Lake Mondsee in Austria
Image: K. Bilek

By Tim Radford

On both sides of the Atlantic scientists studying lakes have discovered they are warming – and this is bad news both for water quality and the fish.

London, 14 June - The Alpine lakes of Austria are warming up. By 2050, their surface waters could be up to 3°C warmer, according to new research in the journal Hydrobiologia.

Martin Dokulil of the Institute for Limnology at the University of Innsbruck studied data from nine lakes larger than 10km². The largest, Bodensee or Lake Constance, touches Austria’s border with Germany and Switzerland to the west; 800 kms to the east, Neusiedler See borders Germany and Hungary.

The nine lakes range from 254 to 1.8 metres maximum depth and they are vital to Austria’s tourist industry: they play powerful roles in the Alpine ecosystem and they are of course reservoirs of water.

But the Alpine valleys are warming: between 1980 and 1999 the region warmed at three times the global average and by 2050 the median temperatures for the region could have risen by 3.5°C. The challenge has been to anticipate the impact of global warming on the lakes.

“The predicted changes in surface water temperatures will affect the thermal characteristics of the lakes,” says Dr Dokulil. “Warmer water temperatures could lead to enhanced nutrient loads and affect water quality by promoting algal blooms and impairing the biological functions of aquatic organisms.

“Significant increases in summer temperatures will affect the carbon cycling in the lakes, with potential consequences on atmospheric carbon dioxide levels and the Earth’s climate.”

 Next, the fish

The Austrian research so far is concerned only with freshwater temperatures. Peter Moyle, a biologist at the University of California Davis, has been more concerned with the freshwater fish that make their homes in, or migrate to, California’s rivers and lakes.

He and colleagues report in the journal PLOS One – the Public Library of Science – that if current climate trends continue, then 82 per cent of California’s native fish could be extinct, and their native homes colonized by invasive species. The scientists looked at 121 native species and found that four fifths of them were likely to be driven to extinction or at least to very low numbers. These include prized sporting fish such as the Klamath River summer steelhead and other trout, the Central Valley Chinook salmon, the Central Coast coho salmon and many others that depend on cold water.

“These fish are part of the endemic flora and fauna that makes California such a special place,” said Prof Moyle. “As we lose these fishes, we lose their environments and are much poorer for it.” - Climate News Network

Graceful Chameleon (Chamaeleo gracilis)
Image: Paul Freed

By Tim Radford

Work by 100 scientists over five years reveal that more than half the species studied are in danger because of a warming planet.

LONDON, 13 June - Climate change doesn’t just threaten species that are already vulnerable – it could have alarming consequences for a huge range of birds, corals and amphibians that no-one had considered in danger of extinction before, according to a new study.

Wendy Foden of the International Union for the Conservation of Nature’s global species programme and colleagues examined the findings of 100 scientists over the last five years and looked for the biological and ecological characteristics that might make an animal more or less sensitive or adaptable to climate change.

Many of the planet’s birds, corals and amphibians are already threatened with extinction, often because of unsustainable logging, the growth of agriculture and so on, and climate change is likely to make their plight even more precarious.

But unexpectedly, the authors report in the journal PLOS One – the Public Library of Science  - that they also found that 83% of the birds, 66% of the amphibians and 70% of the corals highly vulnerable to climate change, are not, right now, considered to be in need of conservation measures.

Alarming surprises

The study focused on the three taxonomic groups because all three have been well studied – naturalists have described 9,856 species of bird; 6204 species of amphibian and 797 reef building corals and the fact that they can be numbered so precisely is an indicator of the attention paid to these groups – and because they contain creatures that dwell on land, in freshwater and in the oceans: the three great “biomes” or homes for life.

“The findings reveal alarming surprises,” said Foden. “We hadn’t expected that so many species and areas that were not previously considered to be of concern would emerge as highly vulnerable to climate change.

“Clearly, if we simply carry on with conservation as usual, without taking climate change into account, we’ll fail to help many of the species and areas that need it most.”

Her IUCN colleague and co-author Jean-Christophe Vié called the research “a leap forward” for conservation.  Besides providing a clearer picture of the challenge, he said “we now also know the biological characteristics that create their climate change ‘weak points’. This gives us an enormous advantage in meeting their conservation needs.”

Resources disappear

That climate change due to human-induced greenhouse greenhouse gas emissions presents a threat to other species is not of itself news: Climate Network News stories have almost every month highlighted hazards to humans and mammals, to figs and fig wasps, to species caught in swiftly-moving climate zones, and to those sub-Arctic plants and animals that actually depend on snowfall to offer some sort of stable cover for the winter.

But there has always been a tacit assumption that the first victims of changing climate would be among those species already at risk: the IUCN’s Red List number 20,000 of these. The new maps of areas at risk now suggest that the problems of conservation extend much wider.

The Amazon region hosts the highest concentrations of vulnerable birds and amphibians, and the “coral triangle” of the central Indo-West Pacific is home to the highest numbers of vulnerable corals.

A separate study of the so-called Albertine Rift – the western part of East Africa’s Great Rift Valley – has already listed plants and animals most likely to decline because of climate change: these include 33 plants used for fuel, construction, food and medicine and 19 species of freshwater fish and 24 mammals used by humans as sources of food.

Jamie Carr of the IUCN said “This is particularly important for the poorest and most marginalised communities who rely most directly on wild species to meet their basic needs.” - Climate News Network

President Obama talks with President Xi in Rancho Mirage, California. June 7, 2013
Image: Pete Souza/ whitehouse.gov

By Paul Brown

The agreement by China to phase out one of the most potent greenhouse gases hydrofluorocarbons (HFCs) has led to hopes that progress to combat climate change might finally be made.

LONDON June 12 - One of the great stumbling blocks of climate talks in the last 15 years has been that America refuses to move to cut emissions of greenhouse gases until China does – but at the weekend leaders of the world’s two great polluters reached agreement to phase out one of the most potent of them hydrofluorocarbons (HCFs).

It was heralded as a great breakthrough, and if it works it will seriously improve the chances of the world avoiding dangerous climate change. But curiously the phasing out of HCFs will be carried out under the Montreal Protocol and not the UN Framework Convention on Climate Change.

The Montreal Protocol was set up before the climate change convention to deal with a completely different threat, the hole in the ozone layer. It has always been a more successful international forum for agreement.

This is because the chemicals that were causing the problem with the ozone layer were made in a relatively few countries and by large manufacturers. As a result governments were able to control emissions quickly and directly by regulating the industry and creating deadlines to find non-harmful substitutes.

Optimism

The problem was that in solving one problem by producing substitute chemicals that did not hurt the ozone layer, another was made worse. HFCs are potent greenhouse gases, 1,000 times more so than carbon dioxide.

So the agreement to phase them out taken at the week-end, instigated by President Barack Obama and agreed by President Xi Jinping of China, will save the equivalent of two years worth of current global warming emissions. Very important is the fact that while carbon dioxide stays in the atmosphere for at least 100 years HFCs fall out of the atmosphere in a few years staving off rapid warming.

So phasing them out is extremely good news for the environment. The big question is whether this will translate into action on other greenhouse gases, particularly since this needs to be done under the Climate Change Convention and not the Montreal Protocol.

Achim Steiner, UN Under-Secretary-General and Executive Director of the UN Environment Programme (UNEP), was optimistic. The announcement, Mr. Steiner said  “could signal a new and perhaps transformational chapter in international cooperation on climate change.

“Along with a variety of recent signals from several key countries including China and the United States, this one on HFCs by these two key economies is welcome as the world moves towards a universal UN treaty on climate change by 2015.”

“It is widely recognized that securing a meaningful treaty and keeping an average global temperature rise under 2 degrees C this century will require all hands on deck—what, however, must not be overlooked or sidelined is the urgency to also tackle the principal greenhouse gas, carbon dioxide, as part of negotiations underway under the UN Climate Convention.”

Six million die

This last of Mr Steiner’s points appears to be the problem. By comparison with carbon dioxide HFCs are an easier problem to solve. Even before the US/China agreement 112 countries had urged phasing them out and a group called the Consumer Goods Forum, a global network of several hundred retailers, manufacturers, service providers, and other stakeholders from over 70 countries had agreed to begin phasing out HFC refrigerants beginning in 2015.

But governments may also be able to reach agreement on other short-lived greenhouse gases, according to the Institute for Governance and Sustainable Development.

Of these the principle culprits are methane, low-level ozone, which also damages health and crops, and black carbon soot, which kills an estimated six million people a year. Methane can be captured and used as a fuel and cutting out the other two has important economic incentives as well as saving lives.

Perhaps the biggest single factor is the attitude of the new Chinese government. Despite the lack of democracy the Chinese are under pressure from the population because of the horrific effect of pollution on daily life, particularly the health of children. Unlike most of the American population the Chinese also realize that climate change is a threat to their economy as well as their health.

Come the next round of climate talks in Warsaw in November it may be China trying to persuade the Americans and reluctant parties like Brazil and India that action on carbon dioxide is needed too. – Climate News Network

Ganjiaxiang industrial complex in Nanjing, China
Image: Vladimir Menkov

By Tim Radford

A scheme to reduce emissions from polluting factories in China’s richer provinces by imposing limits on them has resulted in shifting mucky plants to less prosperous places with fewer rules.

LONDON, 11 June - Just as rich nations have passed the responsibility for carbon dioxide emissions to the developing nations, so the rich provinces of China have exported the problem to the poorest regions, according to new research.

The world’s biggest single emitter of the greenhouse gas – 10 billion tonnes in 2011 – has undertaken to reduce the “carbon intensity” of its economy. But, according to Klaus Hubacek of the University of Maryland and colleagues, the richest and most sophisticated regions of China with the most stringent and specific pollution abatement targets, are buying manufactured goods from places like Inner Mongolia, a poorer region where targets are less constraining.

“This is regrettable, because the cheapest and easiest reductions – the low-hanging fruit – are in the interior provinces, where modest technological improvements could make a huge difference in emissions,” said Steven Davis of the University of California, Irvine, and one of the authors.

“Richer areas have much tougher targets, so it’s easier for them just to buy goods made elsewhere. A nationwide target that tracks emissions embodied in trade would go a long way towards solving the problem. But that’s not what’s happening.”

Klaus Hubacek, his colleague Laixiang Sun, Dr Davis and five others report in the Proceedings of the National Academy of Sciences that they examined China’s output and emissions in 2007 in 57 industry sectors across 26 provinces and four cities.

Exporting pollution

 In that year, China’s emissions totalled more than 7 billion tonnes, of which more than half came from fossil fuels burned to make goods and services that were consumed either in other parts of China, or beyond China’s borders to 107 countries.

In effect, the authors provided a geography of China’s internal trade. More than 75% of the emissions associated with the goods consumed in Beijing-Tianjin – one of the three most affluent regions – were pumped into the air in other provinces.

In 2009, at a UN conference in Copenhagen, China undertook to reduce the carbon dependence of its economy by lowering CO₂ emissions per unit of gross domestic product from 2010 levels by 17% by 2015. This would be achieved by imposing 19% reductions in the affluent east coast provinces, and 10% in the less developed west.

The implication is that emissions-reducing policies tend to push factories and production into regions where costs are lower, and pollution standards less stringent.

“We must reduce CO₂ emissions, not just outsource them,” said Professor Sun. “Developed regions and countries need to take some responsibility, providing technology support or investment to promote cleaner, greener technology in less developed regions.”

The authors say “Our results demonstrate the economic interdependence of Chinese provinces, while also highlighting the enormous differences in wealth, economic structure, and fuel mix that drive imbalances in interprovincial trade and the emission embodied in trade.” - Climate News Network

Floods in Prague, June 2013
Image:Jiří Sedláček

By Tim Radford

Some parts of the world face frequent catastrophic floods by the end of this century while other regions could get less hazardous.

LONDON, 10 June - Floods during the 21^st century are expected to get worse. Really calamitous floods that, during the 20^th century were considered once-in-a-century events could come round ever 10 years or so by the end of the 21^st century, according to Japanese scientists.

Yukiko Hirabayashi of the University of Tokyo and colleagues report in Nature Climate Change that they looked at the likely pattern of hazard in 29 of the world’s great river basins. They considered the risk in those places where greater numbers of people were settled, and used 11 global climate models to project flood dangers by the end of this century.

They warn that the frequency of floods will increase in Southeast Asia, Peninsular India, eastern Africa and the northern half of the Andes of South America.

More at stake

Conditions in northern and eastern Europe – the scene of recent and current calamitous flooding – could get less hazardous, along with Anatolia, central Asia, North America and southern South America.

The predictions, of course, come with the usual caveat: that the real exposure to flooding will depend to a great extent on what governments finally decide to do about greenhouse emissions, how much the world warms, what water management or flood control plans are put in place and on population growth in the regions at risk.

But those lower latitude countries where both population and economic investment are on the increase will have more at stake in the decades to come, and should prepare for greater flood risks.

 Floods in the last three decades have claimed 200,000 lives and caused around $400 billion in economic damage: they have also cost an estimated three billion people their homes, farms, businesses and livestock.

Great river basins

The most recent assessment by the Intergovernmental Panel on Climate Change said that overall, there was a “low confidence in projections of changes in fluvial floods. Confidence is low due to limited evidence and because the causes of regional changes are complex.”

The Tokyo team took a detailed look at all the available data for the world’s great river basins, from the Yukon, the Mackenzie and the Columbia in the North American west to the Mississippi and the St Lawrence; the Rhine, the Danube and the Volga in Europe; the Ob, the Yenisei and the Amur in Siberia; the Orinoco, Parana and Amazon in South America; the Euphrates, the Indus, the Ganges, the Mekong and the Yangtze in Asia: the Niger, Nile, Zambezi and Congo in Africa and even the Murray in Australia.

Their projections are just that: projections, to be tested by outcomes long after some of the authors have died. The researchers acknowledge the limitations in their methodology

“The 20C 100-year flood event is projected to occur about every 10-50 years in many of these rivers in the 21C. Such a large change in return period is caused by a 10-30% increase in flood discharge,” they warn. “Major attention should be paid to low-latitude countries where flood frequency and population are both projected to increase.” - Climate News Network

The Mackenzie River Basin showing how it drains north to the Arctic Ocean
Image:Rosenburg International Forum on Water Policy

By Paul Brown

A vast area of Canada, from southern forests to the Arctic Sea is administered by a weak government, but is threatened by warming and a rush to exploit precious minerals.

LONDON, June 10 – The Mackenzie River Basin, a vast globally important area in Canada, is at great risk from climate change and a catastrophic oil spill from the tailing ponds of tar sands mining, according to a panel of nine Canadian, American and British scientists.

The warning came just days after the Canadian Oil Producers Association says it expects oil production from tar sands in the region to double by 2030.

A report produced after a series of hearings last year says effective governance is vital for the river basin, which is five times the size of France. Water pours into the Arctic Ocean from the 1,800 kilometre long Mackenzie River at the rate of four Olympic sized swimming pools a second.

The watershed’s biodiversity and its important role in hemispheric bird migrations, stabilizing climate, and the health of the Arctic Ocean means it needs protection urgently.

 Methane release fear

Already the temperatures in the region have increased more than 2C as a result of climate change and permafrost areas are melting causing damage to roads, bridges and homes. It is also deforming the ground and changing water flows.

The report says that large quantities of methane trapped in the soil by permafrost are in danger of being released threatening to rapidly increase the rate of climate change.

Glacier cover has declined 25 % in the last 25 years and in spring snow cover on the Canadian Rockies disappears about a month earlier. The vast area contains 45,000 productive lakes, which also need protection.

The panel, convened by the US-based Rosenburg International Forum on Water Policy, identified the exploitation of the region’s mineral and fossil fuels as a major threat to its biodiversity, the Arctic and a threat to the way of life of the indigenous peoples.

Cutting the forests and the danger to river life from hydro-electric dams needs to be tightly controlled, the scientists say.

The biggest single current threat is the existing tailing ponds on the lower Athabasca River. If a breach occurred in the winter it would be “virtually impossible to clean up because it would disappear underneath the ice and run down through the whole waterway” through Lake Athabasca, the Slave River and Delta, the Great Slave Lake, the Mackenzie River and Delta and as far as the Beaufort Sea.

This would have an unprecedented effect on human societies in the North West territories.

Weak management

The report – concerned about the financial resources required to deal with a spill -includes a strong recommendation that “extractive industries be required to post a significant performance bond before site development and operations commence.

“This ensures that clean up costs and mitigation following closure of the site will be fully paid by the industry itself.

“Failure to require a significant performance bond or some similar incentive almost surely means that the legacy of despoiled environments, toxic wastes and other waste will continue unabated, and that taxpayers will be left to bear costs that are properly those of the mining industry,” the report says.

Another of the panel’s main findings was that the ecology, hydrology and climate of the region were all at risk and already changing as a result of planetary warming. Careful investigation was needed to try and reduce the effects and dangers. “This is essential to protect the welfare of people locally and to some extent globally,” the report said.

The basin is so large it is administered by three different Canadian states and although there was a Mackenzie River Basin Transboundary Waters Master Agreement of 1997 the Board that was set up to manage it is weak. The Federal Government of Canada should take overall responsibility for the basin and the Board must be strengthened. “A reinvigorated Board will need significantly more financial support and will benefit from the advice and counsel of an independent International Science Advisory Committee,” the report says.

The extractive industries and the impact of hydroelectricity schemes must be carefully controlled. – Climate News Network

Concentrated solar power plant in Seville, Spain.
Image:Torresol Energy

By Paul Brown

Over 40 years cloud cover has been steadily falling in Spain providing more sunshine but that is a threat as well as a bonus.

London, 9 June  - The sun is getting more powerful in Spain increasing the threat of desertification but providing more energy for the country’s growing solar industry – the largest in Europe.

According to a study the University of Girona and the Federal Institute of Technology (ETH) in Zurich solar radiation in Spain has increased by 2.3% every decade since the 1980s.

This is mainly due to the decrease in clouds, which has increased the direct sunlight. The largest increase was in the summer and autumn, but the sun shone more in the winter and spring as well.

Solar radiation is measured both as direct sunlight and diffuse light via clouds, atmospheric gases and aerosols. What was striking was the decrease in the diffuse component of sunlight according to the research published in the magazine ‘Global and Planetary Change’.

Clouds decrease

One of the authors, Arturo Sánchez-Lorenzo, currently a postdoctoral researcher at the University of Girona, said the amount of sunlight reaching the Spanish land surface had increased in every decade since 1980.

“Only in 1991 and 1992 did diffuse radiation rise, and this was due to the ashes from Mount Pinatubo (volcanic eruption in the Philippines).

“The explanation (of the increase) lies in the fact that in Spain the amount of cloud has decreased markedly since the 1980s – as we have ascertained through other studies – and the tropospheric aerosol load may also have decreased,” said Sánchez Lorenzo.

“It seems to be very simple: fewer clouds result in higher solar radiation on the surface.”

Skin cancer

According to the scientists, this increase may also go hand in hand with more ultraviolet rays, an excess of which presents a health risk, potentially leading to skin cancer.

The increase in global solar radiation is a phenomenon that has been observed in other parts of the world for almost 30 years, especially in developed countries, and it has been named “global brightening”.

The fall in the diffuse component has also been observed in Central European and Eastern countries. The team behind the study has not yet analysed the solar radiation data for 2011-2013 provided by the Spanish State Meteorological Agency, but the data from other European weather stations suggests that this brightening is still on the rise.

“Studies such as these may be of interest to the solar energy industry, especially in countries like Spain, where not only do we already have a lot of direct solar radiation but now we are getting even more,” said another of the authors, Josep Calbó, who is a professor at the University of Girona.

Deserts

Until the recent recession began to bite Spain was in the middle of a building boom for all types of solar energy capture. Since 2010 Spain has been the world leader in concentrated solar power, a method of directing the sun’s rays with mirrors to boil water or oil to drive turbines and generate electricity. By the end of 2012 more than 2,000 megawatts of concentrated solar power had been installed, the equivalent of two large conventional power stations.

Although the rate of increase has slowed solar power is expected to contribute an increasingly large share of the country’s electricity needs over coming decades as large areas are now too dry for agriculture.

On the downside there is serious concern about the lack of rainfall and the increasing risk of desertification in the south of the country. The increase in sunshine is in line with scientific predictions for the northern Mediterranean coast and Italy, France and Greece are all threatened with desert conditions if the trend continues.

All four countries are members of the United Nations Convention to Combat Desertification and are taking measures like planting forests to try and prevent the Sahara Desert crossing the Mediterranean to Europe as is predicted by long term climate models. - Climate News Network

GM crops – a hot topic but many insist they’re needed
Image: Gerry Manacsa

By Paul Brown

Leading scholar says attitudes to GM must change and backs introduction in Africa

LONDON, 5 June – One of Africa’s most distinguished scientists insists that in a warming climate the world needs to adopt genetically modified crops on a massive scale in order to feed the planet’s growing population.

Professor Calestous Juma appealed to political leaders who have rejected the technology to think again and young scientists to embrace the possibilities of GM following years of controversy over the crops. GM has been shunned by much of Africa.

Seventeen years after the first commercial introduction of GM corn there are still sharp divisions in the scientific community about genetically modified plants, fish and animals.

But Professor Juma from the Harvard Kennedy School’s Belfer Center for Science and International Affairs in the US – who also co-chairs the High-Level Panel on Science, Technology and Innovation of the African Union – believes GM developments in crops important to Africa should make people far more positive about new technologicy.

CO2 reductions

Speaking to graduates of McGill University, Montreal he said that from 1996 to 2011, transgenic crops “saved nearly 473 million kg of active pesticide ingredients.”

Juma said such crops also reduced 23.1 billion kg of carbon dioxide, the equivalent of taking 10.2 million cars off the road.

“Without transgenic crops, the world would have needed another 108.7 million hectares of land (420,000 square miles — roughly the area of Ethiopia) for the same level of output.

“The benefits to biological diversity from the technology have therefore been invaluable. On the economic front, nearly 15 million farmers and their families, estimated at 50 million people, have benefited from the adoption of transgenic crops.”

However, of the 28 countries today growing transgenic crops, only four are in Africa – South Africa, Burkina Faso, Egypt, and Sudan  - said Juma, a Kenyan. He hoped this would change.

Golden Bananas

He cited examples of important transgenic plant science innovations in Africa. One, a transgenic black-eyed pea variety using insecticide genes from a bacteria, Bacillus thuringiensis, was developed by scientists at Nigeria’s Ahmadu Bello University.

Currently a moth-like insect, Maruca vitrata, destroys nearly US$300 million worth of black-eyed pea crops every year, despite the annual use of US$500 million in imported pesticides. Not only are the hearty, drought-resistant black-eyed peas important in local diets, they’re a major export — Africa grows 96% of the 5.4 million tons consumed worldwide each year.

In Uganda scientists are deploying biotechnology against the problem of Xanthomonas wilt, a bacterial disease that ruins bananas and costs Africa’s Great Lakes Region an estimated US$500 million annually. Using genes from a species of sweet pepper, Ugandan researchers are developing a transgenic banana that resists the disease.

Also in Uganda scientists have developed “Golden Bananas” that offer enhanced Vitamin A content, important for growth and development, a healthy immune system and good vision, said Juma.

Kenyan scientists are also enhancing the micronutrient content of bananas as well as two other staples — sorghum and cassava.

“The techniques mastered can be extended to a wide range of indigenous African crops,” said Juma. “This would not only help Africa broaden its food base using improved indigenous crops, but it would have the potential to contribute to global nutritional requirements.”

Controversy

The delay in subjecting these products to testing and approval for commercial use is due in part to “technological intolerance,” he said, much of which reflects European anti-biotechnology activism.

“This opposition, however vexatious, amounts to petty political mischief.”

As the world’s food challenges increase humanity must include genetic modification and other technologies such as satellites for monitoring land resources, Juma said. “But these techniques are not silver bullets. They must be part of a wider system of innovation that includes improving interactions between academia, government, business and farmers.”

Despite Professor Juma’s enthusiasm 160 countries have so far rejected GM technology: at present more than 80% of GM crops are grown in just four countries in the Americas.

The main crops are soy, corn, canola and cotton. Critics say the first generation of GM plants are mostly herbicide resistant crops that have benefitted big agri-business because they patented both the seeds and the herbicide used.

Some scientists also point out that use of the pesticides had created so-called “superweeds” that have become resistant to herbicides and difficult to wipe out.

Environmental groups say negative attitudes to GM might  change if drought and salt resistant crops are developed to help agriculture on marginal land rather than concentrating on commercial crops for already rich farmers. – Climate News Network

Climate change could affect tree growth in a variety of ways
Image: Jim Champion

By Tim Radford

Estimating how alterations in rainfall patterns will affect tree growth in different regions is a puzzling business

LONDON, 4 June – Nobody knows for certain what climate change will bring but on the basis of the latest research by plant ecologists, one thing has been established: there will be surprises.

Milena Holmgren of Wageningen University in the Netherlands and colleagues report in Nature Climate Change that they used satellite data to look at the patterns of change in tree cover in three tropical belts: Africa, Australia and South America. The chief conclusion is that changes in rainfall patterns from year to year were linked to lower tree cover in the rainforests of all three continents.

In the dry tropics, however, the picture changed in puzzling ways. In South America, for instance, the higher overall variation in rainfall between years turned out to be a good thing, encouraging tree growth in the semi-arid regions. That confirmed other studies that had suggested that those unexpected episodes of heavy rainfall in normally arid areas provided a happy window of opportunity for trees to get a better hold.

But in Australia, although extremes of rainfall in the desert and dry plains certainly had some effect on tree growth and regeneration, this was usually overwhelmed by the negative effects of extremely dry years.

Meanwhile in the baking, dusty regions of tropical Africa, the procession of up-and-down rainfall levels seemed to make no great difference.

“During extremely rainy years, there is massive tree germination and if these young seedlings grow fast enough to escape from herbivores, then woodlands can expand,” says Dr Holmgren.

“With our analysis of satellite data, we can assess how general this response it. We found the positive effects of extremely rainy years is localised, and can be offset by certain conditions, as in Australia, by negative effects of extremely dry years.”

Ecosystem changes

This is not climate science as such, but rather another exploration of how the world works – and what, if anything, climate change will do for tropical tree cover.

The scientists say their work is relevant to global climate change as warming could increase the frequency of extreme events: so as floods and droughts and heat waves blight the tropics, ecosystems could change in ways that might present problems for humanity – or a bonus.

For instance, if trees do take hold in semi-arid grasslands, is that going to be a good thing for grazing livestock or wild herbivores? On the other hand, in those places where the woodland has perished – leaving eroded, dusty plains and valleys – sudden colossal downpours might just give trees a chance to regenerate, put down roots, provide some hospitality for the local biodiversity and perhaps even sequester a bit more carbon and lock it away in an increasingly fertile soil.

But these remain possibilities, not predictions. “The overall effects of climate variability are puzzling,” says Dr Holmgren. – Climate News Network

Regional weather data will be vital for understanding the future impacts of climate change.
Image: NOAA

By Alex Kirby

Leading climate scientist highlights the importance of regional data in understanding the effects of global climate change.

LONDON, 29 May - If you want to know how climate change is going to affect us you really need to see what the weather is doing, a leading British climate scientist has told Climate News Network.

The scientist is Martin Parry, visiting professor at the Centre for Environmental Policy, Imperial College London, and visiting research fellow at Imperial’s Grantham Institute for Climate Change.

He was speaking while attending Impacts World 2013, a conference on climate change effects organised by the Potsdam Institute for Climate Impact Research and the International Institute for Applied Systems Analysis, IIASA.

Professor Parry is a former co-chair of Working Group II (Impacts, Adaptation and Vulnerability) of the Intergovernmental Panel on Climate Change, the IPCC.

He told the Network it was vital to know more about the probable regional impacts of climate change, as well as its overall consequences for the planet..

“To get the granularity at regional level would help to inform policy”, he said. “The global numbers are thin: some parts of the world are blank.”

The conference heard from one earlier speaker that the impact on India, for example, could mean that dry areas would become 30% more arid while those that were already well-watered would become 30% wetter.

Another said the effects of climate change on food security in the Northern Hemisphere had been seriously underestimated.

He said the further warming to which the world was already unavoidably committed meant that severe regional problems lay ahead, which would have a worldwide effect.

Crop losses

He concluded: “The evidence from the science is overwhelming. Under our best ideas of mitigation, the Northern Hemisphere is committed… to large losses of all crops. We are clearly committed to a dire food security emergency situation in the Northern Hemisphere and, therefore, globally.”

Professor Parry said: “Weather changes will have just as important an effect as changes in the climate itself, and understanding them can help us to choose better options for climate adaptation, and what they will cost us.

“Look at the way the North Atlantic jet stream has been varying over the last two or three years, bringing unseasonally cold and wet weather to countries like the UK. That’s a nice little microcosm of granularity.”

Professor Parry said one of the pressure points to have emerged from the conference was  the fact that weather was showing more variability over the shorter term, for instance the occurrence in Europe of monsoon-type rains. - Climate News Network