America’s National Oceanic and Atmospheric Administration (NOAA) has released its State of the Climate report for 2013, and its verdict is that the planet is continuing to warm rapidly. 2013 ties with 2003 as the fourth warmest year globally since records began in 1880. The yearly global average temperature has remained above the twentieth century average for 37 consecutive years. Since records began, nine of the ten warmest years have been in the twenty-first century, 1998 being an anomaly because of the El Niño effect, a periodic oscillation of Eastern Pacific ocean temperatures.
During June, the extent of Arctic sea ice was smaller than average while the extent of Antarctic sea ice during the southern hemisphere winter was larger than average. No region of the globe observed a record cold temperature. Temperatures in the Arctic were above average, and with the Arctic Oscillation in air pressure this resulted in lower than average temperatures in many population centers in northern Europe and North America.
These figures are all gravely concerning, but it can sometimes be hard to communicate the importance of the issue to the public which in turn can undermine political will to deal with the issue. Global warming deniers always come out in force whenever it snows in Chicago, illustrating a gap between climate science and public understanding of it.
While any high school geography student should be able to know the difference between climate and weather, the visible effects of climate change can be difficult to explain because of the nature of the science. Climate does not deal with specific weather events but with averages and statistics. Not every individual shower of rain can be directly attributable to global warming, but we can say that extreme weather events are becoming more violent, more frequent, and increasingly taking place outside of their usual areas. Tropical storms are no longer confined to the tropics, as residents of New Jersey are all too aware.
Ocean currents are also susceptible to disruption from the phenomenon, which should be of grave concern to people in countries like Ireland where the climate is kept mild by the Gulf Stream that whisks heat from the Caribbean to northern Europe.
There is one measurable effect that is much more understandable: sea level rise. This results from thermal expansion due to rising temperatures as well as melting ice pouring into oceans from ice floes and glaciers. From 1870 to 2004 global average sea levels rose by 1.46 mm (0.057in) per year. Current sea level rise is 3 mm per year worldwide. The NOAA says “this is a significantly larger rate than the sea-level rise averaged over the last several thousand years” and could be increasing. Estimates of twenty-first century sea level rise range from 20 cm to a meter (7.8 to 39.3 in).
Sea level rise may have been an ongoing process over thousands of years, but human civilization did not exist for much of that time, and there was certainly less human settlement in low-lying and coastal regions.
Island nations now under threat include Bermuda, the Bahamas, and many more. The Marshall Islands, population 55,000, are no higher than two meters above sea level and could face obliteration. Large population centers in larger nations are also at risk. Miami, population over 400,000, is in one of the least defended but highly populated low-lying coastal areas in North America. The Nile Delta could be rendered infertile if agricultural land is overrun by even a thin coating of seawater. Average global flood losses in 2005 have been estimated at approximately US$ 6 billion per year, and this could increase to US$ 52 billion by 2050.
The United Nations Framework Convention on Climate Change (UNFCCC) was adopted in 2002, and in 2010 its signatories agreed to limit annual global warming to 2°C (3.6 °F). Some analysts warn that this would require greenhouse gas emissions to peak in 2020 and decline thereafter, but current policies are not going to deliver that objective. Others suggest that even the 2°C limit is not enough.
Perhaps more flooding and more violent storms are needed to concentrate the minds of policymakers.