degrees

New highs for carbon dioxide

April 11, 2025 By EarthWise Leave a Comment

Last year was the hottest year on record and the ten hottest years on record have in fact been the last ten years. Ocean heat reached a record high last year and, along with it, global sea levels. Those are rising twice as fast as they did in the 1990s.

The World Meteorological Organization reports that the global atmospheric concentration of carbon dioxide reached a new observed high in 2023, which is the latest year for which global annual figures are available. The level was 420 ppm, which is the highest level it has been in 800,000 years.

The increase in carbon dioxide levels was the fourth largest one-year change since modern measurement began in the 1950s. The rate of growth is typically higher in El Niño years because of increases from fire emissions and reduced terrestrial carbon sinks.

Concentrations of methane and nitrous oxide – which are two other key greenhouse gases – also reached record high observed levels in 2023. Levels of both of these gases have also continued to increase in 2024.

The annually averaged global mean near-surface temperature in 2024 was 1.55 degrees Celsius above the 1850-1900 average. Apart from being the warmest year in the 175 years records have been kept, it is also above the 1.5-degree limit set as the goal of the Paris Climate Agreement. While a single year above 1.5 degrees of warming does not mean that the efforts to limit global warming have failed, it is a strong warning that the risks to human lives, economies, and the planet are increasing.

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Carbon Dioxide Levels Highest in 800,000 Years

Photo, posted January 30, 2018, courtesy of Johannes Grim via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A record warm January

March 4, 2025 By EarthWise Leave a Comment

Americans experienced unusually cold and wintery weather in January. Places like southern Louisiana and Florida saw appreciable amounts of snow. For those who experienced January’s Arctic blast, it was a cold January. But despite that, January was the world’s warmest on record, extending a run of extraordinary heat in which 18 out of the last 19 months saw an average global temperature more than 1.5 degrees Celsius above pre-industrial times. In fact, the global average temperature in January was 1.75 degrees above the pre-industrial average.

The exceptional warmth was surprising to climate researchers. It happened despite the emergence of La Niña conditions in the Pacific Ocean, which tend to lower global temperatures, at least for a while.

Researchers are investigating whether there is something beyond the effects of greenhouse gas emissions that is boosting temperatures to an unexpected degree. It is true that emissions, associated with the burning of coal, gas, and oil, reached record levels in both 2023 and 2024. But January’s warmth was still something of a surprise.

One prevalent theory is that cutting dangerous pollution is playing a role in causing global warming to accelerate. As regulators have curbed sulfate pollution to protect people’s lungs, the cooling effect of these particles that help form more and brighter clouds has diminished.

January demonstrates that the global climate system is complex and the weather in any particular region does not necessarily reflect what is happening to the planet as a whole.

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Global Temperatures Shattered Records in January

Photo, posted December 22, 2013, courtesy of SD Anderson via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Limiting global warming

December 4, 2024 By EarthWise Leave a Comment

A pressing question from the recently concluded 29th annual United Nations Climate Change Conference in Azerbaijan is how to transition away from fossil fuels and speed up climate mitigation in line with the 1.5 °C global warming target.

Keeping global average temperatures below 1.5 °C above pre-industrial levels is crucial to avoid the most severe impacts of climate change, including extreme weather, rising seas, biodiversity loss, and disruptions to food and water security.

According to a new study by researchers from Stockholm University, Chalmers University of Technology, and Uppsala University in Sweden, it is still possible to limit global warming to 1.5 °C. But the study found that the United States, the European Union, and 16 other countries will have to exceed their own current targets in order to achieve this global goal.

The study, which was recently published in the journal Nature Communications, introduced an “additional carbon accountability” indicator, which quantifies countries’ responsibility for mitigation and carbon dioxide removal in addition to achieving their own targets.

The study identified 18 countries that should be accountable for increasing their ambitions to stay within their equal per capita share of the global carbon budget for 1.5 °C. Additional carbon accountability is highest for the United States and China, and highest per capita for the United Arab Emirates, Russia, Saudi Arabia, and the U.S.

Failure to limit global warming risks catastrophic impacts of climate change.

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COP29: Possible to limit climate change to 1.5°C – if EU and 17 other countries go beyond their own targets

Photo, posted December 27, 2015, courtesy of Gerry Machen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

How to make cities cooler

March 26, 2024 By EarthWise Leave a Comment

In cities, the air, surface, and soil temperatures are almost always warmer than in rural areas. This is known as the urban heat island effect. Urban heat islands occur when cities replace natural land cover with dense concentrations of pavement, buildings, and other surfaces that absorb and retain heat.

Urban planners around the world have been researching ways to reduce the effects of heat in cities. For example, trees, green roofs, and vegetation can help reduce urban heat island effects by shading building surfaces, deflecting radiation from the sun, and releasing moisture into the atmosphere.

A new study led by researchers from the University of Surrey in the U.K. has analyzed how well various green spaces and waterways are able to cool down cities. The study, which was recently published in the journal The Innovation, found that wetlands, parks, and even botanical gardens are among the best ways to keep cities cool.

In fact, the researchers found that botanical gardens can cool city air by a whopping 9°F during heatwaves on average. Wetlands can cool city air by 8.5°F on average, followed by rain gardens at 8.1°F, green walls at 7.4°F, street trees at 6.8°F, city farms at 6.3°F, city parks at 5.8°F, and reservoirs and playgrounds at 5.2°F.

The researchers also found that cities can unlock even greater benefits by connecting green spaces into green corridors. Greening projects can also help remove carbon emissions and prevent flooding.

The research team hopes its findings will help urban planners design more resilient cities.

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Wetlands, parks and even botanical gardens among the best ways to cool cities during heatwaves

Photo, posted April 25, 2022, courtesy of Catherine Poh Huay Tan via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio