There is strong evidence that extreme weather events – such as hurricanes, floods, droughts and heat waves – are increasing because of climate change.
While it is difficult to blame any single weather event on climate change, scientists agree that climate change brings more extreme weather events with it.
In very broad terms, this is because climate change is putting more energy (heat) into the world's weather systems. This energy speeds up the whole system, increasing the number and intensity of storms.
14 August 2007 - Record-breaking rains have flooded Leizhou, Guangdong province, due to tropical typhoon Pabuk. This man in Egan village is moving his television set.
The Financial Initiative of the UN Environment Program (UNEP) recently calculated that the economic costs of global warming are doubling every decade. The cumulative number of people affected by disasters rose to two billion in the 1990s, up from 740 million in the 1970s. Virtually all of these millions were concentrated in poorer countries.
Here are some of the weather impacts of climate change:
Heat waves
Models show that climate change could cause thousands more heat-related deaths per year in many major cities by 2050, independent of population growth. Heat waves can also harm crops, livestock, fish populations and wildlife.
The European heat wave of 2003 killed 14,800 people in France alone and more than 30,000 across the continent. According to the French National Institute of Health, the death rate was 60% higher than normal for that time of year. It was by far the worst heat wave on record.
In a breakthrough paper on climate change impacts, UK scientists concluded with greater than 90% certainty that the probability of a heat wave of that magnitude had doubled because of climate change.
Increased rain and flooding
Warm air can hold more water than cool air. Thus, as the atmosphere warms, it can hold more and more water vapour.
This will very likely dry up some areas, dramatically increase precipitation in others, and cause more volatile weather systems in general. The increased precipitation will cause more flooding, flash floods, landslides, erosion, crop damage, and strain on dams.
Just one example: In summer 2004, two-thirds of Bangladesh, along with much of Assam and Bihar in India, was under water. Over 50 million people were affected, with tens of thousands suffering from diarrhea as sewage mingled with the flood waters. The main monsoon rice crop was also severely damaged, forcing perhaps 20 million people to seek aid. A similar devastating flood occurred only six years ago, in 1998.
Droughts
1 January 2005 - A fishpond in the midst of a long-term drought, in Guangdong province
Climate change will likely cause dry areas to become drier. In general, there is likely to be an increase in the risk of drought in the mid-latitudes interiors of continents. The increase in droughts will hurt rich and poor nations alike, but regions that are already experiencing food and water shortages will be the harder hit. A study published by scientists at the National Center for Atmospheric Research in Colorado indicates that the areas of the Earth experiencing 'very dry' conditions have more than doubled since the 1970s.
For example, Africa already has a highly variable and unpredictable climate. Climate change is making that worse. In the Sahel, there has been on average a 25% decrease in annual rainfall over the past 30 years – consistent with climate change models.
Hurricanes
Climate change will likely not only increase the frequency of hurricanes, but also their severity.
Hurricanes need seawater temperatures above 27°C (81°F) in order to form. Water at this temperature allows for massive evaporation, which can then condense and form the storm's "vortex". As the seawater temperature goes even higher, the likelihood of storms increases exponentially.
Although there are other complex factors involved in hurricane formation, the link between warmer seawater and hurricanes is well established. It is also certain that climate change is raising ocean temperatures. Therefore, climate change is making the conditions under which hurricanes, cyclones and tropical storms form more common.
Extreme weather events in China
China has been historically prone to extreme weather events, especially when it comes to floods along the country's two main rivers, the Yangtze and the Yellow Rivers.
Annually, 400 million people in China are affected by extreme weather, with average annual losses totaling RMB 200 billion.
Climate change is already impacting the distribution of China's water resources. In the last twenty years, rivers in the north – including the Yellow, Huai, Hai and Liao rivers – have had a significant reduction in water levels, while rivers in southern China have experienced a gain in water resources. Floods have become more frequent, while droughts are becoming more severe, and extreme weather events are increasing overall.
Severe Weather Events in Mainland China and Taiwan
As of 8 Dec 2010, in that year China experienced one of its worst droughts in history, floods of 437 rivers, historically large floods of 111 rivers, 7 tropical cyclones, and 4,200 deaths due to extreme weather events – the highest since 1998.
- In the spring of 2011, two of China's largest lakes, the Hong and the Poyang, have dried up in one of the worst droughts in history. Over 35 million people along the Yangtze River have been affected, with 4.2 million people have little access to drinking water. This region in central China is known traditionally as "the land of fish and rice" for its abundant natural resources, but now farmers are likely to lose the first of their two annual rice harvests, and all of the fish stocks may die.
- Another devastating drought hit Southwestern China, lasting five months from the winter of 2009 to the spring of 2010. Over 60 million people and nearly 83 million acres of land were affected, resulting in direct economic losses of 23.66 billion dollars.
- Severe drought in October 2009 affected Beijing, as well as Hunan, Fujian, and Guangdong provinces. Water levels in the Dongting Lake, China's second-largest freshwater lake, fell to its lowest levels in 60 years. Thousands of people and acres of land were affected in each province.
- A sever heat wave hits Chongqing city from August 31 to September 11, 2009. The average temperature was 28.6°C, the third highest for Chongqing in recorded history. Over 400,000 people faced shortages in drinking water.
- Over 3,000 lightning bolts struck the city of Wuhan, in Hunan province, in a severe thunderstorm on August 14, 2009. From midnight to 7am, 1987 lightning bolts struck the city. Two people died.
- In August 2009, typhoon Morakot was the deadliest typhoon to hit Taiwan in recorded history. The typhoon dumped 2.7 meters of rain on the island, causing enormous mudslides and severe flooding. An entire village was buried beneath a mudslide, killing its entire population. Overall, there were 461 deaths, 192 missing people and 46 injuries.
- From June 26 to late July 2009, extraordinarily severe rainfall and thunderstorms affected large swathes of southern China, including Sichuan, Guangxi, Guizhou, Jiangxi, Hubei and Hunan provinces. At least 10 million people were affected by the rainfall, flooding, landslides and mudslides, with hundreds of casualties. Many provinces recorded their strongest storms to date.
- These storms were preceded by a heat wave unusual in its geographical spread and severity. Starting from June 20, the heat wave affected 17 provinces and regions in central and southern China, with the highest temperatures occurring between June 23 and 27. On June 25, Xi'an city recorded ground temperatures of 47°C (116°F), completely unusual.
- Typhoons in 2008 affected 11 provinces in China and 33.75 million people, causing economic damages of 27.5 billion RMB.
- Unusual snow, sleet and freezing temperatures struck southern China from January to February 2008, affecting 10 provinces and severely obstructing the annual holiday trips home for Spring Festival. Hundreds of millions of people were prevented from traveling, as railroads were buried and coal reserves ran low.
- The summer of 1998 will be remembered for the worst flooding in a century. Severe storms and unusual weather led the Yangtze River to flood catastrophically, while there were also record-breaking floods on the Nen and Songhua Rivers in northeastern China. It is estimated that 50 million acres of farmland were destroyed, and 220 million people were affected, with direct economic damages of 20 billion RMB.
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