1 March 2017, The Conversation, As global food demand rises, climate change is hitting our staple crops. While increases in population and wealth will lift global demand for food by up to 70% by 2050, agriculture is already feeling the effects of climate change. This is expected to continue in coming decades. Scientists and farmers will need to act on multiple fronts to counter falling crop yields and feed more people. As with previous agricultural revolutions, we need a new set of plant characteristics to meet the challenge. When it comes to the staple crops – wheat, rice, maize, soybean, barley and sorghum – research has found changes in rainfall and temperature explain about 30% of the yearly variation in agricultural yields. All six crops responded negatively to increasing temperatures – most likely associated with increases in crop development rates and water stress. In particular, wheat, maize and barley show a negative response to increased temperatures. But, overall, rainfall trends had only minor effects on crop yields in these studies. Since 1950, average global temperatures have risen by roughly 0.13°C per decade. An even faster rate of roughly 0.2°C of warming per decade is expected over the next few decades. As temperatures rise, rainfall patterns change. Increased heat also leads to greater evaporation and surface drying, which further intensifies and prolongs droughts. A warmer atmosphere can also hold more water – about 7% more water vapour for every 1°C increase in temperature. This ultimately results in storms with more intense rainfall. A review of rainfall patterns shows changes in the amount of rainfall everywhere. Read More here
Tag Archives: Extreme Events
28 February 2017, Climate News Network, Inequalities fuel human impacts on climate. For the second time this year, a group of climate scientists has called for a new approach to climate change research to produce a better and more precise idea of how the world will change as global average temperatures rise. The call comes only weeks after a distinguished international team reminded researchers that some details of the planetary climate machine are still unresolved – such as what happens to all the carbon released by fossil fuel combustion, and how rainfall patterns will change in the decades to follow. Neither group is challenging the general climate models, which broadly predict that, unless action is taken, global average temperatures could rise by 4°C and global sea levels by a metre or so. What each wants is more detailed answers. The latest call comes from a team of US and Japanese scientists, who argue in their report in National Science Review journal that the human dimension is missing. What people do over the next decades will feed back into the mechanics of climate change. Missing dimensions The missing dimensions of the human impacts and contribution, they say, are threefold: the economic inequalities that stoke conflict and drive migration; the levels and patterns of consumption of resources that fuel these inequalities; and the numbers of people consuming these resources and demanding energy to improve their lives over the next two generations. For instance, the scientists say, human choices make a difference. The rate of atmospheric concentrations of the greenhouse gases carbon dioxide, methane and nitrous oxide increased 700-fold, 1,000-fold and 300-fold respectively after the “green revolution” of the 1960s, compared with pre-industrial levels. Population growth was a factor. So was economic growth. And this corresponded to a doubling of human impacts every 17 years. “The doubling of this impact is shockingly rapid,” says the study leader, Safa Motesharri, a systems scientist at the University of Maryland’s National Socio-Environmental Synthesis Centre. Read More here
21 December 2016, Climate Central, The U.S. Has Been Overwhelmingly Hot This Year. In a politically divisive year, there’s been one tie that has bound most of the U.S. together. We all live in the United States of Warming (USW! USW! USW!). In all likelihood, the U.S. is going to have its second-hottest year on record, trailing only 2012. Every state is slated to have a top 10 warmest year and even at the city level, unrelenting warmth has been the main story in 2016. Climate Central conducted an analysis of more than 1,730 weather stations across the Lower 48 that include daily temperature data up until Dec. 15. A paltry 2 percent are having a colder-than-normal year. That leaves 98 percent running above normal. Not only that, 10 percent of those weather stations are having their hottest year on record. Those record-hot places can be found from coast to coast. They include medium-sized cities like Asheville, N.C., Modesto, Calif., and Flint, Mich., as well as lesser-known locales like Neosho, Mo., Callahan, Calif., and Climax, Colo. While some of the heat was driven by the super El Niño earlier this year, that alone doesn’t explain all the records being set, particularly in the latter half of the year after El Niño faded. Climate change has caused the U.S. average temperature to increase about 1.5°F since the 1880s. Read More here and to access graphics
19 December 2016, Climate News Network, Growing tornado impact puzzles scientists. The US seems to be experiencing more and worse tornado outbreaks – groups of twisters in quick succession. But climate change may not be the culprit. Tornado outbreaks – those sudden, multiple whirlwinds that can randomly destroy whole townships or pass by and do little more than ruffle the prairie grass – may be getting more frequent and more powerful in the United States. And nobody can be sure why. Climate change driven by global warming which is in turn the consequence of greenhouse gas emissions from fossil fuel combustion could be a candidate cause. But meteorologists cannot rule out some other potential explanation, such as some natural cycle in climate behaviour involving oceans and atmosphere. But they do know that tornado outbreaks are becoming potentially more destructive. Two years ago, researchers checked the data and found that the tornado “season” in the US was now two weeks earlier than it had been in the early 20th century. In the spring of 2016 a team from Columbia University checked the records since 1954 and found that the number of individual tornadoes during any single episode of tornado outbreaks has been rising for the past six decades. Worse winds And now Michael Tippett, a physicist at Columbia Engineering, has returned to the challenge. He and two colleagues report in the journal Science that not only are the numbers of twisters in each outbreak growing, but the overall severity of the whirlwinds is on the increase. And the fastest increase is in the most extreme range of the phenomenon. Read More here