10 Things Global Warming Could Change Forever

1Great Barrier Reef may be gone in 20 years

The Great Barrier Reef will be so degraded by warming waters that it will be unrecognizable within 20 years. Charlie Veron, former chief scientist of the Australian Institute of Marine Science, told The Times: “There is no way out, no loopholes. The Great Barrier Reef will be over within 20 years or so.” Once carbon dioxide had hit the levels predicted for between 2030 and 2060, all coral reefs were doomed to extinction, he said. “They would be the world's first global ecosystem to collapse. I have the backing of every coral reef scientist, every research organization. I've spoken to them all. This is critical. This is reality.”

2Amazon Rain Forest may turn into a desert

Teeming with millions of species and one-fifth of the world's fresh water, the Amazon is the world's largest tropical rainforest. However, global warming and deforestation are reversing the forest's role as a carbon sink, converting 30-60% of the rainforest into dry savannah. Projections show the forest could disappear completely by 2050.

3Sahara Desert may become green

Scientists are seeing signals that the Sahara desert and surrounding regions are greening due to increasing rainfall. If sustained, these rains could revitalize drought-ravaged regions, reclaiming them for farming communities. This desert-shrinking trend is supported by climate models, which predict a return to conditions that turned the Sahara into a lush savanna some 12,000 years ago.

4Hurricanes may become more devastating than Katrina

It has not been determined whether Katrina was linked to global warming. But there are indications that global warming will produce more Category 5 hurricanes --and Katrina was only Category 4 when it hit Louisiana. Hurricanes derive their power in part from warm water, and so forecasting models show future hurricanes becoming more severe as sea surface temperatures rise. Global warming also makes hurricanes more destructive by raising the sea level, which leads to more serious coastal flooding. (According to the EPA, a two-foot rise would swallow a chunk of the U.S. bigger than Massachusetts.)

5London may disappear underwater by 2100

It isn't only reefs and low-lying islands that are under threat from global warming. In fact, a major threat is for those large urban areas which are at risk of eventually being submerged underwater. This is caused by a change in sea levels that occurs when global warming takes place, resulting in coastal cities being destroyed by flooding. Dozens of the world's cities, including London and New York, could be flooded by the end of the century, according to research which suggests that global warming will increase sea levels more rapidly than was previously thought. London is one of the major world capitals at high risk of this type of flooding, as depicted in this shot from the 2007 movie Flood. Scientists say that the city could be under water as early as within the next one hundred years.

6Animals may shrink

Warming climate may favor small species over large ones. The research, based on analysis of body mass of fish, plankton, and bacteria in European ecosystems, comes just weeks after scientists reported that sheep on a Scottish island are shrinking due to warmer conditions.

The new study reveals that individual species lost an average of 50 percent of their body mass over the past 30 years. The reduced body size is the third universal ecological response to global warming. An earlier sheep study suggested that shorter and milder winters mean lambs do not need to put on as much as weight as they once did in order to survive their first year of life, a factor that could also impact fish populations. Nonetheless the researchers say the shift could alter food chains, with apex predators being particularly affected by shrinking prey.

72,000 Indonesian islands may disappear

At least 2,000 small islands across archipelagic Indonesia may disappear by 2030 as a consequence of excessive mining and other environment-damaging activities. Indonesia has already lost 24 of its more than 17,500 islands.

8Global warming may increase terrorism

Global warming could destabilize "struggling and poor" countries around the world, prompting mass migrations and creating breeding grounds for terrorists. People are likely to flee destabilized countries, and some may turn to terrorism. The conditions exacerbated by the effects of climate change could increase the pool of potential recruits into terrorist activity. According to the chairman of the National Intelligence Council in the US, economy refugees will perceive additional reasons to flee their homes because of harsher climates. That will put pressure on countries receiving refugees, many of which will have neither the resources nor interest to host these climate migrants.

9The Alps may melt completely

Glaciers are retreating in warm, dry winters and hotter summers caused by global warming, and although snowfall in the 2008-2009 ski seasons was substantial, overall recent years have seen less snow at low altitudes, and receding glaciers and melting permafrost higher up - with a significant impact on winter tourism activities. It is predicted that the glaciers will be gone between 2030 and 2050. Italy and Switzerland have decided to redraw their border after global warming dissolved Alpine glaciers that marked out the frontier between the two countries.

10The Maldives may be submerged

The lowest and flattest country in the world is suffering coastal erosion, and could find itself submerged if sea levels carry on rising, with the islands growing smaller and smaller. This extreme prediction is a devastating prospect for residents and bad news for the tourists who descend on its soft white beaches and warm waters each year. Scientists give it only about one hundred years before it completely disappears into the ocean surrounding it.