11 December 2015, The Conversation, Climate and the rise and fall of civilizations: a lesson from the past. 2015 will likely be the hottest year on record, beating the previous record set only in 2014. It is also likely to be the first year the global average temperature reaches 1℃ above pre-industrial temperatures (measured from 1880-1899). Global warming is raising temperatures, and this year’s El Niño has pushed temperatures higher still. Although 2015 is unusually hot, 1℃ symbolically marks the halfway point to 2℃, widely considered to be the threshold of “dangerous” climate change. In fact an additional 0.5-1℃ is actually masked by sulphur aerosols which we have added to the atmosphere alongside greenhouse gases. A temperature level of 1℃ (above pre-industrial levels) is similar to or warmer than the peak temperatures of the early Holocene epoch approximately 8,000-7,200 years ago. Studies of the early Holocene provide clues to what was such a world like. The climate roller-coaster The last ice age (or Last Glacial Maximum) peaked around 26,000 years ago. The earth warmed over the coming millennia, driven by an increase in radiation from the sun due to changes in the earth’s orbit (the Milankovic cycles) amplified by CO₂ released from warming water, which further warmed the atmosphere. But even as the earth warmed it was interrupted by cooler periods known as “stadials”. These were caused by melt water from melting ice sheets which cool large regions of the ocean. Marked climate variability and extreme weather events during the early Holocene retarded development of sustainable agriculture. Sparse human settlements existed about 12,000 – 11,000 years ago. The flourishing of human civilisation from about 10,000 years ago, and in particular from 7,000 years ago, critically depended on stabilisation of climate conditions which allowed planting and harvesting of seed and growing of crops, facilitating growth of villages and towns and thereby of civilisation. Read More here
Tag Archives: Agriculture
7 December 2015, Huffington Post, Will Climate Change Break the Global Food System? Extreme weather events scuttling harvests. Skyrocketing food prices causing famine for millions and driving multitudes into poverty. Governments toppling – again – in Pakistan and Ukraine. Massive floods driving millions of refugees from their homes in Bangladesh and putting pressure on neighboring India. Droughts devastating harvests in traditional bread baskets like the U.S. and Brazil. The E.U., in a panicked move, suspending its environmental rules for agriculture and instituting a tax on meat. The world’s top greenhouse gas emitters ultimately banding together to raise a global carbon tax.The events described above are not the real world, but they could be. They were part of what transpired at Food Chain Reaction a few weeks ago, a high-level crisis simulation in Washington, DC that brought together 65 international leaders to explore how climate change may strain the world’s food system from 2020 to 2030. What the simulation taught us, is that policymakers attending this week’s U.N. climate summit in Paris cannot afford to neglect food security. The world’s population is on a path to 9.5 billion by mid-century. That means we will have to grow up to 70 percent more food. To make matters more complicated, we’ll have to do so in a changing climate that alters the very way we grow our crops. We must figure out how we can make that happen within the limits of the Earth’s natural resources. We’ve talked long enough. It is time to decide on a course of action that will actually improve the situation. Read more here
1 December 2015, The Conversation, When climate change hits our food supply, city foodbowls could come to the rescue. Australians may need to get used to coping with more disruptions to their food supply and rising food prices in a warming climate. But the food produced near our cities – our “city foodbowls” – could play a vital role in increasing the resilience of our food supply, as discussed in a new briefing from our Foodprint Melbourne project. The urban fringes of Australia’s major cities are some of the most productive agricultural regions in Australia. They also have access to valuable urban waste streams to support food production, including recycled water from city water treatment plants and desalination plants. Nonetheless, Australia’s city foodbowls are at risk of urban development, and the opportunity to develop them as climate resilient foodbowls could be lost unless their value is recognised in metropolitan planning policy. Climate shock The Queensland floods of 2010-11 showed how a sudden extreme weather event could disrupt a city’s food supply. Major transport routes to Brisbane and other cities were cut off and supermarkets began to run short of some food. And the Millennium Drought demonstrated the impact that drought could have on food prices, when fruit prices in Australia increased 43% between 2005 and 2007, and vegetable prices by around 33%. Climate change is expected to reduce the capacity for food production across southern Australia due to water scarcity, increasing temperatures and more frequent extreme weather events. Read More here
25 November 2015, New Matilda, Halting Climate Change Means More Than Cutting Carbon. With the Paris climate talks just around the corner a focus on carbon dioxide is not enough. Geoff Russell explains. With yet another in the seemingly infinite sequence of climate summit conferences looming it’s time to take stock of what’s been happening over the past 25 years. But I’ll be taking stock properly, which means not being CO2 centric. Focusing exclusively on CO2 is rather like focusing on protein when thinking about nutrition: it’s simply silly. It’s been seven years since Barry Brook and I wrote an article about the misleading nature of the so-called “carbon dioxide equivalence” factor used to aggregate methane emissions in Greenhouse Inventories. This isn’t a priority claim; many understood the problem before us. Among the first was Kirk Smith of the University of California, Berkeley. Smith is an expert in air quality, among other things, and was the first to measure and understand the impact of indoor cooking smoke on health in India. Globally, it kills people, mainly women and children, by the hundreds of thousands every year. He’s also been tackling the problem in a practical way by spinning off students and companies designing and building cleaner cookers. Smith’s latest work, with main author Manish Desai, calculates a metric called the International Natural Debt (IND) which is a better than average measure who is responsible for our climate woes. Their study uses national emission inventories and greenhouse gas equations to calculate precisely the impact of emissions on radiative forcing (that’s just jargon for warming). In effect, while they don’t include all the components of a full climate model, they do at least account for the full impact of methane on warming. Their estimate, based on the best inventory data is that anthropogenic methane, on its own, contributes about half of our net warming influence on the climate. In technical language methane is about ~850 mW/m2 of the net ~1600 mW/m2 of anthropogenic radiative forcing. That makes methane a big deal. Even more importantly, reductions in methane have an almost immediate cooling impact. Read More here