Extreme tornado activity began the first week of January in the United States and didn't let up until summer.
In all, about 1,700 tornadoes touched down, according to a preliminary count. That's the second-most ever recorded, since 1953. The 125 deaths that resulted were among the most ever.
The spate of tornadoes include the first in decades to hit Wisconsin and Illinois, in January, more than 100 reported tornadoes -- which left dozens dead and hundreds of homes destroyed -- on the Super Tuesday primary in February, and in May, dozens died and Iowa recorded the strongest twister since 1976.
Research in 2007 predicted that tornadoes and thunderstorms will become more frequent due to global warming, because the atmosphere will hold more energy and there will be a greater likelihood of updrafts, a precursor of severe storms.
Tropical Cyclone Ivan
Along with severe storms, flooding is predicted to become more frequent and intense due to global warming, since heated air can hold more moisture and release it with more fury.
A January storm dumped 10 inches of rain on California and six feet of snow in Nevada. A levee breach near Reno flooded about 800 homes. On Feb. 2, Hilo, Hawaii, recorded 11 inches of rain in a single day, more than tripling the previous record for rain in a 24-hour period. March brought record, and deadly, flooding to the Mississippi and its tributaries (pictured here). Record rainfall measurements were taken across a wide swath of the nation. In June, Iowa suffered through the second "100-year flood" in 15 years, as it sat at the epicenter of a record-setting flood that affected tens of thousands of people and caused billions of dollars in damage.
Argentina, Bolivia and Ecuador suffered from torrential rains and flooding in February, described in Ecuador as the worst in that nation's history. In September, Chile experienced the heaviest rain recorded in about 40 years. And in November, flooding and mudslides in Brazil left dozens dead, isolated eight cities behind overflowing rivers and affected 1.5 million people in what is being called that nation's worst weather disaster in history.
In June, China's Guangdong Province suffered from the heaviest rainfall in a half century, and the flooding from the storm killed dozens and caused $4 billion in damages. The same storm brought a record 5.73 inches of rain to Hong Kong in a single hour. Much of the region had its wettest month ever recorded in June.
The spring and early summer was a busy time for wildfires. In April, 1,200 residents of Colorado evacuated ahead of a destructive wildfire. In May, 90 wildfires burned more than 40,000 acres in Florida, including several structures worth nearly $10 million. in June, northern California lit up after lightning strikes ignited hundreds of fires that burned 272,000 acres.
Nothing quite rivaled the Southern California wildfires in November, however (shown here). At least 900 homes were destroyed as major fires fed by dry, hot Santa Ana "devil winds" raced across the region.
Wildfire activity has already increased due to global warming, according to some studies. Reduced snowpack and runoff, higher temperatures and less humidity all conspire to create conditions conducive to wildfire ignition. Still, 2008 was not a record-setting year for wildfires. The nearly 79,000 fires recorded was 2% above the 10-year average, but the area burned -- 5.3 million acres -- was 28% below average.
Tropical Cyclone Nargis
Bringing new meaning to the word "devastation," Tropical Cyclone Nargis struck Burma on May 2 as a Category 4 monster hurricane.
It left, by some estimates, nearly 150,000 dead, making it the most deadly storm since 1991, and the most devastating ever to hit Burma (Myanmar). The relief effort was long hampered by the repressive regime in control of the country.
The storm reared up out of the Bay of Bengal, sweeping into the Irrawaddy Delta. Whether or not global warming spawns more frequent or intense hurricanes -- a point that is still hotly debated by experts in the field -- all agree that low-lying and heavily populated nations like Burma and neighboring Bangladesh are likely to experience increasingly devastating storms, as sea level rises, leading to greater damage from storm surges. Nargis spawned a 12-foot storm surge.
Tropical Storm Alma
The first tropical storm of 2008 in the eastern Pacific, Alma also was a record-setter. When it formed May 29, it was the easternmost storm ever to form in the Pacific.
Tropical Storm Alma was the first storm to strike Central America's Pacific coast since 1949, and the first ever known to make landfall in Nicaragua.
Alma was responsible for two direct deaths and the destruction of thousands of homes.
Southeast Asian Monsoon
The 2008 Southeast Asian monsoon started earlier than at any time in more than a century, and it was among the deadliest and most destructive seasons on record. India, Bangladesh, Pakistan, Nepal, Vietnam and other nations in the region suffered hundreds of deaths from June to September, tens of thousands displaced and the inundation of whole villages.
Any relation between global warming and monsoon strength has yet to be proved, but some studies suggest that changes in ocean temperature and atmospheric circulation could increase the duration or intensity of the Southeast Asian monsoon.
This image shows the flooding of the Kosi River on Sept. 2, 2008, and pre-flood conditions in June.
Debilitating droughts plagued parts of China, Australia and the United States in 2008.
The extent of drought in the U.S. reached its maximum in June and July, with 61% of the Southeast, 46% of the South, 36% of the West and 23% of the High Plains suffering moderate to severe drought conditions. The Southwest is in the midst of a multiyear drought, and the Southeast is now entering its third year of drought. Though the severity of drought has lessened in the latter part of the year, drought conditions persist across about 43% of the U.S.
The drought in parts of Australia, including its bread basket farmland, has been so pronounced, and so extreme for so many years now that in 2008 some researchers suggested that a long-term climactic pattern could leave the continent in a state of permanent drought, in part due to changes wrought by global warming.
By the time Hurricane Bertha finally wound down July 20 in the northern Atlantic, she had become the longest-lived July tropical storm in the Atlantic ever recorded. She was 16 days old -- 33% older than the second most long-lived tropical storm on record.
Tropical Storm Fay
Proving that a storm doesn't have to reach hurricane strength to cause destruction, Tropical Storm Fay killed 23 in the Caribbean before making a record four landfalls in Florida, as it crisscrossed the peninsula Aug. 18-20.
Some parts of Florida received 26 inches of rain, and at least 13 people died in the U.S. as the storm continued as a tropical depression across the Southeast.
The strongest hurricane to form in the Atlantic in 2008, and the third costliest storm ever to hit the United States, Hurricane Ike was a major Category 4 storm that, like the storms before it, battered Haiti, causing dozens of deaths there, and another seven in Cuba before it headed to the Texas coast.
An amazingly large storm, Ike seemed to cover a huge portion of the Gulf of Mexico as it slowly regained strength, before striking Galveston as a Category 2 storm Sept. 13, Ike became a hurricane on Sept. 3 and rapidly intensified to a Category 4 hurricane northeast of the Leeward Islands. The storm struck the Turks and Caicos Islands and Great Inagua Island in the Southeastern Bahamas on Sept. 7, and the northeast coast of Cuba later that day. Ike made its final landfall at Galveston Island, Texas on Sept. 13 as a Category 2 hurricane. Ike killed more than 80 people across the Caribbean and Bahamas, and another 20 in Texas, Louisiana and Arkansas. Total estimated U.S. property damage from Ike is estimated at $19.3 billion.
The ozone hole over Antarctica reached its largest extent Sept. 12, and it was the fifth-largest ever recorded.
Despite its near-record size, progress is being made in reducing the extent of the ozone hole. Since the Montreal Protocol in 1987 ushered in a series of bans on ozone-depleting chemicals, the concentration of those chemicals has declined 3.8% in the atmosphere. It will still take decades for the hole to disappear, and with it the increased threat of skin cancer and other ailments that come with unfettered ultraviolet radiation.
Ironically, fixing the ozone problem will likely result in increased warming over Antarctica and the southern oceans, according to research published in 2008. The ozone hole allows heat that would otherwise be trapped to escape, which has blunted the effect of global warming on Antarctic ice.
The summer of 2008 left the Arctic with less ice than any other time in recorded history when the annual sea ice minimum was measured Sept. 14. While the extent of sea ice left at the height of the melt -- on Sept. 14 -- fell shy of the extraordinary record set in 2007, the volume of sea ice declined to a record extent.
With the melting of the Arctic, seen as the clearest example yet of global warming's real-world impacts, comes more danger of increased warming. As more ice melts, more open water absorbs more heat, and more permafrost loses methane, both of which accelerate the pace of warming in the region, and around the world.
The Arctic's vital signs are showing consistent signs of stress from global warming, and in many cases the region is changing at a much faster pace than had been predicted just years, or even months, earlier, as the 2008 Arctic Report Card showed.