Pause in Global Warming? Likely Not
In 2013, a report by the Intergovernmental Panel on Climate Change (IPCC) identified the rate of climate change in the new millennium as less than the previous half-century. A recent study published in Science reports that this assessment is not correct.
The original NOAA data did not correct for biases in sea-surface temperature records. These biases are the result of a difference in temperature measurement from ships vs buoys; ships typically record higher temperatures than buoys in the same water. Buoy data has increased relatively in the last twenty years, which appeared to offset the increase in water temperatures as they were not fairly compared to older data taken by ships. Variation in ship data also affected the 2013 result. In the late 40s, ships collected temperature data via engine intakes instead of sampling from buckets. Researchers revised these calculations, included data from 2013 and 2014, and added new data that extends deeper into the Arctic, an area not previously well-observed that has experienced the most extreme warming in recent decades.
According to Tom Karl, director of National Centers for Environmental Information in North Carolina, the warming trend is well-supported by data through 2014, even if the starting point of the comparison is 1998, an extremely hot year as a result of the El Niño weather pattern. Incidentally, 2014 was the hottest year on record.
Global temperatures, according to Karl’s team, increased by 0.116°C per decade between years 2000 and 2014, compared to a rate of 0.116°C per decade in the previous fifty years. As more data gets incorporated from the land-based temperature monitoring systems in the Arctic, this new data may even increase the current calculation.
IPCC projections still suggest that warming is continuing, but scientists have discovered other factors contributing to lower temperatures recently including volcanic aerosols blocking sunlight, weaker solar irradiation, and ocean circulation. These factors temporarily suppress observable changes as a result of the human impact on the environment, but that impact will become more apparent over time regardless.
Image by Victor Korniyenko via Wikimedia Commons