Preparing land for palm oil causes most climate damage

New research has found preparing land for palm oil plantations and the growth of young plants causes significantly more damage to the environment, emitting double the amount of greenhouse gases than mature plantations.

Peat swamp deforestation and drainage for new oil palm plantations in North Selangor
Peat Swamp Forest, Malaysia [Credit: Stephanie Evers]

This is the first study to examine the three main greenhouse gas emissions across the different age stages of palm oil plantations. It was carried out by plant scientists from the University of Nottingham in the North Selangor peat swamp forest in Malaysia with support from the Salangor State Forestry Department. It has been published in Nature Communications.

Palm oil is the most consumed and widely traded vegetable oil in the world. Global demand has more than tripled in the last eighteen years, from around 20 million tonnes in 2000 to over 70 million in 2018 and Malaysia is the world's second largest producer. The University of Nottingham researchers analysed five sites at four different stages of land use: secondary forest, recently drained but uncleared forest, cleared and recently planted young oil palm plantation and mature oil palm plantation.

Laboratory analysis of soil and gas from these sites showed that the greatest fluxes of CO2 occurred during the drainage and young oil palm stages with 50% more greenhouse gas emissions than the mature oil palms. These emissions also account for almost a quarter of the total greenhouse emissions for the region.

Tropical peat swamp forests hold around 20% of global peatland carbon. However, the contribution of peat swamp forests to carbon storage is currently under threat from large-scale expansion of drainage-based agriculture including oil palm and pulp wood production on peatlands.

Draining peatlands increases the oxygen levels in the soil, which in turn increases the rate of decomposition of organic material, resulting in high CO2 emissions from drained peatlands. In addition to CO2, peatlands also emit the powerful greenhouse gases (CH4 and N2O8)..

Dr Sofie Sjogersten from the University of Nottingham's School of Biosciences led the research and said: "Tropical peat swamps have historically been avoided by palm oil growers due to the amount of preparation and drainage the land needs, but as land becomes more scarce there has been an increased demand to convert sites and the periphery of North Selangor is being heavily encroached upon by palm oil plantations. Our research shows that this conversion comes at a heavy cost to the environment with greater carbon and greenhouse gas emissions being caused by the early stages of the growth of palm oil."

Source: University of Nottingham [January 21, 2020]

Ozone-depleting substances caused half of late 20th-century Arctic warming, says study

A scientific paper published in 1985 was the first to report a burgeoning hole in Earth's stratospheric ozone over Antarctica. Scientists determined the cause to be ozone-depleting substances - long-lived artificial halogen compounds. Although the ozone-destroying effects of these substances are now widely understood, there has been little research into their broader climate impacts.

A new study shows that half of all Arctic warming and corresponding sea-loss during the late 20th century was
caused by ozone-depleting substances. Here, icebergs discharged from Greenland's Jakobshavn Glacier
[Credit: Kevin Krajick/Earth Institute]

A recent study published in Nature Climate Change by researchers at Columbia University examines the greenhouse warming effects of ozone-depleting substances and finds that they caused about a third of all global warming from 1955 to 2005, and half of Arctic warming and sea ice loss during that period. They thus acted as a strong supplement to carbon dioxide, the most pervasive greenhouse gas; their effects have since started to fade, as they are no longer produced and slowly dissolve.

Ozone-depleting substances, or ODS, were developed in the 1920s and '30s and became popularly used as refrigerants, solvents and propellants. They are entirely manmade, and so did not exist in the atmosphere before this time. In the 1980s a hole in Earth's stratospheric ozone layer, which filters much of the harmful ultraviolet radiation from the sun, was discovered over Antarctica. Scientists quickly attributed it to ODS.

The world sprang into action, finalizing a global agreement to phase out ODS. The Montreal Protocol, as it is called, was signed in 1987 and entered into force in 1989. Due to the swift international reaction, atmospheric concentrations of most ODS peaked in the late 20th century and have been declining since. However, for at least 50 years, the climate impacts of ODS were extensive, as the new study reveals.

Scientists at Columbia's School of Engineering and Applied Science and the Lamont-Doherty Earth Observatory used climate models to understand the effects of ODS on Arctic climate. "We showed that ODS have affected the Arctic climate in a substantial way," said Lamont-Doherty researcher Michael Previdi. The scientists reached their conclusion using two very different climate models that are widely employed by the scientific community, both developed at the U.S. National Center for Atmospheric Research.

The results highlight the importance of the Montreal Protocol, which has been signed by nearly 200 countries, say the authors. "Climate mitigation is in action as we speak because these substances are decreasing in the atmosphere, thanks to the Montreal Protocol," said Lorenzo Polvani, lead author of the study and a professor in Columbia's Department of Applied Physics and Applied Mathematics. "In the coming decades, they will contribute less and less to global warming. It's a good-news story."

Source: Columbia University [January 20, 2020]

Pyrenees glaciers 'doomed', experts warn

Glaciers nestled in the lofty crags of the Pyrenees mountains separating France and Spain could disappear within 30 years as temperatures rise, upending ecosystems while putting local economies at risk, scientists say.

A view of the Pyrenees from the observatory at the Pic du Midi de Bigorre, where the average temperature
has risen by 1.7 degrees since 1880 [Credit: Pascal Pavani/AFP]

"We can't set a precise date but the Pyrenees glaciers are doomed," Pierre Rene, a glaciologist with the region's Moraine glacier study association, told AFP.

He estimates the end will come by 2050, based on the group's measurements of nine of the 15 glaciers on the French side over the past 18 years.

The United Nations has said the past decade has been the hottest on record and warned that persistent greenhouse gas emissions were expected to push average global temperatures even higher, leading to retreating ice cover, rising sea levels and increasingly extreme weather. It also confirmed that 2019 was the second hottest year on record, after 2016.

Surveys, core samples and GPS tracking of the Pyrenees glaciers all point to the same conclusions already noted at glaciers in the Alps and elsewhere: Warmer and drier winters appear to be inexorably shrinking and thinning the ice fields.

The total surface area of the nine glaciers tracked by Moraine now stands at 79 hectares (195 acres) compared with 140 hectares just 17 years ago, Rene said.

That is just a small fraction of the 450 hectares they covered in the middle of the 19th century—and the pace of decline is accelerating.

Since 2002, the nine glaciers have lost 3.6 hectares every year, the equivalent of five soccer pitches, Moraine says in its report on the 2019 season.

Last year was no exception, with the bottom edge of five glaciers tracked by Moraine retreating by 8.1 metres (27 feet) on average last summer, up from 7.9 metres recorded in previous years, it said.

'Wiped off the map'

Scientists also warn of the hit to high-altitude ecosystems and biodiversity, with consequences that will ripple well beyond the mountainous zones.

Glaciers and the cold rivers they feed harbour bacteria and fungi that have adapted to the harsh conditions, including the near-absence of light, said Sophie Cauvy-Fraunie, a researcher at the INRAE agricultural and environmental institute.

Microscopic algae also provides a first link in the food chain of glacier environments, sustaining glacial fleas and other insects.

As temperatures rise and more ground is exposed as the glaciers retreat, the landscape will become vulnerable to colonisation from plants and animals that currently can survive only at lower altitudes.

"If native species in the Pyrenees depend on glacial influences, you can imagine that they are going to be wiped off the map," Cauvy-Fraunie said.

The regional OPCC climate observatory estimated in a 2018 report that average maximum temperatures across the Pyrenees could rise by 1.4 to 3.3 degrees Celsius (2.5 to 4 Fahrenheit) by the middle of this century.

The increase has been even more dramatic at higher altitudes, where shrinking glaciers are seen as a harbinger of dire consequences across the range.

On the 2,870-metre (9,416-foot) Midi de Bigorre peak above the La Mongie ski resort—favoured by French President Emmanuel Macron—the average temperature has risen by 1.7 degrees since 1880, compared with a global average of 0.85 degrees, Moraine says.

Tourism affected

That could spell disaster for the roughly three dozen ski resorts on both the French and Spanish sides, as well as the popular stations in Andorra.

Already this year, around half of French resorts had to push back their scheduled openings before the Christmas holidays because of warm winds sweeping up from the south.

That came after a 2018-2019 season that saw the lowest snowfalls since regular measurements began 22 years earlier, according to the Meteo France weather service.

It took a heavy toll on tourism as lift ticket sales and hotel reservations plunged, with many skiers heading to higher slopes in the French Alps.

Already several glaciers have been reduced to little more than year-round snow packs, which will also impact the summer tourist season.

Rene said climbers will lose their "stepladders" for ascents to the highest peaks, "making their routes to the top more difficult".

And for hikers at lower elevations, the retreat will destabilise the newly exposed slopes, heightening the risk of rock falls or even avalanches.

Author: Herve Gavard | Source: AFP [January 20, 2020]