3 August 2015, The Conversation, The scariest part of climate change isn’t what we know, but what we don’t. We know a lot about what climate change will do, but ‘when’ is a tougher question. “It’s tough to make predictions, especially about the future”: so goes a Danish proverb attributed variously to baseball coach Yogi Berra and physicist Niels Bohr. Yet some things are so important — such as projecting the future impacts of climate change on the environment — that we obviously must try. An Australian study published last week predicts that some rainforest plants could see their ranges reduced 95% by 2080. How can we make sense of that given the plethora of climate predictions? In a 2002 press briefing, Donald Rumsfeld, President George W. Bush’s Secretary of Defence, distinguished among different kinds of uncertainty: things we know, things we know we don’t know, and things we don’t know we don’t know. Though derided at the time for playing word games, Rumsfeld was actually making a good point: it’s vital to be clear about what we’re unclear about. So here’s my attempt to summarise what we think we know, don’t know, and things that could surprise us about climate change and the environment. Read More here
Category Archives: The Science
2 August 2015, Climate News Network, Global temperatures have risen by 1°C in the past 150 years, and one scientist says doubling that level could unleash catastrophic sea level rise this century. The world is now halfway towards the internationally-agreed safety limit of a maximum 2°C rise in global average temperatures, researchers say. That limit seeks to prevent the global warming caused by the burning of fossil fuels exceeding 2°C above the pre-industrial global temperature. The UN’s Paris climate summit later this year aims to ensure that it is not breached. It appears that the human race has taken roughly 250 years to stoke global warming by 1°C. On present trends, we look likely to add the next 1°C far more quickly – across much of the world, many climate scientists believe, by the middle of this century. The research is published in the journal New Scientist, which commissioned it. As so often with climate projections, it needs qualifying and teasing apart. Some scientists, for example, warn that there’s uncertainty about just what the pre-industrial global temperature was. The New Scientist research is careful to be specific: it says global surface temperature is now passing 1°C of warming “relative to the second half of the 19th century”. Farewell, hiatus. And one of the four main trackers of temperature thinks that milestone will be passed only if there is a strong El Niño, the cyclic Pacific weather phenomenon that periodically brings widespread chaos in its wake. However, the research looks likely finally to lay to rest the argument that global warming is slowing and stuttering to a virtual halt, the so-called hiatus theory. Kevin Trenberth, of the USNational Center for Atmospheric Research in Boulder, Colorado, told New Scientist: “There’s a good chance the hiatus is over.” Read More here
30 July 2015, New Scientist, Earth now halfway to UN global warming limit – Earth now halfway to UN global warming limit: IT’S the outcome the world wants to avoid, but we are already halfway there. All but one of the main trackers of global surface temperature are now passing more than 1 °C of warming relative to the second half of the 19th century, according to an exclusive analysis done for New Scientist. We could also be seeing the end of the much-discussed slowdown in surface warming since 1998, meaning this is just the start of a period of rapid warming. “There’s a good chance the hiatus is over,” says Kevin Trenberth of the National Center for Atmospheric Research in Boulder, Colorado. “The slowdown in warming since 1998 was partly due to oceans taking up more heat. That could be over”. Last year was the hottest since records began, but only just. With an El Niño now under way – meaning warm surface waters in the Pacific are releasing heat into the atmosphere – and predicted to intensify, it looks as if the global average surface temperature could jump by around 0.1 °C in just one year. “2015 is shaping up to smash the old record,” says Trenberth. The UN negotiations on climate change aim to limit warming to 2 °C above pre-industrial temperatures. There is, however, no agreement on how to define pre-industrial temperature, says Ed Hawkins of the University of Reading, UK. Because some global temperature records only begin in 1880, the period 1880 to 1899 is the easiest “pre-industrial” baseline for measuring warming. It is somewhat misleading, though, because the 1880s were particularly cold after the eruption of the Krakatoa volcano. The period 1850 to 1899 is a better baseline, says Hawkins. What’s more, there are several long-term records of global annual average surface temperatures. All differ slightly because they use slightly different data sets and have their own ways of adjusting for relocations of weather stations and changes in instrumentation over time. Read More here
27 July 2015, Yale Climate Connections, From Warming Estimates to Measurements. Scientists measure the heat trapped by atmospheric carbon dioxide for the first time. Feldman: “People have long talked about CO2 being a greenhouse gas, but the actual greenhouse effect, that’s the actual warming of the atmosphere caused by CO2, has not been measured in the field.” That’s Daniel Feldman of the Lawrence Berkeley National Laboratory. He says no one had actually measured the link between increased carbon dioxide in the atmosphere and rising temperatures, because it requires a lot of very high quality measurements over a long period of time. By looking at weather data collected over eleven years in Oklahoma and Alaska, Feldman was able to pinpoint the exact amount of infrared radiation, or heat, being trapped by increasing amounts of atmospheric carbon dioxide, instead of being released into space. Using very precise instruments, he determined how much of the warming came from CO2 instead of other sources. It’s significant because Feldman was able to measure the exact relationship between increased carbon dioxide in the atmosphere and additional energy, or heat, at the earth’s surface. His results are very consistent with the estimates of climate change computer models, and the measurements will help scientists develop even more accurate predictions of future global warming. Read More here