A new study suggests the global warming "hiatus" is linked to the Inter-decadal Pacific Oscillation (IPO).
Atmospheric greenhouse gases have been on the rise in recent years, but warming has mysteriously slowed down, the University at Albany reported. This contradicts climate model simulations that show strong warming following the year 2000.
"Naturally, people would ask the question: if the models cannot simulate the current global warming rate, how can we trust their projections of future climate change? This is a very reasonable question that deserves a satisfactory answer from the climate science community," said Xingang Dai of Institute of Atmpsoheric Physics/Chinese Academy of Sciences (IAP/CAS). "The global warming hiatus has also been used to dismiss climate science entirely by some deniers of global warming. Thus, explaining the warming hiatus has become an urgent task for climate scientists."
The researchers used multi-model ensemble simulations to estimate the warming and separate it from internal climate variations. The findings showed the Inter-decadal Pacific Oscillation (multi-decadal variations in Pacific sea surface temperatures) is associated with temperature over the ocean and land. These results were combined with other modes of climate variation, revealing the IPO could explain the discrepancy between climate models and global warming.
Climate models still have trouble estimating IPO and other natural climate variations because of lack of data on model physics and model starting conditions.
"The model-versus-observation discrepancies do not imply that the model-simulated climate change due to rising greenhouse gases and other anthropogenic forcing is wrong," Dai said. "Recent history suggests that the IPO could reverse course soon. Should that happen, we may see accelerated global warming rates in the coming decades."'
The findings were published in a recent edition of the journal Nature Climate Change.