UN: Last Three Years Hottest Since Records Began, Extreme Weather Caused Record-Breaking Damage in 2017

On Thursday the United Nations Word Meteorological Organization (WMO) released its annual report on the global climate—and it doesn't make for comforting reading.

According to 25th edition of the Statement on the State of the Global Climate, 2017 was the costliest year ever for extreme weather and climate events, while the past three years have been confirmed as the hottest on record.

In addition, global sea levels continue to rise, ocean warming and acidification are on the increase and the extent of polar sea ice was well below the 1981-2010 average throughout 2017.

Among last year's damaging extreme weather events were the particularly active North Atlantic hurricane season, major monsoon floods in India and continuing severe drought in Africa, which contributed to total natural disaster-related losses of $320 billion—a record figure after adjustment for inflation—according to estimates from German reinsurer Munich Re quoted in the report.

The United States was severely affected with the 2017 North Atlantic hurricane season ranking as the costliest ever for the nation. Total damages and losses from Harvey, Irma and Maria combined were estimated to amount to a staggering $265 billion by the National Centers for Environmental Information.

These kinds of weather events have the potential to cause massive disruption to communities. In 2016, for example, weather-related disasters displaced around 23.5 million people around the world, the report notes, the majority of whom were forced to move as a result of floods in the Asia-Pacific region.

The Statement confirmed 2017 as the hottest year on record that was not influenced by an El Niño weather event—which tends to raise global temperatures temporarily—and 2016 as the warmest year overall. In fact, the world's nine warmest years have all occurred since 2005, while the five-year temperature average between 2013 and 2017 is also a new high. Global mean temperatures in 2017 were 1.1 °C above pre-industrial temperatures, the WMO noted.

As a result, the overall risk of heat-related illness or death is higher than ever, with 30% of the world's population now living in climatic conditions where potentially deadly temperatures occur on at least 20 days of the year, according to World Health Organization figures quoted in the Statement.

People are rescued from a flooded neighborhood after it was inundated with rain water, remnants of Hurricane Harvey, on August 28, 2017 in Houston, Texas. Scott Olson/Getty Images

Furthermore, sea level rise has increased in recent years, with the melting of polar ice sheets—mostly in Greenland, and to a lesser extent Antarctica—largely to blame. The maximum extent of winter sea ice in the Arctic was also at a record low in 2017, while in the Antarctic, sea ice extent was at, or near, record lows for most of the year.

While global sea surface temperatures were only ranked as the third warmest on record in 2017, a measure of the heat in the oceans from the upper layers down to 2,000 meters reached new highs.

The twin effects of warming sea temperatures and ocean acidification—a process caused by the absorption of carbon dioxide from the atmosphere into the seas—is having a devastating impact on the marine environment, which millions of people around the world rely on. Significant coral bleaching events in the Great Barrier Reef over the past two years have only served to highlight this problem.

The report states that levels of carbon dioxide in the atmosphere now exceed 400 parts per million. This figure is far greater than natural variation in the past 800,000 years, lending weight to the view held by the majority of scientists that this recent warming trend is primarily being driven by greenhouse gas emissions from human activity.

Atmospheric concentrations of carbon dioxide "will remain above that level for generations to come, committing our planet to a warmer future, with more weather, climate and water extremes," WMO Secretary-General Petteri Taalas said in a statement.

And from the initial signs, 2018 is not shaping up to be much of an improvement.

"The start of 2018 has continued where 2017 left off — with extreme weather claiming lives and destroying livelihoods," Taalas added. "The Arctic experienced unusually high temperatures, whilst densely populated areas in the northern hemisphere were gripped by bitter cold and damaging winter storms. Australia and Argentina suffered extreme heatwaves, whilst drought continued in Kenya and Somalia, and the South African city of Cape Town struggled with acute water shortages."