1.5

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

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 will we know if the world is 1.5 degrees warmer?

January 12, 2024 By EarthWise Leave a Comment

The Paris Climate Agreement has a goal of limiting global warming to less than 1.5 degrees Celsius above pre-industrial levels. How do we know if we are succeeding and, more importantly, how would we know if we have failed?

This may seem like something fairly obvious, but it isn’t. Global temperatures are definitely creeping upward. This past year has been the warmest on record. In fact, the global average temperature was more than 1.4 degrees above pre-industrial levels. November was 1.75 degrees above pre-industrial levels. So, does that mean that our climate goals have already failed? Not really.

On a monthly scale there have already been individual months where warming has exceeded 1.5 degrees in 2016, 2017, 2019, 2020, and 2023. Would an entire year above the target constitute failure? Not necessarily. There really isn’t an agreed-upon answer and that in itself represents something that could undermine global efforts to tackle climate change.

If we don’t know whether we are succeeding or failing, it is more difficult to pursue success. The United Nations IPCC says the threshold will be surpassed when average warming exceeds 1.5 degrees for 20 years. But that seems like a building a mountain highway with no guardrails and hoping to be safe.

Scientists are calling for new approaches to defining a universally agreed-upon measure of global warming that could trigger urgent action to avoid further rises. What we really don’t need are justifications and excuses for continued inaction. Clearly the climate is not waiting for us to debate the issue.

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Why We Won’t Know When We’ve Passed the 1.5-Degree Threshold

Photo, posted August 2, 2018, courtesy of J Bartlett Team Rubicon/BLM for USFS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

An Unwanted Temperature Threshold Is Approaching | Earth Wise

July 3, 2023 By EarthWise Leave a Comment

According to the World Meteorological Organization, there is a 66% chance over the next five years that the Earth’s global temperature will exceed 1.5 degrees Celsius above pre-industrial levels for at least one year.

A combination of the continued accumulation of greenhouse gases in the atmosphere along with a looming El Niño condition will contribute to surging temperatures. The WMO also reports that there is a 98% likelihood that at least one of the next five years will be the warmest on record and that the five-year period as a whole will be the warmest on record.

Reaching or surpassing the 1.5-degree threshold may only be temporary but would be the strongest indication yet of how quickly climate change is accelerating. The 1.5-degree point is considered by many scientists to be a key tipping point, beyond which the chances of extreme flooding, drought, wildfires, heatwaves, and food shortages could increase dramatically.

The world has already seen about 1.2 degrees of warming as we continue to burn fossil fuels and produce enormous quantities of greenhouse gas emissions. As recently as 2015, the WMO put the chance of breaching the 1.5-degree threshold as close to zero.

It is important to understand that the 1.5-degree temperature increase is an average for the entire planet. Many individual locations around the world have been experiencing tremendously greater amounts of warming with record-breaking temperatures.

The 1.5-degree threshold is important, but it is not itself a tipping point. There is still time to reduce global warming by moving away from fossil fuels and towards clean energy. But the clock is ticking and so far, the world is not showing any urgency.

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‘Sounding the alarm’: World on track to breach a critical warming threshold in the next five years

Photo, posted May 20, 2015, courtesy of Kevin Gill via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio