Climate change set to bring Western Europe more hurricanes

In January 2009 a cyclone called Klaus, which is shown here and boasted hurricane-force winds, hit France, Spain and Italy. Such conditions could become much more common in Europe by the end of the 21st century, according to Rein Haarsma and his KNMI team. Credit: H de C via Flickr Creative Commons license

Current once-in-a-century hurricane-force winds may become as much as 25 times as likely in parts of Western Europe at the end of the 21^st century. That’s what Rein Haarsma and a team from the Royal Netherlands Meteorological Institute (KNMI) have shown using one of the highest-resolution climate models around today. Their findings spring from a change in where hurricanes will develop that could also affect western North America, though more research is needed to study this. “The statement that the wind climate in Western Europe will not change significantly is questionable,” Rein told me. “Significant changes in wind climate will have consequences for agriculture – the increased winds are during the autumn – infrastructure and coastal defence.”

With Europe so far from the tropical regions where warmth and unstable atmosphere spawns hurricanes, it rarely sees them today. But when hurricane conditions do happen, like the ‘Great Storm’ in 1987, or Hurricane Floyd in 1993, they live long in the memory. The hurricane remnants that sometimes reach Western Europe usually bring a lot of rain, Rein noted, and only occasionally hurricane-force winds.

The warming Arctic is reducing ocean temperature differences that help create Europe’s traditional storms, meaning they pose less of a threat. But recently findings have shown that a warmer atmosphere raises hurricane risks. “Many model simulations suggest that the strength of hurricanes will increase due to climate change,” Rein explains. “The area where hurricanes develop appears to move poleward and the moisture content in a warmer atmosphere will increase. These factors might alter the possibility that these remnants of hurricanes are still strong enough to produce hurricane-force winds.”

Iconic authors help reveal record early flowering

“When I wrote the following pages, or rather the bulk of them, I lived alone, in the woods, a mile from any neighbor, in a house which I had built myself, on the shore of Walden Pond, in Concord, Massachusetts, and earned my living by the labor of my hands only.” Those are the famous opening lines to Henry David Thoreau’s Walden. Now, scientists have used Thoreau’s notes on his surroundings to show how much earlier global warming has pushed plant flowering. Credit: Tim Hettler, via Flickr

Notes from the last 150 years made by two environmental pioneers have helped show that the speed at which global warming is pushing spring events forward is not slowing. Boston University’s Libby Ellwood and her teammates compared flowering times recorded by Henry David Thoreau and Aldo Leopold to spring 2010 and 2012, the warmest and second warmest on record.  “Plants flowered earlier than ever before in these recent record warm years,” Libby told me. That advance is so closely linked to the warming our world’s experiencing, the researchers showed that they can predict flowering time from temperature. This knowledge could help predict climate change’s impact on crops.

“There will likely be winners and losers with climate change,” Libby said. “It is quite possible that some species will be able to use the warmer temperatures and longer growing season to their advantage. The risk for plants that begin growing as soon as the weather is warm though, is that the new spring growth and flowers are susceptible to late season frosts, and this can set back plant growth and reproduction.”

To understand what global warming is doing to other organisms, scientists have to find records about them from times when fossil fuel burning wasn’t as widespread as today. Thoreau and Leopold are best known as authors of books that lay the foundations of modern environmentalism. Both Thoreau’s Walden and Leopold’s A Sand County Almanac, published in 1854 and 1949 respectively, hold powerful ideas on the relationship between humans and nature. But both authors also studied phenology – the cycle of biological events such as plant flowering throughout the year.

Climate limits room at the global dinner table

Reducing tillage used to prepare soil in farming can help reduce carbon emissions without also reducing crop yields. Credit: USDA Natural Resources Conservation Service

Part two of two

Another mid-winter feast has passed since I published the first part of this round-up of research linking food and global warming, its memory still pleasantly fresh in my mind. I’d hate to have to sacrifice any of it in the future. But what if I were forced to change or shrink my menu? You might not have to make these choices today, but scientists are helping farming adapt to a changing climate. They’re facing up to a big challenge: trying to reduce emissions, while maintaining food supplies.

As well as being affected by climate change, farming also produces some of the greenhouse gases that cause it – between one-tenth and one-third of the world’s emissions. Agricultural consultant Rob Carlton and his colleagues therefore looked at four different crop farming methods in March last year to see which would emit least greenhouse gas if the whole UK adopted it. The best approach was to dig up less left over plant material than conventional farming currently does, keeping more carbon trapped in the soil. This approach importantly produced the same amount of crops as conventional methods. That’s necessary, because converting pasture to arable land to make up crop shortfalls seen with other methods releases large amounts of greenhouse gas. “The need for emissions reductions should be viewed against demands on agriculture, which are increasing as the population and consumption increases and farmers diversify into industrial and fuel crops,” Rob said.

Warming brings home the value of a meal

The 2012 Plant Hardiness Zone Map unveiled by the US Department of Agriculture this year shows average annual extreme minimum temperatures based on data from 1976-2005. In this version 2012 is modified to use the same colour code as 1990. Much of the US was one 5°F (2.8°C) half-zone colder in the 1990 Plant Hardiness Zone Map compared to the latest version. Credit: US Department of Agriculture/Friend of the Earth

Part one of two

Over the past few days I’ve been lucky enough to enjoy the kind of celebrations that would have been called feasting in the past. They’ve brought home how important food is as basic fuel, a source of pleasure and a reason for friends and family to get together. This year, that importance has drawn me increasingly to research into what climate change means for our food supply. What I’ve covered only begins to scrape the surface of the effects we can expect. However, these studies highlight how life could become yet harder for farmers, and what that could cost us all.

The warming world has already noticeably changed plant growing conditions, for example shifting the regions they are suited to grow in the US. In January, the US Department of Agriculture (USDA) redrew its map of planting zones to reflect warming seen since the 1990 version. Partly due to climate change, and partly due to new technology and better weather data, many places are now one 5°F (2.8°C) half-zone warmer. At around the same time, Chinese researchers found that the phases in the seasonal cycle of crop growth in their country had shifted between 1960 and 2008. Springtime events are now 6-15 days earlier and Autumn events 5-6 days later, they found.

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

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.

Carbon conundrum could push firmer emission action

Measuring CO2 emitted by soil in tropical forests from tree debris with a particular chemical signature, with a wire mesh tent excluding other tree debris. Climate change could enhance tree growth in tropical forests, and the resulting increase in litterfall could stimulate soil micro-organisms leading to a release of stored soil carbon. Such uncertainties in the carbon cycle aren’t well captured by climate models. Credit: Dr. Emma Sayer

Rather than sucking up ever more of the greenhouse gas CO2 as the world warms, plants and soil could begin releasing it instead. This hasn’t been included in climate models, and means their predictions of the temperature rise following us burning more fossil fuels might be too low.  That’s what US researchers have found after linking two models, one simulating climate and the other the ‘carbon cycle’ moving through living creatures and the environment. “That means that to keep concentrations of CO2 in the atmosphere at ’safe’ levels, we might have to reduce our emissions more aggressively than we currently realise,” said Paul Higgins from the American Meteorological Society in Washington DC.

Plants take up CO2 to power their growth through photosynthesis. Many climate models that consider the carbon cycle assume that more CO2 in the air will speed their growth, and mean they absorb the gas faster. But when Paul looked at what plants actually did during his master’s degree at Stanford University, California, more than a decade ago he found this ‘CO2 fertilisation’ didn’t always happen. “Carbon cycle models did tend to make an optimistic assumption about CO2 enrichment that was not entirely consistent with what the experiments were suggesting,” he told me.

That thought stayed in Paul’s mind as he continued his research, which brought him to John Harte’s labs at University of California, Berkeley, in 2003. There he found that plants faced limits on how readily they can move to places where conditions suit them best as climate changes. That can also affect how much CO2 they store overall, he noted. “Over the next couple of years, I kept going back to that and thinking ‘Why don’t we think about CO2 enrichment in the context of this work as well?’”

Monsoon instability raises food questions for India

A street in Calcutta floods during monsoon season. After some decades of increasing rainfall, climate change could bring drier monsoons, said Jacob Schewe from the Potsdam Institute for Climate Impact Research. Credit: Mark E Dyer/Flickr

Monsoon rains in India may fail more frequently as climate change proceeds into the 22^nd century, German researchers said this week. That danger could be critical for farming in what is set to become the world’s most highly populated country by 2030, and would follow an already expected wetter period. “Previous studies showed that Indian monsoon rainfall would increase more or less linearly with global warming over the next century,” said Jacob Schewe from the Potsdam Institute for Climate Impact Research. “The monsoon can respond to climate change in a more complicated way. We’ve seen that it matters to look further into the future.”

In South Asia, summer monsoon rains fall as winds blow from the southwest Indian Ocean over the continent between June and September. They end when the wind direction reverses in September or October. What Indian monsoon rain seasons will do as the world warms is an important and difficult question that many researchers are trying to answer. Though more rainfall has been predicted, recent years haven’t matched that expectation. While factors like pollution have an effect, changes climate scientists already know a major climate pattern plays a very important part in monsoons.

“There is a coupling between the El Niño Southern Oscillation and the monsoon that’s been observed for a long time,” Jacob told me. In years when El Niño occurs, an air movement pattern called the Walker circulation pattern gets shifted eastward. That brings high pressure over India and weakens the monsoon. While some changes in El Niño are already happening, the Walker circulation is expected to weaken, but not for some time yet. That could mean scientists’ climate models don’t pick up its effects. “People have looked at monsoon changes but not many studies have looked beyond 2100,” Jacob said. “You really have to consider longer timescales – beyond 2100 – to assess the full range of consequences for the monsoon.”

Climate provides weak power to predict African violence

Two boys from the Local Defence Unit (LDU) in Kitgum, Northern Uganda, whose job is to protect the people at a refugee camp from attacks and kidnappings by the Lord’s Resistance Army, which has been responsible for much violence in East Africa in recent years. Credit: John & Mel Kots/Flickr

Rainfall and temperature changes are linked to conflict in East Africa, but have less power to predict violence than links to political, economic and geographical factors. That’s according to one of the most detailed studies into climate-violence relationships yet, done by John O’Loughlin from the University of Colorado, Boulder, and his team-mates. “Fears of climate wars across Africa are exaggerated,” John told me. “Any effect of climate change will likely be localized and subject to other conditions.”

One political argument made about our changing climate is that it will bring more violence, particularly in Africa. For example, in 2009, US President Barack Obama told the United Nations that a warming world represents an “urgent, serious, and growing threat” because “more frequent drought and crop failures breed hunger and conflict”. But, with a background of looking in detail at where violence happens and having studied African conflicts before the 1990s, John was concerned that the evidence didn’t back such statements. That’s even though other researchers have reported statistical links between climate and conflict. “I believe that previous studies were limited by data problems and also that the policy discussions were not connected to the research findings,” John explained.

John’s team described how they fixed this in a paper published in the research journal Proceedings of the National Academy of Sciences of the USA on Monday. Previous attempts to study climate-violence have either lacked detail, looking at data per country, per year, or have been too narrowly focussed to allow generalisations, they wrote. John added that this type of work needs detailed data on both conflicts and all the factors that might predict it. Collecting the information needed on conflicts as well as political, health, location and other possibly predictive data was the biggest challenge in the work, he said.

Temperature rises could hamper developing world growth

Higher temperatures can lower productivity in non air-conditioned factories like this one owned by bead manufacturer Kazuya in Nairobi, Kenya, says MIT’s Ben Olken. Credit: Amy the Nurse/Flickr

Higher temperatures play a role in economic progress that brings bad news for poorer countries. Their development efforts may be slowed as the world warms further, suggest researchers at the Massachusetts Institute of Technology (MIT) and Northwestern University in Evanston, Illinois. Looking at over 50 years of weather data, MIT’s Ben Olken and his colleagues showed that every 1°C temperature increase shaves 1.3 percent off a poor country’s growth, over the course of a given year. That can have a big impact, considering the World Bank projects that developing countries’ economies will grow by 5.4 percent in 2012. “The key points of our study for thinking about climate change are that a) the impact seems to be larger for poorer countries and b) there is at least the possibility that the economic magnitude of the costs of higher temperatures for poorer countries could be quite large,” he told Simple Climate.

People have been asking whether temperature influences how rich a country is for centuries, with historian Ibn Khaldun discussing it in his book Muqaddimah in 1377. But researchers are still trying to tease out the various ways it can play a part even today. Getting a grip on this subject becomes more important as the world warms in response to human CO2 emissions, Ben noted. “Given the interest in global climate change, the link between temperature and economic growth is clearly important to understand,” he said. “While there are many studies that try to simulate these impacts, we thought it was very important to try to look, historically, at what actually happens when it gets warmer. When we thought of doing this, we were very surprised that nobody had really done it before.”

Ben, MIT’s Melissa Dell and Northwestern’s Ben Jones brought together temperature, rainfall and economic output data for 1950-2003 from 125 countries. In a paper published in the July edition of the American Economic Journal: Macroeconomics they compared temperature and rainfall changes against economic growth. By studying year-to-year changes they could avoid assumptions about what links exist and remove the effects of unchanging national factors. Looking at economic growth both in the same year as the weather data and up to ten years later allowed them to see how long any impacts lasted. While economic growth in poor countries was affected by temperature, there was little effect on growth in rich countries. Changes in rainfall have relatively mild effects on national growth in both rich and poor countries. Their data showed that these were permanent effects on growth, rather than temporary dips in output after which the countries continued the progress they were making before.

CO2-focused breeding can arm crops for food fight

Growth of modern farmed rice varieties rise proportionally less when CO2 levels go up than wild types. Lewis Ziska and his colleagues said that more effort needs to be made in plant breeding to make sure crops benefit from higher CO2 levels. Credit: Héctor de Pereda/Flickr

While CO2 emissions from humans burning fossil fuels are wrapping the world in a worryingly warming blanket, they could also help make our crops grow faster. But more direct effort is needed to make the most of this chance, say Lewis Ziska from the US Department of Agriculture and an international team of scientists. “Plant breeders often assume that on-going breeding efforts, for example for pest or disease resistance, would by themselves lead to adaptation to any rise in background CO2 levels,” Lewis told Simple Climate. “We’ve shown that this is not the case.”

Throughout the 20^th century crop breeding has been one part of a green revolution that has made farmers today able to produce much more food from their fields. But Ziska notes that these improvements in crop yields are slowing. Though climate change and the droughts it brings makes this problem even harder, the gas driving it could provide a way out.

“The gains of the green revolution with respect to population growth have ended,” Ziska said. “As agricultural scientists our goal is to ensure a safe and nutritious supply of food.  It is clear we will have to do so with fewer resources, specifically arable land, water and fertilizer. We have long recognized that CO2 is, by itself, a resource as it supplies plants with carbon, the basic building block for growth. Hence we are urging a systematic active effort in selecting cereal lines that could respond to rising CO2 levels by increasing their yields.”

This view springs from a wide range of evidence Ziska and his colleagues brought together in a paper published in the research journal Proceedings of the Royal Society B this week. This included Ziska’s own research showing how CO2 concentrations affected wheat bred during the 20^th century, when CO2 rose from around 290 parts per million (ppm) to 380 ppm. That study showed that higher CO2 concentrations increased the amount of wheat produced by forms developed nearer to 1900 more than modern varieties.