research; and pressuring regulators to approve Covid 19 vaccines and treatments. Those actions provoked bipartisan concern during his administration.

... William K. Reilly, the E.P.A. administrator under the first President George Bush and a critic of both Mr. Pruitt and Mr. Wheeler, said he disagreed.

“There’s no precedent for the attack on science, the sweep of it, the blatancy of it that we saw in the last administration,” Mr. Reilly said. He said a public reckoning was precisely what the E.P.A. needed now.

“Although it could look like politics, and probably does to the Trumpies, it’s a reasonable adjustment to what has to be a major transformation,” he said. “It’s a response both to the reality of the scientific abuse that occurred and also important to agency morale.”
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Climate change, periodic modification of Earth’s climate brought about as a result of changes in the atmosphere as well as interactions between the atmosphere and various other geologic, chemical, biological, and geographic factors within the Earth system.

Source: Climate change - Evidence for climate change | Britannica
Climate Change is the defining issue of our time and we are at a defining moment. From shifting weather patterns that threaten food production, to rising sea levels that increase the risk of catastrophic flooding, the impacts of climate change are global in scope and unprecedented in scale. Without drastic action today, adapting to these impacts in the future will be more difficult and costly.

Source: Climate Change | United Nations