The unprecedented climate events of 2015 should prompt action on the policy stage.
2015 began with the warmest winter on record on a global scale, and ended as the hottest year since records began, with average global temperatures reaching 1 °C above pre-industrial levels for the first time1. But these were not the only records broken this year, as a large number of extreme-intensity events unfolded.
The winter snowpack in California hit a record low, prolonging one of the most severe and longest droughts in the USA2. El Niño appeared shyly in May and then went on to become a monster, heating up the equatorial Pacific ocean by more than 3 °C by November3. Tropical cyclone Patricia went off the hurricane category scale with winds of over 320 km per hour, and the Arabian peninsula was hit by two consecutive cyclones — an unprecedented occurrence in the climate record of the region1.
It is clear that many different factors have contributed to these events, and care must be taken before linking any particular event to climate change. But one thing is sure: human influence has significantly increased the likelihood of extremes4.
Extreme weather has the power to change people's perception of climate change — as happened after extensive flooding in England over the winter of 2013/145. The unprecedented events of this past year prompted many world and religious leaders to make important public announcements to raise awareness on the seriousness of the issue. It is in this context that the international climate negotiations in Paris took place, where a global deal for the future of the planet was being discussed as these very words were being written.
Such events make one thing clear: time is at a premium. Global average atmospheric CO2 concentrations have indefinitely passed the 400 ppm mark6, reflecting the relentless increase in emissions. This puts us on a fast track to 2 °C of warming, which is considered to be a dangerous climate change threshold beyond which even more extreme events can be expected. If 2015 was a year full of climate milestones, 2016 has the potential to be another: the year when global society took firm and collective action to begin changing the dangerous path that we are currently treading. It is certainly a big New Year's resolution.
Belmecheri, S. et al. Nature Clim. Change 6, 2–3 (2016).
Herring, S. C. et al. (eds) Explaining Extreme Events of 2014 from a Climate Perspective Bull. Am. Meteor. Soc. 96, S1–S172 (2015).
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A milestone year?. Nature Clim Change 6, 1 (2016). https://doi.org/10.1038/nclimate2911