“With the record for 2007 now complete, it is clear that temperatures around the world are continuing their upward climb,” according to a statement from the Earth Policy Institute. “The global average in 2007 was 14.73 degrees Celsius (58.5 degrees Fahrenheit)—the second warmest year on record, only 0.03 degrees Celsius behind the 2005 maximum. January 2007 was the hottest January ever measured, a full 0.23 degrees Celsius warmer than the previous record. August was also a record for that month and September was the second warmest September recorded.”
2007 Hottest Year for Northern Hemisphere
Looking at the northern hemisphere alone, 2007 temperatures averaged 15.04 degrees Celsius (59.1 degrees Fahrenheit)—easily the hottest year in the northern half of the globe since the record began in 1880, and more than a degree warmer than the 1951–1980 average. Paleo-temperature records from ancient tree rings suggest that the northern hemisphere is now warmer than at any time in at least the last 1,200 years.
2007 fits into a pattern of steadily increasing global average temperature, with the eight warmest years on record all occurring in the last decade. According to data maintained by NASA’s Goddard Institute for Space Studies, global average temperature rose from 14.02 degrees Celsius in the 1970s to 14.26 degrees in the 1980s and then to 14.40 degrees in the 1990s. In the first eight years of the 21st century, the world averaged 14.64 degrees Celsius. (See the data.) Since 1990, mean global temperature has risen by 0.33 degrees, a rate of increase faster than climate models had predicted.
2007 Second Warmest Year Despite Cooling Climate Conditions
Although 2007 did not post a new record high, the year stands out as being extremely warm despite several natural factors that usually cool the planet. El Niño conditions in the southern Pacific tend to increase the global average temperature, and yet the second half of 2007 saw the opposite—a La Niña pattern that would usually depress global temperature.
This is in stark contrast to conditions in 1998, now the third warmest year on record, when temperatures were boosted around 0.2 degrees Celsius by the strongest El Niño of the century. In addition to the moderate La Niña in 2007, solar intensity in 2007 was slightly lower than average because the year was a minimum in the 11-year solar sunspot cycle. The combination of these factors would normally produce cooler temperatures, yet 2007 was still one of the warmest years in human history. According to the Earth Policy Institute, this strongly suggests that the warming effect of increased greenhouse gas concentrations is now dwarfing other influences on the Earth’s climate.
Warm 2007 Marked by Extreme Weather
Regionally, several areas saw record-setting temperatures in 2007. Southeastern Europe suffered through temperatures as high as 45 degrees Celsius (113 degrees Fahrenheit) in a heat wave that killed up to 500 people. In Japan, thermometers in August reached 40.9 degrees Celsius (about 106 degrees Fahrenheit), the highest temperature ever recorded in that country. Chart-topping temperatures and severe drought conditions proved a lethal combination, as extensive wildfires spread in both Greece and the American West.
While some areas baked under intensive heat or drought conditions, others were inundated by record amounts of rain. England and Wales experienced widespread flooding and damage estimated at £3 billion ($6 billion) during the wettest May to July period since records began in 1766. In South Asia, some of the worst flooding in decades occurred during the monsoon season, affecting at least 25 million people and killing more than 2,500.
Fifteen countries across Africa—from Ghana to Ethiopia—were affected by severe floods in the summer of 2007. The flooding displaced hundreds of thousands of people and washed away crops and farmland, seriously damaging food security in the region.
Intense rainfall events and flooding will become more common in the future. Climate models show that warmer temperatures will cause a greater share of total precipitation to fall in extreme events. This means more heavy rainstorms but also more dry periods, producing more severe droughts as well as more frequent and intense floods. Rainfall data from the 20th century show precipitation intensity increasing over the last two decades, suggesting this trend is already beginning.
UN Science Panel Confirms Effects of Humans on Global Climate
In 2007, the Intergovernmental Panel on Climate Change (IPCC), the Nobel prize–winning body of more than 1,250 scientists, released its Fourth Assessment Report, which detailed the likely climatic consequences if human beings continue to pump greenhouse gases into the atmosphere. It reported that unabated emissions would result in a temperature rise of between 1.1 and 6.4 degrees Celsius (2 to 12 degrees Fahrenheit) during the 21st century.
To put this in perspective, temperatures over the last 100 years rose by a comparably small 0.74 degrees Celsius, and yet this appears to have already contributed to trends of more heat waves, longer and more intense droughts, higher sea level, more frequent heavy rain, and stronger hurricanes.
“The many effects of warmer temperature, which we are already beginning to see, will only become more severe and more costly to society if greenhouse gas emissions are not cut quickly and dramatically," according to the Earth Policy Institute. “Our future now depends on what we do to limit warming by moving away from climate-disrupting fossil fuels and toward renewable energy and energy-efficient technologies”
Source: Earth Policy Institute
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