Permafrost is a major reservoir of carbon and methane. Stockdonkey/Shutterstock
Beneath much of the Arctic resides vast stores of greenhouse gases,
locked up for millennia in icy soils. With this in mind, a pair of
studies provides a double whammy of bad news: Not only are these frozen
reservoirs thawing out more extensively than previously thought, but at
this stage, there’s little that can be done about it.
Carbon dioxide and methane are indubitably the two most potent greenhouse gases. Vast reservoirs of both exist within the world’s permafrost,
which is hydrated soil that has remained below the freezing point for
two or more years. Remarkably, these permafrost soils hold almost twice as much carbon than that found in the atmosphere – and one study, published in Nature Geoscience, shows them thawing all across the northern hemisphere.
Thanks to consistently warmer summers, permafrost in Russia, Alaska
and Canada is being “uncapped;” icy wedges that form at the top of the
permafrost were observed to be almost universally melting even in the
coldest regions of the Arctic. These wedges make up around 20 percent of
the upper permafrost volume, so their melting is exposing massive areas
of concealed, deeper permafrost.
“The scientific community has had the assumption that this cold
permafrost would be protected from climate warming, but we’re showing
here that the top of the permafrost, even if it’s very cold, is very
sensitive to these warming events,” Anna Liljedahl, the lead author of
the study and a researcher at the University of Alaska in Fairbanks,
told the Washington Post.
Permafrost is melting in even the coldest regions, and by 2100,
massive amounts of greenhouse gases will be released skywards. Liljedahl
et al./Nature Geoscience
Importantly, permafrost isn’t the only icy prison for greenhouse gases. Around 56 million years ago,
there was a mysterious, sizeable, global spike in atmospheric carbon.
One of the prevailing theories is that this occurred when a huge cache
of frozen methane beneath the seabed was suddenly destabilized, causing
it to release its contents into the atmosphere as both methane gas and
carbon dioxide. This, in turn, caused dramatic global warming, and a similar turn of events could happen today if the permafrost stores are unleashed.
It might even be worse: The initial uptick in global temperatures
could further destabilize both reservoirs of frozen greenhouse gases,
which in turn would release more trapped gas, and so on. Once this cycle
reaches a certain tipping point, it may be impossible to prevent.
So is there any way to avoid this, aside from agreeing
to cut greenhouse gas emissions on a global scale? Some have suggested
that plants, which would begin to proliferate in a warmer Arctic, could
end up soaking up the escaping carbon dioxide, acting as a biological
buffer to this increasingly troubling phenomenon.
Another study was commissioned to ask 100 Arctic researchers if this
was plausible, and they gave a resounding answer: no, it’s not. The
research, published in Environmental Research Letters, concluded that “the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario.”
This means that, whatever happens, a vast chunk of its carbon will
inexorably escape to the atmosphere by the end of the century. However,
they do point out that up to 85 percent of permafrost carbon release
could be stopped if human emissions are “actively reduced.”
Extensive bleaching has been caused by higher ocean temperatures. To prevent further damage, governments should commit to lowering emissions, an Australian team says.
The Great Barrier Reef is experiencing the worst bleaching event in 15 years, Australian scientists announced Tuesday after conducting aerial surveys of more than 500 coral reefs from Cairns to Papua New Guinea. Terry Hughes/ARC Centre of Excellence for Coral Reef Studies
News that 95 percent of the northern Great Barrier Reef is suffering
extreme coral bleaching may be the Australian government's final wake-up
call, climate scientists warned Tuesday, if it is to preserve the
Earth's largest single structure made by living organisms.
“This has been the saddest research trip of my life,”
James Cook University professor Terry Hughes, the convener of the
National Coral Bleaching Taskforce, said in a press release after the
team aerially surveyed almost 2,500 miles of the northern reefs.
Although
the northern sections are considered most pristine, only four reefs out
of the hundreds they studied between Cairns, Australia, and Papua New
Guinea had escaped bleaching, making it the worst bleaching event on
record. Previous events in 1998 and 2002 did not impact more than 20
percent.
And there may be more. The Taskforce will try to
determine the southern limit of bleaching this week. But while Minister
for the Environment Greg Hunt sounded optimistic last week, pointing out
that “the bottom three quarters of the reef is in strong condition,”
the Taskforce sees it differently.
"It was devastating to look at out of the
chopper window and see reef after reef destroyed by bleaching. But
really my emotion is not so much sadness as anger,"
Professor Hughes told the Australian Broadcasting Corporation. "I'm
really angry that the government isn't listening to the evidence that
we're providing them since 1998."
Scientists say the Great Barrier Reef is in great
danger. The National Coral Bleaching Taskforce says 95% of Australia’s
reefs are now severely bleached. Veuer’s Carly Figueroa has more.
Coral bleaching is a modern
phenomenon, marine scientists say; Over the past 400 years, there's no
evidence of bleaching events until the late 20th century. Changing
environmental factors like rising sea temperatures can cause the coral
to expel their photosynthetic algae, called zooxanthellae, making many
turn stark white. Others remain vivid, but have lost the green and brown
hues that signal health. Without the symbiotic algae to process
sunlight into oxygen and other nutrients, the coral dies.
Some
could recover if temperatures drop, but it would still be a decade-long
process. Underwater surveys suggest that half of the impacted coral has
already died, the team says. But the northern reef is otherwise one of
the healthiest sections, so it may stand a better chance of eventually
bouncing back. Southern sections have "dodged a bullet" thanks to cooler
temperatures, according to Hughes.
A long-term solution requires
long-term commitment to reducing climate change, such as lowering
greenhouse gas emissions, the team says.
"What we're seeing now
is unequivocally to do with climate change," University of Queensland
professor Justin Marshall told the ABC. "I guess what upsets me the most
is that we are literally stealing the future from our children.... I
probably won't see the possible end of the Great Barrier Reef. But it's
possible that my grandchildren will."
The World Wildlife Fund called for Prime Minister Malcolm Turnbull to survey the bleaching, and see "the face of climate change,"
spokesman Nick Heath told the Sydney Morning Herald. "We can have our
corals, or we can have our complacency. If we don't start to see some
real leadership on the Reef, it will be gone."
Earth's Arctic ocean freezer is making fewer ice cubes, and that could be a problem throughout the Northern Hemisphere, researchers at the National Snow and Ice Data Center are warning.
Story highlights
Arctic sea ice spread is the smallest on record, researchers say
The loss of sea ice could influence global weather patterns, they say
The
center, part of the University of Colorado at Boulder, reported Monday
that the spread of Arctic sea ice set a new record low for the second
straight year, stopping last week at 5.607 million square miles.
That's
5,000 square miles less than last year's record low, as observed by
satellites, and 431,000 square miles less than the average for winters
between 1981 and 2010, the center said.
"The
Arctic is in crisis. Year by year, it's slipping into a new state, and
it's hard to see how that won't have an effect on weather throughout the
Northern Hemisphere," said Ted Scambos, a lead scientist at the center.
Arctic sea ice reflects heat from the
sun. Less ice means more heat given off the from ocean and higher Arctic
temperatures. That can affect weather around the world by, among other
things, disrupting the jet stream -- the high-speed, high-altitude wind
current that carries weather patterns from west to east.
Those disruptions can slow weather systems to a crawl and induce temperature extremes, researchers say.
Scientists
say the loss of Arctic ice -- an average of 20,800 square miles a year
since the 1970s, according to NASA -- is the result of climate change.
This
winter has been a particularly warm one in the Arctic, with air
temperatures as much as 10 degrees Fahrenheit above average near the
edges of the ice pack, according to Walt Meier, a sea ice scientist at
NASA's Goddard Space Flight Center in Greenbelt, Maryland.
Unusual winds from the south and an influx of warm Atlantic water have also played a role, the snow and ice center said.
The smaller maximum ice footprint this year doesn't necessarily foretell a record low this summer, researchers say.
That
has more to do with how early ice begins melting in the upper Arctic,
according to researchers. But, given the warm winter, ice and snow cover
is shallower than usual and could produce more melting.
The
Arctic ice pack shrank to record low summertime levels in 2005, again
in 2007 and most recently in 2012, according to the center.
Farming land in New South Wales.
from www.shutterstock.com
Australia’s agricultural lands help to feed about 60 million people worldwide, and also support tens of thousands of farmers as well as rural communities and industries.
But a growing global population with a growing appetite is placing
increasing demands on our agricultural land. At the same time, the
climate is warming and in many places getting drier too.
Agriculture, and particularly livestock, is currently a major contributor to greenhouse gas emissions.
But new markets and incentives could make storing carbon or producing
energy from land more profitable than farming, and turn our agricultural
land into a carbon sink.
How might these competing forces play out in changing Australian land use? Our research, published in Global Environmental Change, assesses a range of potential pathways for Australia’s agricultural land as part of CSIRO’s National Outlook.
Changing landscapes
The only constant in landscapes is change. Ecosystems are always changing in response to natural drivers such as fire and flood.
Humans have complicated things. Indigenous Australians manipulated the Australian landscape and climate through burning for millennia, sustaining a population of around 750,000 and underpinning a culture.
European colonisation brought a different and more pervasive change, clearing land, building cities, damming rivers and establishing an increasingly mechanised and industrialised agriculture.
These iconic but changed landscapes inspired the romantic art of Arthur Streeton and poetry of Banjo Paterson among many others — and helped forge a young nation’s identity.
‘Still glides the stream, and shall for ever
glide’, 1890. Arthur Streeton. The Art Gallery of NSW describes the
painting as ‘an idealised vision of the Yarra River at Heidelberg, with
the Doncaster Tower in the middle distance and the Dandenong Ranges
beyond’.
Change can happen surprisingly quickly. Often before we know it we’ve
gone too far and need to scramble for fixes that are so often costly,
slow and ultimately inadequate.
For example, in South Australia, researchers in the early 1960s
raised the alarm that the feverish post-war period of soldier
resettlement, land clearance and agricultural development threatened
entire native plant and animal communities with extinction. The
government’s response over the following 30 years was to expand greatly
the conservation reserve network and eventually prohibit land clearing.
History repeating?
Agricultural lands produce a range of goods and services. But in many
places the focus on agricultural productivity has come at the expense
of ecosystems. Biodiversity, soil and water are all on downward trends.
Is the balance right? Opinion varies. Many would say no, and consider the status quo to be stacked strongly against the environment.
Others see agriculture as entering a boom time, driven by growing population and rising food prices. Substantial interest from overseas investors in Australian agricultural land reflects this opportunity.
Parts of Australia’s agricultural land continue to change fast.
Lessons hard-learned by South Australia seem to have been forgotten.
Rates of land clearance in Queensland are rising again since 2010 after a long-term trend of decline.
In the 1990s, new financial incentives led to the planting of over 1 million hectares of forest in southern Australia. Now a failed business model, many of these plantations are being returned to agriculture.
Demand for more secure sources of energy has generated rapid
expansion of coal seam gas and wind power generation, and the
development of northern Australia remains a bipartisan priority.
Worldwide, Australia is not alone — many international examples also
exist of recent, massive, rapid and accelerating changes in how land is
used.
Australia has historically taken a hands-off approach to managing
land use change, instead focusing on increasing the productivity and
competitiveness of agriculture. Apart from a handful of planning and
environmental regulations, the use of land has been subject to minimal
governance or strategic direction.
Where to from here?
What is it that Australians really want from our land? We know what
we don’t want: wall-to-wall crops, pasture, buildings, gas wells, mines,
wind farms or trees.
We can expect healthy debate around the margins, but, in general,
diversity, productivity and sustainability seem to be widely valued.
Most of us want to leave the place in decent condition for future
generations.
Europe has had this conversation and knows what it wants from its
landscapes — and it’s not afraid to pay for it (for instance, through
agricultural subsidies). A deep aesthetic and cultural heritage is the
central objective, with a balance of recreation opportunities, tourism, a
clean and healthy environment and high-quality produce all being high
priorities.
Once we know what we want, we can work out how to get there.
That’s where science can help. We now have the ability to project changes in land use in response to policy and global change, and the environmental and economic consequences.
CSIRO’s recent National Outlook mapped Australia’s potential future pathways. A companion paper in Nature
found that it is possible to achieve strong economic growth and reduce
environmental pressure, if we put the right policies in place now. It
provides a glimpse of how our rural lands might respond to coalescing
future change pressures.
Farming carbon
In our modelling, carbon sequestration in the land sector plays a key role of Australia’s future. Land systems can help with the heavy lifting required to hold global warming to 2℃ as recently agreed in Paris.
There are several factors that could drive this change, including climate, carbon pricing, global food demand and energy prices.
We modelled the economic potential for land use change and its impacts in over 600 scenarios (full data available here), combining a suite of global outlooks and national policy options.
A carbon price, which enables landholders to make money from storing
carbon in trees and soils (often much more money than from farming), may
increase pressure to shift farmland to restored forests.
Who knows? A pay rise while watching trees grow could be an attractive proposition for our ageing farmers. Complementary biodiversity payments could also help arrest declines in wildlife and help it adapt to climate change.
If we redouble our focus on productivity, by 2050 agriculture will
produce more than today, even as farmland contracts. The least
productive areas are less able to compete with reforestation and other
new land uses, leaving the most efficient agricultural land in production. But trade-offs are likely. Trees use a lot more water than crops and pasture, so we will need to think carefully about managing water resources.
Economic potential for land use change and sustainability impacts from 2013 to 2050 under national global environmental and economic conditions consistent with 2℃ warming by 2100
Australians care about their land and are more aware than ever about
what is happening to it. While we can have some control over the future
of our land, and we do exercise this control in certain circumstances
(such as urban planning), our long-term approach to rural land has been
to let environmental and economic forces play out and let the invisible
hand of economics determine what will be.
Given the pace at which change can happen, a smarter approach will be
to start the conversation, work out what it is we want from our land,
and put the policies and institutions in place to get us there.
Earth's Arctic ocean freezer is making fewer ice cubes, and that could be a problem throughout the Northern Hemisphere, researchers at the National Snow and Ice Data Center are warning.
