World greenhouse gas levels made unprecedented leap in 2016

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.

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

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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.

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

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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.

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The 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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Galapagos species are threatened by the very tourists who flock to see them

Life’s not such a beach for Galapagos native species these days.
shacharf/shutterstock

Veronica Toral-Granda, Charles Darwin University and Stephen Garnett, Charles Darwin University

Native species are particularly vulnerable on islands, because when invaders such as rats arrive, the native species have nowhere else to go and may lack the ability to fend them off.

The main characteristic of an island is its isolation. Whether just off the coast or hundreds of kilometres from the nearest land, they stand on their own. Because of their isolation, islands generally have a unique array of plant and animal species, many of which are found nowhere else. And that makes all islands one of a kind.

However, islands, despite being geographically isolated, are now part of a network. They are globally connected to the outside world by planes, boats and people. Their isolation has been breached, offering a pathway for introduced species to invade.

The Galapagos Islands, 1,000km off the coast of Ecuador, provide a great example. So far, 1,579 introduced species have been documented on the Galapagos Islands, of which 98% arrived with humans, either intentionally or accidentally.

More than 70% of these species have arrived since the 1970s – when Galapagos first became a tourist destination – an average of 27 introduced species per year for the past 40 years.

New arrivals

Introduced species – plants or animals that have been artificially brought to a new location, often by humans – can damage native fauna and flora. They are among the top threats to biodiversity worldwide, and one of the most important threats to oceanic islands. The Convention on Biological Diversity has a dedicated target to help deal with them and their means of arrival. The target states that:

by 2020, invasive alien species and pathways are identified and prioritised, priority species are controlled or eradicated and measures are in place to manage pathways to prevent their introduction and establishment.

The Galapagos Islands are home to giant tortoises, flightless cormorants, and the iconic Darwin’s finches – species that have evolved in isolation and according to the differing characteristics of each of the islands.

However, the Galapagos’ natural attributes have also made these islands a top tourist destination. Ironically enough, this threatens the survival of many of the species that make this place so unique.

Humans on the rise

In 1950 the Galapagos Islands had just 1,346 residents, and no tourists. In 2015 more than 220,000 visitors travelled to the islands. These tourists, along with the 25,000 local residents, need to have most of their food and other goods shipped from mainland Ecuador.

These strengthening links between Galapagos and the mainland have opened up pathways for the arrival and spread of introduced species to the archipelago, and between its various islands.

Major species transport routes into and between the Galapagos Islands.
PLoS ONE

More and more alien species are finding their way to the Galapagos Islands.
PLoS ONE

Plants were the most common type of introduced species, followed by insects. The most common pathway for species introduction unintentionally was as a contaminant on plants. A few vertebrates have also been recorded as stowaways in transport vehicles, including snakes and opossums; whilst others have been deliberately introduced in the last decade (such as Tilapia, dog breeds and goldfishes).

The number, frequency and geographic origin of alien invasion pathways to Galapagos have increased through time. Our research shows a tight relationship between the number of pathways and the ongoing increase in human population in Galapagos, from both residents and tourists.

For instance, the number of flights has increased from 74 flights a week in 2010 to 107 in 2015; the number of airplane passengers has also increased through time with about 40% being tourists, the remainder being Galapagos residents or transient workers.

Global connections between Galapagos and the outside world have also increased, receiving visitors from 93 countries in 2010 to 158 in 2014. In 2015 and 2016, the Galapagos Biosecurity Agency intercepted more than 14,000 banned items, almost 70% of which were brought in by tourists.

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We think it likely that intentional introductions of alien species will decline when biosecurity is strengthened. However, with tourists as known vectors for introduced species and with tourism much the largest and fastest growing sector of the local economy, unintentional introductions to Galapagos will almost certainly increase further.

If islands are to be kept as islands, isolated in the full sense of the word, it is of high priority to manage their invasion pathways. Our research aims to provide technical input to local decision makers, managers and conservation bodies working in Galapagos in order to minimise a further increase on the number of available pathways to Galapagos and the probable likelihood of new arrivals. Our next step is to evaluate how local tourism boats are connecting the once isolated islands within Galapagos, as a way to minimise further spread of harmful introduced species to this UNESCO World Heritage Site.

Veronica Toral-Granda, PhD candidate, Charles Darwin University and Stephen Garnett, Professor of Conservation and Sustainable Livelihoods, Charles Darwin University

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