Climate and environment updates: October was 2nd warmest month on record, NOAA says

Our planet is facing another unfortunate climate milestone.

According to a new report from the World Meteorological Organization (WMO), carbon dioxide concentrations have increased by more than 11% in just two decades, making 2023 a record for the amount of the greenhouse gas currently in our atmosphere.

The WMO says CO2 is now building up in the atmosphere faster than at any time in human existence. They say massive vegetation fires, which emit greenhouse gases, and El Niño, which can reduce our forests' ability to absorb CO2 due to drought, contributed to the recent surge. However, the U.N. agency also points out, "The reason behind this decade-long significant increase in CO2 is historically large fossil fuel CO2 emissions in the 2010s and 2020s."

The WMO began reporting on greenhouse gas emissions in 2006. That year, they found that atmospheric CO2 levels for 2004 were at 377.1 parts per million. Last year, they were recorded at 420 parts per million. That puts CO2 concentrations at 151% above the preindustrial era.

Methane, one of the worst greenhouse gases in terms of global warming, also reached a record level for atmospheric concentrations. It is now 265% higher than preindustrial readings at 1,934 parts per billion.

Because CO2 stays in the atmosphere for 300 to 1,000 years, according to NASA, the WMO is warning that these high levels of greenhouse gases "lock in future temperature increase" even if emissions are cut to net zero.

-ABC News Climate Unit's Matthew Glasser

It may be fall, but it feels a lot like summer in much of the country. That has some people wondering: Is climate change responsible for these record-high temperatures? With climate attribution science, we can now answer that question and determine when human-amplified climate change is responsible for extreme weather events and the significance of that impact.

Using advanced computer models, climate attribution science takes a real-world weather event, such as a record high-temperature day or a hurricane, and compares it to the world where human-caused, post-industrial greenhouse gas emissions don't exist. By comparing what is actually happening with what would have happened without human intervention, science can estimate how likely or severe a weather event has become due to climate change.

Climate Central, a nonprofit climate research and communications organization, uses climate attribution science to provide real-time data that shows "how much climate change influences the temperature on a particular day." The information is displayed on a global interactive map called the Climate Shift Index.

For example, the Index showed that human-amplified climate change made Sunday's record high in Tucson, Arizona of 98 degrees at least three times more likely. The same was true for Waco, Texas, which broke a record with 92-degree heat, and Mobile, Alabama, which hit a record 90 degrees.

Extreme heat is the deadliest weather-related hazard in the U.S., with children and adults over 65 being among the most vulnerable to heat-related illnesses and death. And the average number of heat waves that major U.S. cities experience each year has doubled since the 1980s, according to the federal government's Fifth National Climate Assessment.

-ABC News Climate Unit's Matthew Glasser

The U.S. is experiencing the driest fall on record, which could potentially impact the quality of upcoming autumn harvests, experts told ABC News.

About 77% of the mainland U.S. is abnormally dry, and almost half of the country is experiencing drought, according to the U.S. Drought Monitor. The spatial pattern of the dry conditions varies widely across the continent, Josue Medellin-Azuara, a professor of civil and environmental engineering at the University of California Merced, told ABC News.

Improvement in the drought is not expected for most of the South, the Plains and parts of the Upper Midwest due to expected La Nina conditions this winter that would further reinforce the dryness, according to forecasts by the National Oceanic and Atmospheric Administration.

However, a lot of the crops in these regions that harvest in the fall had good growing conditions throughout the summer and are in the process of being harvested, meaning overall output should not be heavily impacted, Joseph Glauber, senior research fellow at the International Food Policy Research Institute and former chief economist for the U.S. Department of Agriculture, told ABC News.

Read more here.

The United States Environmental Protection Agency (EPA) said it's canceling any product containing the pesticide dimethyl tetrachloroterephthalate (DCPA), also known as Dacthal.

According to the EPA, their decision is based on comprehensive scientific studies that indicate potential thyroid toxicity linked to DCPA. The agency says research suggests that exposure to this pesticide during pregnancy can lead to changes in thyroid hormone levels in unborn children. Studies cited by the EPA indicate that these hormonal changes could be associated with various health concerns, including low birth weight, impaired brain development and reduced IQ. That research suggests that these developmental challenges may also have long-term effects on motor skills.

DCPA is used in the industrial farming of broccoli, Brussels sprouts, cabbage and onions. While pregnant women working in agriculture are most at risk, pesticides can travel into neighboring communities via the air and runoff, putting non-agricultural workers at risk as well.

In a press release, EPA's assistant administrator for the office of chemical safety and pollution prevention, Michal Freedhoff, wrote, "With the final cancellation of DCPA, we're taking a definitive step to protect pregnant women and their unborn babies. The science showing the potential for irreversible harm to unborn babies' developing brains, in addition to other lifelong consequences from exposure, demands decisive action to remove this dangerous chemical from the marketplace," Freedhoff added.

-ABC News Climate Unit's Matthew Glasser