News•November 6, 2013

Greenhouse Gases Have Soared to Record Levels: WMO

The amount of planet-warming greenhouse gases in the atmosphere reached a record high in 2012, with rapid growth in both carbon dioxide and methane concentrations, according to a new report released Wednesday by the World Meteorological Organization (WMO). The report provides new insights into the extent to which human activities, combined with natural processes, have reshaped the makeup of the atmosphere since the dawn of the industrial revolution.

Each of the past three decades has been among the warmest in the instrument record, and likely the Northern Hemisphere's warmest in more than 1,000 years.
Click image to enlarge. Credit: Climate Central

As a result of all the extra CO2 pumped into the air, worldwide average temperatures have already risen by 1.6°F between 1901-2012 and are projected to increase by between 0.54°F to 8.64°F by 2081-2100 compared to 1986-2005 levels, depending on the future amounts of greenhouse gases in the air, according to a recent report from the U.N. Intergovernmental Panel on Climate Change.

The report from the WMO, which is based in Geneva, Switzerland, found that between 1990 and 2012 there was a 32 percent increase in the warming effect on the climate, known as radiative forcing. By far the biggest contributor to that trend was a steep rise in atmospheric concentrations of CO2, which came mainly from burning fossil fuels and land use change, the report said.

“As a result of this (increase in greenhouse gases), our climate is changing, our weather is more extreme, ice sheets and glaciers are melting and sea levels are rising,” Michael Jarraud, WMO secretary-general, said in a press release.

Compared to the preindustrial era, the global average atmospheric concentration of CO2 — the most important long-lived greenhouse gas — has increased by 41 percent, the report found. During the same time period, the concentration of methane in the atmosphere jumped by 160 percent and nitrous oxide, which is another greenhouse gas and a contributor to smog, rose by 20 percent. Methane is a more powerful warming agent than CO2, but only lasts in the atmosphere for a few decades, whereas CO2 molecules can linger in the air for many centuries to more than a thousand years.

The long lifespan of CO2 means that if emissions are not curtailed soon, major impacts of climate change, from extreme weather events to melting glaciers and rising seas, will be locked into the climate for centuries to come.

“We need to act now, otherwise we will jeopardize the future of our children, grandchildren, and many future generations,” Jarraud said. “Time is not on our side.”

In 2012 the global average concentration of CO2 in the atmosphere was 393.1 parts per milion, or 141 percent of the pre-industrial level of 278 parts per million. The amount of CO2 increased at a faster rate between 2011 and 2012 when compared to the average yearly increase during the past decade.

According to the recent IPCC report, CO2 is now at the highest level it has been in at least 800,000 years. That was a time when megatoothed sharks prowled the oceans, the world's seas were up to 100 feet higher than they are today and the global average surface temperature was up to 11°F warmer than it is now.

CO2 levels are far higher now than they have been for anytime during the past 800,000 years.
Click image to enlarge. Credit: Scripps Institution of Oceanography.

During 2012, several Arctic observing stations recorded CO2 concentrations peaking above 400 ppm and in 2013 that expanded to include other stations, including at Mauna Loa Observatory in Hawaii, which is the oldest continuously operated station tracking greenhouse gas concentrations.

The WMO found that if current emissions trends continue, the global average annual concentration of CO2 will cross the 400 ppm threshold by 2016. Some scientists and climate activists have said that CO2 concentrations need to be brought down to as low as 350 ppm in order to avert dangerous effects of climate change, although emissions trends show that the world is well on its way to reaching 450 ppm or more during the next several decades, unless drastic changes are made in energy policy.

According to the WMO report, which is its 9th annual report on greenhouse gases, about half of the CO2 emitted by human activities remains in the atmosphere. The oceans absorb much of the rest, but are becoming more acidic as a result, and more hostile to many marine species that depend on certain chemicals for making their shells, such as oysters and corals.

The report draws from observations collected by 50 countries that are members of the WMO, which is a U.N. organization. The report does not detail greenhouse gas emissions, but other assessments have found that global emissions reached a record high of 35.6 billion tonnes in in 2012, which was up 2.6 percent from 2011. That increase was driven mainly by rapid economic growth in developing countries such as China and India.

In the U.S., CO2 emissions in 2012 declined relative to the previous year, largely due to the increased use of natural gas, which has been displacing coal as a favored source of electricity.

No evidence of Arctic methane bubble, yet

After remaining level between 1999 and 2006, methane concentrations have been on the rise again, reaching a new high of about 1819 parts per billion in 2012, which is 260 percent of the pre-industrial level, the report found. Manmade sources of methane include natural gas drilling and transport, rice cultivation, cattle burning, and biomass burning.

Record of atmospheric carbon dioxide concentrations dating back 800,000 years (left) and during the course of the Mauna Loa record).
Click image to enlarge. Credit: Climate Central.

The WMO said there is evidence that tropical and mid-latitude regions of the Northern Hemisphere have contributed to the rise in methane concentrations, and there has not yet been a detectable surge in methane coming from the Arctic. Studies have shown that rapid Arctic climate change could set free some of the methane stored in permanently frozen soil, known as permafrost, which is thawing as temperatures increase, as well as in frozen formations beneath the sea, known as methane hydrates.

If a considerable amount of methane were to be released from the Arctic, it would likely mean that global warming would accelerate even further, a scenario that has worried some scientists who have referred to this phenomenon as the Arctic “methane bomb.”

The WMO report said more detailed observations are needed to determine how much of the recent methane increase is due to manmade factors compared to natural processes.