Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved.
Study
Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems
abstract
The 2007 melt extent on the Greenland ice sheet broke the 2005 summer melt record by 10 percent, making it the largest ever recorded there since satellite measurements began in 1979
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We estimate that as much as 10 times the amount of methane that is currently in the atmosphere will come out of these lakes as permafrost thaws in the future.
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The issue here is that we are creating the climate change, and we are creating the climate change at an unprecedented rate ... clearly we are creating the events for a climate-related mass extinction that wouldn't otherwise be happening.
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For every ton of CO2 emitted [into] the atmosphere, the natural sinks are removing less carbon than before ... This trend will continue into the future ... A greater buildup of CO2 means more warming.
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A team of American and Canadian scientists has devised a new way to study Earth's past climate by analyzing the chemical composition of ancient marine fossils. The first published tests with the method further support the view that atmospheric CO2 has contributed to dramatic climate variations in the past, and strengthen projections that human CO2 emissions could cause global warming.
article
if the processes occurring at Cobham were widespread, then the increase in
methane emissions could have caused further warming, amplifying the climate
change at this time.
Huge belches of methane from bogs in what is now Britain likely contributed to global warming some 55 million years ago ... The finding adds weight to the idea that methane being released from wetlands today may accelerate modern global warming.
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Methane already appears to be seeping out of once frozen bogs in Siberia.
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The atmosphere's water vapor content has increased by about 0.41 kilograms per square meter (kg/m²) per decade since 1988, and natural variability in climate just can't explain this moisture change. The most plausible explanation is that it's due to the human-caused increase in greenhouse gases.
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More water vapor -- which is itself a greenhouse gas -- amplifies the warming effect of increased atmospheric levels of carbon dioxide.
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Hurricane researchers say they have uncovered an ongoing rise in the number of Atlantic hurricanes that tracks the increase in sea surface temperature related to climate change.
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Increasing ozone near the Earth's surface could lead to significant reductions in regional plant production and crop yields. Surface ozone also damages plants, affecting their ability to soak up carbon dioxide from the atmosphere and accelerating global warming. Near-surface ozone has doubled since 1850 due to chemical emissions from vehicles, industrial processes, and the burning of forests.
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If heat-trapping emissions are not significantly curtailed, global warming will substantially change critical aspects of the Northeast's character and economy ... Winters will be on average 8 to 12 degrees warmer by the end of the century, and summers 6 to 14 degrees hotter ... the environment of the Northeast would be transformed, and Boston, Atlantic City, New York and other cities would all be subject to disastrous flooding on a regular basis.
study
Cyclical changes in the sun's energy output are not responsible for Earth's recent global warming ... Instead the findings put the blame for climate change squarely on human-created carbon dioxide (CO2) and other greenhouse gases—reinforcing the beliefs of most climate scientists.
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study
Climate models can replicate the ocean warming observed during the latter half of the 20th century, and that most of this recent warming is caused by human activities ... casts doubt on recent findings that the top 700-meters of the global ocean cooled markedly from 2003-2005.
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Human-made greenhouse gases have brought the Earth’s climate close to critical tipping points, with potentially dangerous consequences for the planet.
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Greenland has experienced a significant loss of ice ... a continuing trend of ice loss on the island.
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CO2 emissions from cars, factories, and power plants grew at an annual rate of 1.1 percent during the 1990s, according to the Global Carbon Project, which is a data clearinghouse set up in 2001 as a cooperative effort among UN-related groups and other scientific organizations. But from 2000 to 2004, CO2 emissions rates almost tripled to 3 percent a year – higher than any rate used in emissions scenarios for the reports by the Intergovernmental Panel on Climate Change (IPCC).
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We find that the remarkable feature of the 2002-03 anomaly seems to be that climate fluctuations - not only related to El Niño and occurring across all latitudes - acted together to create an unusually strong out-gasing of CO2 of the terrestrial biosphere.
...four-year study concluded that an increase in winds over the Southern Ocean is preventing it from absorbing more carbon and is causing the sea to release some of the gas that it had stored ... This is serious. All climate models predict that this kind of 'feedback' will continue and intensify during this century
As fossil fuel burning continues to pump carbon dioxide (CO2) into the air, the world's land plants will be unable to absorb as much of it as had been predicted ... limitations on the availability of nitrogen, a necessary nutrient, will likely translate to limitations on the ability of plants to absorb the extra CO2.
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global large dams annually release about 104 million metric tons of methane to the atmosphere through reservoir surfaces, turbines and spillways ... calculations imply that the world's 52,000 large dams contribute more than four percent of the total warming impact of human activities.
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The Arctic icecap is melting much faster than expected and is now about 30 years ahead of predictions made by a UN climate panel, a US ice expert says.
This means the ocean at the top of the world could be free or nearly free of summer ice by 2020, three decades sooner than the global panel's gloomiest forecast of 2050 from the Intergovernmental Panel on Climate Change (IPCC).
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no doubt that this is caused in large part by greenhouse gases in the atmosphere
article
From 1981-2002, fields of wheat, corn and barley throughout the world have produced a combined 40 million metric tons less per year because of increasing temperatures caused by human activities. There is clearly a negative response of global yields to increased temperatures.
The researchers compared historical records of the climate impact of changes in the sun's output with model projections of how a warmer climate driven by greenhouse gases would change rainfall patterns. They found that a warmer future climate likely will produce droughts in the same areas as those observed in ancient times, but potentially with greater severity ... The same model showed that greenhouse-gas warming has similar effects on the atmosphere, suggesting drier conditions may become more common in the subtropics. Rainfall could decrease further in already water-stressed regions such as the southwest United States, Mexico, parts of North Africa, the Middle East, and Australia.
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Global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values determined from ice cores spanning many thousands of years. The global increases in carbon dioxide concentration are due primarily to fossil fuel use and land-use change, while those of methane and nitrous oxide are primarily due to agriculture.
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The understanding of anthropogenic warming and cooling influences on climate has improved since the Third Assessment Report (TAR), leading to very high confidence that the globally averaged net effect of human activities since 1750 has been one of warming.
summary for policy makers
