cross-posted from: https://slrpnk.net/post/21852805

archived (Wayback Machine)

Global temperature leaped more than 0.4°C (0.7°F) during the past two years, the 12-month average peaking in August 2024 at +1.6°C relative to the temperature at the beginning of last century (the 1880-1920 average). This temperature jump was spurred by one of the periodic tropical El Niño warming events, but many Earth scientists were baffled by the magnitude of the global warming, which was twice as large as expected for the weak 2023-2024 El Niño. We find that most of the other half of the warming was caused by a restriction on aerosol emissions by ships, which was imposed in 2020 by the International Maritime Organization to combat the effect of aerosol pollutants on human health. Aerosols are small particles that serve as cloud formation nuclei. Their most important effect is to increase the extent and brightness of clouds, which reflect sunlight and have a cooling effect on Earth. When aerosols – and thus clouds – are reduced, Earth is darker and absorbs more sunlight, thus enhancing global warming. Ships are the main aerosol source in the North Pacific and North Atlantic Oceans. We quantify the aerosol effect from the geographical distribution of sunlight reflected by Earth as measured by satellites, with the largest expected and observed effects in the North Pacific and North Atlantic Oceans. We find that aerosol cooling, and thus climate sensitivity, are understated in the best estimate of the United Nations Intergovernmental Panel on Climate Change (IPCC).

Global warming caused by reduced ship aerosols will not go away as tropical climate moves into its cool La Niña phase. Therefore, we expect that global temperature will not fall much below +1.5°C level, instead oscillating near or above that level for the next few years, which will help confirm our interpretation of the sudden global warming. High sea surface temperatures and increasing ocean hotspots will continue, with harmful effects on coral reefs and other ocean life. The largest practical effect on humans today is increase of the frequency and severity of climate extremes. More powerful tropical storms, tornadoes, and thunderstorms, and thus more extreme floods, are driven by high sea surface temperature and a warmer atmosphere that holds more water vapor. Higher global temperature also increases the intensity of heat waves and – at the times and places of dry weather – high temperature increases drought intensity, including “flash droughts” that develop rapidly, even in regions with adequate average rainfall.

Polar climate change has the greatest long-term effect on humanity, with impacts accelerated by the jump in global temperature. We find that polar ice melt and freshwater injection onto the North Atlantic Ocean exceed prior estimates and, because of accelerated global warming, the melt will increase. As a result, shutdown of the Atlantic Meridional Overturning Circulation (AMOC) is likely within the next 20-30 years, unless actions are taken to reduce global warming – in contradiction to conclusions of IPCC. If AMOC is allowed to shut down, it will lock in major problems including sea level rise of several meters – thus, we describe AMOC shutdown as the “point of no return.”

We suggest that an alternative perspective – a complement to the IPCC approach – is needed to assess these issues and actions that are needed to avoid handing young people a dire situation that is out of their control. This alternative approach will make more use of ongoing observations to drive modeling and more use of paleoclimate to test modeling and test our understanding. As of today, the threats of AMOC shutdown and sea level rise are poorly understood, but better observations of polar ocean and ice changes in response to the present accelerated global warming have the potential to greatly improve our understanding.

archived (Wayback Machine)

Climate models have a history of underestimating the cooling effect of aerosol pollution.

Related: Will Brazil’s President Lula wake up to the climate crisis? (commentary)

Tropical deforestation was found to cause large reductions in precipitation using a range of observation-based datasets1. However, the limitations of satellite-based space-for-time statistical analysis have hindered understanding of the roles of reshaped mesoscale atmospheric circulation and regional precipitation recycling at different scales. These effects are considered nonlocal effects, which are distinct from the local effects governed by deforestation-induced reductions in evapotranspiration (ET). Here we show reversed precipitation responses to Amazon deforestation across wet and dry seasons. During the wet season, deforested grids experienced a noteworthy increase in precipitation (0.96 mm per month per percentage point forest loss), primarily attributed to enhanced mesoscale atmospheric circulation (that is, nonlocal effect). These nonlocal increases weaken with distance from deforested grids, leading to significant precipitation reductions in buffers beyond 60 km. Conversely, during the dry season, precipitation decreases in deforested grids and throughout all analysis buffers, with local effects from reduced ET dominating. Our findings highlight the intricate balance between local effects and nonlocal effects in driving deforestation-precipitation responses across different seasons and scales and emphasize the urgent need to address the rapid and extensive loss of forest in the Amazon region.

archived (Wayback Machine)

There was a time when an ecologist’s education was not complete without the mud of a marsh on their boots or the scent of damp earth after a rainforest downpour. Increasingly, however, the discipline is moving indoors. A paper published in Trends in Ecology & Evolution by Masashi Soga and Kevin J. Gaston highlights a disconcerting trend: the decline of fieldwork in ecological research and education.

archived (Wayback Machine)

Scientists now say it's likely that the closest active volcano to Anchorage will erupt soon.

https://www.newsweek.com/hurricane-crossing-equator-weather-physics-1790522

Experts say that the devastating earthquake in Myanmar on Friday was likely the strongest to hit the country in decades, with disaster modeling suggesting thousands could be dead.

Myanmar's ruling junta said on Saturday morning that the number killed had passed 1,000, with more than 2,000 injured.

However, the USGS analysis said there was a 35% chance that possible fatalities could be in the range of 10,000-100,000 people.

The USGS offered a similar likelihood that the financial damage could total tens of thousands of millions of dollars, warning that it might exceed the GDP of Myanmar.

cross-posted from: https://slrpnk.net/post/20013316

China's glacier area has shrunk by 26% since 1960 due to rapid global warming, with 7,000 small glaciers disappearing completely and glacial retreat intensifying in recent years, official data released in March showed.

...

As the important water towers continue to shrink, less availability of freshwater is expected to contribute to greater competition for water resources, environmental groups have warned. Glacier retreat also poses new disaster risks.

China's glaciers are located mainly in the west and north of the country, in the regions of Tibet and Xinjiang, and the provinces of Sichuan, Yunnan, Gansu and Qinghai.

Data published on March 21 on the website of the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences, showed that China's total glacier area was around 46,000 square kilometres, with around 69,000 glaciers in 2020.

This compares to around 59,000 square kilometres and around 46,000 glaciers in China between 1960 and 1980, the study showed.

...

The Tibetan plateau is known as the world's Third Pole for the amount of ice long locked in the high-altitude wilderness.

...

The dramatic ice loss, from the Arctic to the Alps, from South America to the Tibetan Plateau, is expected to accelerate as climate change, caused by the burning of fossil fuels, pushes global temperatures higher.

This would likely exacerbate economic, environmental and social problems across the world as sea levels rise and these key water sources dwindle, [a UNESCO report says].

cross-posted from: https://slrpnk.net/post/19378689

MIT aerospace engineers have found that greenhouse gas emissions are changing the environment of near-Earth space in ways that, over time, will reduce the number of satellites that can sustainably operate there.

In a study appearing today in Nature Sustainability, the researchers report that carbon dioxide and other greenhouse gases can cause the upper atmosphere to shrink. An atmospheric layer of special interest is the thermosphere, where the International Space Station and most satellites orbit today. When the thermosphere contracts, the decreasing density reduces atmospheric drag — a force that pulls old satellites and other debris down to altitudes where they will encounter air molecules and burn up.

Less drag therefore means extended lifetimes for space junk, which will litter sought-after regions for decades and increase the potential for collisions in orbit.

[...]

Their predictions forecast out to the year 2100, but the team says that certain shells in the atmosphere today are already crowding up with satellites, particularly from recent “megaconstellations” such as SpaceX’s Starlink, which comprises fleets of thousands of small internet satellites.

“The megaconstellation is a new trend, and we’re showing that because of climate change, we’re going to have a reduced capacity in orbit,” Linares says. “And in local regions, we’re close to approaching this capacity value today.”

“We rely on the atmosphere to clean up our debris. If the atmosphere is changing, then the debris environment will change too,” Parker adds. “We show the long-term outlook on orbital debris is critically dependent on curbing our greenhouse gas emissions.”

[...]