Drought "More intense and longer droughts have been observed over wider areas since the 1970s" (1) Cyclones & Extreme Weather "There is observational evidence for an increase of intense tropical cyclone activity in the North Atlantic since about 1970, correlated with increases of tropical sea surface temperatures." (2) "Widespread changes in extreme temperatures have been observed over the last 50 years. Cold days, cold nights and frost have become less frequent, while hot days, hot nights, and heat waves have become more frequent." (3)

Fire Hazard

According to fire ecology expert Dr Kevin Tolhurst, from the new Australian Bushfire Research Centre "global warming has already started to produce more severe bushfires over recent Australian summers." ₍₄₎

He says that, "much of the east coast and the southern states can look forward to more frequent and more intense bushfires". The ABC (Australian Broadcasting Corporation) reported, "The dimensions of climate change are the subject of intense debate among scientists. But those who take a close look at exactly how climate change is measured say Dr Tolhurst's predictions appear valid." ₍₅₎

Dr Kevin Tolhurst goes on to say that, "Combine that with a greater frequency of drought and more severe weather conditions, we would expect fires to not only be more intense because of the greater fuel amounts, but the likelihood of having severe fire weather conditions is likely to increase as well." ₍₆₎

The ice in the north pole has shrunk for the fourth year in a row, to "lowest extent of ice cover for more than a century"₍₇₎. This is according to scientists from the National Snow and Ice Data Center (NSIDC), Boulder, Colorado. They also warned that "the shrinkage could lead to even faster melting in coming years."₍₈₎

The data shows that since 1978 the artic ice has lost 2 million square kilometres to the current are of 5.35 sq km. ₍₉₎

The area covered by ice in the North Pole changes with the seasons, it is usually the lowest level during September of each year.

In a March 2007 article for Far North Science, climate scientists from the US National Snow and Ice Data Center, as well as scientists from the National Center for Atmospheric Research stated:-

"Given the agreement between models and observations, a transition to a seasonally ice-free Arctic Ocean as the system warms seems increasingly certain," ₍₁₀₎

"The take home message from my perspective is that a human influence on the Arctic’s shrinking sea ice cover is a lock, and that as we continue to lose ice, we will start to see effects extending beyond the Arctic," ₍₁₁₎

"the Arctic Ocean will soon be free of ice during late summer, possibly as soon as 2040 and almost certainly by 2100". ₍₁₂₎

The Arctic Climate Impact Assessment report 'Impacts of a Warming Arctic' stated:

"Sea-ice covered with snow reflects about 85-90% of sunlight, while ocean water reflects just 10%. Thus, as sea ice melts, revealing more and more of the ocean beneath, the increasing absorption of solar radiation adds to global warming, which causes more melting, which in turn causes more warming, and so on…" ₍₁₃₎

With most of the warmth of sunlight being absorbed by land and the oceans, this increases the effects of global warming. The more ice and snow melts, the greater the effect of global warming. This is seen in the diagram below. ₍₁₄₎

In a September 2006 press release by the Colorado University, Cooperative Institute for Research in Environmental Sciences stated the following: ₍₁₅₎

"Data gathered by a pair of NASA satellites orbiting Earth show Greenland continued to lose ice mass at a significant rate through April 2006, and that the rate of loss is accelerating, according to a new University of Colorado at Boulder study."

"The study indicates that from April 2004 to April 2006, Greenland was shedding ice at about two and one-half times the rate of the previous two-year period" and that the "The acceleration rate really took off in 2004".

CIRES Director Konrad Steffen, who has maintained more than 20 climate stations in Greenland for nearly two decades, said "temperatures have warmed by more than 4 degrees F along the western slope of its ice sheet since 1990."

He went on to comment that: ₍₁₆₎

"The increased surface melt of snow and ice provides additional meltwater to lubricate the bottom of the ice sheet and increases the ice flow velocity toward the coast," said Steffen, a CU-Boulder geography professor"

"Greenland, the largest island in the world, harbors about 10 percent of the world's freshwater in its ice sheet, which is up to two miles thick in places. If the Greenland ice sheet melted completely, the world's oceans would rise more than 20 feet, according to scientists."

"Scientists believe that large amounts of freshwater purged from Greenland's eastern coast could help to weaken the counter-clockwise flow of the North Atlantic Current, lowering water and wind temperatures and potentially triggering abrupt cooling events in northern Europe."

The weight of sea-ice pushes it down, so that most of its mass is under the surface of the water. The thickness sea-ice under the water is called the ‘draft’ and this is what scientists measure to see if there is more or less ice. Since 1958, submarines have been patrolling the North Pole. During each voyage, submarine crew measure the thickness of the sea-ice draft. (17) Scientists have evaluated this data and it shows that in the last 30 years, the average ‘draft’ or depth of the ice has decreased 40% (1.3 metres). (18)

As you can see from the diagram below the readings were taken at a number of locations, over a wide area. While the depth of the ice in some locations reduced by less than a metre, other locations suffered much worse.

Glaciers are large masses of ice which form in areas of high snowfall and cool temperatures, even in summer. Glaciers are located in Antarctica, or at high altitudes on the slopes of large mountains (Alpine Glaciers).

"A glacier is maintained by accumulation of snow at high altitudes, balanced by melting at low altitudes or discharge into the sea." ₍₁₉₎

Alpine glaciers are particularly susceptible to shifts in climate and respond to long term changes in the Earth’s climate. As the temperature of the Earth increases the melting at the base of the glacier happens faster than the speed at which it moves down the slope or valley. ₍₂₀₎

Once a glacier has disappeared altogether, there is far less melt-water. Currently, millions of people around the world rely in part, or completely on rivers fed by glaciers.

Upsala Glacier, Argentina 1928 / 2004

Muir Glacier, Alaska

Global ocean currents help regulate the climate in many parts of the world. Many models have suggested that these currents can be affected by global warming (There is more detail in the Future Impacts & Policy section: Melting glaciers, ice-sheets and the Global Ocean Currents)

What is concerning is that changes to these currents will have very serious impacts around the world, especially Europe and that these changes have already started.

The following is from a report from the BBC Environmental correspondent Richard Black (30 NOV 05)

The University of Colorado's National Snow and Ice Data Center using satellite imagery, "revealed that the northern section of the Larsen B ice shelf, a large floating ice mass on the eastern side of the Antarctic Peninsula, has shattered and separated from the continent. The shattered ice formed a plume of thousands of icebergs adrift in the Weddell Sea. A total of about 3,250 km2 of shelf area disintegrated in a 35-day period beginning on 31 January 2002. Over the last five years, the shelf has lost a total of 5,700 km2, and is now about 40 percent the size of its previous minimum stable extent." ₍₂₁₎

"This is the largest single event in a series of retreats by ice shelves in the Peninsula over the last 30 years. The retreats are attributed to a strong climate warming in the region. The rate of warming is approximately 0.5 degrees Celsius per decade, and the trend has been present since at least the late 1940s. Overall in the Peninsula, extent of seven ice shelves has declined by a total of about 13,500 km2 since 1974. This value excludes areas that would be expected to calve under stable conditions." ₍₂₂₎

The National Snow and Ice Data Center describes the formation of ice shelves;

"An ice shelf is a thick slab of ice fed by glacier flow, that attaches to land along a coastline, and floats on the ocean. Ice shelves range in thickness from about 100 to 600 meters, and some shelves last for thousands of years or longer. They fringe the continent of Antarctica, and occupy a few fjords and bays along the Greenland and Ellesmere Island coasts. At their seaward edge, ice shelves periodically calve icebergs, some the size of a small U.S. state or European country." ₍₂₃₎

"Together, an ice shelf and the glaciers feeding it form a stable system. Warmer temperatures can destabilize this system by increasing glacier flow speed and - more dramatically - by disintegrating the ice shelf. Without the shelf to slow its speed, the glacier accelerates. After the 2002 Larsen B Ice Shelf disintegration, nearby glaciers in the Antarctic Peninsula accelerated up to eight times their original speed in the next 18 months." ₍₂₄₎

1. Stable glacier and ice shelf	2. Two effects of warmer temperatures
3. Unstable glacier front after ice shelf collapses	4. Glacier acceleration

"While calving or disintegrating ice shelves don't raise ocean level, the resulting glacier acceleration does, and it poses a direct threat to coastal communities. More than 100 million people currently live within 1 meter of mean sea level. Greenland contains enough ice to raise sea level by 7 meters, and Antarctica holds enough ice to raise sea level by 57 meters." ₍₂₅₎

According to the Australian Roundtable on Climate Change;

"Globally, 37 of the 40 largest insured losses from natural catastrophes since 1970 have been weather related, as shown in Figure 2. The total economic cost of Hurricane Katrina in 2005 is estimated at US$135 billion, including up to US$45 billion insured losses." ₍₂₆₎

"In Australia, 19 out of the 20 largest property insurance losses since 1967 have been weather related, the largest being the April 1999 Sydney hailstorm ($A2 billion in 2005 dollars). Australia is prone to bushfires, cyclones, hail, storms and flood, all of which are expected to increase in frequency and/or intensity due to climate change." ₍₂₇₎

"The West Nile encephalitis virus is a recent example of how far and fast a disease can spread once it becomes established in a new region. The West Nile virus can infect many bird and mammal species (including humans) and is transmitted by mosquitoes."

"It was first identified on the East Coast of North America in 1999 and spread to 43 states and six Canadian provinces by 2002. Migratory birds are responsible for its spread to other regions. Mosquitoes spread the virus to other birds (as well as to other animals and humans) within a region. Although the virus originated in tropical Africa, it has adapted to many North American mosquitoes, and so far, to over 110 species of North American bird, some of which migrate to the Arctic."

"Mosquito species known to transmit the virus are also found in the Arctic. Climate has historically limited the range of some insect-borne diseases, but climate change and adaptive disease agents such as the West Nile virus tend to favor continued northerly expansion. Some arctic regions, such as the State of Alaska, have initiated West Nile virus surveillance programs."