While it is true that it is difficult to attribute any single weather event to climate change, it is agreed 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.
Watch a slideshow on extreme weather.
|Flames consume huge areas of forest in Montalvao, Portugal. Portugal declared a national disaster after the worst forest fires in more than two decades killed nine people, torched thousands of hectares of forest and destroyed homes in 2003.
Although there is an expected reduction in cold-related deaths, the increase in heat-related deaths due to climate change is likely to far outweigh it. 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 percent higher than normal for that time of year.
Models show that climate change could cause thousands more heat-related deaths per year in many major cities by 2050 — independent of population growth. In a breakthrough paper on the attribution of climate change impacts, scientists from the UK published a study that concluded with greater than 90 percent likelihood that climate change doubled the risk of that heat wave, which was by far the worst in the historical record.
Heat waves don't only affect people; they can also harm crops, livestock, fish populations and wildlife.
Increased rain and flooding
As the atmosphere warms, it can hold more and more water vapor. 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 of homes, 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, with over 50 million people affected and 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.
|Camel owner Baoyin Culu says prayers at the place where his last camel died. All of his 80 camels died due to desertification in the region.
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 recent study published by scientists at the National Center for Atmospheric Research in Colorado indicates that the area of the Earth experiencing 'very dry' conditions has 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 percent decrease in annual rainfall over the past 30 years — consistent with climate change models.
Hurricanes need seawater temperatures above 81°F in order to form. Water this warm allows massive evaporation that 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.