'Major melt' for Alpine glaciers

[Janus]

Originally posted by BBC News
Europe's Alps could lose three-quarters of their glaciers to climate change during the coming century.

That is the conclusion of new research from the World Glacier Monitoring Service (WGMS) in Zurich.

Scientists base their conclusion on forecasts of temperature and precipitation changes in a new computer model of Alpine glaciation.

Glaciers are crucial in providing fresh drinking water, and are also key for tourism, irrigation and hydro-power.

There is already strong evidence of a major ongoing melt.

In the 1850s, according to WGMS data presented at the European Geosciences Union (EGU) annual meeting in Vienna, nearly 4,474 sq km of the Alps were glaciated.

By the 1970s, the area covered had fallen to just under 2,903 sq km, and in 2000, it was down to 2,272 sq km.

"From 1850 to the 1970s, there is an average loss of 2.9% per decade," WGMC's Michael Zemp told EGU delegates.

"From the 1970s until 2000 it is 8.2% per decade, and we see most of that increase since 1985," he said.

Warm projections

As temperatures rise, the minimum altitude at which glaciers form also rises.

To some extent that can be mitigated by changes in precipitation; more snow in winter will help glaciers accumulate more ice.

The WGMS has developed a computer model which calculates what projected temperature and precipitation changes for the Alps will mean for the glaciation altitude.

According to the OCCC, a national Swiss scientific grouping, summers are likely to get warmer by about 3C before the end of the century, and precipitation is likely to increase by about 10%.

"The summer temperature increase is 3C, which is very bad for glaciers," Dr Zemp told the BBC News website, "and the annual precipitation increases, which creates a bit better conditions for glaciers.

"You get a rise of 340m in the level that enables glaciation."

Across the Alps, this would mean a loss of 75% in the glaciated area.

Summer needs

This is only one projection for future Alpine climate, albeit one endorsed by an august scientific panel.

Summers could be cooler, winters could see higher snowfall.

But, commented Michael Zemp: "Even a rise of just 1C would see a loss of 40%.

"And even if you halted climate on today's level, glaciers would continue to retreat because of very bad years in the last two decades."

Melting of glaciers could be serious news for people living in or near the Alps.

They act as freshwater reservoirs, storing winter snowfall and releasing it over the summer, when it is most needed for drinking and agriculture.

Without them, the stored water would descend in a rush in spring, as soon as the snow began to melt.

[Janus]

It seems that nature is adapting to climate changes.


Originally posted by BBC News
Antarctic seabirds may be breeding later in response to climate change, according to a scientific study.

French researchers analysed records stretching back to the 1950s and think the breeding delays are linked to changes in East Antarctic sea ice.

Bird species are arriving at their colonies an average of nine days later and laying eggs on average two days later than they did in the 1950s.

Details appear in Proceedings of the National Academy of Sciences journal.

Researchers have found that spring events such as the arrival of migrant birds and the blossoming of trees, have been occurring progressively earlier in the Northern Hemisphere during the 20th Century.

But little information exists for the Southern Hemisphere due to a paucity of long term data sets.

Late arrivals

Christophe Barbraud and Henri Weimerskirch from the Centre d'Etudes Biologiques de Chize in Villiers en Bois, France, have now analysed the only long term record of arrival and egg-laying for all species of seabird that come to breed in continental Antarctica.
Data on the nine species of bird were collected by ornithologists at the Dumont d'Urville Antarctic research station between 1950 and 2004.

Over this period, four species showed a clear trend towards arriving later in Antarctica and two showed a clear trend toward later breeding.

Most other species arrived and bred later, but the trends were not statistically significant at levels set by the French team.

This is the opposite pattern to that seen in the Northern Hemisphere. It is likely that progressively warmer Northern Hemisphere spring temperatures since the mid-20th Century have increased the availability of food supplies.

In eastern and continental Antarctica, no warming or cooling has been observed since the early 1950s.

Breeding success

Here, a 12-20% reduction in the extent of sea ice over the last 50 years has been linked to a decline in numbers of the krill and other marine organisms that are the major food source for seabirds.

In addition, the sea ice season has been getting longer since the 1970s. The late break-up of sea ice is known to delay access to seabird colonies and food resources at sea.
These two factors reduce the quantity and accessibility of food supplies available in early spring, with birds requiring more time to build up the reserves they need to breed.

"We think both these factors contribute to the delays observed but do not explain all of the delays observed," Dr Barbraud told the BBC News website.

The changes in sea ice explain only 24% of the variation in arrival and egg-laying, so other factors must be at work. Dr Barbraud said these would need to be identified before predicting how the observed trends would affect breeding success.

But if seabirds continue to arrive and breed later and later, it looks likely that juveniles will fledge - gain the ability to fly - just before winter.

"They would face very harsh conditions just after fledging," Dr Barbraud explained, "They would have less time to learn how to find resources on their own."