Saturday :: Aug 13, 2005

Ice and Global Climate Change

by eriposte

Via Real Climate, NASA continues to report not so good news about Arctic sea ice (emphasis mine):

June marks the beginning of the melt season for Arctic sea ice, which reaches its minimum extent at the end of the season in September. In the past few Septembers, Arctic sea ice concentration (the amount of ice in a given area) has been markedly reduced. September 2002 set a new record low at 15 percent below average. It was followed closely by September 2003 and September 2004. So far, 2005 is shaping up to be another record-low sea ice year in the Arctic.

While we are on the topic of the Northern Hemisphere, there is even more disturbing news.

Thomas Leavitt at Seeing the Forest has a link to this report in the BBC (emphasis mine):

The world's largest frozen peat bog is melting, which could speed the rate of global warming, New Scientist reports.

The huge expanse of western Siberia is thawing for the first time since its formation, 11,000 years ago.

The area, which is the size of France and Germany combined, could release billions of tonnes of greenhouse gases into the atmosphere.
Western Siberia has warmed faster than almost anywhere on the planet, with average temperatures increasing by about 3C in the last 40 years.

The warming is believed to be due to a combination of man-made climate change, a cyclical atmospheric phenomenon known as the Arctic oscillation and feedbacks caused by melting ice.

The 11,000-year-old bogs contain billions of tonnes of methane, most of which has been trapped in permafrost and deeper ice-like structures called clathrates.

But if the bogs melt, there is a big risk their hefty methane load could be dumped into the atmosphere, accelerating global warming.

Scientists have reacted with alarm at the finding, warning that future global temperature predictions may have to be revised.

"When you start messing around with these natural systems, you can end up in situations where it's unstoppable," David Viner, of the University of East Anglia, UK, told the Guardian newspaper. "There are no brakes you can apply.
The intergovernmental panel on climate change speculated in 2001 that global temperatures would rise between 1.4C and 5.8C between 1990 and 2100.

However these estimates only considered global warming sparked by known greenhouse gas emissions.

"These positive feedbacks with landmasses weren't known about then," Dr Viner said. "They had no idea how much they would add to global warming."

Switching over to Antarctica, the news is marginally less disturbing, but disturbing nonetheless. Here's the BBC:

The ice sheet covering the interior of Antarctica is thickening, researchers report in the journal Science.

This bulge, which was recorded by satellite, may temporarily buffer rising sea levels, they believe.

Antarctica's "weight gain" is due to extra snowfall, caused by rising temperatures, the US-UK team thinks.

However, the scientists worry the overall mass of the Antarctic may be decreasing because ice near the coasts is melting, possibly at a greater rate.
The Antarctic contains the bulk of our planet's ice, so understanding its growth or shrinkage is critical to predicting future sea level changes.

Sea levels are currently rising at about 1.8mm per year, largely because ice sheets in polar regions are melting, the Intergovernmental Panel on Climate Change (IPCC) has said.

However, the panel also predicted that global warming would lead to an increase in snow fall over the Antarctic, because warmer air leads to more evaporation and precipitation.
Even though Antarctica is, at the moment, taking the edge off the effects of a warming global climate, we should not take too much comfort, say the researchers.

Snowfall over East Antarctica will not continue to increase indefinitely in a warming world but, conversely, ice melt will accelerate proportionately with every degree of rising temperature, swelling oceans further.

"The effect will only work for a finite period of time," Professor Davis said. "Eventually, the snow will start to melt."

Also, the overall mass of Antarctica may be decreasing, because coastal melt may be happening faster than internal ice sheet gain.

"Since sea levels are rising, that would be a reasonable assumption to make, although we don't know for sure," added Professor Davis.

The instruments used in this particular study were unable to monitor the coastal regions because they could not cope with the steep terrain.

However, the European Space Agency satellite CryoSat, due to be launched in the next year, should be up to the task, Professor Davis believes.

Also see Real Climate for a discussion of worldwide glacier retreats.

Do the crackpots running this Government - and their feckless supporters - care that they are risking the life of millions of people with their do-nothing approach to global climate change?

eriposte :: 10:30 AM :: Comments (7) :: TrackBack (1) :: Digg It!