As Permafrost Thaws, Scientists Study the Risks

8/2/2019 As Permafrost Thaws, Scientists Study the Risks

1/25

As Permafrost Thaws,Scientists Study the Risks

A Summary of the 16 December

2011 NY Times article by JustinGillis


2/25

Permafrost

Perennially frozen ground

Underlies nearly 25% of the Northern

Hemisphere

Experts have long known that northern

lands stored frozen carbon, locked up in

the form of leaves, roots, and otherorganic matter trapped in icy soil


3/25

Permafrost


4/25

Permafrost When thawed, this mix can produce

methane and carbon dioxide gases

that trap heat and warm the planet

(greenhouse gases) Recent studies have shown that

permafrost contains twice as much

carbon as the entire atmosphere


5/25

Permafrost

The peculiar geology of western North

America and eastern Siberia caused so

much plant debris to get locked in anice box there

These areas were not covered by

glaciers during the last ice age, butthe climate was frigid


6/25


7/25

Permafrost

Powerful winds and rivers carriedimmense volumes of silt and dust thatsettled in the lowlands of Alaska and

Siberia A thin layer of this soil thawed on top duringthe summers grasses grew, capturingcarbon dioxide

During the winters, grass roots, leaves, and

even animal parts froze before they coulddecompose

Layer after layer of permafrost built up


8/25


9/25

Scientists believe temperatures arewarming across much of the

northern region primarily because of

the rapid human release ofgreenhouse gases

Thawing of permafrost just one of the

emerging signs that the frozen carbonmay be becoming unstable


10/25

If a substantial amount of carbon enters the

atmosphere, it would intensify planetarywarming.

Possibility: significant proportion will emerge

NOT as carbon dioxide (the gas that usually

forms when organic material breaks down), but

as methane (produced when the breakdown

occurs in lakes or wetlands)

Methane especially potent at trapping the suns heat

One of the biggest wild cards in climate science:the potential for large new methane emissions in

the Arctic


11/25

Recent preliminary computer analyses

suggest that the Arctic and sub-Arctic

regions could eventually become an

annual source of carbon equal to 15%

or so of todays yearly emissions fromhuman activities

These calculations are deliberately

cautious


12/25


13/25

Recent survey of 41 permafrost scientists

they estimated that if human fossil-fuel burning

remained high and the planet warmed sharply,

the gases from permafrost could eventually

equal 35% of todays annual human

emissions they said that if humanity began getting its own

emissions under control soon, the greenhouse

gases emerging from permafrost could be kept

to a much lower level, perhaps equivalent to10% of todays human emissions


14/25

Even at the low end, such numbers

mean the long-running international

negotiations over greenhouse gases

are likely to become more difficult

less room for countries to continue burning

large amounts of fossil fuels


15/25


16/25

Scientists have declared that

understanding the problem is a major

priority

US Department of Energy and the EU

recently committed to new projects aimedat doing so

NASA considering a similar plan


17/25

Researchers say the money and people

devoted to the issue are still minimalcompared with the risk Chief worry of most experts once

carbon decomposition in the permafrost

starts, it will be impossible to stop Chronic source of emissions that will last

hundreds of years

Troubling trend: increase of wildfires in thenorth early research suggests extensiveburning could lead to a more rapid thaw ofpermafrost


18/25

Now, as people burn immense amounts

of carbon in the form of fossil fuels, the

planets temperature is rising

The Arctic is warming twice as fast

That puts the remaining permafrost

deposits at risk


19/25

Researchers have been monitoring

permafrost temperatures in hundreds of

boreholes across the north for several

decades.

Temperatures have occasionally

decreased in some regions for periods as

long as a decade, BUT the overall trend

has been a relentless rise, withtemperatures now increasing fastest in the

most northerly areas


20/25


21/25

Best estimate of carbon published in

2009 by Canadian scientist Charles

Tarnocai and some colleagues

About 1.7 trillion tons of carbon in

soils of the northern regions

88% of it locked in permafrost 2.5

times the amount of carbon in the

atmosphere


22/25

When thaw begins, the ground

(supported by permafrost) sometimes

turns to mush and the entire land

surface collapses into a low-lying area,

known as a thermokarst.

A lake or wetland can form there, with

the dark surface of the water

capturing the suns heat and causingstill more permafrost to thaw nearby


23/25

Essential question scientists need to

answer:

Will the many factors they do not

yet understand speed the release

of carbon from permafrost, or

possibly slow it more than they

expect?


24/25

Portent of things to come?

2007: a lightning strike set the northern

Alaskan tundra on fire

Scientists have calculated that the fire and

its aftermath sent a huge pulse of carbon

into the air as much as would be emitted

in 2 years by a city the size of Miami

The fire thawed the upper layer ofpermafrost and set off what scientists fear

will be permanent shifts in the landscape


25/25

As Permafrost Thaws, Scientists Study the Risks

Documents

Transcript of As Permafrost Thaws, Scientists Study the Risks