World greenhouse gas levels made unprecedented leap in 2016



File 20171031 18689 lpras9.jpg?ixlib=rb 1.1
Human activity, along with a strong El Nino, drove 2016 greenhouse gas levels to new heights.
AAP Image/Dave Hunt

Paul Fraser, CSIRO; Paul Krummel, CSIRO, and Zoe Loh, CSIRO

Global average carbon dioxide concentrations rose by 0.8% during 2016, the largest annual increase ever observed. According to figures released overnight by the World Meteorological Organisation, atmospheric CO₂ concentrations reached 403.3 parts per million. This is the highest level for at least 3 million years, having climbed by 3.3 ppm relative to the 2015 average.

The unprecedented rise is due to carbon dioxide emissions from fossil fuels (coal, oil and gas) and the strong 2015-16 El Niño event, which reduced the capacity of forests, grasslands and oceans to absorb carbon dioxide from the atmosphere.

Greenhouse gas levels are unprecedented in modern times.
WMO

The figures appear in the WMO’s annual Greenhouse Gas Bulletin. This is the authoritative source for tracking trends in greenhouse gases that, together with temperature-induced increases in atmospheric water vapour, are the major drivers of current climate change.


Read more: Southern hemisphere joins north in breaching carbon dioxide milestone


Laboratories around the world, including at CSIRO and the Bureau of Meteorology in Australia, measure atmospheric greenhouse gas concentrations at more than 120 locations. The gases include carbon dioxide, methane and nitrous oxide, as well as synthetic gases such as chlorofluorocarbons (CFCs).

At Cape Grim in Tasmania, we observed a corresponding increase during 2016 of 3.2 ppm, also the highest ever observed.

For 2017 so far, Cape Grim has recorded a smaller increase of 1.9 ppm. This possibly reflects a reduced impact of El Niño on atmospheric carbon dioxide growth rates this year.

Long-term record of background carbon dioxide from Cape Grim, located at the northwest tip of Tasmania.
CSIRO/BoM

For roughly 800,000 years before industrialisation began (in around the year 1750), carbon dioxide levels remained below 280 parts per million, as measured by air trapped in Antarctic ice. Geological records suggest that the last time atmospheric levels of carbon dioxide were similar to current levels was 3-5 million years ago. At that time, the climate was 2-3℃ warmer than today’s average, and sea levels were 10 to 20 metres higher than current levels.

Human-driven change

The extraordinarily rapid accumulation of CO₂ in the atmosphere over the past 150 years is overwhelmingly and unequivocally due to human activity.

Methane is the second-most-important long-lived greenhouse gas in the atmosphere, with 40% coming from natural sources such as wetlands and termites and the remaining 60% from human activities including agriculture, fossil fuel use, landfills and biomass burning.

In 2016, global atmospheric methane also hit record levels, reaching 1,853 parts per billion, an increase of 9 ppb or 0.5% above 2015 levels. At Cape Grim, methane levels climbed by 6 ppb in 2016, or 0.3% above 2015 levels.

Nitrous oxide is the third-most-important greenhouse gas, of which [around 60% comes from natural sources such as oceans and soils], and 40% from fertilisers, industrial processes and biomass burning.

In 2016, global atmospheric nitrous oxide hit a record 328.9 ppb, having climbed by 0.8 ppb (0.2%) above 2015 levels. At Cape Grim, we observed the same annual increase of 0.8 ppb.


Read more: The three-minute story of 800,000 years of climate change with a sting in the tail


If we represent the climate change impact of all greenhouse gases in terms of the equivalent amount of CO₂, then this “CO₂-e” concentration in the atmosphere in 2016 would be 489 ppm. This is fast approaching the symbolic milestone of 500 ppm.

These record greenhouse gas levels are consistent with the observed rise in global average temperatures, which also hit record levels in 2016.

The only way to reduce the impact is to significantly reduce our greenhouse gas emissions. The Kyoto Protocol and the subsequent Paris Agreement are important first steps in a long and challenging process to reduce such emissions. Their immediate success and ultimate strengthening will be crucial in keeping our future climate in check.


The ConversationThe authors thank Dr David Etheridge for his advice on the use of proxy measurements to infer carbon dioxide levels in past atmospheres.

Paul Fraser, Honorary Fellow, CSIRO; Paul Krummel, Research Group Leader, CSIRO, and Zoe Loh, Research Scientist, CSIRO

This article was originally published on The Conversation. Read the original article.

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Current emissions could already warm world to dangerous levels: study


Andrew Glikson, Australian National University

Current greenhouse gas concentrations could warm the world 3-7℃ (and on average 5℃) over coming millennia. That’s the finding of a paper published in Nature today.

The research, by Carolyn Snyder, reconstructed temperatures over the past 2 million years. By investigating the link between carbon dioxide and temperature in the past, Snyder made new projections for the future.

The Paris climate agreement seeks to limit warming to a “safe” level of well below 2℃ and aim for 1.5℃ by 2100. The new research shows that even if we stop emissions now, we’ll likely surpass this threshold in the long term, with major consequences for the planet.

What is climate sensitivity?

How much the planet will warm depends on how temperature responds to greenhouse gas concentrations. This is known as “climate sensitivity”, which is defined as the warming that would eventually result (over centuries to thousands of years) from a doubling of CO₂ concentrations in the atmosphere.

The measure of climate sensitivity used by the Intergovernmental Panel on Climate Change (IPCC) estimates that a doubling of CO₂ will lead to 1.5-4.5℃ warming. A doubling of CO₂ levels from before the Industrial Revolution (280 parts per million) to 560ppm would likely surpass the stability threshold for the Antarctic ice sheet.

As the world warms, it triggers changes in other systems, which in turn cause the world to warm further. These are known as “amplifying feedbacks”. Some are fast, such as changes in water vapour, clouds, aerosols and sea ice.

Others are slower. Melting of the large ice sheets, changes in the distribution of forests, plants and ecosystems, and methane release from soils, tundra or ocean sediments may begin to come into play on time scales of centuries or less.

Other research has shown that during the mid-Pliocene epoch (about 4.5 million years ago) atmospheric CO₂ levels of about 365-415ppm were associated with temperatures about 3–4 °C warmer than before the Industrial Revolution. This suggests that the climate is more sensitive than we thought.

This is concerning because since the 18th century CO₂ levels have risen from around 280ppm to 402ppm in April this year. The levels are currently rising at around 3ppm each year, a rate unprecedented in 55 million years. This could lead to extreme warming over the coming millennia.

Temperature histories from paleoclimate data (green line) compared to the history based on modern instruments (blue line) suggest that global temperature is warmer now than it has been in the past 1,000 years, and possibly longer.
NASA, Author provided

More sensitive than we thought

The new paper recalculates this sensitivity again – and unfortunately the results aren’t in our favour. The study suggests that stabilisation of today’s CO₂ levels would still result in 3-7℃ warming, whereas doubling of CO₂ will lead to 7-13℃ warming over millennia.

The research uses proxy measurements for temperature (such as oxygen isotopes and magnesium-calcium ratios from plankton) and for CO₂ levels, calculated for every 1,000 years back to 2 million years ago.

Some other major findings include:

The Earth cooled gradually to about 1.2 million years ago, followed by an increase in the size of ice sheets around 0.9 million years ago, and then followed by around 100,000-year-long glacial cycles.

Over the last 800,000 years, and particularly during glacial cycles, atmospheric greenhouse gas concentrations and global temperature were closely linked.

The study shows that for every 1℃ of global average warming, Antarctica warms by 1.6℃.

So what does all this mean for the future?

Global warming past and future, triggered initially by either changes in solar radiation or by greenhouse gas emissions, is driven mainly by amplifying feedbacks such as warming oceans, melting ice, drying vegetation in parts of the continents, fires and methane release.

Current CO₂ levels of around 400ppm, combined with methane (rising toward 1,900 parts per billion) and nitric oxide (around 310ppb), are already driving such feedbacks.

According to the new paper, such greenhouse gas levels are committing the Earth to extreme rises of temperature over thousands of years, with consequences consistent with the large mass extinctions.

The IPCC suggests warming will increase steadily as greenhouse gases increase. But the past shows there will likely be abrupt shifts, local reversals and tipping points.

Abrupt freezing events, known as “stadials”, follow peak temperatures in the historical record. These are thought to be related to the Mid-Atlantic Ocean Current. We’re already seeing marked cooling of ocean regions south of Greenland, which may herald collapse of the North Atlantic Current.

A global temperature map for 2015 showing the cold water region in the North Atlantic Ocean.
NASA, Author provided

As yet we don’t know the details of how different parts of the Earth will respond to increasing greenhouse gases through both long-term warming and short-term regional or local reversals (stadials).

Unless humanity develops methods for drawing down atmospheric CO₂ on a scale required to cool the Earth to below 1.5°C above pre-industrial temperature, at the current rate of CO₂ increase of 3ppm per year we are entering dangerous uncharted climate territory.

The Conversation

Andrew Glikson, Earth and paleo-climate scientist, Australian National University

This article was originally published on The Conversation. Read the original article.

Arctic Sea Ice Levels Are at the Lowest Ever Recorded


TIME

Arctic sea ice levels last winter recorded their lowest peak since satellite monitoring began in 1979, U.S. scientists said Thursday.

According to the University of Colorado’s Snow and Ice Data Center, Arctic ice levels crowned on Feb. 25 with a maximum extent of 14.54 million sq. km — 130,000 sq. km less than the previous record low set in 2011, and 1.1 million sq. km lower than the 1981-2010 recorded average.

The drop was also widespread, with below-average ice levels recorded everywhere except for the Labrador Sea between Greenland and Canada and the Davis Strait slightly further north.

The data center did say that a late season surge in ice growth is still conceivable, but unlikely to match the winter’s high-point. Meaning this year’s Feb. 25 peak date was two weeks earlier than the average. The earliest ice-level maximum was in 1996, reaching its ceiling only one day earlier on…

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Antarctic Ice Melt Increasing Rising Sea Levels


The link below is to an article that looks at the rising threat of the Antarctic ice melt to sea levels around the world.

For more visit:
http://inhabitat.com/melting-east-antarctic-ice-sheet-could-raise-sea-levels-for-thousands-of-years/

Rising Sea Level Threat


The link below is to an article that takes a look at the threat of rising sea levels to islands caused by global warming and climate change.

For more visit:
http://news.mongabay.com/2014/0408-edwards-sealevels-extinction.html