Historical sea voyage sends manmade warming signal

The HMS Challenger sailed 69,000 miles, taking around 360 temperature soundings on the first global marine expedition from 1873-1876. This painting, by William Frederick Mitchell, is from  its earlier life as a warship, in 1858.

The HMS Challenger sailed 69,000 miles, taking around 360 temperature soundings on the first global marine expedition from 1873-1876. This painting, by William Frederick Mitchell, is from its earlier life as a warship, in 1858.

Data from a 19th century scientific mission, the first global marine research expedition, have provided strong evidence that humans have influenced climate throughout the entire 20th century. From 1873–1876 the HMS Challenger, a corvette of the British Royal Navy, sailed 69,000 miles and took hundreds of ocean temperature soundings. Last year, scientists used its measurements to show the top 700 metres of the ocean has warmed around 0.33°C since Challenger’s voyage. Understandably, seeing a global effect in the limited Challenger data is fraught with difficulty. Nevertheless, Will Hobbs from the University of Tasmania, Australia, and Joshua Willis at NASA’s Jet Propulsion Laboratory in Pasadena, California, have now checked if this warming is linked to humans. “Even accounting for all uncertainties and limitations, the temperature change could not be realistically explained by natural variability alone, implying a long-term human signal,” Will told me.

Having swapped cannons for labs, among HMS Challenger’s projects was a series of around 360 soundings for temperature. At each sounding, its scientists dropped pressure-protected thermometers into the ocean attached to a rope every 100 fathoms (182 m) down to 1000 fathoms depth. “The scientists kept detailed records of how each measurement was taken, problems encountered, and how accurate and precise their measurements were,” Will said. “All instruments were calibrated in a lab before and after the expedition. So we have a lot of information about what level of accuracy we can expect, in some ways more than from modern automated observing systems, which are usually left to their own devices after deployment.” Read the rest of this entry »

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Lifting the fog of war and climate

FIDO (Fog Investigation Dispersal Operations) petrol burners are ignited on either side of the main runway at Graveley, Huntingdonshire, as an Avro Lancaster of No. 35 Squadron RAF takes off in deteriorating weather, 28 May 1945.Guy Callendar helped devise the FIDO system.

FIDO (Fog Investigation Dispersal Operations) petrol burners are ignited on either side of the main runway at Graveley, Huntingdonshire, as an Avro Lancaster of No. 35 Squadron RAF takes off in deteriorating weather, 28 May 1945. Guy Callendar helped devise the FIDO system.

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

In November 1943, the British Royal Air Force used a new secret weapon in anger for the first time. Called FIDO, or Fog Investigation and Dispersal Operation, it was a system of petrol burners that cleared fogbound airfields by raising their temperatures several degrees. It let the Allies launch and land warplanes safely when their enemies were still grounded by poor visibility. Newspapers billed it as near miraculous, crediting it with shortening the war and saving the lives of 10,000 airmen. But for one of the engineers behind it, Guy Callendar, it was just another way to combine his interest in weather and climate with his heat expertise.

From 1922-1941 Guy had worked on the Callendar Steam Tables, which he filled with data to help other engineers and scientists working with steam equipment. But after a decade carefully measuring the interaction between temperature, pressure and other properties in steam, his thoughts turned increasingly to climate. By 1938 he had stood up in front of a room of sceptical meteorologists, telling them that the world was warming, and burning fossil fuels was the cause. And while that marked a key turning point in identifying and understanding global warming, his later work in collecting evidence for that argument may have been still more important.

With his CO2 theory getting a frosty reception, and with his steam work winding down, Guy scoured scientific papers for evidence to back his argument. Since scientists like Svante Arrhenius had first suggested an important role for CO2 in climate in the 19th century and even earlier, physics had made some important advances. Earlier scientists knew that gases like CO2 absorbed infrared radiation but in the 1920s they made leaps forward in understanding why.

The frequency of the wave of infrared radiation, the number of oscillations it goes through per second, matches motions in the gas molecules that absorb it. For example, if the molecules spin at a similar frequency to the radiation’s oscillations, they can absorb the its energy. Also, atoms such as oxygen and carbon in the molecule can move, pushed by thermal energy and pulled by chemical bonds between them. That creates a vibration, and if the frequency of the vibration matches that of the infrared radiation, the vibration can absorb the radiation’s energy Read the rest of this entry »

Arctic mission recovers record of surprising warmth

All cargo for the drilling operation on Lake El'gygytgyn in winter 2008/09 had to be transported to the lake from the nearest settlement, Pevek, located 360 km north across the frozen tundra with trucks supported by bulldozers. Credit: Pavel Minyuk

All cargo for the drilling operation on Lake El’gygytgyn in winter 2008/09 had to be transported to the lake from the nearest settlement, Pevek, located 360 km north across the frozen tundra with trucks supported by bulldozers. Credit: Pavel Minyuk

A warm climate with CO2 levels similar to today delayed ice sheets from forming over land in the Arctic until less than 2 million years ago. That’s the latest instalment in a climate history scientists are building using sediment from a lake created by a giant meteorite impact around 3.6 million years ago. The international team has found that 3-3.2 million years ago, summer temperatures in the region were about 8°C warmer than they are today.

Julie Brigham-Grette from the University of Massachusetts, Amherst, explained that other scientists have estimated CO2 levels in the Pliocene period from 5.3 to 2.6 million years ago. “Though the estimates are quite broad, most scientists suggest that 2-3 million years ago CO2 levels may have been similar to today,” she told me. “Our data are consistent with that – the world today could be headed toward a Pliocene-like world.” And as well as pointing to the warmer future, these findings could also help unpick climate puzzles from our past.

These insights are the prize Julie and her team-mates sought on an epic trek to North-East Russia’s frozen wilderness in 2009. She was chief scientist for the US side of the team, leading the expedition alongside Martin Melles and Pavel Minyuk, chief scientists for the German and Russian sides. Their goal lay at the bottom of Lake El’gygytgyn, or Lake E. A 13 km wide crater blasted by a meteorite up to a kilometre in diameter that filled with water, Lake E has slowly collected sediment ever since. It’s unusual because it largely escaped damage from the creep of ice sheets, meaning scientists can use its sediment to rebuild conditions further back in time.

And to get there, Julie, Martin and Pavel had to pave political, financial, logistical, and actual physical paths, Julie explained. “This lake sits in an area that has no roads,” she said. “It was an amazing logistical feat to gather the drillers and equipment and get there, without damaging the environment. It was the most difficult scientific project I’ve ever undertaken.” Read the rest of this entry »

The climate scientist whose world spun on through war

A young Milutin Milanković as a student in Vienna,  where he became the first Serb to achieve a doctorate in technical sciences. Image via Wikimedia Commons, used under Creative Commons licence

A young Milutin Milanković as a student in Vienna, where he became the first Serb to achieve a doctorate in technical sciences. Image via Wikimedia Commons, used under Creative Commons licence

On 6 April 1941, a world war left its mark on Milutin Milanković’s life and climate research for a second time. Nazi bombs destroyed the print works where his new book, summarising 30 years’ work, sat half-complete. As German-led forces occupied Serbia a month later, Milutin still had just one finished copy of his “Canon of Insolation and the Ice-Age Problem”.  In it, he brought together his general astronomical theory of climate, which would explain how Earth’s motion in space drives ice sheet advance and retreat over tens of thousands of years.

And when two German officers came to visit the University of Belgrade maths professor, he might have feared no-one else would ever see all his ideas in a single volume. But the officers were geology students, bringing greetings from Wolfgang Soergel at the University of Freiburg, who had previously published studies supporting Milutin’s calculations. Amid the drama unfolding around them, Milutin gave them his only copy to send to Freiburg for safe-keeping. But both Milutin and his work escaped to ultimately make strides forward in understanding what controls Earth’s temperatures.

Milutin fixed his focus on climate after joining the University of Belgrade in 1909, while reading a paper about the Sun’s heat on the Earth’s surface, whose starting equation was wrong. To study how climate could produce dramatic changes like ice ages courted controversy even then because it was unclear the puzzle could ever be solved. So little was known that when Svante Arrhenius correctly identified CO2 in the air as an important factor his findings were ruled out by flawed experiments.

Using heat from the Sun, the incoming solar radiation also known as insolation, Milutin looked at climate both on the Earth and other planets in our solar system. “A connection should be found between planets’ insolation and their atmosphere and surface temperatures,” he wrote. And thanks to the many different complex sciences such an astronomical climate theory combined, Milutin was the only one trying to make that link. Read the rest of this entry »

Temperature patterns produce perplexing Pliocene puzzle

Lafayette College's Kira Lawrence and her teammates have used ocean bed sediment cores, like this one, to produce a 5 million year climate record. © Intergrated Ocean Drilling Program

Lafayette College’s Kira Lawrence and her teammates have used ocean bed sediment cores, like this one, to produce a 5 million year climate record. © Intergrated Ocean Drilling Program

US, UK and Hong Kong Researchers have produce a unique ‘movie’ of climate reaching back 5 million years, by bringing together data drilled from ocean beds. It reveals three important temperature patterns during the warm early part of the Pliocene period that they couldn’t recreate together in climate models using existing explanations. That’s important because scientists hope the Pliocene could help us know what the future of a warmer Earth might be like. And having uncovered another layer to the Pliocene puzzle, team member Kira Lawrence from Lafayette College in Easton, Pennsylvania, underlined the value of finding its solution.

“Our community of scientists think of the Pliocene as though it was about 3°C warmer than modern temperatures with CO2 concentration about where we are right now,” Kira told me. “But we haven’t recognised before that the pattern of temperature was a lot different. If that’s where we’re headed in the not too distant future, if the temperature and precipitation patterns change in that way, we should have some significant things to think about.”

The Pliocene period started 5.3 million years ago, during which primates made important evolutionary steps towards humanity. Since 2000, there has been a climate data explosion reaching back through this era. Around the world, international drilling expeditions have pierced ocean beds kilometres below sea level, reaching hundreds of metres into sediment to bring back ‘core’ samples. Tiny fossils within that rock and mud can tell scientists temperatures through history, which can give climate scientists real data to test their models against.

Read the rest of this entry »

Evidence rethink puts CO2 and ancient warming back in sync

A thin layer of ice from an area of the Antarctic where ancient ice records are collected, in polarized light that reveals ice crystals. Rethinking how ice crystal formation affects ancient data collection is helping to solve an outstanding climate puzzle. © Frédéric Parrenin

A thin layer of ice from an area of the Antarctic where ancient ice records are collected, in polarized light that reveals ice crystals. Rethinking how ice crystal formation affects ancient data collection is helping to solve an outstanding climate puzzle. © Frédéric Parrenin

A different way to dig up links between past levels of CO2 in the air and temperatures could solve a troubling question over the historical climate. Previously, data collected from long cylinders drilled from Antarctica’s ice sheet seemed to show temperatures rising hundreds of years before CO2 levels did. If ancient warming came before a CO2 rise, then the greenhouse gas seemingly couldn’t have caused the warming. Climate skeptics have used this to argue  that the CO2 we produce today isn’t causing global warming.

Now, Frédéric Parrenin at the French National Centre for Scientific Research in Grenoble and his teammates have used a different method on these cylindrical ice cores. They say that their approach shows CO2 and temperature rises happened together during the last ‘deglaciation’, when ice sheets retreated during an abrupt warming period 20,000-10,000 years ago. “This makes it possible that CO2 was actually a cause of warming corresponding to the last deglaciation,” Frédéric told me.

Scientists have been using Antarctic ice cores, and bubbles of air from the time the ice formed trapped inside, to study climate history for over 30 years. The time capsule-like bubbles show what chemicals were in the air. Meanwhile, the amounts of different forms, known as isotopes, of elements like hydrogen, carbon and oxygen in the ice reveals the temperature it formed at. And finally, scientists figure out how old the ice and bubbles are from how deep they are in the core – and that’s where Frédéric found problems. Read the rest of this entry »

2012’s record events put climate in mind

Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. As a whole, they provide a picture of an extreme melt event about which scientists are very confident. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory

Extent of surface melt over Greenland’s ice sheet on July 8 (left) and July 12 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. The satellites are measuring different physical properties at different scales and are passing over Greenland at different times. As a whole, they provide a picture of an extreme melt event about which scientists are very confident. Credit: Nicolo E. DiGirolamo, SSAI/NASA GSFC, and Jesse Allen, NASA Earth Observatory

This has been another year of striking climate events and records – but they seem to be happening so much more often today that their effect on me has weakened. That’s pretty cold-hearted, I admit. ‘Extreme weather’ is having terrible effects on peoples’ lives all around the world. But the truth is that we can only handle so many problems before becoming too numbed and overwhelmed to act. And last year, Stefan Rahmstorf and coworkers at the Potsdam Institute for Climate Impact Research showed temperature records are much more likely today than in a stable climate. “I don’t think many people appreciate how much the odds for such extremes have increased due to global warming,” he told me at the time. “I certainly didn’t until we had performed this study.” So it’s hardly surprising if we begin to get complacent when records are flowing thick and fast. But when I actually faced up to what’s happened in the climate this year, it was intriguing how well you could see global warming’s fingerprint.

Warming’s most dramatic effects have long been obvious in the Arctic, and 2012 was no different. Images from three satellites showed that almost Greenland’s entire ice sheet surface was temporarily melted by July 12. That’s the largest area in over 30 years of satellite observations. Then, on September 16, sea ice in the Arctic reached a record annual minimum area of 1.32 million square miles, approximately half the size of the average annual minimum for 1979 to 2000. Just two weeks later, Antarctic sea ice covered its highest area on record at the peak of winter, at 7.49 million square miles. In case you think that’s a natural balance that shows the planet isn’t warming, it’s worth noticing the scale of the changes. The Antarctic record is 193,000 square miles higher than its average maximum area for the last 30 years. That’s much less than the 1.32 million square miles the Arctic lost compared to its long-term average. Read the rest of this entry »