How ocean data helped reveal the climate beast

Wally Broecker's famous quote on display at California Academy of Sciences.  Image copyright: Jinx McCombs, used via Flickr Creative Commons license

Wally Broecker’s famous quote on display at California Academy of Sciences. Image copyright: Jinx McCombs, used via Flickr Creative Commons license

  • This is part two of a two-part post. Read part one here.

On the wall of Wally Broecker’s building at the Lamont-Doherty Earth Observatory hangs a 16-foot long terry-cloth snake, blue with pink spots, that he calls the ‘climate beast’. Left in his office as a surprise by his workmates, its name refers to one of Wally’s most powerful quotes about the climate: “If you’re living with an angry beast, you shouldn’t poke it with a sharp stick.”

Today, the sharp stick is the CO2 we’re emitting by burning fossil fuels, which Wally was warning about by 1975. By that time he had also helped confirm that throughout history, changes in Earth’s orbit have given the climate beast regular kicks, triggering rapid exits from ice ages. He became obsessed with the idea that climate had changed abruptly in the past, and the idea we could provoke the ‘angry beast’ into doing it again.

Among the many samples that Wally was carbon dating, from the late 1950s onwards he was getting treasure from the oceans. Pouring sulphuric acid into seawater, he could convert dissolved carbonate back into CO2 gas that he could then carbon date. And though nuclear weapon tests had previously messed with Wally’s results, they actually turned out to help improved our knowledge of the oceans. The H-bomb tests produced more of the radioactive carbon-14 his technique counts, and as that spike moved through the oceans, Wally could track how fast they absorbed that CO2.

In the 1970s, as Wally and a large team of other scientists sailed on RV Melville and RV Knorr tracking such chemicals across the planet’s oceans, a debate raged. Was cutting down forests releasing more CO2 than burning fossil fuels? Dave Keeling’s measurements showed the amount of CO2 being added to the air was about half the amount produced by fossil fuels. But plants and the oceans could be taking up huge amounts, scientists argued. Thanks to the H-bomb carbon, Wally’s team found the CO2 going into the oceans was just 1/3 of what fossil fuels had emitted. Faster-growing plants therefore seemed to be balancing out the impact of deforestation, and taking up the remaining 1/6 portion of the fossil fuel emissions. Read the rest of this entry »

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Diving deep into ocean data uncovers ‘missing heat’ treasure

A new ocean reanalysis called ORAS4, here showing the difference between September 2012 sea temperatures and the average for 1989-2009 (not part of the latest study), has helped show that extra heat trapped in the atmosphere by CO2 humans are emitting is buried in the deep ocean. Credit: ECMWF

A new ocean reanalysis called ORAS4, here showing the difference between September 2012 sea temperatures and the average for 1989-2009 (not part of the latest study), has helped show that extra heat trapped in the atmosphere by CO2 humans are emitting is buried in the deep ocean. Credit: ECMWF

A newly-made picture of ocean history has backed a theory that the missing piece of a climate puzzle at the edge of space lies deep in Earth’s waters. The puzzle comes because the amount of heat energy our planet has absorbed should have warmed it more than it seems to have done. But now, using an ocean reanalysis assembled from data gathered from many sources, UK and US researchers have shown especially strong recent warming in oceans below 700m. “We have found some energy buried at depths,” Kevin Trenberth from the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. “We also have a plausible explanation for it related to changes in winds.”

In 2010, Kevin went public over his worries about a budget that didn’t balance. But rather than money, that budget tallies heat energy from the Sun entering the top of the atmosphere against energy the Earth radiates back out into space. Satellite measurements show more energy coming in than leaving, which is what causes global warming. But Kevin noticed that existing measurements showed the world hadn’t warmed as much since 2003 as this budget would suggest.

With over nine-tenths of the surplus energy coming into the Earth going into the sea, the deep ocean has always looked the likeliest hiding place for the missing heat. However, temperature data from those depths is scarce, making the theory hard to prove. Yet, in the years since Kevin pointed out the problem, scientists have gathered some clues to back that explanation. For example, some used a model that includes the complex links between the atmosphere, land, oceans, and sea ice to run five simulations of the 21st century. They found warming slowdowns on the Earth’s surface similar to what has happened in the 2000s, with the heat going into the deep oceans. But even this just underlined the importance of using measurements to see the effect directly. Read the rest of this entry »

Could pollution be stopping warming’s impact on rain?

A brown cloud of pollution over Phoenix, Arizona. Brown clouds of aerosol pollutant particles could be overwhelming the expected changes in rainfall arising from increasing greenhouse gas levels in the air. Credit: Flick/Flickr

A brown cloud of pollution over Phoenix, Arizona. Brown clouds of aerosol pollutant particles could be overwhelming the expected changes in rainfall arising from increasing greenhouse gas levels in the air. Credit: Flick/Flickr

Contrary to previous predictions and measurements, rain patterns have got more uniform as the world has warmed over the past 70 years. So say Michael Roderick and his teammates from Australian National University, Canberra, who’ve developed an ‘accounting system’ that looks closely at where and when rain fell. And the reason could be aerosols – clouds of pollutant particles – produced by humans. “The existing dogma is that increasing greenhouse gas concentrations in the atmosphere have raised rainfall variability,” Michael told me. “In that context, our results emphasise the importance of taking a whole system approach in trying to understand how something complex, like rainfall, is changing in different places.”

When scientists want to understand how climate has been changing over large areas, they usually look at maps of long-term average data that ignore patterns of change in time, Michael explained. When they want to look at how it’s changed over time, they usually either look at a single place or a worldwide average, which ignores patterns in where the changes are. But Michael, along with fellow scientists Fubao Sun and Graham Farquhar, wanted to find a way to link place and time.

To do this Fubao started from a common statistical test called Analysis of Variance or ANOVA. Normally it’s used to compare the effect of different “treatments” – such as a variety of temperatures – on the yield of a crop, for example. In such cases each treatment must be repeated more than once, giving different “replicates”, for the test to be valid. ANOVA can be used to give a value for variance – a measure that shows how spread out an experiment’s measurements are. Read the rest of this entry »

Water’s climate risks show high temperature sensitivity

Like having a fleet of miniature research vessels, the global flotilla of more than 3,000 robotic profiling floats provides crucial information on upper layers of the world's ocean currents. Credit: CSIRO/Alicia Navidad

Like having a fleet of miniature research vessels, the global flotilla of more than 3,000 robotic profiling floats provides crucial information on upper layers of the world’s ocean currents. Credit: CSIRO/Alicia Navidad

Climate change is strengthening the cycle of rain falling and evaporating by twice as much as models predict. That’s what data collected by Susan Wijffels from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Hobart, Australia, and her co-workers suggest. They’ve studied how rainfall has changed the sea’s surface salinity – or ‘saltiness’ – over the past 50 years, and compared that against current climate models. Wet areas have become wetter and dry areas drier as the water cycle strengthened by 4 per cent over this time. The scientists’ findings suggest the cycle will get 8 per cent stronger for every 1°C warming at the world’s surface, with 2-3°C warming expected by the end of the century. “As a mother I’m hoping that we’re wrong, but if this high sensitivity holds up then it could potentially be quite a significant impact to the future,” Susan told Simple Climate.

Climate change strengthens the water cycle because a warmer atmosphere can
hold and transport more moisture as water vapour. Scientists had expected this to enhance worldwide patterns of rainfall and evaporation. But understanding how rainfall is changing across the world is hard, as around four-fifths of it falls on oceans, where we have little monitoring equipment. So together with Paul Durack, who is currently at the Lawrence Livermore National Laboratory in Livermore, California, Susan had previously used salinity to get round this. As oceans lose water to the atmosphere, the sea gets saltier, and as it then returns to the sea as rain or snow it freshens again. Using salinity measurements reaching back 60 years, including from the Argo network of floating data recorders since 1995, Susan and Paul showed that the water cycle had strengthened. But they didn’t show by exactly how much, even though they wanted to. One other group of scientists had tried, but they had assumed they knew how salinity and the water cycle are linked, something Susan and Paul wanted to avoid. “We actually asked the question: How is salinity and the water cycle related and how is it related to the observed increase in temperature?”

Read the rest of this entry »

Thick ice decline could advance watery Arctic summers

NASA's shipborne ICESCAPE mission cuts a path through multiyear Arctic ice last year. This thicker form of ice is declining fastest, NASA's Joey Comiso has shown in a separate study. Credit: NASA/Kathryn Hansen

NASA's shipborne ICESCAPE mission cuts a path through multiyear Arctic ice last year. This thicker form of ice is declining fastest, NASA's Joey Comiso has shown in a separate study. Credit: NASA/Kathryn Hansen

The oldest and thickest ice in the Arctic is vanishing the fastest, data studied by NASA scientist Joey Comiso and published last month have shown. “This is alarming since it is usually the thick component that would survive the long summer melt period,” Joey told Simple Climate. “Since the thick component is declining more rapidly, the Arctic summer ice cover is more vulnerable to further decline. Assuming that the surface temperature continues to warm up as it has in the last several decades, this makes it more likely that we will have very little or no sea ice cover in the summer sooner than we previously expected.” And when the Arctic is ice-free in summer, dramatic environmental changes could follow that would speed warming further and limit the supply of fish for food.

Having long studied Arctic sea ice cover, Joey previously showed that 2007’s record smallest summer area was around one quarter smaller than the previous minimum in 2005. That “has been regarded as the event that could trigger an irreversible change in the Arctic sea ice cover”, Joey wrote in this latest research paper in the Journal of Climate. But after that low the area of thickest ice that can survive the summer melts, known as perennial ice, recovered slightly before dipping again this winter.

Intrigued by that recovery, Joey wanted to understand it. He therefore turned to data collected by tools called microwave radiometers that have been flying over the Arctic on satellites since 1979. These can collect information on the ability of different objects to emit microwave energy, or their microwave emissivity. Salt content, or salinity, influences this emissivity. As sea ice is initially around one-third as saline as sea water, microwave emissivity can be used to tell one from the other. It can also separate multiyear ice, which has survived at least two summer melt seasons, from thinner second year ice that has only survived one summer. Read the rest of this entry »

Europeans not all at sea on marine climate threats

An illustration of some of the invasive species that are entering the Mediterranean as its seawaters warm. Credit: Glynn Gorick/Clamer

An illustration of some of the invasive species that are entering the Mediterranean as its seawaters warm. Credit: Glynn Gorick/CLAMER

While the public is rightly concerned by sea-level rise, climate change’s impact on European seas will also affect people through shifts in where bacteria and fish are found. That means that as well as the distant threat of property damage, the risks of disease, unemployment and hunger are raised. Those are among the findings collected in a 200-page book summarising research done since 1998 about climate change’s effects on Europe’s ocean environments. “The main message is that changes are happening,” said Carlo Heip, Director of the Royal Netherlands Institute for Sea Research. “The second thing is that they are happening much faster than we thought.”

Heip was among scientists unveiling the results of the Climate Change and European Marine Ecosystem Research, or CLAMER, project in Brussels, Belgium, on Wednesday and Thursday this week. Funded by the European Commission, CLAMER brought researchers from 17 European marine institutes both to create this summary, and look at how well-known the messages within it were among everyday people. “The European Commission has spent, over the last ten years or so, hundreds of millions of Euros in research to find what the impacts of climate change are on the environment, including the marine environment,” Heip said. “They wanted to know, first of all, what the public knows about it, how this research has contributed to public knowledge, what people’s perception is and whether they are willing to do something about it.”

Alongside compiling their book of science, to find out what people think, the scientists surveyed 10,000 people from 10 European countries in an online poll. In January, in association with Brussels-based TNS Opinion, they questioned 1,000 people each from Spain, Italy, Germany, France, Czech Republic, Netherlands, Ireland, United Kingdom, Norway and Estonia. The results showed that Europeans are concerned about climate change’s impact on the seas, with sea level rise and coastal erosion among their leading worries. Not only this, but their estimates of sea level rise and temperature generally matched scientific forecasts, suggesting that “some fundamental messages” are spreading widely. Read the rest of this entry »

Enough gas already?

The Chinese research vessel Xue Long that bore Wei-Jun Cai and his colleagues on their 2008 research mission. Credit: Yong Wang, State Ocean Administration of China - the Chinese Arctic and Antarctic Administration, Beijing, China.

The Chinese research vessel Xue Long that bore Wei-Jun Cai and his colleagues on their 2008 research mission. Credit: Yong Wang, State Ocean Administration of China - the Chinese Arctic and Antarctic Administration, Beijing, China.

When the ice covering the Arctic Ocean retreated to a record low in summer 2007, what remained held a revelation for Wei-Jun Cai. Aware that the re-shaped environment could affect levels of greenhouse gas CO2 in the atmosphere as well as be affected by it, the following summer the University of Georgia marine scientist embarked on a mission to study exactly how. Together with his co-workers aboard Chinese research vessel Xue Long – which means “Snow Dragon”Cai sought to discover just how much CO2 the uncovered water could absorb. “It was widely accepted in the scientific community that once the ice was removed, there would be a huge amount of CO2 going into the basin,” he explained.

Over 90 percent of the world’s CO2 is absorbed by the ocean. The first step in that process is simply dissolving the gas in the water in a similar way to, but in lower amounts than, it would be in a fizzy drink. Algae living in the water can then breathe in the CO2, like any plant does, bringing the amount of the gas in the ocean back down. As the algae grows, feeding on other nutrients as it does so, the carbon stays locked within its cells. “In the Arctic, in the marginal areas, we have nutrients coming in from the Pacific, so that promotes biological fixation into algae,” Cai explained. “Previously, people only measured the ocean margin areas, and the Arctic basin when it was completely covered by ice. In those cases, you see very low CO2 levels in the ocean margins, and that’s still the same, we measured very low CO2 levels in the margins.” Scientists had therefore begun to assume that if more of the Arctic was uncovered this would help balance the CO2 emitted into the atmosphere by burning fossil fuels. Read the rest of this entry »