Two studies published in Nature bolster the conclusion that the consequences of global warming have already begun to arrive. Human-caused climate change is already devastating human settlements and economies. The research directly links rising greenhouse-gas levels with the growing intensity of rain and snow in the Northern Hemisphere.

The article Human contribution to more-intense precipitation extremes first explains:

Given that atmospheric water-holding capacity is expected to increase roughly exponentially with temperature—and that atmospheric water content is increasing in accord with this theoretical expectation—it has been suggested that human-influenced global warming may be partly responsible for increases in heavy precipitation.

The study then finds:

[H]uman-induced increases in greenhouse gases have contributed to the observed intensification of heavy precipitation events found over approximately two-thirds of data-covered parts of Northern Hemisphere land areas. * * * Changes in extreme precipitation projected by models, and thus the impacts of future changes in extreme precipitation, may be underestimated because models seem to underestimate the observed increase in heavy precipitation with warming.

The study Anthropogenic greenhouse gas contribution to flood risk in England and Wales in autumn 2000 sets out the problem – it’s difficult to tie a specific weather event to global warming:

Interest in attributing the risk of damaging weather-related events to anthropogenic climate change is increasing. Yet climate models used to study the attribution problem typically do not resolve the weather systems associated with damaging events such as the UK floods of October and November 2000. Occurring during the wettest autumn in England and Wales since records began in 1766, these floods damaged nearly 10,000 properties across that region, disrupted services severely, and caused insured losses estimated at £1.3 billion. Although the flooding was deemed a ‘wake-up call’ to the impacts of climate change at the time, such claims are typically supported only by general thermodynamic arguments that suggest increased extreme precipitation under global warming, but fail to account fully for the complex hydrometeorology associated with flooding.

The study’s authors explain how they approached a solution:

Here we present a multi-step, physically based ‘probabilistic event attribution’ framework showing that it is very likely that global anthropogenic greenhouse gas emissions substantially increased the risk of flood occurrence in England and Wales in autumn 2000. Using publicly volunteered distributed computing, we generate several thousand seasonal-forecast-resolution climate model simulations of autumn 2000 weather, both under realistic conditions, and under conditions as they might have been had these greenhouse gas emissions and the resulting large-scale warming never occurred. Results are fed into a precipitation-runoff model that is used to simulate severe daily river runoff events in England and Wales (proxy indicators of flood events).

They found that the signature of global warming on weather events is undeniable:

The precise magnitude of the anthropogenic contribution remains uncertain, but in nine out of ten cases our model results indicate that twentieth-century anthropogenic greenhouse gas emissions increased the risk of floods occurring in England and Wales in autumn 2000 by more than 20%, and in two out of three cases by more than 90%.

The first paper covers climate trends from 1951 to 1999 and therefore does not include any analysis of weather events over the last decade – the warmest decade on record. Last year’s extreme precipitation events included catastrophic floods in Pakistan, China and Australia as well as, in the United States, Tennessee, Arkansas and California.

One- to two-thirds of Earth’s permafrost will disappear by 2200, unleashing vast quantities of carbon into the atmosphere.

That’s the frightening conclusion of a new study by NOAA and the National Snow and Ice Data Center (NSIDC) published in the journal Tellus, titled Amount and timing of permafrost carbon release in response to climate warming.

NSIDC scientist Kevin Schaefer comments in the NSIDC press release:

The amount of carbon released is equivalent to half the amount of carbon that has been released into the atmosphere since the dawn of the industrial age. That is a lot of carbon.

If we want to hit a target carbon concentration, then we have to reduce fossil fuel emissions that much lower than previously calculated to account for this additional carbon from the permafrost. Otherwise we will end up with a warmer Earth than we want.

The study’s authors estimate an extra 190 plus or minus 64 gigatons of carbon will enter the atmosphere by 2200—about one-fifth the total amount of carbon currently in the atmosphere. But, they warn, their estimates are certainly too conservative, in part because the study doesn’t incorporate the feedback from permafrost carbon release into its model.

The study itself is behind a paywall – but here’s the abstract:

The thaw and release of carbon currently frozen in permafrost will increase atmospheric CO₂ concentrations and amplify surface warming to initiate a positive permafrost carbon feedback (PCF) on climate. We use surface weather from three global climate models based on the moderate warming, A1B Intergovernmental Panel on Climate Change emissions scenario and the SiBCASA land surface model to estimate the strength and timing of the PCF and associated uncertainty. By 2200, we predict a 29–59% decrease in permafrost area and a 53–97 cm increase in active layer thickness. By 2200, the PCF strength in terms of cumulative permafrost carbon flux to the atmosphere is 190 ± 64 Gt C. This estimate may be low because it does not account for amplified surface warming due to the PCF itself and excludes some discontinuous permafrost regions where SiBCASA did not simulate permafrost. We predict that the PCF will change the arctic from a carbon sink to a source after the mid-2020s and is strong enough to cancel 42–88% of the total global land sink. The thaw and decay of permafrost carbon is irreversible and accounting for the PCF will require larger reductions in fossil fuel emissions to reach a target atmospheric CO₂ concentration.

Joseph Romm at Climate Progress explains one reason why the study’s estimate is too conservative:

The permafrost permamelt contains a staggering “1.5 trillion tons of frozen carbon, about twice as much carbon as contained in the atmosphere, much of which would be released as methane.  Methane is 25 times as potent a heat-trapping gas as CO2 over a 100 year time horizon, but 72 times as potent over 20 years!  One of the most conservative assumptions the study made, the lead author Dr. Kevin Schaefer confirmed in an email, is that all of the carbon would be released as CO2 and none as methane.

Despite the immanent danger to human life and global systems posed by global warming, humans continue their frantic quest for ever more fossil fuels to burn: in South America and West Africa, in the Arctic which is becoming newly accessible as it thaws, from tar sands in Canada, from shales in the U.S. and the Middle East. The search for fossil fuels goes on, despite the immediate environmental devastation wrought by mountaintop removal, by the strip mining of tar sands, by the fracking which despoils aquifers – and despite the ultimate and irreparable ecological devastation that will result from destabilizing Earth’s climate.

We think heroin is addictive? The war on drugs begs to be replaced by a war on fossil fuels.

A devastating 100-year drought parched the Amazon in 2005, killing rainforest trees and releasing 5 billion tonnes of CO2 – almost as much as the 5.4 billion tonnes of CO2 emitted  from fossil fuel use in the United States in 2009.

Now a new study confirms that the 2010  Amazon drought was even more widespread and severe than in 2005. The carbon impact is expected to be correspondingly worse than in 2005.

In a normal year intact Amazon forests absorb approximately 1.5 billion tonnes of CO2, offsetting emissions from deforestation, logging and fire across the Amazon. The study’s authors predict that Amazon forests will not absorb their usual 1.5 billion tonnes of CO2 from the atmosphere in both 2010 and 2011, and that at least 5 billion more tonnes of CO2 will be released to the atmosphere over the coming years once the trees that are killed by the new drought rot. Dr. Brando, from Brazil’s Amazon Environmental Research Institute, says it’s too soon to be more precise:

We will not know exactly how many trees were killed until we can complete forest measurements on the ground.   It could be that many of the drought susceptible trees were killed off in 2005, which would reduce the number killed last year. On the other hand, the first drought may have weakened a large number of trees so increasing the number dying in the 2010 dry season. Our results should be seen as an initial estimate. The emissions estimates do not include those from forest fires, which spread over extensive areas of the Amazon during hot and dry years. These fires release large amounts of carbon to the atmosphere.

Lead author Dr. Simon Lewis, from the University of Leeds, fears the Amazon may be on the verge of tipping from a net carbon sink to a carbon source:

Two unusual and extreme droughts occurring within a decade may largely offset the carbon absorbed by intact Amazon forests during that time. If events like this happen more often, the Amazon rainforest would reach a point where it shifts from being a valuable carbon sink slowing climate change, to a major source of greenhouse gasses that could speed it up.

Considerable uncertainty remains surrounding the impacts of climate change on the Amazon. This new research adds to a body of evidence suggesting that severe droughts will become more frequent leading to important consequences for Amazonian forests.

If greenhouse gas emissions contribute to Amazon droughts that in turn cause forests to release carbon, this feedback loop would be extremely concerning. Put more starkly, current emissions pathways risk playing Russian roulette with the world’s largest rainforest.

The Science article is titled “The 2010 Amazon Drought.”

A new study published in the journal Science concludes ocean currents entering the Arctic Ocean are the warmest in more than 2,000 years – well outside the natural bounds. The warm waters will likely lead to ice-free seas around the North Pole in summers.

[E]arly–21st-century temperatures of Atlantic Water entering the Arctic Ocean are unprecedented over the past 2000 years and are presumably linked to the Arctic amplification of global warming.

The scientists say that waters at the Fram Strait – at the northern end of the Gulf Stream, between Greenland and the Norwegian archipelago of Svalbard – averaged 6 degrees Celsius (42.8°F) in recent summers.

The study showed that water from the Fram Strait has warmed roughly 3.5 degrees Fahrenheit in the past century. The Fram Strait water temperatures today are about 2.5 degrees F warmer than during the Medieval Warm Period, which heated the North Atlantic from roughly 900 CE to 1300 CE and affected the climate in Northern Europe, Greenland, and northern North America. Air temperatures in Greenland have risen roughly 7 degrees F in the past several decades.

Joseph Romm at Climate Progress has posted a key graph from the study:

Due to positive feedbacks between the ice, the Arctic Ocean and the atmosphere, the rate of Arctic sea ice decline has been accelerating – as seen is this graph from the University of Washington’s Polar Science Center:

As Arctic temperatures rise, summer ice cover declines, more solar heat is absorbed by the ocean and additional ice melts. Warmer water delays freezing in the fall, leading to thinner ice cover in winter and spring, making the sea ice more vulnerable to melting during the next summer.

Lead author Robert Spielhagen of the Academy of Sciences, Humanities and Literature in Mainz, Germany says the decline of Arctic sea ice is due in part to the warmer waters reaching the Arctic:

We must assume that the accelerated decrease of the Arctic sea ice cover and the warming of the ocean and atmosphere of the Arctic measured in recent decades are in part related to an increased heat transfer from the Atlantic.

Arctic sea ice is in a death spiral.

The World Meteorological Organization has confirmed NASA’s determination that 2010 equaled the record for the world’s warmest year:

The year 2010 ranked as the warmest year on record, together with 2005 and 1998, according to the World Meteorological Organization. Data received by the WMO show no statistically significant difference between global temperatures in 2010, 2005 and 1998.In 2010, global average temperature was 0.53°C (0.95°F) above the 1961-90 mean. This value is 0.01°C (0.02°F) above the nominal temperature in 2005, and 0.02°C (0.05°F) above 1998. The difference between the three years is less than the margin of uncertainty (± 0.09°C or ± 0.16°F) in comparing the data.

The ten warmest years on record have all occurred since 1998.

Recent warming has been especially strong in Africa, parts of Asia, and parts of the Arctic, with many subregions registering temperatures 1.2 to 1.4°C (2.2 to 2.5°F) above the long-term average. 2010 was an exceptionally warm year over much of Africa and southern and western Asia, and in Greenland and Arctic Canada, with many parts of these regions having their hottest years on record.

Newly published research shows that 2010 set new records for the melting of the Greenland ice sheet. The melt season in some areas was up to 50 days longer than average, starting exceptionally early at the end of April and ending quite late in mid- September. Nuuk, the capital of Greenland, had the warmest spring and summer since records began in 1873.

The year 2010 was characterized by a high number of extreme weather events, including the heat wave in Russia and the devastating monsoonal floods in Pakistan. That trend has been continuing into 2011:

• Severe flooding occurred in eastern Australia in December and the first half of January, associated with the continuing strong La Niña event. The most extensive damage was in the city of Brisbane, which had its second-highest flood of the last 100 years after that of January 1974. In financial terms it is expected to be the most costly natural disaster in Australia’s history. Previous strong La Niña events have also been associated with severe and widespread flooding in eastern Australia, notably in 1974 and 1955.
• In early January floods affected more than 800 000 people in Sri Lanka according to the UN Office for the Coordination of Humanitarian Affairs. The Philippines were also severely affected by floods and mudslides during January.
• Flash floods in the mountain areas near the city of Rio de Janeiro in Brazil in the second week of January resulted in more than 700 deaths, many of them in mudslides. This is one of the highest death tolls due to a single natural disaster in Brazilian history.

Arctic sea-ice cover in December 2010 was the lowest on record. Why?  One reason: it’s been extraordinarily warm in Canada:

If the weather seems whacked out now, just wait. A new paper by James Hansen and Makiko Sato titled Paleoclimate Implications for Human-Made Climate Change asserts climate change is likely to be the predominant scientific, economic, political and moral issue of the 21st century.

We conclude that Earth in the warmest interglacial periods was less than 1°C warmer than in the Holocene and that goals of limiting human-made warming to 2°C and CO2 to 450 ppm are prescriptions for disaster. Polar warmth in prior interglacials and the Pliocene does not imply that a significant cushion remains between today’s climate and dangerous warming, rather that Earth today is poised to experience strong amplifying polar feedbacks in response to moderate additional warming. Deglaciation, disintegration of ice sheets, is nonlinear, spurred by amplifying feedbacks. If warming reaches a level that forces deglaciation, the rate of sea level rise will depend on the doubling time for ice sheet mass loss. Gravity satellite data, although too brief to be conclusive, are consistent with a doubling time of 10 years or less, implying the possibility of multi-meter sea level rise this century. The emerging shift to accelerating ice sheet mass loss supports our conclusion that Earth’s temperature has returned to at least the Holocene maximum. Rapid reduction of fossil fuel emissions is required for humanity to succeed in preserving a planet resembling the one on which civilization developed.

Nothing less than the fate of humanity and of nature itself is at stake. But the chances that humanity will act decisively enough, quickly enough, are fading fast. Fatih Birol, chief economist for the International Energy Agency (IEA), admits the outlook is bleak:

When I look at the next 10 years, even if I take into consideration the pledges made after the Copenhagen meeting, the best case is that this could put us on a trajectory in line with 3.5 degrees Celsius.

The best case scenario would result in a 3.5 degrees Celsius rise. But as Birol goes on to point out, in most cases those targets are not backed by concrete policies. Believing the world can or will voluntarily do what’s necessary to avert catastrophic climate change is just wishful thinking.

A new analysis of the magnitude of climate change during Earth’s deep past concludes that future temperatures may eventually rise far more than projected if society continues its pace of emitting greenhouse gases.

The study, “Lessons from Earth’s Past” by National Center for Atmospheric Research (NCAR) scientist Jeffrey Kiehl, is published in this week’s issue of Science. Only this pathetically inadequate summary is available for free:

Climate models are invaluable tools for understanding Earth’s climate system. But examination of the real world also provides insights into the role of greenhouse gases (carbon dioxide) in determining Earth’s climate. Not only can much be learned by looking at the observational evidence from Earth’s past, but such know ledge can provide context for future climate change.

The study finds that the planet’s climate system, over long periods of times, may be at least twice as sensitive to carbon dioxide than currently projected by computer models, which have generally focused on shorter-term warming trends. This is largely because even sophisticated computer models have not yet been able to incorporate critical processes, such as the loss of ice sheets, that take place over centuries or millennia and amplify the initial warming effects of carbon dioxide.

The study warns that, if carbon dioxide emissions continue at their current rate through the end of this century, atmospheric concentrations of the greenhouse gas will reach levels that last existed about 30 million to 100 million years ago, when global temperatures averaged about 29 degrees Fahrenheit (16 degrees Celsius) above pre-industrial levels. At the current pace of increasing the burning of fossil fuels, atmospheric levels of carbon dioxide are expected to reach about 900 to 1,000 parts per million by the end of this century. That compares with current levels of about 390 parts per million, and pre-industrial levels of about 280 parts per million.

Carbon dioxide levels likely reached 900 to 1,000 parts per million about 35 million years ago. At that time, temperatures worldwide were substantially warmer than at present – especially in polar regions – even though the Sun’s energy output was slightly weaker. The tropics were about 9-18 degrees F (5-10 degrees C) above present-day temperatures. The polar regions were about 27-36 degrees F (15-20 degrees C) above present-day temperatures. Earth’s average annual temperature 30 to 40 million years ago was about 88 degrees F (31 degrees C) – substantially higher than the pre-industrial average temperature of about 59 degrees F (15 degrees C).

An optimist would point out there’s no possible way carbon dioxide emissions can continue at their current rate for another 90 years. The fossil fuels simply aren’t there, and as production of oil, coal, and gas begin to fall the economies that depend on them will first stall and then collapse long before fossil fuel reserves run out. Then again, by the time emissions fall significantly irreparable damage will most likely already have been done.

The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice extent for December 2010 was the lowest in the satellite record for that month.

The linear rate of decline for the month is –3.5% per decade.

Low ice conditions are linked to a strong negative phase of the Arctic Oscillation, similar to the situation that dominated the winter of 2009-2010. As in November, ice extent in December 2010 was unusually low in both the Atlantic and Pacific sides of the Arctic, but particularly in Hudson Bay, Hudson Strait (between southern Baffin Island and Labrador), and in Davis Strait (between Baffin Island and Greenland). Normally, these areas are completely frozen over by late November.

The low ice conditions in December occurred in conjunction with above-average air temperatures in regions where ice would normally expand at this time of year. The warm temperatures in December came from two sources: unfrozen areas of the ocean continued to release heat to the atmosphere, and an unusual circulation pattern brought warm air into the Arctic from the south. Although the air temperatures were still below freezing on average, the additional ocean and atmospheric heat slowed ice growth.

New analyses of the heat content of the waters off Western Antarctic Peninsula are now showing a clear and exponential increase in warming waters – undermining the sea ice, raising air temperatures, and melting glaciers.

Says physical oceanographer Doug Martinson of the Lamont-Doherty Earth Observatory, who has been collecting ocean water heat content data for more than 18 years at Palmer Island, on the western side of the Antarctic Peninsula:

In the area I work there is the highest increase in temperatures of anywhere on Earth. Eighty-seven percent of the alpine glaciers are in retreat. Some of the Adele penguin colonies have already gone extinct.

The extraordinary warming of the Antarctic Peninsula shows up clearly on new global warming maps released by NASA:

The map shows temperature anomalies for 2000-2009 and 1970-1979 relative to a 1951-1980 baseline. The average global temperature has increased by about 0.8° Celsius (1.4° Fahrenheit) since 1880. About two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°C per decade.

What the rising water heat means, according to Martinson, is that even if humanity got organized and stopped emitting greenhouse gases tomorrow, there is already too much heat in the oceans to stop a lot of impacts – like the melting of a huge amount of Antarctic ice.

A new study finds that the world’s fishing industry is depleting older fishing grounds through unsustainable harvesting practices – and that there’s no place left to look for new ones.

The study, titled The Spatial Expansion and Ecological Footprint of Fisheries (1950 to Present), was conducted by researchers at Vancouver’s University of British Columbia in conjunction with the National Geographic magazine.

The study says that 90 million tons of fish were landed in the late 1980s, up from 19 million in the 1950s. The researchers tracked the expansion of fishing activity, examining both the total number of fish caught and the impact that catching different types of fish has had on the ocean’s productivity. By the late 1990s, the world’s fishing fleets had largely run out of new fishing grounds to exploit.

Co-author Enric Sala says we can’t afford to do nothing.

The sooner we come to grips with it, the sooner we can stop the downward spiral by creating stricter fishing regulations and more marine reserves.

The researchers said that in 1950 most heavy fishing was done in the North Atlantic and the Western Pacific, but by the mid 1990s, a third of the world’s oceans and two-thirds of the continental shelves were exploited. That expansion has left only unproductive fishing areas on the high seas and the ice-covered waters of the Arctic and Antarctic for boats to move into.

Here’s the abstract.

Using estimates of the primary production required (PPR) to support fisheries catches (a measure of the footprint of fishing), we analyzed the geographical expansion of the global marine fisheries from 1950 to 2005. We used multiple threshold levels of PPR as percentage of local primary production to define ‘fisheries exploitation’ and applied them to the global dataset of spatially-explicit marine fisheries catches. This approach enabled us to assign exploitation status across a 0.5° latitude/longitude ocean grid system and trace the change in their status over the 56-year time period. This result highlights the global scale expansion in marine fisheries, from the coastal waters off North Atlantic and West Pacific to the waters in the Southern Hemisphere and into the high seas. The southward expansion of fisheries occurred at a rate of almost one degree latitude per year, with the greatest period of expansion occurring in the 1980s and early 1990s. By the mid 1990s, a third of the world’s ocean, and two-thirds of continental shelves, were exploited at a level where PPR of fisheries exceed 10% of PP, leaving only unproductive waters of high seas, and relatively inaccessible waters in the Arctic and Antarctic as the last remaining ‘frontiers.’ The growth in marine fisheries catches for more than half a century was only made possible through exploitation of new fishing grounds. Their rapidly diminishing number indicates a global limit to growth and highlights the urgent need for a transition to sustainable fishing through reduction of PPR.

Global warming is driving forest fires in northern latitudes to burn more frequently and fiercely. Consequently, boreal forests may now giving off more CO2 than they are absorbing.

So concludes a new study published in Nature Geoscience.

University of Guelph professor Merritt Turetsky, lead author of the study, warns of a dangerous feedback loop.

When most people think of wildfires, they think about trees burning, but most of what fuels a boreal fire is plant litter, moss and organic matter in surface soils. These findings are worrisome because about half the world’s soil carbon is locked in northern permafrost and peatland soils. This is carbon that has accumulated in ecosystems a little bit at a time for thousands of years, but is being released very rapidly through increased burning.

Essentially this could represent a runaway climate change scenario in which warming is leading to larger and more intense fires, releasing more greenhouse gases and resulting in more warming. This cycle can be broken for a number of reasons, but likely not without dramatic changes to the boreal forest as we currently know it.

Northern ecosystems are bearing the brunt of climate change.  Longer snow-free seasons, changes in vegetation, loss of ice and permafrost, and now fire are shifting these systems from a global carbon sink toward a carbon source.

Here’s the abstract:

Climate change has increased the area affected by forest fires each year in boreal North America. Increases in burned area and fire frequency are expected to stimulate boreal carbon losses. However, the impact of wildfires on carbon emissions is also affected by the severity of burning. How climate change influences the severity of biomass burning has proved difficult to assess. Here, we examined the depth of ground-layer combustion in 178 sites dominated by black spruce in Alaska, using data collected from 31 fire events between 1983 and 2005. We show that the depth of burning increased as the fire season progressed when the annual area burned was small. However, deep burning occurred throughout the fire season when the annual area burned was large. Depth of burning increased late in the fire season in upland forests, but not in peatland and permafrost sites. Simulations of wildfire-induced carbon losses from Alaskan black spruce stands over the past 60 years suggest that ground-layer combustion has accelerated regional carbon losses over the past decade, owing to increases in burn area and late-season burning. As a result, soils in these black spruce stands have become a net source of carbon to the atmosphere, with carbon emissions far exceeding decadal uptake.