The annual State of the Climate report from the National Oceanic and Atmospheric Administration (NOAA) states the evidence is unmistakable that we live in a warming world, with the past decade the warmest on record.
The report consolidates data from the oceans as well as the atmosphere, representing the first time for such a large-scale integration. Published in the Bulletin of the American Meteorological Society, the study is based on observational data, not computer models. "It's telling us what's going on in the real world, rather than the imaginary world," says senior scientist Kevin Trenberth at the National Center for Atmospheric Research based in Boulder, Colorado.
This year's report is the 20th annual State of the Climate report from NOAA, making it the "climate system’s annual scorecard,” says the report's authors.
For the first time, and in a single compelling comparison, the analysis brings together multiple observational records from the top of the atmosphere to the depths of the ocean,” Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator. “The records come from many institutions worldwide. They use data collected from diverse sources, including satellites, weather balloons, weather stations, ships, buoys and field surveys. These independently produced lines of evidence all point to the same conclusion: our planet is warming,”
More than 300 hundred scientists on every continent contributed to the study using ten planet-wide indicators, all pointing to a decade-on-decade warming trend. Seven of the ten indicators are rising: air temperature over land, air temperature over oceans, sea-surface temperatures, sea level, ocean heat, humidity, and tropospheric temperature in the "active weather" layer of the atmosphere nearest Earth's surface. The final three indicators are declining, namely glaciers, spring snow cover in the Northern hemisphere, and Arctic sea ice. All the indicators "tell the same story," the study says, "global warming is undeniable."
The report also emphasizes that human society has developed over thousands of years under one "climactic state," and that "a new set of climactic conditions are taking shape." These new conditions are "consistently warmer" that will bring to some areas increased and severe drought, torrential rain, and violent storms.
Natural variability - weather vs. climate
Peter Scott, head of climate monitoring for the U.K.'s Hadley Centre, stresses that even with year-to-year fluctuations from natural climactic event such as El Nino and La Nina, longer term decade-to-decade trends consistently derived from multiple data sources reveal a changing and warming global climate.
Despite the variability caused by short-term changes," Stott said in a statement, "the analysis conducted for this report illustrates why we are so confident the world is warming.When we look at air temperature and other indicators of climate, we see highs and lows in the data from year to year because of natural variability. Understanding climate change requires looking at the longer-term record. When we follow decade-to-decade trends using multiple data sets and independent analyses from around the world, we see clear and unmistakable signs of a warming world.”
Deke Arndt, the report's co-editor and chief of the Climate Monitoring Branch at NOAA's National Climactic Data Center, says that even the observed one degree Fahrenheit average global increase in temperature has changed the climate:
The temperature increase of one degree Fahrenheit over the past 50 years may seem small, but it has already altered our planet,” Arndt said. “Glaciers and sea ice are melting, heavy rainfall is intensifying and heat waves are more common. And, as the new report tells us, there is now evidence that over 90 percent of warming over the past 50 years has gone into our ocean.”