1 August 2015, Climate Network News, Wildfire threat spreads across warming world. As climate change warms the world vegetation dries, rainfall patterns waver and the threat of wildfire spreads. Wildfire – nature’s way of turning fallen vegetation into the next season’s nutrients – is a growing hazard. In the last 35 years, the wildfire season has grown longer by a fifth, and wildfire is now a threat to one fourth of all the plant-covered land on the planet. US researchers report in Nature Communications that since 1970 the number of days without rain has increased by well over one day every decade. William Jolly of the US Forest Service in Missoula, Montana and colleagues say they examined the fire season worldwide for the study period, taking into consideration all the factors that are used to calculate fire hazard: wind, humidity and temperature, as well as rainfall levels. They found that the combined changes in the surface weather have meant that the fire season has increased so far by 18.7%. Worldwide, wildfires sear, scorch or incinerate about 350 million hectares of ground cover every year. Changes in the rainfall patterns were a factor, with the number of rain-free days increasing by 1.31 days per decade. The season of smoke and cinders and smouldering stumps had been extended almost everywhere. Read More here
Category Archives: Impacts Observed & Projected
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
30 July 2015, Science Daily, Drought’s lasting impact on forests. Forests across the planet take years to rebound from drought, storing far less carbon dioxide than widely assumed in climate models. In the virtual worlds of climate modeling, forests and other vegetation are assumed to bounce back quickly from extreme drought. But that assumption is far off the mark, according to a new study of drought impacts at forest sites worldwide. Living trees took an average of two to four years to recover and resume normal growth rates after droughts ended, researchers report today in the journal Science. “This really matters because in the future droughts are expected to increase in frequency and severity due to climate change,” says lead author William R.L. Anderegg, an assistant professor of biology at the University of Utah. “Some forests could be in a race to recover before the next drought strikes.” Forest trees play a big role in buffering the impact of human-induced climate change by removing massive amounts of carbon dioxide emissions from the atmosphere and incorporating the carbon into woody tissues. The finding that drought stress sets back tree growth for years suggests that Earth’s forests are capable of storing less carbon than climate models have calculated. 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