stimate conseguenze del riscaldamento globale

["AlessandroGimona"<agimona@libero.it>]

E' ufficiale: il pianeta si riscaldera' sensibilmente nei prossimi 50-
100 anni e gli USA hanno stilato un rapporto che elenca le conseguenze 
previste per i loro sistemi biologici.
Queste sono piuttosto serie.

Ora l'europa dovrebbe cercare di fare un opera altrettanto sistematica 
e implementare politiche tese ad arginare le conseguenze delle 
eccessive emissioni di gas serra.

Una delle domande che sorge spontanea e': qual e' il destino delle aree 
protette nos solo in USA, ma anche in Europa ed in Italia.

Esiste il concreto rischio che gli ecosistemi protetti si spostino 
fuori dal confine dei parchi...o si estinguano per mancanza di 
territorio in cui eventualmente migrare.

sono domande a cui gli esperti di conservazione debbono dare risposta 
al piu' presto, per approntare eventuali rimedi.

Saluti

Alessandro Gimona



dal sito UCS http://www/ucsusa.org/

"Places that Americans love, such as Florida's coral reefs and the 
alpine meadows of the Rocky Mountains, could suffer greatly from global 
warming, according to the report. America's alarm bells should go off 
today," said Jennifer Morgan, director of the World Wildlife Fund's 
Climate Change Campaign. "The National Assessment shows that now more 
than ever the US must act to protect its national treasures."

The report reveals that natural ecosystems are the most vulnerable to 
the harmful effects of climate change because they have very limited 
options to adapt to those changes and because they are already stressed 
through air and water pollution, habitat fragmentation, and overuse.

"Major alteration of natural ecosystems due to a changing climate is 
particularly significant because our lives and our economy depend on 
the sustained bounty of our Nation's lands, waters, and native plant 
and animal communities," the report stated.

Among the key findings of the report:


According to the climate models used in the assessments, temperatures 
will rise 5 - 10° F on average in the next 100 years if tr
 emissions continue, but increases will vary somewhat 
from one US region to the next. It is also very likely that more rain 
will come in heavy downpours, increasing the risk of floods.


Ecosystems are highly vulnerable to the projected rate and magnitude of 
climate change. The goods and services lost through the disappearance 
or fragmentation of certain ecosystems are likely to be costly or 
impossible to replace.


Throughout the US, water is likely to become one of the key concerns in 
coming decades: droughts, floods, declining snow packs and water 
quality, and possibly greater water use conflicts could become even 
more common problems than they are today.


Climate change and the resulting rise in sea level are likely to worsen 
threats to buildings, roads, powerlines and other infrastructure along 
the coast. Sea-level rise is very likely to cause the loss of some 
barrier beaches, islands, and wetlands, and worsen storm surges and 
flooding during storms.


Overall, US crop productivity is likely to increase over the next few 
decades, but the gains will not be uniform across the nation. Falling 
prices and competition are likely to stress some farmers. And pests, 
droughts and floods could reduce some of the benefits from higher 
temperatures, precipitation and carbon dioxide.


Similarly, forest productivity is likely to increase in some areas over 
the next few decades, but fires, insects, droughts and diseases will 
possibly decrease productivity. Climate change will cause long-term 
shifts in forest species, such as sugar maples moving north out of the 
Northeast or economically important soft wood species moving from the 
Southeast to the Mid-Atlantic.

The report covers all regions of the country, and assesses the 
potential impacts of climate variability and change on water, 
agriculture, human health, forests, coastal areas, and marine resources.
"This report brings the meaning of global climate change home to every 
American," said Dr. Susanne Moser
ientists. 
"Even if the impacts ultimately manifest differently from what the 
report projects, everyone will experience some changes, and everyone 
should know that climate change is not science fiction. In some 
regions, like Alaska, the impacts of warming are here, now."

The report consists of an overview and a much longer foundation 
document, and is a snapshot of the current state of knowledge produced 
through a series of regional and sectoral assessments, supplemented 
through the peer-reviewed literature. The report release was preceded 
by an extensive, multistage peer-review process involving more than 300 
scientific and technical experts throughout the country, and overseen 
by a blue ribbon panel of renowned scientists.

The so-called National Assessment Synthesis Team, a group of 14 climate 
change impacts experts, who authored the report, was convened by the 
president's Council of Advisors on Science and Technology. Federal 
agencies, under the guidance of the Office of Science and Technology 
Policy, also reviewed the report.

"Climate change is already happening," said Dr. Janine Bloomfield, 
senior scientist at Environmental Defense. "Because greenhouse gases 
stay in the earth's atmosphere for decades, the time for action is now. 
Reducing emissions is the most important action we can take now to 
minimize damage to people, ecosystems, and economies."


The report does not cover the current state of climate science, the 
question of human causation, or how heat-trapping gases can be reduced 
but instead focuses exclusively on the potential impacts of global 
warming, given selected climate change scenarios. It identifies regions 
and sectors most vulnerable to climate change, opportunities to adapt 
to likely changes, and the most critical information needs for the US 
to be better positioned to predict climate change impacts.

"No matter how aggressively emissions are reduced, the world will still 
experience some climate change," the report stated. This i

elevated concentrations of greenhouse gases will remain in the 
atmosphere for decades, as the climate system responds only slowly to 
changes in human inputs.

"The assessment shows that many of the country's distinct natural 
features could deteriorate as a result of changing climate," said Dr. 
Susan Subak, a senior research associate at the Natural Resources 
Defense Council. "Whether we're talking about fisheries and 
recreational areas on the coasts, or the habitats of America's 
mountains and deserts, rising temperatures will put further stress on 
our natural areas."

"This report is yet another blow to the global warming naysayers. It 
confirms the validity of the science and the seriousness of the impacts 
on human health, our economy, and our environment," said Philip E. 
Clapp, president of the National Environmental Trust. "And it 
demonstrates that the current international negotiations in Bonn and 
the November negotiations in The Hague are critical."