Yes. Earth is already showing many signs of worldwide climate change.
? The 20th century's last two decades were the hottest in 400 years and possibly the warmest for several millennia, according to a number of climate studies.
? The IPCC reports that 11 of the past 12 years are among the warmest since 1850.
? Average temperatures in Alaska, western Canada, and eastern Russia have risen at twice the global average, according to the multinational Arctic Climate Impact Assessment report compiled between 2000 and 2004.
