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GROWING PRESSURES: Indicators of climate change in 2004

The year 2004 strengthened the evidence of global warming and underlined the impacts of climate change on economies and the environment, as well as on human health and well-being. Four severe hurricanes in sequence brought havoc, tragedy and huge economic losses to the Caribbean and southern United States. While not all extreme weather events can be attributed directly to climate change, the intensity of such events is likely to increase as a result of global warming (Knutson and Tuleya 2004).

Measurements in 2004 recorded an unprecedented surge in atmospheric carbon dioxide (CO2) levels. The value of 379 parts per million registered in March 2004 was 3 parts higher than in 2003 (NOAA 2004). The average annual increase in the 1960s, soon after measurements began, was less than one part per million, while over the past decade it has been approximately 1.8 parts per million (Figure 1).

A number of studies published during the year found worrying impacts of climate change. Only half of the CO2 that human activity released over the last 200 years has remained in the atmosphere. A 15-year-long study of the role of anthropogenic CO2 in the Earth's oceans found that oceans had absorbed 30 per cent of the other half, causing an acidification process. Calcium carbonate plays an important role in regulating carbon sequestration in oceans. Increased CO2 uptake gives rise to fears that acidification and dissolution of marine carbonates from corals, algae and carbonate shells of marine plankton could have significant impacts on the biological systems in the oceans in ways we are only beginning to understand (Feely and others 2004). A further study warned that climate change could drive over a million species into extinction by 2050 (Thomas, Cameron and others 2004).

The European Environment Agency found clear trends of climate change impacts on glaciers, snow and ice, marine systems, terrestrial ecosystems and biodiversity, water, agriculture, human health and economy (EEA 2004).

A number of other reports on the impacts of global warming found significant increases in the rate of melting of land and sea ice from the Arctic to Mount Everest to the Antarctic, with major implications for humans and biodiversity (see Polar section; Bøggild and others 2004; Chinese Academy of Sciences 2004; Thomas, Rignot and others 2004). Meanwhile, evidence for the dominant human role in climate change continued to accumulate. Some scientists suggested that recent variations in solar activity have only had a minor influence in global warming (Krivova and Solanki 2004).

A further investigation concluded that emissions during the past century doubled the chances of the heat wave that hit Europe last summer, and predicted that by the 2040s, more than half of Europe's summers will be warmer than that of 2003 (Scott and others 2004). The finding could make it easier to bring lawsuits against large emissions-producers. Eight US states and New York City have a lawsuit against five of the country's power companies. The plaintiffs want a federal judge to force five power producers to reduce emissions 3 per cent annually for ten years (SFC 2004).

Figure 1: Increase in atmospheric carbon dioxide levels registered at the Mauna Loa Observatory
Source: NOAA 2004

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