28 June 2017, The Conversation, The world’s tropical zone is expanding, and Australia should be worried. The Tropics are defined as the area of Earth where the Sun is directly overhead at least once a year — the zone between the Tropics of Cancer and Capricorn. However, tropical climates occur within a larger area about 30 degrees either side of the Equator. Earth’s dry subtropical zones lie adjacent to this broad region. It is here that we find the great warm deserts of the world.Earth’s bulging waistline Earth’s tropical atmosphere is growing in all directions, leading one commentator to cleverly call this Earth’s “bulging waistline”. Since 1979, the planet’s waistline been expanding poleward by 56km to 111km per decade in both hemispheres. Future climate projections suggest this expansion is likely to continue, driven largely by human activities – most notably emissions of greenhouse gases and black carbon, as well as warming in the lower atmosphere and the oceans. If the current rate continues, by 2100 the edge of the new dry subtropical zone would extend from roughly Sydney to Perth. As these dry subtropical zones shift, droughts will worsen and overall less rain will fall in most warm temperate regions. Poleward shifts in the average tracks of tropical and extratropical cyclones are already happening. This is likely to continue as the tropics expand further. As extratropical cyclones move, they shift rain away from temperate regions that historically rely upon winter rainfalls for their agriculture and water security. Researchers have observed that, as climate zones change, animals and plants migrate to keep up. But as biodiversity and ecosystem services are threatened, species that can’t adjust to rapidly changing conditions face extinction. In some biodiversity hotspots – such as the far southwest of Australia – there are no suitable land areas (only oceans) for ecosystems and species to move into to keep pace with warming and drying trends. We are already witnessing an expansion of pests and diseases into regions that were previously climatically unsuitable. This suggests that they will attempt to follow any future poleward shifts in climate zones. Read More here
Tag Archives: Agriculture
23 May 2017, The Conversation, Australian farmers are adapting to climate change. 2016-17 has been a great year for Australian farmers, with record production, exports and profits. These records have been driven largely by good weather, in particular a wet winter in 2016, which led to exceptional yields for major crops. Unfortunately, these good conditions go very much against the long-term trend. Recent CSIRO modelling suggests that changes in climate have reduced potential Australian wheat yields by around 27% since 1990. While rising temperatures have caused global wheat yields to drop by around 5.5% between 1980 and 2008, the effects in Australia have been larger, as a result of major changes in rain patterns. Declines in winter rainfall in southern Australia have particularly hit major broadacre crops (like wheat, barley and canola) in the key southeastern and southwestern cropping zones. There is strong evidence that these changes are at least partly due to climate change. Climate change is affecting farm productivity A recent study by the Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) confirms that changes in climate have had a negative effect on the productivity of cropping farms, particularly in southwestern Australia and southeastern Australia. In general, the drier inland parts of the cropping zone have been more heavily affected, partly because these areas are more sensitive to rainfall decline. Smaller effects have occurred in the wetter zones closer to the coast. Here less rain can have little effect on – and can even improve – crop productivity. Farmers are reacting However, it’s not all bad news. The study finds that Australian farmers are making great strides in adapting to climate change. Much has been written about the fact that farm productivity in Australia has essentially flatlined since the 1990s, after several decades of consistent growth. The ABARES research suggests that changes in climate go some way towards explaining this slowdown. After controlling for climate, there has been relatively strong productivity growth on cropping farms over the past decade. However, while farms have been improving, these gains have been offset by deteriorating conditions. The net result has been stagnant productivity. Read More here
15 May 2017, Climate Home, Bangladesh faces food supply crunch after flash floods. The price of rice has spiked in Bangladesh after flash floods wiped out vast stretches of paddy field just ahead of harvest time. Unusually heavy pre-monsoon rainfall submerged 400,000 hectares of wetland in the northeast of the country, damaging some 2 million tonnes of rice. It is already having an impact on the market. Agricultural economist Quazi Shahabuddin, former head of the Bangladesh Institute of Development Studies, told Climate Home it will cause suffering across the country this year. A kilogram of coarse rice costs 38 Bangladeshi taka ($0.57), a 58% hike since the same period in 2016, according to official data. The government is planning to procure 600,000 tonnes of rice from countries including India and Thailand, the first time in six years it has relied on international markets. The food department has put out a tender for the first 100,000-tonne tranche. “The sudden flash flood has forced us to do that,” explained Badrul Hasan, director general of the food department. The affected districts Netrokona, Sunamganj, Brahmanbaria, Moulovibazar, Hobignaj, Kishoreganj and Sylhet are located at the foothills of Indian Meghalaya and Assam states. Known as “haor” or wetland, this region is typically inundated every year in mid-May and stays underwater for six months. The problem this year was not the volume of rain, but the timing. Flash floods came at the end of March, before the farmers had harvested the “boro” crop they rely on for their annual income. Read More here
7 March 2017, The Conversation, Five-yearly environmental stocktake highlights the conflict between economy and nature. Australia’s population growth and economic activity continue to pose major environmental challenges, according to a comprehensive five-yearly stocktake of the country’s environmental health. The federal government’s State of the Environment 2016 report (prepared by a group of independent experts, which I chaired), released today, predicts that population growth and economic development will be the main drivers of environmental problems such as land-use change, habitat destruction, invasive species, and climate change. These main pressures are broadly the same as those listed in the first ever State of the Environment report in 1996. Yet since the last report in 2011, there have been some improvements in the state and trend of parts of the Australian environment. Our heritage (built, natural, and cultural) and marine environments are generally in good condition, as is the Australian Antarctic Territory. However, the Great Barrier Reef was affected significantly by Cyclone Yasi in 2011 and record high sea surface temperatures in 2015-16, resulting in extensive coral bleaching and die-off, particularly across the northern regions. Pressures and changes The new report shows that some individual pressures on the environment have eased since the 2011 report, such as those associated with air quality, poor agricultural practices and commercial offshore fishing, as well as oil and gas exploration and production in Australia’s marine environment. During the same time, however, other pressures have increased, including those associated with coal mining and the coal-seam gas industry, habitat fragmentation and degradation, invasive species, litter in our coastal and marine environments, and greater traffic volumes in our capital cities. Climate change is an increasingly important and pervasive pressure on all aspects of the Australian environment. It is altering the structure and function of natural ecosystems, and affecting heritage, economic activity and human well-being. Read More here