Weather extremes take twin crop and disease toll

Using MODIS data of red and infra-red emissions from the Earth's surface Assaf Anyamba and his colleagues can track conditions including temperature and levels of plant growth. In this shot the Normalized Difference Vegetation Index (NDVI) for southeast Australia from September to November 2010 shows that plants were thriving after a bout of extremely cool, wet weather. Image copyright: PLOSone, used via Creative Commons license, see reference below.

Using MODIS data of red and infra-red emissions from the Earth’s surface Assaf Anyamba and his colleagues can track conditions including temperature and levels of plant growth. In this shot the Normalized Difference Vegetation Index (NDVI) for southeast Australia from September to November 2010 shows that plants were thriving after a bout of extremely cool, wet weather. Image copyright: PLOSone, used via Creative Commons license, see reference below.

The wet and dry weather extremes the world felt between 2010 and 2012 caused wild variations in farm output and encouraged serious diseases spread by insects like mosquitoes. That’s according to scientists from NASA and the US Department of Agriculture (USDA) who studied severe droughts and rainfall that happened in six places during this period. Harvests in the four drought-stricken regions fell to as little as one-fifth of normal levels, but grew dramatically in the two rain-soaked areas, almost doubling in one case. But wet or dry, extreme conditions favoured certain species of mosquitoes (also known as vectors) that went on to cause outbreaks of illnesses like the potentially-fatal Rift Valley Fever. “Extreme weather events can have both negative and positive impacts,” observed NASA’s Assaf Anyamba. “For example eastern Australia and South Africa had bumper harvests of some crops but at the same time had outbreaks of vector-borne disease.”

Assaf and his coworkers help provide ways for the US government to closely monitor the whole world to see where droughts or wet periods might be happening. One way Assaf does this is with a pair of ‘eyes in the sky’ – NASA’s Terra and Aqua satellites. Each carries a Moderate Resolution Imaging Spectroradiometer, or MODIS, which precisely records the colours of the Earth’s atmosphere and surface, including those we can see and reaching far beyond. Scientists use the infra-red data it collects to track surface temperatures, while a combination of red and infra-red can tell them how leafy places are. From these, NASA makes this awesome ‘NDVI’ map of how well vegetated crop-growing regions across the world are, while the USDA includes them in monthly Rift Valley Fever risk reports.

While it’s important to know the impacts of extreme weather, not all countries are able to measure them. But from 2010 to 2012, the MODIS records captured the most intense set of weather they had recorded since Terra’s launch in 1999. The US, Russia, east Africa and southwest Australia endured droughts, and rain drenched South Africa and southeast Australia. Assaf and his team noticed that this weather was influencing both farming and disease in these cases, and decided to look at ‘the big picture’. “We wanted to showcase this connectedness as an example of the mixed bag of impacts anomalous weather conditions impose on society at large,” he explained. Read the rest of this entry »

Advertisements

Give those we love the climate they deserve

Residents in Azaz, Syria on 16 August 2012 clear up after their buildings were bombed during the country's civil war, for which one of the many causes was a drought that has been linked to climate change.

Residents in Azaz, Syria on 16 August 2012 clear up after their buildings were bombed during the country’s civil war, for which one of the many causes was a drought that has been linked to climate change.

Over the next week I hope to be spending time with those I love the most. But this week I’ve been reading the latest newsletter from Medecins Sans Frontiers/Doctors Without Borders (MSF) about the horrible situation in Syria. The country’s civil war has been ongoing since 2011, with a toll that puts the good fortune me and my family enjoy into chilling context.

It’s estimated that there have been 120,000 deaths with over 4.5 million – in a country of just 22.5 million – having to leave their homes. Though that’s a lot of people, I am increasingly numb to the numbers, like many of you might be. But the stories from MSF really hit home. Yes, Syria had serious problems before the war, but it had a comparatively good health system. Now, if you have asthma, diabetes, or appendicitis, it can be life threatening. Ever more children are being born with severe defects, possibly due to the mothers not getting enough folic acid in their diet.

Though there are many factors behind the conflict, an important one is a drought that hit the country’s poorest areas in early 2011. Commentators have highlighted that droughts in Syria have become more common in recent years, linking this to climate change. Earlier this month, US scientists reported that a recent three year drought in Syria was too unusual to be a natural event. All of us who use fossil fuel energy likely bear some responsibility.

While it’s always hard to be certain about such links, they’re backed up by what University of California, Berkeley’s Ted Miguel told me in August. “Many global climate models project global temperature increases of at least 2°C over the next half century,” Ted told me. “Our findings suggest that global temperature rise of 2°C could increase the rate of intergroup conflicts, such as civil wars, by over 50% in many parts of the world, especially in tropical regions where such conflicts are most common.”

Earlier this month, Jim Hansen from Columbia University in New York and his team warned that even world average temperatures 1°C above pre-industrial levels would be dangerous. The Earth has already warmed 0.8°C in the past 100 years, meaning that threshold is near. And many other researchers I’ve spoken to this year have found evidence that shows the dangers. Read the rest of this entry »

Fighting for useful climate models

  • This is part two of a two-part post. Read part one here.
Princeton University's Suki Manabe published his latest paper in March this year, 58 years after his first one. Credit: Princeton University

Princeton University’s Suki Manabe published his latest paper in March this year, 58 years after his first one. Credit: Princeton University

When Princeton University’s Syukuro Manabe first studied global warming with general circulation models (GCMs), few other researchers approved. It was the 1970s, computing power was scarce, and the GCMs had grown out of mathematical weather forecasting to become the most complex models available. “Most people thought that it was premature to use a GCM,” ‘Suki’ Manabe told interviewer Paul Edwards in 1998. But over following decades Suki would exploit GCMs widely to examine climate changes ancient and modern, helping make them the vital research tool they are today.

In the 1970s, the world’s weather and climate scientists were building international research links, meeting up to share the latest knowledge and plan their next experiments. Suki’s computer modelling work at Princeton’s Geophysical Fluid Dynamics Laboratory (GFDL) had made his mark on this community, including two notably big steps. He had used dramatically simplified GCMs to simulate the greenhouse effect for the first time, and developed the first such models linking the atmosphere and ocean. And when pioneering climate research organiser Bert Bolin invited Suki to a meeting in Stockholm, Sweden, in 1974, he had already brought these successes together.

Suki and his GFDL teammate Richard Weatherald had worked out how to push their global warming study onto whole world-scale ocean-coupled GCMs. They could now consider geographical differences and indirect effects, for example those due to changes of the distribution of snow and sea ice. Though the oceans in the world they simulated resembled a swamp, shallow and unmoving, they got a reasonably realistic picture of the difference between land and sea temperatures. Their model predicted the Earth’s surface would warm 2.9°C if the amount of CO2 in the air doubled, a figure known as climate sensitivity. That’s right in the middle of today’s very latest 1.5-4.5°C range estimate.

Comparison between the measured sea surface temperature in degrees C calculated by the GFDL ocean-coupled GCM, from a 1975 GARP report chapter Suki wrote - see below for reference.

Comparison between the measured sea surface temperature in degrees C calculated by the GFDL ocean-coupled GCM, from a 1975 GARP report chapter Suki wrote – see below for reference.

At the time no-one else had the computer facilities to run this GCM, and so they focussed on simpler models, and fine details within them. Scientists model climate by splitting Earth’s surface into 3D, grids reaching up into the air. They can then calculate what happens inside each cube and how it affects the surrounding cubes. But some processes are too complex or happen on scales that are too small to simulate completely, and must be replaced by ‘parameterisations’ based on measured data. To get his GCMs to work Suki had made some very simple parameterisations, and that was another worry for other scientists. Read the rest of this entry »

Twin rainfall effects strengthen human climate impact case

While existing studies of rainfall changes rely on data collected on land, by switching to satellite data LLNL's Kate Marvel and Céline Bonfils could include changes in rainfall at sea. Image copyright snoboard1010 used via Flickr Creative Commons license.

While existing studies of rainfall changes rely on data collected on land, by switching to satellite data LLNL’s Kate Marvel and Céline Bonfils could include changes in rainfall at sea. Image copyright snoboard1010 used via Flickr Creative Commons license.

The way we humans are affecting the climate is changing rainfall patterns over land and sea, scientists at Lawrence Livermore National Laboratory (LLNL) in California have found. Kate Marvel and Céline Bonfils compared precipitation ‘fingerprints’ in satellite data against what climate models showed would result from actions like adding greenhouse gases to the atmosphere. “Everyone knows that temperatures are rising, but figuring out how that affects other aspects of the climate is tricky,” Kate told me. “We’ve shown that global precipitation is changing in the way climate scientists expect it to. The odds of the observed trends being due to natural climate variability are very low.”

Changes to rain, snow and all the other forms of falling wetness collectively known as precipitation are undeniably important, given their power to bring floods and droughts. Scientists have already shown that, over land, wet areas are getting wetter and dry areas are getting drier. These studies rely on data measured directly on land, reaching back almost a century. The long record gives scientists a lot of data to test, making it easier to tell human influences from the many natural rainfall patterns. Yet Kate and Céline wanted to use satellite data instead. Though these have only been recorded since 1979, each measurement is more reliable, and the satellites also cover the oceans.

“With such a short record, it’s often difficult to identify the ‘signal’ of climate change against the background of completely natural variability,” Kate explained. For example, the wet-gets-wetter, dry-gets-dryer strengthening of the Earth’s water cycle happens because warmer air can hold more water vapour. But that can be caused by the El Niño climate pattern, as well as by increasing greenhouse gases. Our activities can also change how air circulates above the planet, pushing dry regions and storm tracks toward the poles – but so can the La Niña pattern.

Read the rest of this entry »

The underprepared figurehead that led climate science from calculation to negotiation

Bert Bolin discussing weather maps in Stockholm circa 1955. Image copyright Tellus B, used via Creative Commons license, see Rodhe paper referenced below.

Bert Bolin discussing weather maps in Stockholm circa 1955. Image copyright Tellus B, used via Creative Commons license, see Rodhe paper referenced below.

In 1957, at the young age of 32 and just one year after completing his PhD, Bert Bolin officially gained a new skill: leadership. Taking over the International Meteorological Institute (IMI) in Stockholm, Sweden, after his mentor Carl-Gustaf Rossby’s sudden death must have been a huge shock. But Bert gained responsibility after responsibility over the next 40 years, ultimately becoming the first chairman of the United Nations’ Intergovernmental Panel on Climate Change (UN IPCC). And though it’s hard to beat setting up a Nobel-prize winning organisation, Bert was not just an administrator – his research helped build the foundations of climate science too.

Growing up in Nyköping, south of Stockholm, Bert recorded the weather with encouragement from a schoolteacher father who had studied meteorology at university. After the pair met the Swedish Meteorological and Hydrological Institute’s deputy director when Bert was 17, he moved north to study maths, physics and meteorology at the University of Uppsala. Immediately after graduating in 1946 he went to Stockholm to do military service, where he first saw Carl-Gustaf giving a series of lectures.

By that time Carl-Gustaf had been living in the US for 21 years, pioneering mathematical and physical analysis of the atmosphere, becoming the country’s foremost meteorologist. He had set up meteorology departments at Massachusetts Institute of Technology in the 1930s, and the University of Chicago, Illinois, in the 1940s. He had also modernised the US Weather bureau and by 1946 wanted to help improve meteorology’s status in his native Sweden. As Carl-Gustaf’s renowned organisational prowess gradually pulled together the IMI, Bert came to study with him, gaining his Master’s degree in 1950.

Carl-Gustaf was collaborating with leading scientists of his time, and through some of these links Bert spent a year working in the US after his Master’s. Perhaps the most notable such relationship was with John von Neumann at Princeton University in New Jersey, who had helped develop the hydrogen bomb. John and his team had made history using arguably the world’s first computer, ENIAC, to predict weather mathematically. But when errors emerged, Carl-Gustaf asked Bert to help analyse why, using his understanding of the atmosphere to prevent such forecasts being ‘mathematical fantasy’. Read the rest of this entry »

Bouncing lasers off satellites backs faster Greenland melt

NASA's Goddard Geophysical and Astronomical Observatory in Greenbelt, Maryland, routinely bounces lasers off satellites, to perform Satellite Laser Ranging (SLR). This facility works with other SLR telescopes around the world. Credit: NASA

NASA’s Goddard Geophysical and Astronomical Observatory in Greenbelt, Maryland, routinely bounces lasers off satellites, to perform Satellite Laser Ranging (SLR). This facility works with other SLR telescopes around the world. Credit: NASA

Japanese and Taiwanese researchers have used old satellite technology to add a decade onto modern gravity-based measurements of Greenland’s ice loss. They used measurements gained by tracking satellites with lasers, getting ‘rough data’ compared to more modern technology, but still confirming an acceleration already seen between the 1990s and 2000s. “There was no mass loss in the 1990s, but there was an acceleration after the year 2000,” says Kosuke Heki from Hokkaido University in Japan.

Though we don’t notice it, Earth’s gravity changes slightly across its surface, because mass isn’t shared equally over it. The link Isaac Newton famously discovered between mass and gravity means that where there’s more mass – for example, where ice sheets sit – gravity is stronger. Since their launch in 2002, twin satellites called Tom and Jerry have been chasing each other around the planet in a game of orbital cat-and-mouse to track these changes. They bounce microwaves from one to the other that scientists can use, among other methods, to track hair’s-breadth changes in the distance between them caused by changes in gravity.

Using Tom and Jerry, also known as the GRACE experiment, scientists have already shown the severity of global warming’s impact on Greenland. They found evidence that Greenland’s ice mass loss is now five times faster than it was in 1992. But for the data from the 1990s there were no gravity measurements. Instead, the researchers worked out the ice mass using laser or radar signals that had been bounced off the glaciers to record their shape, which is known as altimetry . Read the rest of this entry »

Scientists spotlight rock’s role in carbon capture success

Equipment for monitoring seismic activity being deployed in a borehole at the Weyburn CO2 storage site in Saskatchewan, Canada. Credit: University of Bristol

Equipment for monitoring seismic activity being deployed in a borehole at the Weyburn CO2 storage site in Saskatchewan, Canada. Credit: University of Bristol

Climate change is a problem that many would like to bury – and indeed ‘burying’ CO2 deep underground might be needed to get it under control. And injecting the greenhouse gas among the rocks below us on a large scale is a serious option, if the storage sites are chosen carefully. That’s according to a study of three sites where ‘carbon capture and storage’ (CCS) has been done, published by University of Bristol’s James Verdon and his teammates this week. “Too often CCS is seen as a binary thing – it’ll either be brilliant or hopeless, depending on whether you are for or against,” James told me. “This study shows that every CCS site will be different – there won’t be a one size fits all solution.”

Scientists think it will be dangerous if global temperatures go more than 2°C above the pre-industrial average from 1850-1899. That’s recognised by governments in a non-binding climate change target in the Copenhagen Accord in 2009, where many also pledged actions to cut their CO2 emissions. But we continue to pump out ever more CO2, making the chances of sticking to the target through emission cuts alone ever slimmer.

CCS, which captures CO2 where lots would otherwise be released and then stores it where it can’t reach the air, is an alternative approach. Though the cost of the technology needed to do this has meant projects have been delayed and even abandoned, eight large-scale CCS projects are operational today. James has worked at two: Weyburn in Canada, and In Salah in Algeria. At a meeting of British CCS scientists he mentioned this to Andy Chadwick from the British Geological Survey in Nottingham, who had worked at the Sleipner CCS project in Norway. They realised that comparing the sites could help answer one of the biggest potential issues around CCS beyond cost: how rocks respond to CO2 injection. Read the rest of this entry »