Feb 27, 2024

​Very cool: plants trees stalling effects of global warming in eastern US.

(The Guardian) Trees provide innumerable benefits to the world, from food to shelter to oxygen, but researchers have now found their dramatic rebound in the eastern US has delivered a further, stunning feat – the curtailing of the soaring temperatures caused by the climate crisis.

While the US, like the rest of the world, has heated up since industrial times due to the burning of fossil fuels, scientists have long been puzzled by a so-called "warming hole" over parts of the US south-east where temperatures have flatlined, or even cooled, despite the unmistakable broader warming trend.

A major reason for this anomaly, the new study finds, is the vast reforestation of much of the eastern US following the initial loss of large numbers of trees in the wake of European settlement in America. Such large expanses have been reforested in the past century – with enough trees sprouting back to cover an area larger than England – that it has helped stall the affect of global heating.

"The reforestation has been remarkable and we have shown this has translated into the surrounding air temperature,"
said Mallory Barnes, an environmental scientist at Indiana University who led the research. "The 'warming hole' has been a real mystery and while this doesn't explain all of it, this research shows there is a really important link to the trees coming back."

There was a surge in deforestation from the start of the US's early colonial history, as woodland was razed for agriculture and housing, but this began to reverse from around the 1920s as more people began to move into cities, leaving marginal land to become populated again with trees. The US government, meanwhile, embarked upon an aggressive tree-planting program, with these factors leading to about 15m hectares of reforested area in the past century in the eastern US.

Read more from Oliver Milman

Research source:

Feb 20, 2024

EPA Issues Regulation Strengthening Air Quality Standards for PM 2.5

The U.S. Environmental Protection Agency (EPA) issued a final rule to strengthen the national ambient air quality standards (NAAQS) for fine particulate matter (PM2.5). The current standard, which has been in place for more than a decade, limits the average annual amount of fine particle pollution to 12 micrograms per cubic meter of air. The EPA will now require a 25% reduction in the allowable PM 2.5 to 9.0 micrograms per cubic meter but will retain the previous standards for all other PM standards.

The tougher standard on particulate matter, often referred to as the "soot rule," will be fully implemented by 2032. The EPA maintains that the reduced PM 2.5 standard will result in $46 billion in public health benefits.  The EPA's new rule will trigger the following actions to implement the revised PM2.5 NAAQS:

For more information on particle pollution and to read the final rule, visit epa.gov/pm-pollution