Virtually tying 1998 as the hottest year on record, 2005 continued a warming trend that has increased rapidly in recent decades and offered more evidence that the planet is experiencing a dramatic climate shift.
Four different temperature analyses released Thursday varied by a few hundredths of a degree, but agreed it was either the hottest or second hottest since records began being kept in the late 1880s. Unlike 1998, however, 2005 had no El Nino, a natural weather phenomenon, to warm ocean waters.
The planet has been slowly warming for a century, and the 10 hottest years on record have all occurred since 1990, a trend that a majority of scientists say is in large part attributable to human production of greenhouse gases, which trap heat in the atmosphere.
“The last 10 years have been exceptionally warm, said Raymond Bradley, a climate scientist at the University of Massachusetts in Amherst. “2005 continues this extraordinary sequence of warm temperatures.”
This year saw above average temperatures across the majority of the planet, with extreme warmth in the high latitudes of the northern hemisphere, including Alaska, Russia and Scandinavia, said Jay Lawrimore, chief of the climate monitoring branch of the National Oceanic and Atmospheric Administration.
A minority of scientists dispute the findings and say the measurements used to take the planet’s temperature are spotty, inaccurate and may exaggerate the amount of warming. “We’re asking too much of the data,” said Roger A. Pielke Sr., Colorado’s state climatologist.
According to scientists at NOAA, a preliminary ranking shows 2005 was 1.06 degrees warmer than the long-term average of 57 degrees, and 1998 was 1.12 degrees warmer. When final numbers for 2005 and an improved analysis system are used early next year, 2005 is likely to end up being ranked as the hottest, Lawrimore said.
A National Aeronautics and Space Administration analysis showed 2005 to be the hottest year, while analyses by the U.N. World Meteorological Organization and the United Kingdom’s climate authority, the Hadley Centre, showed 2005 to be a close second to 1998.
The new data on warming temperatures come amid other manifestations of a changing climate, including a record loss of sea ice in the Arctic this summer.
“The sea ice was a record minimum in the satellite era since 1979 and probably in the last century,” said Mark Serreze, a senior researcher at the National Snow and Ice Data Center at the University of Colorado. “Compared to where it should have been, you’ve lost an area roughly twice the size of Texas.”
Serreze said the Arctic is on track to be ice free in summer by 2070. “What you’re starting to see is the greenhouse effect starting to emerge,” he said.
A number of climate scientists said the steady march of warm temperatures, along with retreating sea ice, melting glaciers and rising sea levels were clear evidence that global warming caused by the human production of greenhouse gases was already dramatically affecting the planet.
“Could these changes arise from natural climate variability alone? The answer is no,” said Ben Santer, a physicist and climate modeler at the Lawrence Livermore National Laboratory. “Even today, one can hear statements – sometimes from senior members of our government saying we know nothing about the causes and effects of climate change. That’s really not true.”
Bush administration officials said Thursday that they were taking climate change seriously by launching an array of voluntary programs to reduce greenhouse gases and investing nearly $2 billion to monitor and study climate change. At the same time, administration officials downplayed the 2005 temperature data, saying it remained unclear how much human activities had contributed to the warming trend.
“The observed conditions of any one particular year are a combination of natural and human-related factors,” said Michele St. Martin, a spokeswoman for the White
House Council on Environmental Quality.