A study published in the September issue of the Journal of the Geological Society found that increasing CO2 levels are causing foram diversity to plummet:

A unique ‘natural laboratory’ in the Mediterranean Sea is revealing the effects of rising carbon dioxide levels on life in the oceans. The results show a bleak future for marine life as ocean acidity rises, and suggest that similar lowering of ocean pH levels may have been responsible for massive extinctions in the past.

Rising carbon dioxide levels acidify the ocean, which has a particularly devastating effect on organisms that have calcium carbonate shells, like Foraminifera.The study, published in the September issue of the Journal of the Geological Society, found that increasing CO2 levels caused foram diversity to fall from 24 species to only 4. The study found a tipping point occurs at mean pH 7.8, the pH level predicted for the end of this century.

Forams record past events in the geological record. The Paleocene-Eocene Thermal Maximum (PETM), 55 million years ago, was a period of massive carbon release and rapid warming, accompanied by extinctions in marine life.

This statement by study co-author Dr. Jason Hall-Spencer in the Geological Society’s press release is not optimistic:

Our natural laboratory provides a glimpse into the future of our oceans.

Joseph Romm at Climate Progress has posted this chart showing trends in ocean CO2 concentrations and pH at one sampling station off Hawaii.

Romm also points out that the disappearance of forams has grave implications for the rest of the food chain.

For an analysis of what that could mean, see 2009 Nature Geoscience study concludes ocean dead zones “devoid of fish and seafood” are poised to expand and “remain for thousands of years.”

A study published in the journal Global Change Biology reports the discovery of very similar colonies of bryozoans – animals that anchor themselves to the seabed – in both the Ross and Weddell Seas.

The bryozoans, sometimes called moss animals, are often microscopic as individuals but form colonies that can look like corals or some seaweeds. Those found were unlike others around the current coast of Antarctica.

So,what’s the big deal?

Bryozoans are largely static and their larvae, dispersed by currents, are short-lived and quickly sink. How is it possible that two virtually identical populations came to exist 2400 kilometers apart, separated by the 2 kilometre thick West Antarctic ice sheet?

An article at ABC News in Science quotes lead author David Barnes:

The most likely explanation of such similarity is that this ice sheet is much less stable than previously thought and has collapsed at some point in the recent past. And if the West Antarctic ice shelf has been lost in recent times we have to re-think the possibility of loss in future with climate change.

If the ice were gone a passage would become open through which currents could carry the larvae between the two seas.

Melting of the West Antarctica ice cap would raise world sea levels by between 3.5 and 5 meters. In a brief warm period about 125,000 years ago, world sea levels were about five meters higher than today and temperatures probably at least 4°C warmer.

A good friend recently asked me why I give so much attention to news about Arctic sea ice extent at this blog, saying he just glosses over posts on this subject.

Here’s the reason: the area of sea ice cover is an important, amplifying climate feedback. Loss of sea ice is a cause of concern because as the area of ice decreases, increased absorption of sunlight by the darker ocean causes more sea ice melting. As this graph from Makiko Sato & James Hansen’s new blog shows, Arctic sea ice extent has been declining steadily . . .

. . . as has sea ice volume. What ice remains is getting thinner.

It’s not just sea ice that is melting. Ice sheets are shrinking too, both in Greenland and in Antarctica.

And the ice loss over the last few years has been at a time of minimum solar irradiance. Solar irradiance is now once again on the upswing.

It seems likely that September Arctic sea ice may be all but gone within a few decades – or perhaps even sooner. What does less Arctic sea ice mean for Earth’s weather patterns?

NASA is predicting loss of summer sea ice will mean more severe winter storms in the northern hemisphere – a prediction which is already being borne out.

Following Arctic sea ice extent is fascinating because it shows that global warming is not something to worry about in the future. Global warming is here and now, and is already affecting us in our daily lives. What’s worrisome is that the impacts will only get more severe. By the time the impacts are bad enough to get our attention, it will be too late – the damage will already have been done. Under the best-case scenario it will take Earth a thousand years or more to recover. Under the worst-case scenario, Earth will flip into a different, stable climate regime which won’t be hospitable to human existence.

NOAA’s State of the Climate Global Analysis for July reports that year-to-date, the global combined land and ocean surface temperature of 14.5°C (58.1°F) was the warmest January-July period on record, 0.68°C (1.22°F) above the 20th century average.

This chart showing just how extraordinary this year has been so far is posted at NOAA’s website.

A number of stories appeared in the media last week about one of Greenland’s largest of  “outlet” glaciers (glaciers ending in the sea) calving an enormous ”ice island” of more than 100 square miles in size.

None of the stories had a good graphic showing what happened. Fortunately, WWF Climate Blog has posted this one:

The glacier has lost about a quarter of its floating ice shelf.

A 2009 survey of 34 of the widest Greenland marine-terminating glacier outlets from the inland ice sheet found the loss rate has been nearly constant since 2000.

Above: cumulative annual area changes for 34 of the widest Greenland ice sheet marine-terminating outlets. Source: Byrd Polar Research Center.

To put the Petermann Glacier’s latest ice island in perspective, the island’s area of at least 260 km² is well over twice what all 34 glaciers surveyed by the  Byrd Polar Research Center have been losing annually (-106 km² per year).

Scientists recently documented the breakup up of a 7 km² (2.7 square mile) section of another glacier in the region, the Jakobshavn Isbrae glacier. The calving front – where the ice sheet meets the ocean is now further inland than at any time previously observed.

Location of the successive calving fronts of the Jakobshavn Isbrae glacier between 1851 and 2009, overlain on a Landsat image from 7/29/2009. Source: NASA/Goddard Space Flight Center Scientific Visualization Studio. Historic calving front locations courtesy of Anker Weidick and Ole Bennike, Geological Survey of Denmark and Greenland.

The National Snow and Ice Data Center (NSIDC) reports Arctic sea ice extent averaged for July 2010 was the second lowest in the satellite record, after 2007.

Stormy, cloudy, and relatively cool weather in July slowed the rate of ice loss. Now the old, thick ice that moved into the southern Beaufort Sea last winter is beginning to melt out.

This map of ice age for the end of July, 2010, shows a region of open water north of Alaska, where old, thick ice has melted out.

NSIDC points out it would take “a very unusual set of conditions” in August to create a new record low – the decline rate in August would have to match the record decline rate of August 2008.

The Polar Science Center reports that Arctic ice thickness is continuing its precipitate decline. September ice volume reached a record low in 2009, 67% below its 1979 maximum (for the 1979-2009 period). If the 2010 anomaly stays below the 2009 level -which looks like a pretty safe bet at this point – 2010 will see a new record low for ice volume.

Microscopic life crucial to the marine food chain is dying out. The consequences could be catastrophic.

So reads the headline of an article in the U.K. Independent reporting on new research published in the journal Nature. The study, titled Global phytoplankton decline over the past century, finds there has been a 40% decline in the ocean’s phytoplankton over the last 100 years – and global warming is to blame.

The microscopic plants that support all life in the oceans are dying off at a rate of about 1% per year. The decline is related to rising sea surface temperatures.

According to the Independent, the scientists said if the findings are confirmed by further studies, the decline in phytoplankton will represent the single biggest change to the global biosphere in modern times, even bigger than the destruction of the tropical rainforests and coral reefs. Phytoplankton are microscopic marine organisms capable of photosynthesis, just like terrestrial plants. They float in the upper layers of the oceans, provide much of the oxygen we breathe and account for about half of the total organic matter on Earth. Phytoplankton are the basis of life in the oceans and are essential in maintaining the health of the oceans. A 40% decline would represent a massive change to the global biosphere.

The press release explains that in warmer oceans, the water becomes stratified, with warmer water on top of colder deeper water. Nutrients which are normally replenished by upwelling colder water are cut off, and the photosynthesizers living in the surface waters starve to death.

Rising sea surface temperatures were negatively correlated with phytoplankton growth over most of the globe, especially close to the equator. Phytoplankton need both sunlight and nutrients to grow; warm oceans are strongly stratified, which limits the amount of nutrients that are delivered from deeper waters to the surface ocean. Rising temperatures may contribute to making the tropical oceans even more stratified, leading to increasing nutrient limitation and phytoplankton declines.

Dave Cohen points out we’re caught in a nasty downward spiral:

It is clear that we have a disastrous positive feedback loop at work here, in which warmer surface water supports fewer phytoplankton, which then take up less CO₂ from the atmosphere, which causes the surface water to warm some more due to the greenhouse effect, etc.

Here’s the abstract of the Nature article:

In the oceans, ubiquitous microscopic phototrophs (phytoplankton) account for approximately half the production of organic matter on Earth. Analyses of satellite-derived phytoplankton concentration (available since 1979) have suggested decadal-scale fluctuations linked to climate forcing, but the length of this record is insufficient to resolve longer-term trends. Here we combine available ocean transparency measurements and in situ chlorophyll observations to estimate the time dependence of phytoplankton biomass at local, regional and global scales since 1899. We observe declines in eight out of ten ocean regions, and estimate a global rate of decline of ~1% of the global median per year. Our analyses further reveal interannual to decadal phytoplankton fluctuations superimposed on long-term trends. These fluctuations are strongly correlated with basin-scale climate indices, whereas long-term declining trends are related to increasing sea surface temperatures. We conclude that global phytoplankton concentration has declined over the past century; this decline will need to be considered in future studies of marine ecosystems, geochemical cycling, ocean circulation and fisheries.

The National Oceanic and Atmospheric Administration reports the global combined land and ocean surface temperature average for May was the warmest on record. The globally averaged temperature for both land and ocean surfaces was 0.69°C (1.24°F) above the 20^th century average of 14.8°C (58.6°F).

May 2010 Blended Land and Sea Surface Temperature Anomalies in degrees Celsius

The combined global land and ocean surface temperature during March–May 2010 was 14.4°C (58.0°F) and ranked as the warmest such period on record, 0.73°C (1.31°F) above the 20^th century average of 13.7°C (56.7°F).

March 2010 – May 2010 Blended Land and Sea Surface Temperature Anomalies in degrees Celsius

The warmest anomalies occurred over eastern and northern North America, eastern Brazil, northern Africa, eastern Europe, and southern Asia. See the deep red dots along the land masses of the Arctic and in southern Greenland and the eastern U.S. and Canada. Anomalously cool conditions were present over eastern Asia and the western United States.

Looks to be a long, hot summer.

May Global Hemisphere plot

The National Snow and Ice Data Center (NSIDC) reports that by the end of May, Arctic ice extent had fallen to near the 2006 level, the lowest in the satellite record for the end of that month.

NSIDC explains why Arctic ice went so rapidly from near normal to approach record lows:

[S]everal regions of the Arctic experienced a late-season spurt in ice growth. As a result, ice extent reached its seasonal maximum much later than average, and in turn the melt season began almost a month later than average. As ice began to decline in April, the rate was close to the average for that time of year. In sharp contrast, ice extent declined rapidly during the month of May. Much of the ice loss occurred in the Bering Sea and the Sea of Okhotsk, indicating that the ice in these areas was thin and susceptible to melt. Many polynyas, areas of open water in the ice pack, opened up in the regions north of Alaska, in the Canadian Arctic Islands, and in the Kara and Barents and Laptev seas.

The polynyas are clearly visible in high-resolution passive microwave images from the Advanced Microwave Sounding Radiometer (AMSR-E) aboard NASA’s Aqua satellite. What do current ice conditions mean for the minimum ice extent this fall? It is still too soon to say: although ice extent at present is relatively low, the amount of ice that survives the summer melt season will be largely determined by the wind and weather conditions over the next few months.

Analysis from scientists at the University of Washington shows that ice volume has continued to decline precipitously.

Joseph Romm comments at Climate Progress on a presentation by Wieslaw Maslowski of the Naval Postgraduate School, one of the country’s leading experts on the Arctic, indicating the Arctic is in a death spiral.  By 2016 (+/- 3 yrs) the Arctic will be essentially ice-free by the end of the melt season – decades ahead of the projections in the 2007 IPCC report.

And here’s the latest multi-year chart of Arctic ice extent from the Japan Aerospace Exploration Agency website.

The National Snow and Ice Data Center reports that, after a late start, Arctic sea ice extent has now dipped below 2007 levels at this stage of the melt season. 2007 is the year Arctic sea ice reached its record low extent.

The Japan Aerospace Exploration Agency (JAXA) has a terrific graphic on its website showing multiple years of Arctic ice extent. As you can see, it’s much too early to predict that 2010 will see a new record low, although conditions in the Arctic such as areas of open water in the pack ice and broad areas of more scattered ice cover indicate that the ice may be posed to retreat rapidly.

The area of sea-ice cover is often defined in two ways: sea-ice “extent” and sea-ice “area.” Sea ice extent is defined as the areal sum of sea ice covering the ocean (sea ice + open ocean), whereas the “area” definition counts only sea ice covering a fraction of the ocean (sea ice only). Thus, the sea-ice extent is always larger than the sea-ice area.

Regardless of ice extent, Arctic ice volume continues to hit record lows.