Climate and environment updates: 7 key measures of Earth's health in danger, report warns

In recent years, wildfire smoke has emerged as a significant cause of diminished air quality across many cities in the United States, according to a new recent study presented at the American Geophysical Union annual meeting in Washington, D.C.

The findings, which have not yet been peer-reviewed, suggest that wildfire smoke can contribute to as much as 50% of annual air pollution in certain parts of the U.S. Regions in Oregon, Nevada, California, Washington, North Dakota and Minnesota were identified as some of the most affected by this smoke-related air pollution.

The researchers say the impact of wildfire smoke doesn't just stop in remote areas; it's also impacting major urban centers. Some of the country's largest cities, including New York, Dallas, Chicago, Atlanta and Washington, D.C., reported significant smoke exposure in 2023. Los Angeles, Phoenix and Riverside experienced their highest smoke levels in 2020. The researchers say this year-to-year variation between locations underscores the unpredictable nature of wildfire seasons and their far-reaching consequences on air quality.

The researchers analyzed data collected from more than 800 particle monitors in over 350 areas, representing nearly 90% of the U.S. population. The team combined data from the NOAA Hazard Mapping System Fire and Smoke Product with surface PM2.5 readings to explore how these smoky days affect overall pollution levels. PM2.5 is a type of particulate matter pollution smaller than human hair that can cause a number of health problems, such as asthma and heart disease.

The results from the study raise important questions about public health and environmental policy, especially as climate change intensifies wildfire seasons. According to a study from researchers at the University of Tasmania, extreme wildfire events have more than doubled in frequency and magnitude globally over the past two decades. And the Environmental Protection Agency has found that the U.S. wildfire season has grown longer and shifted earlier in recent decades due to warmer springs, longer summer dry seasons and drier vegetation.

-ABC News Climate Unit's Matthew Glasser and ABC News Medical Unit's Vinh-Son Nguyen, MD

For thousands of years, the vast Arctic tundra has acted as a critical carbon sink. That means it absorbed more carbon dioxide than it produced. As a result, it has been removing a heat-trapping greenhouse gas from the atmosphere. However, rapidly warming conditions and increasing wildfire activity have now turned the region into a source of carbon dioxide emissions, according to a new report released by the National Oceanic and Atmospheric Administration (NOAA).

The Arctic region is warming much faster than the global average, and rapidly warming temperatures are fueling the troubling shift in several ways.

First, increasing temperatures are thawing the permafrost, releasing carbon that's been stored in the soil into the atmosphere. Second, warmer conditions promote vegetation growth, contributing to more frequent wildfires in the region and additional carbon dioxide emissions.

The Arctic's warmest years on record have all occurred within the last nine years. The persistent warming trend has contributed to declining snow cover and a shortening snow season. According to the report, last winter brought the shortest snow season in 26 years for portions of Arctic Canada, and overall, Arctic snow melt is occurring one to two weeks earlier than historical averages.

Less snow promotes further warming and increases the wildfire threat in the region. And these compounding factors create an unsettling cycle that feeds on itself, boosting global warming while making it increasingly difficult to reduce carbon dioxide emissions.

Rick Spinrad, NOAA's administrator, said the addition of the Arctic tundra as a source of carbon dioxide emissions "will worsen climate change impacts."

Local ecosystems are already having to adapt. According to the report, food sources for ice seal populations are shifting due to water temperature changes and warmer and wetter weather is devastating inland caribou herds.

If this trend continues, cascading impacts could reach far beyond the Arctic region. "What happens in the Arctic has wide-reaching implications for the entirety of North America and Eurasia," Dr. Brenda Ekwurzel, a climate scientist at the Union of Concerned Scientists, said in a press statement.

-ABC News meteorologist Dan Peck

Another season, another climate milestone. According to a new report from the National Oceanic and Atmospheric Administration (NOAA), persistent above-average to record-warm conditions across much of the United States made meteorological autumn, which lasts from September to November, the warmest ever recorded.

The record-warm fall season makes it more likely that 2024 will end up as one of the nation’s warmest, if not the warmest, years on record. As of November 2024, the contiguous U.S. year-to-date temperature was 3.3 degrees Fahrenheit above average.

Despite December’s chilly start for much of the country, with widespread below-average temperatures in many regions, NOAA’s Climate Prediction Center says that the cold will ease during the second half of the month with above-average temperatures favored from the West to the Northeast.

The stretch of abnormally warm temperatures was accompanied by extremely dry weather across much of the country, fueling dangerous wildfire conditions in regions like the Northeast. A very dry start to the season brought drought conditions to more than half of the lower 48 states by late October.

Fortunately, several significant rainfall events in November brought notable drought relief to large swaths of the country, reducing overall drought coverage by nearly 10.5% and suppressing the wildfire danger.

-ABC News meteorologist Dan Peck

Nearly one-third of the world's species could be at risk for extinction because of climate change if the world does nothing to reduce global warming, according to a new analysis from Science.

University of Connecticut researcher and biologist Mark Urban found that while some species are adapting to climate change, 160,000 species are already at risk. Many are now facing declining populations because of changes in our climate.

According to the study, with current global temperatures at 1.3 degrees Celsius above industrial levels, 1.6% of species are projected to become extinct. As the temperatures warm even more, Urban found the extinction rate would also increase, with the most severe scenario included (5.4 degrees Celsius of warming) putting the extinction risk at 29.7%.

"The increased certainty of predicted climate change extinctions compels action," Urban wrote. "Extinction represents just the final endpoint of a species' existence; even when extinction is avoided, declining abundances and shrinking ranges can strongly affect many other species, including humans."

Urban defines the risk of extinction as the probability that any one species will go extinct without mitigation efforts. Urban found that extinction rates could increase dramatically if global temperatures rise over 1.5 degrees Celsius compared to industrial levels.

1. 5 degrees Celsius is the warming limit set by the world's nations under the Paris Agreement after the United Nations Intergovernmental Panel on Climate Change found that crossing that benchmark would lead to more severe climate change impacts.

Risks varied across geographic areas in the study, with Australia/New Zealand and South America facing the highest risks (15.7% and 12.8%, respectively) and Asia facing lower risks (5.5%).

-ABC News Climate Unit's Kelly Livingston