One Degree: drought, fire, extinction

Part one of my guide to Mark Lynas' guide to the peer-reviewed literature on the consequences of global warming

America's desert. The remains of trees have been found in a river bed and lake bed in the West Walker River Canyon and Mono Lake respectively. These remains have been dated to the medieval period. Fire scars on trees in the Yosemite and Sequoia National Parks have been dated to the same period. This evidence suggests medieval California was hit by a severe drought many times more punishing than the "dust-bowl" years of the 1930s. US in medieval times was 1-2 degrees warmer than pre-industrial US.

Stine, S., 1994: 'Extreme and persistent drought in California and Patagonia during medieval time,' Nature, 369, 546-9

Swetnam, T., 1993: 'Fire history and climate change in giant sequoia groves,' Science, 262, 85-9

Kilimanjaro forest fires. Rising temperatures and diminishing rainfall have increased the risk of fires in the high forest on the sides of the mountain. This forest is responsible for 96% of the water coming off the mountain. A hit to the water supply would put fish supplies and hydroelectric turbines at risk in Tanzania.

Agrawala, S., et al, 2003: 'Development and climate change in Tanzania: Focus on Mount Kilimanjaro,' OECD Environmental Directorate, 6799

Arctic melting. In the decade up to 2001, the biggest Alaskan glaciers lost 96 cubic kilometres of ice, raising global sea levels by nearly 3mm. A recent modelling study has concluded that the Artic ocean will be free of ice in summertime by 2040. Scientists expect that a warmer Artic will push the North Atlantic storm belt north. Satellite images from the last 30 years show a 1 degree movement of the wet-weather belt towards the poles of both hemispheres.

Arendt, A., et al.: 'Rapid wastage of Alaska glaciers and their contribution to rising sea level,' Science, 297, 382-6

Holland, M., Bitz., C., and Tremblay, B., 2007: 'Future abrupt reductions in the summer Arctic sea ice,' Geophysical Research Letters, 33, L23503

Fu, Q., et al., 2006: 'Enhanced mid-latitude tropospheric warming in satellite measurements,' Science, 312, 1179

Swiss rockfalls. Meltwater from mountain snow can destabilise rocks, causing lethal and unpredictable landslides. A year after the European heat-wave of 2003, a Swiss team of scientists showed that the 2003 thaw was up to a half a metre deeper than in any of the last 40 summers.

Gruber, S., Hoezle, M., and Haeberli, W., 2004: 'Permafrost thaw and destabilisation of Alpine rock walls in the hot summer of 2003,' Geophysical Research Letters, 31, L13504

Extinction in the Australiam Wet Tropics. The Wet Tropics in Queensland Australia is a UNESCO World Heritage Site, holds -- among many other things -- half of the continent's bird species and 700 plant species that are found nowhere else in the world. A modelling study of 65 species in the area concluded that 63 of the species would lose a third of their core habitat with one degree of warming. The author called this an "environmental catastrophe of international significance."

Williams, S., et al., 2003: 'Climate change in Australian tropical rainforests: an impending environmental catastrophe,' Proceedings of the Royal Society of London B, 270, 1887-92

Atlantic hurricanes. In a 2006 paper, two climatologists wrote that anthropogenic climate change contributed half of the warming that resulted in high ocean water temperatures in 2005. The warm surface water is thought to be responsible for the devastating 2005 hurricane season that caused damage totalling $100bn. An earlier analysis showed that the number of the strongest storms in the Pacific and Atlantic Oceans nearly doubled in the period 1970-2004.

Trenberth, K., and Shea, D., 2006: 'Atlantic hurricanes and natural variability in 2005,' Geophysical Research Letters, 33, L12704

Webster, P., et al., 2005: 'Changes in tropical cyclone number, duration, and intensity in a warming environment,' Science, 309, 1844-1846

Kilimanjaro. In 2002 a US team led by scientist Lonnie Thompson concluded that 80% of the ice on Mt Kilimanjaro had disappeared in the last century, and that at the current rate there would be none at all by 2020. Similar meltrates have been recorded on peaks in other parts of the world, such as the Rwenzori Mountains in Uganda. As Lynas points out, glacial melt is responsible for only 1/15 of the water coming off Kilimanjaro: a "significant, but not catastrophic" amount.

Thompson, L., et al., 2002: 'Kilimanjaro ice core records: Evidence of Holocene climate change in tropical Africa,' Science, 298, 589-593

Taylor, R. G., et al, 2006: 'Recent glacial recession in the Rwenzori Mountains of East Africa due to rising air temperature,' Geophysical Research Letters, 33, 10, L10402