Last month was the third-warmest June on record globally, according to new data analyzed by the Copernicus Climate Change Service (C3S). The previous three Junes now rank one, two and three for the warmest in history.

June was just the third month in the past two years that did not surpass the 1.5 degree Celsius warming threshold established in the 2015 Paris Climate Agreement. Instead, it registered 1.3 degrees above the pre-industrial reference period (1850-1900).

The planet’s average surface air temperature was 16.46 degrees Celsius, or 61.63 degrees Fahrenheit, according to Copernicus.

Scientists anticipated a short-term drop in global temperatures due to the recent La Niña event in the equatorial eastern Pacific Ocean. This climate pattern typically brings a temporary dip in global average temperatures. However, climate scientists caution that this pause is unlikely to last, as human-caused greenhouse gas emissions continue to fuel the long-term warming trend.

Global daily sea surface temperatures across much of the world’s oceans remained above average in June. Between the latitudes of 60 degrees south and 60 degrees north, which include most of the continents and oceans, the average global sea surface temperature was 69.3 degrees Fahrenheit, the third-highest value on record for the month.

In the polar regions, sea surface temperatures also frequently registered above average, negatively impacting sea ice. Antarctic sea ice coverage was 9% below average in June, ranking as the third-lowest value on record for the month. In the Arctic, it was 6% below average, marking the second-lowest June extent on record, Copernicus said.

-ABC News meteorologist Dan Peck

Rising temperatures, amplified by climate change, are contributing to an increase in cases of sleep apnea, a condition in which breathing repeatedly stops during sleep, according to a new study published in the journal Nature Communications.

"If temperature keeps rising the way they project it to, the burden and prevalence of sleep apnea may double, increasing by 20-100%, depending on greenhouse gas emission reduction," Bastien Lechat, the study's author and a senior research fellow at Flinders University in Australia, told ABC News.

Obstructive sleep apnea, or OSA, affects about 1 billion people globally, and 80% of people who have it are unaware and untreated. OSA has been linked to an increased risk of heart disease, stroke, dementia, diabetes and depression. People with OSA also have two times greater risk of getting in a car accident, according to Lechat.

The study followed over 115,000 people from numerous countries for up to two years, measuring their sleep quality with below-the-mattress sleep monitors and then cross-referencing this information with weather data to evaluate the relationship between temperature and OSA.

When comparing 80-degree Fahrenheit days to days in the 40s, there was a 40 to 45% increase in the frequency or severity of sleep apnea. The risk was even higher for males and individuals who normally sleep longer or have higher body weight.

Extreme heat can exacerbate OSA by making it even harder to sleep, the study noted. Higher temperatures can disrupt the body's ability to cool down during the night, which interferes with the natural sleep cycle. This can lead to more frequent awakenings, shallower sleep and worsened airway instability, resulting in more apnea events.

Using existing health-economic models, the researchers estimated over 788,000 healthy years of life were lost or disabled in 2023 due to temperature-related increases in OSA, equivalent to a loss of approximately $68 billion, according to the models.

"When you look at the rate of years of life lost per 100,000 people, this is similar to a disorder like Parkinson's disease, or bipolar disorder, or similar to low physical activity as a risk factor, so it's a significant burden," Lechat told ABC News.

Lechat said that increased access to air conditioning and better diagnosis and treatment of OSA could offset some of the increases caused by climate change. However, he emphasized that limiting global warming through policy changes is the most effective and cost-efficient option.

"Limiting global warming is probably cost effective, when you look at the numbers -- the loss of well-being and the economic costs of increasing temperature," he added.

-Dr. Ilan Kokotek, a board-certified family physician and member of ABC News' Medical Unit

Plastic pollution remains one of the planet’s most critical environmental threats, accounting for the majority of marine litter found across our oceans and coastlines, according to the UN Environment Programme. The UN says the thin, single-use bags can harm and kill aquatic life when the animals get entangled or ingest the plastic. And the nonprofit The Ocean Cleanup reports that plastic can also release toxic chemicals into the ocean.

In response, plastic bag bans and fees have emerged as popular policy tools to combat this issue, aimed at reducing plastic waste and preventing litter from reaching waterways. Now, a new study published in the journal Science shows that these policies have been broadly effective, adding to a growing body of evidence that supports the effectiveness of such regulations.

Researchers examined nationwide data from more than 45,000 shoreline cleanups to assess the effectiveness of plastic bag bans and taxes. They looked at the hundreds of state and local bag policies enacted across the United States between 2017 and 2023 and compared the regions with and without such measures.

The researchers found that plastic bag policies resulted in a 25% to 47% decrease in plastic bags as a share of total items collected compared to areas without policies.

Despite the positive findings, the study’s authors caution that global waste generation is expected to continue rising through the end of the century. Without significant, large-scale policy changes, the leakage of plastic debris into the world’s oceans will likely remain a significant environmental challenge for decades to come.

In August, the United Nations Environment Programme will resume negotiations on a global plastics treaty following a breakdown in talks last December in Busan, South Korea, where countries failed to reach consensus on the scope of a final agreement.

Although there is growing evidence that plastic bag policies are effective, critics have argued the regulations fall short, or even backfire, by increasing the production and use of other types of plastic. Earlier this year, President Trump signed an executive order banning the federal use of paper straws, reigniting the debate on plastic bans.

-ABC News meteorologist Dan Peck

When wildfires fill the air with heat and smoke, the danger isn't just outside. A new study in PLOS Climate finds that when people move indoors en masse, it creates ideal conditions for viruses like flu, RSV and COVID-19 to spread more easily.

Severe weather events, including wildfires, are becoming more frequent as the planet warms. To stay safe during these emergencies, people often seek safety inside -- but that response comes with its own risks, according to the study. Close quarters, poor ventilation and extended time in shared spaces make it easier for viruses to pass from person to person.

During wildfires, smoke can travel far beyond the fire zone, affecting air quality across entire regions. In 2020, counties in Oregon and Washington recorded sustained Air Quality Index levels above 150, the threshold for unhealthy air. The researchers found that in response to the poor air quality, indoor activity in those areas increased between 10.8% and 14.3%, respectively. Urban areas, such as Portland, saw an 11% jump in indoor activity, while Seattle's increase reached 16%.

Even for viruses that spread less easily, and in communities with relatively high immunity, more time spent indoors led to noticeable spikes in viral transmission.

"Places with greater density have worse problems," Giulia Pullano, a Georgetown University researcher and one of the study's authors, explained to ABC News.

While the physical dangers of climate change -- such as extreme heat, wildfire smoke, or poor air quality -- often draw the most attention, Pullano said the indirect effects, like how people behave in response to those threats, also shape public health in meaningful ways.

The PLOS Climate researchers used mobile device data to track indoor versus outdoor activity, comparing wildfire-affected counties with similar counties that had no air quality alerts. They then used computer data to model how this behavior change could affect the spread of respiratory viruses, using different scenarios based on virus characteristics and population immunity.

The study also highlighted one practical way to mitigate the increased disease risk associated with spending more time indoors. Modeling predicted that if 10% of people wore masks indoors during wildfire events, virus spread could be curtailed substantially. If half the population wore masks indoors, infection curve peaks could be flattened.

As climate-amplified disasters become more common, Pullan told ABC News that, "Understanding disruptions of behavior during natural disasters will be critical to protecting public health."

-Board-certified family physician and ABC News medical unit's Dr. Ilan Kokotek

It's all but certain that 2024 will be Earth's warmest year on record, surpassing 2023 as the previous record holder. While this troubling milestone measures global average temperatures, a new study from the Columbia Climate School found that unexplained extreme heat wave hot spots are popping up in specific areas worldwide.

Calling it "a striking new phenomenon," the study's authors write, "Distinct regions are seeing repeated heat waves that are so extreme, they fall far beyond what any model of global warming can predict or explain."

According to the study, "The large and unexpected margins by which recent regional-scale extremes have broken earlier records have raised questions about the degree to which climate models can provide adequate estimates of relations between global mean temperature changes and regional climate risks."

The study identified these hot spots on every continent except Antarctica. Researchers say the heat waves have mostly been a recent phenomenon, occurring primarily over the last five years, although some date back to the early 2000s and before.

Central China, Japan, Korea, the Arabian peninsula, eastern Australia and certain parts of Africa were the hardest-hit areas. The study, however, found that parts of Texas and New Mexico were also impacted, just not as much as the other regions.

"This is about extreme trends that are the outcome of physical interactions we might not completely understand," said lead author Kai Kornhuber, an adjunct scientist at the Columbia Climate School's Lamont-Doherty Earth Observatory, in a statement. "These regions become temporary hothouses."

The researchers say it's unclear what is causing these hot spots. While one study has pointed to wobbles in the jet stream as a possible culprit, the authors say that the hypothesis doesn't explain all the extremes.

Regardless of the cause, heat is the deadliest weather-related hazard in the United States. The Journal of the American Medical Association found that heat deaths in the U.S. have nearly doubled since 1999 and account for a 63% increase in health-related death rates between 1999-2023.

"Due to their unprecedented nature, these heat waves are usually linked to very severe health impacts, and can be disastrous for agriculture, vegetation and infrastructure," said Kornhuber. "We're not built for them, and we might not be able to adapt fast enough."

-ABC News Climate Unit's Matthew Glasser