WMO Distinguishes Long-term Climate Change from Short-term Natural Variation

The World Meteorological Organization has just released its report, “The Global Climate 2001-2010, A decade of climate extremes”, along with a Summary Report, WMO-No. 1119.

The decade was, “marked by dramatic climate and weather extremes such as the European heat wave of 2003, the 2010 floods in Pakistan, hurricane Katrina in the United States of America (USA), cyclone Nargis in Myanmar and long-term droughts in the Amazon Basin, Australia and East Africa.” Still, the decade’s lack of a major El Niño event may have hid the worst effects of continued global warming, “caused largely by humanity’s emissions of greenhouse gases into the atmosphere.”

Mixing ratio of carbon dioxide, methane and nitrous oxide, from Table 1

In a bit of good news, the Montreal Protocol’s phase-out of ozone depleting substances is expected to restore the normal ozone layer in a few decades.

Figure 1. Decadal global combined surface-air temperature over land and sea-surface temperature (°C) obtained from the average over the three independent datasets maintained by the UK Met Office Hadley Centre and the Climatic Research Unit, University of East Anglia, in the United Kingdom (HadCRU), NOAA-National Climatic Data Center (NCDC) and the US National Aeronautics and Space Administration-Goddard Institute for Space Studies (NASA-GISS). The horizontal grey line indicates the long-term average value for 1961–1990 (14°C).

Casualties from extreme events rose over all due to a 23 factor increase in heat related fatalities. Positively, the report notes that there were less casualties from storms and floods – attributable to increased warning and preparedness efforts.

A primary conclusion is that significant progress is being made in teasing apart long-term climate change from short-term natural fluxuations. Long-term cryosphere (glaciers, snow and glaciohydrology) monitoring is a critical need identified as a future priority.