Last year ranked as the sixth-hottest on record for the past 163 years, according to figures released by the World Meteorological Organisation (WMO). This continues the ongoing run of record-breaking temperatures that have changed our climate in the recent past.
Thirteen of the 14 warmest years in modern meteorological records have occurred since 2000, according to the figures released yesterday. This made last year "consistent with the long-term warming trend", said the organisation's secretary general Michel Jarraud.
"The rate of warming is not uniform but the underlying trend is undeniable," he said. And the high amounts of climate-warming gases in the atmosphere, including carbon dioxide and methane, meant global temperatures would rise "for generations to come".
For the past 14 or 15 years, however, these warm summers have not as yet transferred additional warming into the atmosphere. There seems to be a sink for this heat: most climate scientists believe it is being absorbed by the deep oceans, according to Prof Ray Bates, adjunct professor in the Meteorological and Climate Centre in University College Dublin's School of Mathematical Sciences.
This atmospheric warming was seen in the climate data up to about 1998, he said. “Since then no statistically significant warming has been recorded. One theory is it is going into the deep oceans.”
The WMO says 93 per cent of the excess heat being caused by human activities is being absorbed into the deep oceans. This is pushing up ocean temperatures, particularly in parts of the Pacific and Arctic oceans.
Prof Bates said sea level also continued to rise. "Sea level is still going up at the same rate it was before. It is rising by 3.2mm per year or about 30cm per century. That is very worrisome."
He said the absence of a heat build-up in the atmosphere had caused concern amongst scientists because of what it meant for their models. The models have long suggested that there should be a steady build-up of heat in the atmosphere but this is not yet happening.
“The models are saying one thing and the figures something else. The difference is not understood. We are at a difficult stage because what the models have been projecting has been what our main alarm for the future is based on. If the models are failing to represent the data from 1998, what trust can you put in the models for the future?”
He has little doubt, however, that the continued increase in stored heat will soon start adding heat again to the atmosphere.
“Continued warming is very likely but it is possible that it might not happen as fast as we had previously believed, he said. “I am not sceptical about global warming.”
The organisation’s full 2013 report will be published next month.
