Identifying the early 2000s hiatus associated with internal climate variability

Area of Science:

• Climate Science
• Data Analysis
• Statistical Modeling

Background:

• The early 2000s experienced a 'hiatus' or slowdown in the rate of global mean surface temperature (GMST) increase.
• Understanding the drivers of this hiatus is crucial for accurate climate change projections.

Purpose of the Study:

• To re-examine the early 2000s hiatus using multiscale statistics.
• To identify the key components contributing to the GMST trend during this period.
• To determine the precise duration and cause of the hiatus.

Main Methods:

• Analysis of five gridded surface temperature datasets and two reanalysis datasets.
• Application of multiscale statistical methods, including orthogonal wavelet decomposition.
• Statistical characterization of the hiatus using F-tests to identify near-zero decadal trends.

Main Results:

• The hiatus was identified in both GMST and global mean air temperature (GMAT) time series.
• The underlying global warming trend remained constant at approximately 0.08°C/decade.
• Anomalous El Niño Southern Oscillation (ENSO) events were identified as the primary cause of the hiatus.
• The hiatus duration was determined to be primarily 2002-2012.

Conclusions:

• The hiatus represents a decadal balance between cooling from interannual variability (ENSO) and consistent global warming.
• Future climate conditions may depend on the interplay between multidecadal cooling and ongoing global warming.
• The study highlights the importance of distinguishing natural climate variability from long-term warming trends.