News•March 23, 2015

Climate Work Highlighted on World Meteorological Day

The United Nations agency responsible for comprehensively tracking the planet’s weather and climate system has once again raised its voice to add to the chorus proclaiming the exceptional warmth that pervaded the planet as a whole last year, along with many particular regions and countries.

Global temperatures records from NASA, NOAA and the U.K.'s Met Office.
Click image to enlarge. Credit: WMO

A new report released Monday by the World Meteorological Organization (WMO) catalogues the record hot temperatures — hallmark events of a climate warmed by human activities — and other extreme weather events that pummeled places around the world last year. The report’s release and the events fall on World Meteorological Day, which marks the WMO’s founding.

This year, the focus is on spreading and improving knowledge of weather and the changing climate to help better protect against the devastating effects that extreme events can have on agriculture, food and water availability and infrastructure, particularly in the developing world.

“Extreme weather and changing climatic patterns are having a growing impact on our planet and on human well-being,” UN Secretary General Ban Ki-moon said in a statement.

In particular, the report called out the nascent but growing science of extreme event attribution, which seeks to determine whether human-induced warming played a role in various events.

Record heat events were a key focus of the WMO report, with the agency reiterating its earlier announcement that 2014 was the warmest year on record for the globe, going back to the mid-1800s. That ranking was affirmed by national meteorological agencies, including NASA, the National Oceanic and Atmospheric Administration and the Japan Meteorological Agency. While the record was made by a slim margin, many of the warmest years have been clustered in recent decades with 14 of the 15 hottest having occurred in the 21st century.

Various regions and countries also saw record-setting heat in 2014, including the United Kingdom, 18 other European countries and the continent as a whole; several western U.S. states and Mexico; and several areas of the global oceans.

Most of the extra energy added to the globe by heat-trapping greenhouse gases ends up in the oceans, so their warmth is also a measure of how much the globe has been heating up. That extra warmth also helped to raise sea levels, as water expands as it warms. For most of the year, the global average sea level was at a record high, the WMO report said.

The report also tallied major excesses and deficits of precipitation. The Balkans saw repeated torrential rains that caused major flooding and landslides that impacted 1.6 million people in Serbia alone, while the U.K. had its wettest winter on record. At the other extreme, drought reigned in the western U.S., eastern Brazil and Africa’s Sahel, impacting regional agriculture and causes crop losses.

Questions are increasingly being asked about the role that global warming has played in driving these and other extreme weather events. With those questions, scientists are delving into ways to come up with answers using various methods that they are continuing to refine and calculating those answers on faster and faster time scales.

The science is most robust when looking at heat events, in part because the signal from climate change there is much clearer than for precipitation events. The WMO report called out work by UK scientists to examine the role that warming played in causing the global and UK heat records for 2014.

Poster for the World Meteorological Organization's World Meteorological Day.
Credit: WMO

By using climate models to compare the Earth’s climate with and without the influence of human-added greenhouse gases, scientists can discern how much more likely a given heat record was with the influence of anthropogenic warming. In the case of the U.K. record, it was made 10 times more likely, the scientists found.

The method the scientists used is designed so that they can take regional or global heat records for the year or particular seasons and easily plug them into their analysis to see how much the odds were affected, said team member Peter Stott, of the Met Office Hadley Centre.

Stott expects considerable progress to be made this year in the attribution arena, with more work looking at the role of climate change in extreme precipitation events, including the wet winter in the U.K., as well as developing attribution systems that could work something like weather forecasts.

Through a European-focused effort, Stott and his colleagues “are seeking to develop the capability to provide regularly updated estimates of climate risks for Europe, not just for regional scale temperatures but also for the harder challenges of extreme precipitation, drought and storm surge,” he said in an email.

“It is an exciting time for bringing the science of attribution to a wider audience,” Stott added.

The WMO is working more broadly to better disseminate weather and climate information to those on the ground who need it to make informed decisions, including farmers, health workers and emergency managers. The organization has tried to improve coordination between various country’s meteorological agencies, as well as simple projects like distributing rain gauges to farmers in Africa.

Generating and spreading this information becomes even more important “as the international community moves towards ambitious decisions and action to address climate change,” WMO secretary-general Michel Jarraud said in a statement.

“The cost of inaction is high and will become even higher if we do not act immediately and resolutely,” he said.