Slowed global warming? New data suggests otherwise

Ilissa Ocko

While the planet’s surface temperatures over the past century have risen to unprecedented levels, records have shown a slowdown in the pace of warming over the past 15 years.

Scientists have proposed several theories of natural climate variability and heat redistribution that may have contributed to the slowdown to varying degrees. A new study, however, suggests that the slowdown itself may be a mirage—the result of temperature records that have considerably underestimated the pace of warming since 1997.

Incomplete global coverage of measurements can cause biases in temperature records, and datasets deal with data gaps differently. Dr. Kevin Cowtan of the University of York and Dr. Robert G. Way of the University of Ottawa developed a new method for reconstructing temperatures in unsampled regions, such as over the poles and Africa. The researchers validated their technique by applying it in regions with sufficient data coverage, and received significantly better results than previous techniques.

Accounting for data that was omitted in the standard HadCrut4 surface temperature dataset—one of the most prominent temperature datasets—the scientists found that the recent warming trend is two and half times greater than what the original data suggests.

Most of the discrepancy is due to the data gap in the Arctic. Weather stations are sparse at the poles, but filling in the holes with data derived from satellite measurements reveals that the Arctic is warming at an exceptionally quick pace. Inserting previously omitted Arctic data into the HadCrut4 dataset yielded a considerable increase in the global surface temperature trend.

This study is important because it advances the accuracy of monitoring temperatures worldwide, and provides insight into the highly publicized ‘global warming pause.’ In fact, the global warming pause has entirely vanished using this new method.