Le blog : Limite et transgression
Résultats pour:
Phys.org
2024
The temperatures of the Mediterranean Sea in recent days have reached heat records set last summer, the main Spanish maritime research center told AFP Tuesday, with marine heat waves in some places exceeding 30 degrees Celsius.
Unprecedented wildfires in Canada and parts of Amazonia last year were at least three times more likely due to climate change and contributed to high levels of CO2 emissions from burning globally, according to the first edition of a new systematic annual review.
The story of Greenland keeps getting greener—and scarier. A new study provides the first direct evidence that the center—not just the edges—of Greenland's ice sheet melted away in the recent geological past and the now-ice-covered island was then home to a green, tundra landscape.
An intense heat wave gripping South and South-East Asia since late March comes as no surprise to leading meteorologists who have been warning of steadily rising temperatures in the Indian Ocean.
An international team of scientists has warned against relying on nature providing straightforward 'early warning' indicators of a climate disaster, as new mathematical modeling shows new fascinating aspects of the complexity of the dynamics of climate. It suggests that the climate system could be more unpredictable than previously thought.
A long-term sea level dataset shows ocean surface heights continuing to rise at faster and faster rates over decades of observations. Global average sea level rose by about 0.3 inches (0.76 centimeters) from 2022 to 2023, a relatively large jump due mostly to a warming climate and the development of a strong El Niño. The total rise is equivalent to draining a quarter of Lake Superior into the ocean over the course of a year.
Marine heat waves will become a regular occurrence in the Arctic in the near future and are a product of higher anthropogenic greenhouse-gas emissions, according to a study just released by Dr. Armineh Barkhordarian from Universität Hamburg's Cluster of Excellence for climate research CLICCS. Since 2007, conditions in the Arctic have shifted, as confirmed by data recently published in the journal Communications Earth & Environment. Between 2007 and 2021, the marginal zones of the Arctic Ocean experienced 11 marine heat waves, producing an average temperature rise of 2.2 degrees Celsius above seasonal norm and lasting an average of 37 days. Since 2015, there have been Arctic marine heat waves every year.
2023
In March and April 2023, some Earth scientists began to point out that average sea surface temperatures had surpassed the highest levels seen in a key data record maintained by NOAA. Months later, they remain at record levels, with global sea surface temperatures 0.99°C (1.78°F) above average in July. That was the fourth consecutive month they were at record levels.
f global warming reaches or exceeds two degrees Celsius by 2100, University of Western Ontario's Joshua Pearce says it is likely that mainly richer humans will be responsible for the death of roughly one billion mainly poorer humans over the next century. The oil and gas industry, which includes many of the most profitable and powerful businesses in the world, is directly and indirectly responsible for more than 40% of carbon emissions—impacting the lives of billions of people, many living in the world's most remote and low-resourced communities. A new study proposes aggressive energy policies that would enable immediate and substantive decreases to carbon emissions and recommends a heightened level of government, corporate and citizen action to accelerate the decarbonization of the global economy, aiming to minimize the number of projected human deaths.
Population ecologist William Rees, with the University of British Columbia's School of Community and Regional Planning, is reminding denizens of Earth that the planet can only support so many people. In his paper published in the journal World, he points out that many models have been developed over the years that show that only a certain number of animals (such as rats) can live in a given environment—they all show that at some point, a population correction occurs.
As the Arctic warms, shrinking glaciers are exposing bubbling groundwater springs which could provide an underestimated source of the potent greenhouse gas methane, finds new research published in Nature Geoscience. The study, led by researchers from the University of Cambridge and the University Center in Svalbard, Norway, identified large stocks of methane gas leaking from groundwater springs unveiled by melting glaciers.
Around the world, rainforests are becoming savanna or farmland, savanna is drying out and turning into desert, and icy tundra is thawing. Indeed, scientific studies have now recorded "regime shifts" like these in more than 20 different types of ecosystem where tipping points have been passed. Around the world, more than 20% of ecosystems are in danger of shifting or collapsing into something different.
In early May, a groundbreaking study from the University of California, San Francisco of 171 pregnant women found more than 9 in 10 had measurable amounts of 19 different chemicals and pesticides in their bodies. Researchers said many of those substances pass through the placenta and into developing fetuses, adding evidence to a National Institutes of Health report that warned babies are born "pre-polluted" with chemicals.
Current climate policies will leave more than a fifth of humanity exposed to dangerously hot temperatures by 2100, new research suggests. The paper, published in the journal Nature Sustainability, is entitled "Quantifying the Human Cost of Global Warming."
Humanity is not on track to avoid the deadliest effects of climate change, according to University at Buffalo researcher Holly Jean Buck. "Our plans are not adequate to meet the goal of limiting the Earth's temperature increase to no more than 1.5℃ by 2050," said Buck, Ph.D., assistant professor of environment and sustainability....
The Greenland Ice Sheet covers 1.7 million square kilometers (660,200 square miles) in the Arctic. If it melts entirely, global sea level would rise about 7 meters (23 feet), but scientists aren't sure how quickly the ice sheet could melt. Modeling tipping points, which are critical thresholds where a system behavior irreversibly changes, helps researchers find out when that melt might occur.
The damage functions in the models, which relate GDP to temperature and sea-level rise, account for impacts on agriculture, forestry, fisheries, floods, road infrastructure, energy supply and demand, and labor productivity. Using this novel approach, the researchers estimate that the avoided damages are 1.5-3.9 times higher than the costs of climate mitigation. In other words, one euro invested in climate solutions saves the world about 1.5 to 4 euros in effects from climate change.
Microplastic pollution reduces energy production in a microscopic creature found in freshwater worldwide, new research shows. Paramecium bursaria contain algae that live inside their cells and provide energy by photosynthesis. The results of a NEW STUDY showed a 50% decline in net photosynthesis—a major impact on the algae's ability to produce energy and release oxygen
A comprehensive new study led by Professor Gwen Robbins Schug at UNC Greensboro traces the impact of rapid climate change events on humans over the past 5,000 years and offers lessons for today's policymakers. The meta-analysis of approximately a decade's worth of bioarchaeology data was published today as a Proceedings of the National Academy of Sciences perspective article by a team of 25 authors representing 21 universities.
2022
Small patches of land given over to wildlife-friendly planting can make a big difference to pollinator conservation, a new study suggests. Bee and other pollinator populations in Europe and North America are in decline due to a range of factors including habitat loss and insufficient flowers for food.
An international study on the future of insects under climate change scenarios has found the loss of insects will drastically reduce the ability of humankind to build a sustainable future. "A growing body of evidence shows many populations of insects are declining rapidly in many places. These declines are of profound concern, with terms like an emerging 'insect apocalypse' being increasingly used by the media and even some scientists to describe this phenomenon," Laurance said.
An international team of researchers have sounded new alarm bells about the changing chemistry of the western region of the Arctic Ocean after discovering acidity levels increasing three to four times faster than ocean waters elsewhere. The team, which includes University of Delaware marine chemistry expert Wei-Jun Cai, also identified a strong correlation between the accelerated rate of melting ice in the region and the rate of ocean acidification, a perilous combination that threatens the survival of plants, shellfish, coral reefs and other marine life and biological processes throughout the planet's ecosystem.
In the past 50 years, the oceans have absorbed more than 90% of the excess heat caused by our carbon dioxide emissions, with one ocean absorbing the vast majority.
Over the past 60 years, the global forest area has declined by 81.7 million hectares, a loss that contributed to the more than 60% decline in global forest area per capita. This loss threatens the future of biodiversity and impacts the lives of 1.6 billion people worldwide, according to a new study published today by IOP Publishing in the journal Environmental Research Letters.
Global heating could become "catastrophic" for humanity if temperature rises are worse than many predict or cause cascades of events we have yet to consider, or indeed both. The world needs to start preparing for the possibility of a "climate endgame."
The 1972 book "The Limits to Growth" shared a somber message for humanity: the Earth's resources are finite and probably cannot support current rates of economic and population growth to the end of the 21st century, even with advanced technology. Although disparaged by economists at the time, it turns out that, 50 years later, the message still deserves our attention.
Scientists at Scripps Institution of Oceanography at UC San Diego used an unprecedented technique to detect that levels of helium are rising in the atmosphere, resolving an issue that has lingered among atmospheric chemists for decades.
A new study describes a period of rapid global climate change in an ice-capped world much like the present—but 304 million years ago. Within about 300,000 years, atmospheric carbon dioxide levels doubled, oceans became anoxic, and biodiversity dropped on land and at sea.
Researchers from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences (CAS) and their collaborators published a high-accuracy and high-resolution permafrost map over the Northern Hemisphere.
As required by the Climate Change Act 2008, the government has today submitted the Third UK Climate Change Risk Assessment (CCRA3) to Parliament. Professor Richard Betts MBE, who led this team, says that ""ne of the key conclusions from the University of Exeter's work was that current worldwide policies could result in up to 4°C warming by 2100."
2021
Technologies for the removal of carbon dioxide (CO2) from the atmosphere (direct air capture, or DAC for short) are already in use, but neither their actual benefits for climate protection nor their other environmental impact have yet to be investigated.
Scientists have uncovered a fascinating new insight into what caused one of the most rapid and dramatic instances of climate change in the history of the Earth.
A just-published study coins a new metric: the "mortality cost of carbon." That is, how many future lives will be lost—or saved—depending on whether we increase or decrease our current carbon emissions. If the numbers hold up, they are quite high. The study was published today in the journal Nature Communications.
Rapid filling of a giant dam at the headwaters of the Nile River—the world's biggest waterway that supports millions of people—could reduce water supplies to downstream Egypt by more than one-third, new USC research shows.
At the tail end of winter in 2015, the ground in the Wimmera in northwestern Victoria had been a little dry but conditions weren't too bad for farmers. The crop season was going well.
2018
For the first time, the world's tourism footprint has been quantified across the supply chain—from flights to souvenirs—and revealed as a significant and growing contributor to greenhouse gas (GHG) emissions.