Record-breaking hot years due to humans
The cause of the surge in global temperatures since 1998 is a result of anthropogenic warming – global warming driven by people’s activities.
A study released this week, authored by several heavyweights in the world of climate change research, has proved this link. Published in the peer-reviewed journal Scientific Reports, The Likelihood of Recent Record Warmth reported that warming should be cyclical but this was no longer the case.
The authors wrote that during the history of the world, warming and cooling phases have occurred at a relatively slow rate. But in the last two decades that warming has been consistent – and at a rapid rate. This was even during years where the world should have cooled: in 2010 there was a marked drop in both solar and volcanic activity, which traditionally meant colder weather, but that year broke heat records.
“Individual record years and the observed runs of record-setting temperatures are extremely unlikely to have occurred in the absence of human-caused climate change,” said the report.
The year 1998 was the original record-setter, creating a marked spike in long-term temperature graphs. It was not unusual because single hot years have happened throughout recorded history. It came during a long-term warming period. The research published on Monday showed that the 1998 record was matched – or exceeded – in 2005 and again in 2010.
Fifteen of the 16 hottest years on record have been since 2000, with the researchers concluding that this had to be the result of human emissions of greenhouse gases.
These trap hot air in the Earth’s systems, particularly in oceans, and lead to a warming of the world. Before humans began releasing greenhouse gases on an industrial scale, some 250 years ago, their concentration was 250 parts per million. That concentration is now 400 parts per million, a level which has never before been reached during human’s time on Earth. It ensures that temperature records are consistently broken. Excluding the last 16 years, World War I was on the last time a year set a cold record.
By modelling global temperatures with and without human emissions, the researchers concluded that record temperatures are between 600 and 130 000 times more likely to have happened as a result of those emissions.
“Our findings thus underscore the profound impact that anthropogenic forcing has already had on temperature extremes,” the researchers noted.
The research was done based on 2014 being the hottest year on record, and did not take into account the fact that 2015 subsequently went on to break that record.
Data released last week by the UK Met Office, the National Oceanic and Atmospheric Administration in the United States, and Nasa all showed that 2015 had broken the record by a huge margin.
Last year was 0.75°C hotter that the long-term average, and a whole degree hotter than it was before the Industrial Revolution.
The World Meteorological Organisation, the UN’s research body, echoed these findings in its own data, released this week. Its secretary-general, Petteri Taalas, said this gave further impetus to actions addressing global warming. “It is a sobering moment in the history of our planet.”