Arctic heating races ahead of worst-case estimates

September 2, 2020 / activist360 / Leave a comment

Arctic heating is happening far faster than anybody had anticipated. And the ice record suggests this has happened before.

September 2, 2020 by Tim Radford, Climate News Network (CC BY-ND 4.0)

*Svalbard, in whose waters temperatures have risen at 1.5°C every decade for the last 40 years. Image: By Vince Gx on Unsplash*

LONDON, 2 September, 2020 – An international team of scientists brings bad news about Arctic heating: the polar ocean is warming not only faster than anybody predicted, it is getting hotter at a rate faster than even the worst case climate scenario predictions have so far foreseen.

Such dramatic rises in Arctic temperatures have been recorded before, but only during the last Ice Age. Evidence from the Greenland ice cores suggests that temperatures rose by 10°C or even 12°C, over a period of between 40 years and a century, between 120,000 years and 11,000 years ago.

“We have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated,” said Jens Hesselbjerg Christensen, a physicist at the University of Copenhagen in Denmark, one of 16 scientists who report in the journal Nature Climate Change on a new analysis of 40 years of data from the Arctic region.

They found that, on average, the Arctic has been warming at the rate of 1°C per decade for the last four decades. Around Norway’s Svalbard archipelago, temperatures rose even faster, at 1.5°C every 10 years.

We have been clearly underestimating the rate of temperature increases in the atmosphere nearest to the sea level, which has ultimately caused sea ice to disappear faster than we had anticipated.”
—Jens Hesselbjerg Christensen, Physicist, University of Copenhagen

During the last two centuries, as atmospheric levels of carbon dioxide climbed from an average of around 285 parts per million to more than 400ppm, so the global average temperature of the planet rose: by a fraction more than 1°C.

The latest study is a reminder that temperatures in the Arctic are rising far faster than that. And the news is hardly a shock: within the past few weeks, separate teams of researchers, reporting to other journals, have warned that Greenland – the biggest single reservoir of ice in the northern hemisphere – is melting faster than ever; more alarmingly, its icecap is losing mass at a rate that suggests the loss could become irreversible.

Researchers have also confirmed that the average planetary temperature continues to rise inexorably, that the Arctic Ocean could be free of ice in summer as early as 2035, and that the climate scientists’ “worst case” scenarios are no longer to be regarded as a warning of what could happen: the evidence is that what is happening now already matches the climate forecaster’s worst case. The latest finding implicitly and explicitly supports this flurry of ominous observation.

“We have looked at the climate models analysed and assessed by the UN Climate Panel,” said Professor Christensen. “Only those models based on the worst case scenario, with the highest carbon dioxide emissions, come close to what our temperature measurements show over the past 40 years, from 1979 to today.” – Climate News Network

Restoring Forests Can Reduce Greenhouse Gases

August 21, 2020 / activist360 / Leave a comment

*Balangoda-Hatton Road of Sri Lanka, ways through natural forest. It is misty most of the year during the evening. Image by Kanthaja. (CC BY-SA 4.0)*

In a way, money does grow on trees. So it could pay to help nature restore forests and reduce greenhouse gases.

August 20, 2020 by Tim Radford, Climate News Network (CC BY-ND 4.0)

LONDON, 20 August, 2020 – There is one straightforward way to reduce greenhouse gases: by taking better care of the world’s natural forests.

European and US scientists think they may have settled a complex argument about how to restore a natural forest so that it absorbs more carbon. Don’t just leave nature to regenerate in the way she knows best. Get into the woodland and manage, and plant.

It will cost more money, but it will sequester more carbon: potentially enough to make economic good sense.

Researchers from 13 universities and research institutions report in the journal Science that they carefully mapped and then studied a stretch of tropical forest in Sabah, in Malaysian Borneo: a forest that had been heavily logged more than 30 years ago, and converted to plantation, and then finally protected from further damage. The mapping techniques recorded where, and how much, above-ground carbon was concentrated, across thousands of hectares.

Faster Recovery

The researchers report that those reaches of forest left to regenerate without human help recovered by as much as 2.9 tonnes of above-ground carbon per hectare each year. But those areas of forest that were helped a little, by what the scientists call “active restoration”, did even better.

Humans entered the regenerating forests and cut back the lianas – the climbing plants that flourish in degraded forests and compete with saplings – to help seedlings flourish. They also weeded where appropriate and enriched the mix of new plants with native seedlings.

Where this happened, the forest recovered 50% faster and carbon storage above-ground per hectare was measured at between 2.9 tonnes per hectare and 4.4 tonnes.

The lesson to be drawn is that where a natural forest may be thought fully restored after 60 years, active restoration could make it happen in 40 years.

Restoration helps previously over-used forests not only to recover carbon, but also to become ecologically sound and diverse again”
—Christopher Philipson, Swiss Federal Technology Institute

The research demonstrates two things. The first is that forests can and will restore themselves: opportunistic plants will colonise open space and provide cover for those species best adapted to long-term survival in that climate and habitat. Nature will decide what conservationists call “the climax vegetation” of any natural forest. The second is that nature can indeed benefit from selective human help.

“This active restoration encourages naturally diverse forest, and is therefore much more beneficial for biodiversity than monocultures or plantation forests,” said Christopher Philipson, of the Swiss Federal Technology Institute known as ETH Zurich.

“In this way restoration helps previously over-used forests not only to recover carbon, but also to become ecologically sound and diverse again.”

There will be arguments about the finding. One is that what might be a good solution in south-east Asia might not be the best answer for the Congo or parts of the Amazon: as humans degrade the forest, they may also affect the local climate in ways that favour some native species rather than others. That is, it might never be possible to restore a forest to what it had been before the forester’s axe arrived.

Restoration’s Pricetag

There is a second argument: restoration work costs money. How much economic sense it makes depends on what value scientists, politicians and economists put on the carbon that is sequestered as a consequence, and what price humanity pays for that same carbon in the form of additional greenhouse gas that will raise global temperatures, alter rainfall patterns and trigger potentially catastrophic climate change.

What worth do forests have to local populations, and what is the value set on the world’s wildernesses as global natural capital?

“Not long ago we treated degraded tropical forests as lost causes,” said a co-author, Greg Asner of Arizona State University.

“Our new findings, combined with those of other researchers around the world, strongly suggest that restoring tropical forests is a viable and highly scalable solution to regaining lost carbon stocks on land.” – Climate News Network

Annual Planetary Temperature Continues to Rise

August 17, 2020 / activist360 / Leave a comment

More than 500 scientists from 61 countries have again measured the annual planetary temperature. The diagnosis is not good.

*Wildfire strikes Bandipur national park, one of India’s prime tiger reserves. Image: By NaveenNkadalaveni, via Wikimedia Commons*

August 17, 2020 by Tim Radford, Climate News Network (CC BY-ND 4.0)

LONDON, 17 August, 2020 – Despite global promises to act on climate change, the Earth continues to warm. The annual planetary temperature confirms that the last 10 years were on average 0.2°C warmer than the first 10 years of this century. And each decade since 1980 has been warmer than the decade that preceded it.

The year 2019 was also one of the three warmest years since formal temperature records began in the 19th century. The only warmer years – in some datasets but not all – were 2016 and 2015. And all the years since 2013 have been warmer than all other years in the last 170.

The link with fossil fuel combustion remains unequivocal: carbon dioxide levels in the atmosphere increased by 2.5 parts per million (ppm) in 2019 alone. These now stand at 409 ppm. The global average for most of human history has hovered around 285 ppm.

Two more greenhouse gases – nitrous oxide and methane, both of them more short-lived – also increased measurably.

This millennium has been warmer than any comparable period since the Industrial Revolution.”
—Robert Dunn, of the UK Met Office

The study, in the Bulletin of the American Meteorological Society, is a sobering chronicle of the impact of climate change in the decade 2010-2019 and the year 2019 itself. It is the 30th such report, it is signed by 528 experts from 61 countries, and it is a catalogue of unwelcome records achieved and uncomfortable extremes surpassed.

July 2019 was the hottest month on record. Record high temperatures were measured in more than a dozen nations across Africa, Europe, Asia and the Caribbean. In North America, Alaska scored its hottest year on record.

The Arctic as a whole was warmer than in any year except 2016. Australia achieved a new nationally average daily temperature high of 41.9°C on 18 December, breaking the previous 2013 record by 1.6°C. But even Belgium and the Netherlands saw temperatures higher than 40°C.

For the 32nd consecutive year, the world’s alpine glaciers continued to get smaller and retreat further uphill. For the first time on record in inland Alaska, when measured at 26 sites, the active layer of permafrost failed to freeze completely. In September, sea ice around the Arctic reached a minimum that tied for the second lowest in the 41 years of satellite records.

Catalogue of Extremes

Global sea levels set a new high for the eighth consecutive year and are now 87.6mm higher than the 1993 average, when satellite records began. At a depth of 700 metres, ocean temperatures reached new records, and the sea surface temperatures on average were the highest since 2016.

Drought conditions led to catastrophic wildfires in Australia, in Indonesia, Siberia and in the southern Amazon forests of Bolivia, Brazil and Peru. And around the equator, meteorologists catalogued 96 named tropical storms: the average for 1981 to 2010 was 82. In the North Atlantic, just one storm, Hurricane Dorian, killed 70 people and caused $3.4bn (£2.6bn) in damage in the Bahamas.

“This millennium has been warmer than any comparable period since the Industrial Revolution. A number of extreme events, such as wildfires, heatwaves and droughts, have at least part of their root linked to the rise in global temperature,” said Robert Dunn, of the UK Met Office, one of the contributors.

“And of course the rise in global temperature is linked to another climate indicator, the ongoing rise in emissions in greenhouse gases, notably carbon dioxide, nitrous oxide and methane.” – Climate News Network